CN113701640B - Three-axis grating ruler - Google Patents

Three-axis grating ruler Download PDF

Info

Publication number
CN113701640B
CN113701640B CN202010978240.4A CN202010978240A CN113701640B CN 113701640 B CN113701640 B CN 113701640B CN 202010978240 A CN202010978240 A CN 202010978240A CN 113701640 B CN113701640 B CN 113701640B
Authority
CN
China
Prior art keywords
light beam
light
axis
beams
diffraction grating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202010978240.4A
Other languages
Chinese (zh)
Other versions
CN113701640A (en
Inventor
韦春龙
周常河
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shanghai Institute of Optics and Fine Mechanics of CAS
Original Assignee
Shanghai Institute of Optics and Fine Mechanics of CAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shanghai Institute of Optics and Fine Mechanics of CAS filed Critical Shanghai Institute of Optics and Fine Mechanics of CAS
Priority to CN202010978240.4A priority Critical patent/CN113701640B/en
Priority to PCT/CN2020/120568 priority patent/WO2022056971A1/en
Publication of CN113701640A publication Critical patent/CN113701640A/en
Application granted granted Critical
Publication of CN113701640B publication Critical patent/CN113701640B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Optical Transform (AREA)

Abstract

The three-axis grating ruler comprises a three-axis measuring beam generating unit, an X-axis measuring beam detecting unit, a Y-axis measuring beam detecting unit, a Z-axis measuring beam detecting unit and a signal acquisition and processor. The triaxial measurement light beam generation unit comprises a polarization collimation laser light source, a two-dimensional diffraction grating for beam splitting, a first collimation objective, a polarization prism assembly, a second collimation objective and a two-dimensional diffraction grating for measurement. The two-dimensional diffraction grating for beam splitting and the two-dimensional diffraction grating for measurement are two-dimensional orthogonal symmetry, and the two-dimensional grating distances are equal. The light path generated by the X-axis measuring light beam and the Y-axis measuring light beam has 2 times of optical subdivision and optical differential characteristics, the precision is high, and the installation tolerance is large; the optical path of the measuring beam generating unit and the optical path of the measuring beam detecting unit jointly form an integral three-dimensional displacement measurement homodyne grating interferometer, the structure is compact, the cost is low, and Abbe errors and cosine errors caused by unsatisfied orthogonality and common intersection points are avoided.

Description

Three-axis grating ruler
Technical Field
The invention belongs to the field of precise optical measuring instruments, and particularly relates to a three-axis grating ruler for three-degree-of-freedom displacement measurement.
Background
The grating ruler is also called an optical encoder, and is widely applied to displacement and angle measurement in the fields of precision motion tables, precision optical machinery, precision measuring instruments and the like. Compared with the grating ruler based on the low-density common geometric grating, the grating ruler based on the high-density diffraction grating has higher precision and resolution and can reach sub-nanometer level. The most sophisticated equipment in the world, lithography machines, have employed such instruments for high precision displacement and angle measurements.
With the development of precision manufacturing technology, especially the promotion of photoetching machine technology, the requirement of multi-degree-of-freedom displacement measurement continuously emerges. Therefore, the development of a displacement measurement grating ruler facing three degrees of freedom or even more is urgently needed.
In the international market, the germany heidham originally introduced a grating scale based on a diffraction grating, and a biaxial grating scale for two-degree-of-freedom displacement measurement has been developed. The principle is based on its patent US4776701. The optical path and the practical product using effect of the optical path show that the installation distance of the reading head is strict relative to the measuring diffraction grating fixed on the surface of the measured object, and the light spot on the detector transversely moves and generates errors due to slight forward and backward movement. In addition, the expansion of three-free displacement measurement is difficult, and a corresponding three-axis grating ruler is not designed yet.
Another grating scale structure based on diffraction gratings is presented in US 5098190. The method is characterized in that a light source emits collimated laser beams to the surface of a measuring grating, and positive and negative first-order diffracted lights after diffraction are focused on a phase grating through a lens to generate three interference light beams with phase shift of 120 degrees. And then the displacement information of the corresponding measuring grating can be obtained after the photoelectric conversion of the detector and the processing of the signal processor. The patent also has the problem that the grating reading head is sensitive to the distance of the measuring grating and is easy to generate errors. The optical paths of the two patents mentioned above are essentially Mach-Zehnder interferometers. Therefore, the measurement signal of two degrees of freedom is an optical differential signal based on Doppler shift, and the accuracy is higher compared with the electrical differential signal of single displacement measurement.
The two-degree-of-freedom measurement Grating ruler (C.F.KAO, S.H.LU, et al., differential Laser Encoder with a grading in Littrow Configuration, jpn.J.Appl.Phys.47.1833-1837) proposed by Kao et al adopts Littrow self-collimation angle incidence measurement Grating, so that the installation tolerance of the reading head of the Grating ruler becomes larger, but the two-degree-of-freedom measurement Grating ruler is essentially two independent one-dimensional optical path structures, is complex, is not easy to manufacture and is easy to generate Abbe error. In addition, the three-degree-of-freedom measurement extension is more complicated. The optical path is essentially a Mach-Zehnder interferometer.
The Gao research group proposed three-axis, six-axis grating scales for three-degree-of-freedom (a.kimura, wei Gao, w.kim et. Al, asub-nanometric-three-axis surface encoder with short-period-planar grating for stage movement measurement, precision Engineering 36 (2013), 771-781), six-degree-of-freedom (x.li, wei Gao, et. Al, a six-degree-of-freedom surface encoder for Precision positioning of a planar motion stage, precision Engineering 37 (2012), 576-585). Chinese patents CN103307986A and CN103322927B respectively provide a two-axis grating ruler for two-degree-of-freedom measurement and a three-axis grating ruler for three-degree-of-freedom measurement. The above-mentioned documents and patents, whose optical path is essentially michelson interferometer, have no optical subdivision function, i.e. the resolution is relatively reduced by half; in addition, the grating reading head is sensitive to the distance of the measuring grating, and errors are easy to generate. Also, the respective degree-of-freedom signals are electrical differential signals. Relative to optical differences, the accuracy is not high.
Chinese patent CN10862709913 discloses a five-axis grating ruler with five-degree-of-freedom measurement, which, although using Littrow auto-collimation incidence measurement grating to improve the installation tolerance, has stacked structure and difficult manufacturing, and is still a modified form of michelson interferometer, and the respective degree-of-freedom displacement signals are still obtained by electronic difference, and have no optical subdivision function, i.e. the resolution ratio is relatively reduced by half.
Chinese patent CN106017308B provides a six-axis grating ruler with six-degree-of-freedom measurement, in which a reading head is formed by alternately stacking three grating reading heads and three heterodyne laser reading heads, a measurement grating array is formed by alternately stacking three measurement grating assemblies and three heterodyne laser mirrors, which is complex and difficult to manufacture, and the X, Y and Z axes are separated, which easily causes abbe errors.
Disclosure of Invention
The invention provides a three-axis grating ruler, comprising: the device comprises a three-axis measuring beam generating unit, an X-axis measuring beam detecting unit, a Y-axis measuring beam detecting unit, a Z-axis measuring beam detecting unit and a signal acquisition and processor; the three-axis measuring beam generating unit generates an X-axis measuring beam, a Y-axis measuring beam and a Z-axis measuring beam; the X-axis measuring beam detecting unit is arranged along the X-axis measuring beam direction, the Y-axis measuring beam detecting unit is arranged along the Y-axis measuring beam direction, and the Z-axis measuring beam detecting unit is arranged along the Z-axis measuring beam direction;
the triaxial measuring beam generating unit includes: the device comprises a polarization collimation laser light source, a two-dimensional diffraction grating for beam splitting, a first collimation objective, a polarization prism assembly, a second collimation objective and a two-dimensional diffraction grating for measurement; the two-dimensional diffraction grating for beam splitting and the two-dimensional diffraction grating for measurement are two-dimensional orthogonal symmetry, and the two-dimensional grating distances are equal. The two-dimensional diffraction grating pitch d for beam splitting 1 And two-dimensional diffraction grating pitch d for measurement 2 Focal length f of the first collimating objective lens 1 Focal length f of the second collimator lens 2 Satisfies the following relation (1), wherein λ is polarization collimated laserThe wavelength of the light source, the optimized condition is as follows: d 1 ＝2d 2 ，f 1 ＝f 2 。
Figure GDA0003810647770000021
The X-axis measuring beam detecting unit includes: the device comprises a third collimating objective, a first phase-shift grating, a first detector, a second detector and a third detector. The third collimating objective lens focal length f 3 And a first phase shift grating pitch d 3 And a two-dimensional diffraction grating pitch d for beam splitting in the three-axis measuring beam generating unit 1 And a first collimating objective lens focal length f 1 The following relation (2) is satisfied, where λ is the wavelength of the polarization-collimated laser light source, and the optimization case is: d is a radical of 1 ＝d 3 ，f 1 ＝f 3 。
Figure GDA0003810647770000031
The Y-axis measuring beam detecting unit includes: the detector comprises a second total reflection mirror, a third collimating objective, a second phase shift grating, a fourth detector, a fifth detector and a sixth detector. The third collimator lens focal length f 4 And a second phase-shift grating pitch d 4 And a two-dimensional diffraction grating pitch d for beam splitting in the three-axis measuring beam generating unit 1 And the focal length f of the collimator objective 1 The following relation (3) is satisfied, where λ is the wavelength of the polarization-collimated laser light source, and the optimization case is: d 1 ＝d 4 ，f 1 ＝f 4 。
Figure GDA0003810647770000032
The Z-axis measuring beam detection unit comprises a third full-reflecting mirror, a second linear polarizer, a third phase-shift grating, a seventh detector, an eighth detector and a ninth detector.
The two-dimensional diffraction grating for measurement is a reflection type. The two-dimensional diffraction grating for beam splitting is a transmission type, and the polarization prism assembly comprises: the polarizer comprises a first linear polarizer, a first total reflection mirror, a first quarter-wave plate, a polarizing prism and a second quarter-wave plate.
The polarization collimation laser light source is in a P polarization state, and the measurement principle of the three-axis measurement beam generation unit light path and the three-axis grating ruler is as follows: taking a polarizing prism as a polarization state reference: the polarization collimation laser light source emits P polarization light beams, the P polarization light beams are divided into five light beams including a left light beam, a right light beam, a front light beam, a rear light beam and a middle light beam through the transmission type beam splitting two-dimensional diffraction grating, the left light beam and the right light beam are axially symmetrical with the middle light beam in a plane formed by the middle light beam, and the front light beam and the rear light beam are axially symmetrical with the middle light beam in a plane formed by the middle light beam.
After the five beams of light are collimated by the first collimating objective, only the middle beam passes through the first linear polarizer which rotates 45 degrees relative to the polarization axis of the P light, so that the polarization axis of the middle beam rotates 45 degrees, and the middle beam of light has two components of the P light and the S light, wherein the P light and the other four beams of light pass through the polarizing prism together, then pass through the second quarter-wave plate and the second collimating objective together, are converged and enter the surface of the two-dimensional diffraction grating for measurement. The left light beam and the right light beam are respectively incident at a Littrow auto-collimation angle to form an X-axis retroreflection light beam; the front light beam and the rear light beam are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the P light component of the intermediate beam is normally incident and retroreflected to form a Z-axis retroreflected beam P light component.
The P light components of the left light beam, the right light beam, the front light beam, the rear light beam and the middle light beam are converged to one point. The return beams of the P light components of the left light beam, the right light beam, the front light beam, the rear light beam and the middle light beam are subjected to auto-collimation and retro-reflection, then are converted into S-polarized light beams through a second quarter-wave plate, and are reflected through a polarizing prism to respectively obtain a lower light beam and an upper light beam corresponding to the left light beam and the right light beam, an outer light beam and an inner light beam corresponding to the front light beam and the rear light beam respectively, and a central light beam corresponding to the middle light beam, so that two-dimensional diffraction grating displacement signal light beams for measuring an X axis, a Y axis and a Z axis are formed, and are respectively provided with positive Doppler frequency shift signals and negative Doppler frequency shift signals.
The S component of the intermediate beam is reflected by the polarizing prism, then reflected by the first quarter wave plate and the first full-reflecting mirror, and then converted into the P polarization state after passing through the first quarter wave plate again, and directly emitted by the polarizing prism to coincide with the S component of the intermediate beam. P light and S light signal beams for measuring the Z-axis displacement of the two-dimensional diffraction grating are formed.
The upper beam and the lower beam are focused on the first phase shift grating through the third collimating objective lens and then are diffracted to form three interference beams, the three diffraction interference beams have the phase difference of 120 degrees, and the three interference beams are respectively detected by the first detector, the second detector and the third detector. After photoelectric conversion, the X-axis displacement of the two-dimensional diffraction grating for measurement can be obtained through signal acquisition and processing and calculation by a processor.
The inner light beam and the outer light beam are reflected by a second full reflector and are focused on a second phase-shift grating by a fourth collimating objective lens, then three interference light beams are formed by diffraction, the phase difference between the three diffraction interference light beams is preferably 120 degrees, and the three interference light beams are respectively detected by a fourth detector, a fifth detector and a sixth detector. The Y-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained by signal acquisition and processing and calculation by a processor after photoelectric conversion.
The central beam contains two parts of P light and S light components, is reflected by a second full reflector, passes through a second linear polarizer and a third phase shift grating which are arranged at 45 degrees of a polarization axis and is then diffracted to form three interference beams, the three interference beams have the phase difference of preferably 120 degrees, and are respectively detected by a seventh detector, an eighth detector and a ninth detector. After photoelectric conversion, the Z-axis displacement of the two-dimensional diffraction grating for measurement can be obtained through signal acquisition and processing and calculation by a processor.
The three-axis measuring beam generating unit has a second optical path structure which is different from the first one above in that: and the S-polarization state polarization collimation laser source of the opposite polarization prism is adopted. However, the positions of the first quarter-wave plate and the first total reflection mirror, the second quarter-wave plate and the second collimating objective lens and the two-dimensional diffraction grating for measurement are exchanged, and finally, in the five emergent light beams, the polarization axes of the central light beam are still P and S, while the other light beams are changed into P light.
The three-axis measuring beam generating unit has a third optical path structure, which is different from the first one described above in that: the polarization collimation laser source in the S polarization state relative to the polarization prism is adopted, but the overall positions of the polarization collimation laser source, the two-dimensional diffraction grating for beam splitting, the first collimation objective lens and the first linear polarizer are exchanged with the overall positions of the first quarter-wave plate and the first full-reflection mirror. Finally, the polarization state of the five outgoing beams remains the same as in the first case.
The triaxial measuring beam generating unit has a fourth optical path structure, which is different from the first one described above in that: the polarization collimation laser light source adopts a polarization state which forms a certain angle relative to the P light and the S light of the polarization prism. The two-dimensional diffraction grating for beam splitting is a reflection type. In contrast to the first case, the first quarter-wave plate is shifted to replace the first linear polarizer and let all the light beams pass through, and the polarization-collimated laser light source is shifted to replace the first total reflection mirror and the first quarter-wave plate. The polarization states of the five outgoing beams are identical to the first case.
The three-axis measuring beam generating unit has a fifth optical path structure, which is different from the first one described above in that: the polarization collimation laser light source adopts a polarization state which forms a certain angle relative to P light and S light of a polarization prism, and the beam splitting two-dimensional diffraction grating is a reflection type. The polarization collimation laser light source is shifted to replace the whole positions of the second quarter-wave plate, the second collimation objective and the measurement two-dimensional diffraction grating, and the whole positions of the first full-reflection mirror and the first quarter-wave plate are replaced by the second quarter-wave plate, the second collimation objective and the measurement two-dimensional diffraction grating. The first quarter-wave plate replaces the first linear polarizer location and passes all light beams. In the five emergent beams, the polarization state of the central beam is unchanged, and the other beams are all changed into P polarization states.
In the three-axis measuring beam generating unit, an X-axis measuring beam light path and an X-axis measuring beam detecting unit light path, and a Y-axis measuring beam light path and a Y-axis measuring beam detecting unit light path jointly form a two-dimensional Mach-Zehnder (Mach-Zehnder) homodyne interferometer; the Z-axis measuring beam light path and the Z-axis measuring beam detection unit light path form a one-dimensional Michelson (Michelson) homodyne interferometer or a one-dimensional Mach-Zehnder (Mach-Zehnder) homodyne interferometer; thereby forming an integrated three-dimensional displacement measurement homodyne grating interferometer; the adopted optical elements only have one polarizing prism component, so that the structure is compact and the cost is low. The X-axis and Y-axis optical paths have 2 times of optical subdivision and optical differential signals, and the precision is high; the X-axis measuring light beams and the Y-axis measuring light beams are incident at a Littrow auto-collimation angle to measure the two-dimensional diffraction grating, so that the two-dimensional diffraction grating is insensitive to Z-axis displacement and large in installation tolerance. In the light paths generated by the X-axis measuring light beams, the Y-axis measuring light beams and the Z-axis measuring light beams, the straight lines projected on the two-dimensional diffraction grating for measurement are orthogonal in pairs and share an intersection point, and the intersection points correspond to the corresponding measuring axes, so that Abbe errors caused by different intersection points of the measuring axes and cosine errors caused by non-orthogonality of the measuring axes are avoided.
The two-dimensional diffraction grating for beam splitting may be a Dammann grating or a combination of two one-dimensional diffraction gratings.
The first phase shift grating, the second phase shift grating and the third phase shift grating are one-dimensional diffraction gratings and can also be two-dimensional diffraction gratings.
Compared with the prior art, the invention has the beneficial effects that:
1) A three-axis grating scale is provided which is comprised of a three-dimensional Mach-Zehnder (Mach-Zehnder) interferometer or a two-dimensional Mach-Zehnder (Mach-Zehnder) interferometer and a one-dimensional Michelson (Michelson) interferometer. Through the specific design of relevant parameters among optical elements in an optical path, the optical path structure of the Littrow auto-collimation incidence measurement grating with large installation tolerance is obtained, and meanwhile, optical differential high-precision signals of two axes (x, y), 2 times of optical subdivision function and large-range Z-axis displacement measurement are obtained. In addition, three axes of light beams entering the measuring grating intersect at one point, so that Abbe errors and cosine errors are avoided. The homodyne interference technology different from heterodyne interference is adopted, and the optical fiber interferometer is simple in structure, easy to manufacture and low in cost.
2) The defects and shortcomings of the prior art are comprehensively solved by adopting an integrated effective combination of a three-dimensional Mach-Zehnder (Mach-Zehnder) interferometer or a two-dimensional Mach-Zehnder (Mach-Zehnder) interferometer and a one-dimensional Michelson (Michelson) interferometer and a specific design of a light path of the integrated effective combination; further, a three-axis grating ruler with more comprehensive and excellent performance, which is desired by researchers in the field for a long time, can be obtained.
Drawings
FIG. 1 is a schematic view of an optical system of a three-axis grating ruler according to the present invention;
FIG. 2 is a schematic view of a second three-axis measuring beam generating unit according to the present invention;
FIG. 3 is a schematic view of a third triaxial measuring beam generating unit according to the present invention;
FIG. 4 is a schematic view of a fourth triaxial measuring beam generating unit according to the present invention;
FIG. 5 is a schematic view of a fifth three-axis measuring beam generating unit according to the present invention;
FIG. 6 is a schematic diagram showing the derivation of equations (1), (2), and (3).
Detailed Description
The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.
Fig. 1 is a schematic diagram of an optical system of a three-axis grating scale of the present invention, including: a three-axis measuring beam generating unit 101, an X-axis measuring beam detecting unit 104, a Y-axis measuring beam detecting unit 103, a Z-axis measuring beam detecting unit 102, and a signal acquiring and processing unit 38; the three-axis measuring beam generating unit 101 generates an X-axis measuring beam, a Y-axis measuring beam and a Z-axis measuring beam, the X-axis measuring beam detecting unit 104 is arranged along the X-axis measuring beam direction, the Y-axis measuring beam detecting unit 103 is arranged along the Y-axis measuring beam direction, and the Z-axis measuring beam detecting unit 102 is arranged along the Z-axis measuring beam direction;
the three-axis measuring beam generating unit 101 includes: the device comprises a polarization collimation laser light source 1, a two-dimensional diffraction grating 2 for beam splitting, a first collimation objective 8, a polarization prism assembly 1011, a second collimation objective 14 and a two-dimensional diffraction grating 15 for measurement; the two-dimensional diffraction grating 2 for beam splitting and the two-dimensional diffraction grating 15 for measurement are two-dimensionally and orthogonally symmetrical, and the respective two-dimensional grating pitches are equal. The two-dimensional diffraction grating for beam splitting has a 2-grid pitch d 1 15 grid distances d of two-dimensional diffraction grating for measurement 2 Focal length f of the collimator objective 8 1 Focal length f of the focusing collimator objective 14 2 Satisfy the relationshipFormula (1).
Wherein λ is the wavelength of the polarized collimated laser light source, and the optimization situation is as follows: d 1 ＝2d 2 ，f 1 ＝f 2 。
The X-axis measuring beam detecting unit 104 includes: a third collimator objective lens 33, a first phase-shifting grating 34, a 1 st detector 35, a 2 nd detector 36, a 3 rd detector 37. Focal length f of the third collimator objective lens 33 3 And a pitch d of the first phase shift grating 34 3 A distance d from the two-dimensional diffraction grating for beam splitting 2 in the three-axis measuring beam generating unit 101 1 At a focal length f from the first collimating objective lens 8 1 And the relation (2) is satisfied, wherein lambda is the wavelength of the polarization collimation laser light source 1, and the optimization situation is as follows: d is a radical of 1 ＝d 3 ， f 1 ＝f 3 。
The Y-axis measuring beam detecting unit 103 includes: a second holophote 27, a fourth collimator objective lens 28, a second phase shift grating 29, a 4 th detector 30, a 5 th detector 31, a 6 th detector 32. Said fourth collimator-objective lens 28 focal length f 4 And a second phase shift grating 29 with a pitch d 4 A distance d from the two-dimensional diffraction grating 2 for beam splitting in the three-axis measuring beam generating unit 101 1 At a focal length f from the first collimating objective lens 8 1 And satisfies the relation (3). Wherein λ is the wavelength of the polarized collimated laser light source, and the optimization situation is as follows: d is a radical of 1 ＝d 4 ，f 1 ＝f 4 。
The Z-axis measuring beam detecting unit 102 includes a third total reflection mirror 21, a second linear polarizer 22, a third phase-shift grating 23, a 7 th detector 24, an 8 th detector 25, and a 9 th detector 26.
The measuring two-dimensional diffraction grating 15 is a reflection type. The two-dimensional diffraction grating 2 for beam splitting is a transmission type, and the polarization prism assembly 1011 includes: a first linear polarizer 9, a first total reflection mirror 12, a first quarter-wave plate 11, a polarizing prism 10, and a second quarter-wave plate 13.
The polarization collimation laser light source 1 is in a P polarization state.
The measurement principle of the optical path of the triaxial measurement beam generation unit 101 and the optical system of the triaxial grating scale is as follows: taking the polarizing prism 10 as a polarization state reference: the polarization collimation laser light source 1 emits P polarization light beams, the P polarization light beams are divided into five light beams including a left light beam 3, a right light beam 5, a front light beam 7, a rear light beam 4 and a middle light beam 6 through a transmission type beam splitting two-dimensional diffraction grating 2, the left light beam 3 and the right light beam 5 are axially symmetrical with the middle light beam 6 in a plane formed by the middle light beam 6, and the front light beam 7 and the rear light beam 4 are axially symmetrical with the middle light beam 6 in a plane formed by the middle light beam 6;
after the five light beams are collimated by the first collimating objective lens 8, only the middle light beam 6 passes through the first linear polarizer 9 which rotates 45 degrees relative to the polarization axis of the P light, so that the polarization axis of the middle light beam 6 rotates 45 degrees, and the two components of the P light and the S light are provided, wherein the P light and the other four light beams pass through the polarizing prism 10 together, and then are converged and incident on the surface of the two-dimensional diffraction grating 15 for measurement through the second quarter-wave plate 13 and the second collimating objective lens 14 together. The left light beam 3 and the right light beam 5 are respectively incident at the autoregistration angle of Littrow to form an X-axis retroreflection light beam; the rear light beam 4 and the front light beam 7 are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the P light component of the intermediate beam 6 is normally incident and retroreflected, forming a Z-axis retroreflected beam P light component. The back beams of the P light components of the left light beam 3, the right light beam 5, the front light beam 7, the back light beam 4 and the middle light beam 6 are converted into S-polarized light beams through a second collimating objective lens 14 after being autocollimated, and then are reflected through a polarizing prism 10 to obtain a lower light beam 17 and an upper light beam 16 respectively corresponding to the left light beam 3 and the right light beam 5, an outer light beam 20 and an inner light beam 19 respectively corresponding to the front light beam 7 and the back light beam 4 and a central light beam 18 corresponding to the middle light beam 6, so that two-dimensional diffraction grating 15 displacement signal beams for X-axis and Y-axis measurement are formed and respectively provided with positive and negative Doppler frequency shift signals;
the S polarized light beam of the intermediate light beam 6 is reflected by the polarizing prism 10, reflected by the first quarter-wave plate 11 and the first total reflection mirror 12, converted into the P polarized light beam by the first quarter-wave plate 11, and directly emitted by the polarizing prism to coincide with the central light beam 18, so that the P light and S light signal beam for measuring the Z-axis displacement of the two-dimensional diffraction grating is formed.
To this end, a three-axis measuring beam generating unit 101 of X, Y, and Z axes is formed.
The upper beam 16 and the lower beam 17 are focused by the third collimator objective 33 onto the first phase-shift grating 34 to be diffracted into three interference beams, which are phase-shifted from each other by a preferred angle of 120 ° and detected by the first detector 35, the second detector 36 and the third detector 37, respectively. The X-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained by processing and calculation by the signal acquisition and processor 38 after photoelectric conversion.
The inner beam 19 and the outer beam 20 are reflected by the second holophote 27 and focused by the fourth collimator objective lens 28 to be diffracted on the second phase shift grating 29 to form three interference beams, the three diffraction interference beams are mutually out of phase by a preferred angle of 120 degrees and are respectively detected by a fourth detector 30, a fifth detector 31 and a sixth detector 32. The Y-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained by processing and calculation by the signal acquisition and processor 38 after photoelectric conversion.
The central beam 18 contains two parts of P polarization state and S polarization state, and is reflected by the second holomirror and diffracted by the second linear polarizer 22 and the third phase shift grating 23 which are arranged with the polarization axis of 45 degrees to form three interference beams, the three interference beams have phase difference of preferably 120 degrees, and are respectively detected by the seventh detector 24, the eighth detector 25 and the ninth detector 26. The Z-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained after photoelectric conversion and processing and calculation by the signal acquisition and processor 38.
Fig. 2 is a second scheme of the optical path of the three-axis measuring beam generating unit 101 different from the above:
the polarization collimation laser light source 1 is in an S polarization state.
Taking the polarizing prism 10 as a polarization state reference: the polarization collimation laser light source 1 emits S polarization light beams, the S polarization light beams are divided into five light beams including a left light beam 3, a right light beam 5, a front light beam 7, a rear light beam 4 and a middle light beam 6 through a transmission type beam splitting two-dimensional diffraction grating 2, the left light beam 3 and the right light beam 5 are in axial symmetry with the middle light beam 6 in a plane formed by the middle light beam 6, and the front light beam 7 and the rear light beam 4 are in axial symmetry with the middle light beam 6 in a plane formed by the middle light beam 6;
after the five light beams are collimated by the first collimating objective lens 8, only the middle light beam 6 passes through the first linear polarizer 9 which rotates 45 degrees relative to the polarization axis of the P light, so that the polarization axis of the middle light beam 6 rotates 45 degrees and has two components of the P light and the S light, wherein the S light and the other four light beams are reflected by the polarizing prism 10 and then converged and incident on the surface of the two-dimensional diffraction grating 15 for reflection type measurement through the second quarter-wave plate 13 and the second collimating objective lens 14. The left light beam 3 and the right light beam 5 are respectively incident from a collimation angle by Littrow to form an X-axis retroreflection light beam; the rear light beam 4 and the front light beam 7 are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the S light component of the intermediate beam 6 is normally incident and retroreflected, forming a Z-axis retroreflected beam S light component.
The S components of the left light beam 3, the right light beam 5, the rear light beam 4, the front light beam 7 and the middle light beam 6 are converged at one point, so that Abbe errors caused by separation of measuring axes X, Y and Z are avoided. The reflected light beams of the S components of the left light beam 3, the right light beam 5, the rear light beam 4, the front light beam 7 and the middle light beam 6 are collimated and reflected by a second collimating objective lens 14, are converted into P-polarized light beams through a second quarter-wave plate, are emitted through a polarizing prism 10 to obtain a lower light beam 17 and an upper light beam 16 respectively corresponding to the left light beam 3 and the right light beam 5, an outer light beam 20 and an inner light beam 19 respectively corresponding to the front light beam 7 and the rear light beam 4 and a central light beam 18 corresponding to the middle light beam 6, so that a two-dimensional diffraction grating 15 displacement signal light beam for X-axis and Y-axis measurement is formed, and the two-dimensional diffraction grating 15 displacement signal light beam has positive Doppler frequency shift signals and negative Doppler frequency shift signals respectively;
the P-polarized light beam of the intermediate light beam 6 passes through the polarizing prism 10 and the first quarter-wave plate 11, is reflected by the first total reflection mirror 12, passes through the first quarter-wave plate 11 for the second time, is converted into the S-polarized light beam, and is reflected by the polarizing prism to coincide with the light beam 18. P light and S light signal beams for measuring the Z-axis displacement of the two-dimensional diffraction grating are formed.
The X-axis and Y-axis and Z-axis measuring beam probe paths for the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5, respectively, the outer beam 20 and the inner beam 19 corresponding to the front beam 7 and the rear beam 4, respectively, and the central beam 18 corresponding to the middle beam 6 are identical to the first case.
Fig. 3 is a third scheme of the optical path of the three-axis measuring beam generating unit 101 different from the above:
the polarization collimation laser light source 1 is in an S polarization state.
Taking the polarizing prism 10 as a polarization state reference: the polarization collimation laser light source 1 emits S polarization light beams, the S polarization light beams are divided into five light beams including a left light beam 3, a right light beam 5, a front light beam 7, a rear light beam 4 and a middle light beam 6 through a transmission type beam splitting two-dimensional diffraction grating 2, the left light beam 3 and the right light beam 5 are in axial symmetry with the middle light beam 6 in a plane formed by the middle light beam 6, and the front light beam 7 and the rear light beam 4 are in axial symmetry with the middle light beam 6 in a plane formed by the middle light beam 6;
after the five light beams are collimated by the first collimating objective lens 8, only the middle light beam 6 passes through the first linear polarizer 9 which rotates 45 degrees relative to the polarization axis of the P light, so that the polarization axis of the middle light beam 6 rotates 45 degrees, and the first linear polarizer has two components of the P light and the S light, wherein the S light and other four light beams are reflected together by the polarizing prism 10, pass through the first quarter-wave plate 11 and are reflected by the first total reflection mirror 12, pass through the first quarter-wave plate 11 for the second time, the polarization states of the five light beams are all converted into the P polarization state, directly pass through the polarizing prism 10, and then pass through the second quarter-wave plate 13 and the second collimating objective lens 14 together to be converged and incident on the surface of the two-dimensional diffraction grating 15 for reflection type measurement. The left light beam 3 and the right light beam 5 are respectively incident at the autoregistration angle of Littrow to form an X-axis retroreflection light beam; the rear light beam 4 and the front light beam 7 are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the S light component of the intermediate beam 6 is normally incident and retroreflected, forming a Z-axis retroreflected beam S light component.
The S components of the left light beam 3, the right light beam 5, the rear light beam 4, the front light beam 7 and the middle light beam 6 are converged at one point, so that Abbe errors caused by separation of the measuring axes X, Y and Z are avoided. The return beams of the S components of the left beam 3, the right beam 5, the rear beam 4, the front beam 7 and the middle beam 6 are collimated and returned by a second collimator objective 14, then are converted into S-polarized beams by a second quarter-wave plate 13, and are reflected by a polarizing prism 10 to obtain a lower beam 17 and an upper beam 16 corresponding to the left beam 3 and the right beam 5, an outer beam 20 and an inner beam 19 corresponding to the front beam 7 and the rear beam 4, respectively, and a central beam 18 corresponding to the middle beam 6, so as to form a two-dimensional diffraction grating 15 displacement signal beam for measuring the X axis and the Y axis, which has positive and negative doppler shift signals, respectively;
the P-polarized beam of the intermediate beam 6 passes through the polarizing prism 10 and then directly exits to coincide with the central beam 18. P light and S light signal beams for measuring the Z-axis displacement of the two-dimensional diffraction grating are formed.
The X-axis and Y-axis and Z-axis measuring beam probe paths for the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5, respectively, the outer beam 20 and the inner beam 19 corresponding to the front beam 7 and the rear beam 4, respectively, and the central beam 18 corresponding to the middle beam 6 are identical to the first case.
Fig. 4 is a fourth scheme different from the optical path of the three-axis measuring beam generating unit 101 described above:
the two-dimensional diffraction grating 2 for beam splitting is a reflection type, and the polarization prism assembly 1011 is composed of only the first quarter-wave plate 11, the polarization prism 10, and the second quarter-wave plate 13.
The polarization collimating laser light source 1 is linearly polarized at a certain angle with the P light and the S light, and thus has both P light and S light polarization components. The polarization collimation laser light source 1 emits a polarization beam with P light and S light polarization components by taking a polarization prism 10 as a polarization state reference object, the S light component beam is reflected by the polarization prism 10 and then is divided into five beams of a left beam 3, a right beam 5, a front beam 7, a rear beam 4 and a middle beam 6 by a first quarter-wave plate 11 and a first collimation objective 8 through a two-dimensional diffraction grating 2 for normal incidence on reflection type beam splitting, the left beam 3, the right beam 5 are axially symmetrical with the middle beam 6 in a plane formed by the middle beam 6, and the front beam 7 and the rear beam 4 are axially symmetrical with the middle beam 6 in the plane formed by the middle beam 6;
the five light beams are collimated by the first collimating objective 8, pass through the first quarter-wave plate 11 together, are converted into a P polarization state, directly pass through the polarizing prism 10, and then are converged and incident on the surface of the two-dimensional diffraction grating 15 for reflection measurement through the second quarter-wave plate 13 and the second collimating objective 14 together. The left light beam 3 and the right light beam 5 are respectively incident at a Littrow auto-collimation angle to form an X-axis retroreflection light beam; the rear light beam 4 and the front light beam 7 are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the S light component of the intermediate beam 6 is normally incident and retroreflected, forming a Z-axis retroreflected beam S light component.
The S components of the left light beam 3, the right light beam 5, the rear light beam 4, the front light beam 7 and the middle light beam 6 are converged at one point, so that Abbe errors caused by separation of measuring axes X, Y and Z are avoided. All the return beams of the left beam 3, the right beam 5, the rear beam 4, the front beam 7 and the S component corresponding to the middle beam 6 are collimated and returned by a second collimating objective lens 14, are converted into S-polarized beams by a second quarter-wave plate 13 for the second time, and are reflected by a polarizing prism 10 to obtain a lower beam 17 and an upper beam 16 corresponding to the left beam 3 and the right beam 5 respectively, an outer beam 20 and an inner beam 19 corresponding to the front beam 7 and the rear beam 4 respectively and a central beam 18 corresponding to the middle beam 6, so that two-dimensional diffraction grating 15 displacement signal beams for X-axis and Y-axis measurement are formed, and have positive and negative Doppler frequency shift signals respectively;
the P-polarized state beam of the intermediate beam 6 emerges directly through the polarizing prism 10 coincident with the central beam 18. P light and S light signal beams for measuring the Z-axis displacement of the two-dimensional diffraction grating are formed.
The X-axis and Y-axis and Z-axis measuring beam probe paths for the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5, respectively, the outer beam 20 and the inner beam 19 corresponding to the front beam 7 and the rear beam 4, respectively, and the central beam 18 corresponding to the middle beam 6 are identical to the first case.
Fig. 5 shows a fifth alternative to the optical path of the three-axis measuring beam generating unit 101 described above:
the two-dimensional diffraction grating 2 for beam splitting is a reflection type, and the polarizing prism assembly 1011 is composed of only a first quarter-wave plate 11, a polarizing prism 10, and a second quarter-wave plate 13.
The polarization collimated laser light source 1 is linearly polarized at a certain angle with respect to the P light and the S light, and thus has both P light and S light polarization components. The polarization collimation laser light source 1 emits a polarization beam with P light and S light polarization components by taking a polarization prism 10 as a polarization state reference object, the P light component beam passes through the polarization prism 10, a first quarter-wave plate 11 and a first collimation objective lens 8 and is normally incident to a reflection type beam splitting two-dimensional diffraction grating 2 to be split into five beams including a left beam 3, a right beam 5, a front beam 7, a rear beam 4 and a middle beam 6, the left beam 3 and the right beam 5 are axially symmetrical with the middle beam 6 in a plane formed by the middle beam 6, and the front beam 7 and the rear beam 4 are axially symmetrical with the middle beam 6 in a plane formed by the middle beam 6;
the five light beams are collimated by the first collimating objective 8, pass through the first quarter-wave plate 11, are converted into the S-polarization state, are reflected by the polarizing prism 10, and are converged and incident on the surface of the two-dimensional diffraction grating 15 for reflection measurement by the second quarter-wave plate 13 and the second collimating objective 14. The left light beam 3 and the right light beam 5 are respectively incident at the autoregistration angle of Littrow to form an X-axis retroreflection light beam; the rear light beam 4 and the front light beam 7 are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the P light component of the intermediate beam 6 is normally incident and retroreflected, forming a Z-axis retroreflected beam P light component.
The P light components of the left light beam 3, the right light beam 5, the rear light beam 4, the front light beam 7 and the middle light beam 6 are converged at one point, so that Abbe errors caused by separation of the measuring axes X, Y and Z are avoided. The reflected light beams of the P light components of the left light beam 3, the right light beam 5, the rear light beam 4, the front light beam 7 and the middle light beam 6 are collimated and reflected by a second collimating objective lens 14, are converted into P polarized light beams through a second quarter-wave plate 13 for the second time, and are directly emitted through a polarizing prism 10 to obtain a lower light beam 17 and an upper light beam 16 respectively corresponding to the left light beam 3 and the right light beam 5, an outer light beam 20 and an inner light beam 19 respectively corresponding to the front light beam 7 and the rear light beam 4 and a central light beam 18 corresponding to the middle light beam 6, so that two-dimensional diffraction grating 15 displacement signal beams for X-axis and Y-axis measurement are formed, and are respectively provided with positive Doppler frequency shift signals and negative Doppler frequency shift signals;
the S-polarized beam of the intermediate beam 6 is reflected by the polarizing prism 10 and emerges coincident with beam 18. And forming P light and S light signal beams for measuring the Z-axis displacement of the two-dimensional diffraction grating.
The X-axis and Y-axis and Z-axis measuring beam probe paths for the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5, respectively, the outer beam 20 and the inner beam 19 corresponding to the front beam 7 and the rear beam 4, respectively, and the central beam 18 corresponding to the middle beam 6 are identical to the first case.
The polarization collimation laser light source 1 is split to obtain a left light beam 3, a right light beam 5 and a light path which is diffracted and emitted by the first phase shift grating 34 and is essentially an X-axis Mach-Zehnder interferometer, signals obtained by the first detector 35, the second detector 36 and the third detector 37 are optical differential signals for measuring the X-axis Doppler frequency shift of the two-dimensional diffraction grating 15, the optical differential signals have 2 times of optical subdivision characteristics, and compared with electronic differential, the precision is higher.
Similarly, the light path from the polarization collimated laser source 1 after beam splitting to the rear beam 4 and the front beam 7 to the second phase shift grating 29 is essentially a Y-axis Mach-Zehnder interferometer, and the signals obtained by the fourth detector 30, the fifth detector 31, and the sixth detector 32 are actually Y-axis doppler shift optical differential signals of the two-dimensional diffraction grating 15 for measurement, and have 2-fold optical subdivision characteristics, and higher precision compared with electronic differential.
The X-axis Mach-Zehnder interferometer and the Y-axis Mach-Zehnder interferometer form a two-dimensional Mach-Zehnder interferometer.
In fig. 1, 2, and 3, the light path from the polarized collimated laser light source 1 after beam splitting to obtain the intermediate beam 6 to the third phase-shift grating 23 is a Z-axis Michelson interferometer in nature; in fig. 4 and 5, the light path from the polarized collimated laser source 1 after beam splitting to the intermediate beam 6 to the third phase-shift grating 23 is essentially a Z-axis Mach-Zehnder interferometer, thereby forming a three-dimensional Mach-Zehnder interferometer; the signals obtained by the seventh detector 24, the eighth detector 25 and the ninth detector 26 are actually Z-axis displacement signals for measuring the two-dimensional diffraction grating 15.
In the light path generated by the X-axis, Y-axis, and Z-axis measuring beams, the straight lines projected on the two-dimensional diffraction grating 15 for measurement are orthogonal to each other and share an intersection point, and correspond to the corresponding measuring axis. The Abbe error caused by different intersection points of the measuring axes and the cosine error caused by non-orthogonality of the measuring axes are avoided.
The three-dimensional Mach-Zehnder interferometer or the two-dimensional Mach-Zehnder interferometer and the one-dimensional Michelson interferometer form a three-dimensional displacement measurement homodyne grating interferometer, and the three-axis grating ruler and the signal acquisition and processor 38 form the three-axis grating ruler. The structure is compact, the cost is low, the X-axis and Y-axis optical paths have 2 times of optical subdivision and optical differential signals, the precision is high, and the installation tolerance is large.
Fig. 6 is a schematic diagram of the derivation of equation 1. G1 represents a two-dimensional diffraction grating 2 for beam splitting with a pitch d 1 (ii) a L1 denotes a first collimating objective 8 with a focal length f 1 (ii) a L2 denotes a second collimator lens 14 with a focal length f 2 G2 represents a two-dimensional diffraction grating 15 for measurement with a pitch d 2 。
θ 1 Is G of grade + -1 1 The diffraction angle of the diffraction beam of the grating satisfies the following conditions:
d 1 sinθ 1 ＝λ (4)
R＝f 1 t g θ 1 (5)
θ 2 is G 2 The Littrow auto-collimation incidence angle satisfies the following conditions:
2d 2 sinθ 2 ＝λ (6)
R＝f 2 t g θ 2 (7)
the formula (4) - - - (7) can be deduced to be the relation formula (1).
Similarly, L2 represents the third collimator objective lens 33, with a focal length f 3 G2 represents the first phase shift grating 34, the pitch is D3, and the upper beam 16 and the lower beam 17 are focused on the first phase shift grating 34 by the third collimator objective lens 33 to be diffracted into three interference beams, which are emergent beams D1, D2, D3 in a dotted line in fig. 6. The three diffracted interfering beams are phase-shifted from each other by a preferred angle of 120 deg., and are detected by a first detector 35, a second detector 36, and a third detector 37, respectively. This yields relation (2). The three interference beams satisfying the relation (2) are formed by completely superposing two incident beams after diffraction, the contrast is maximum, and the signal is optimal.
Similarly, L2 denotes the fourth collimator objective 28, in focusA distance of f 4 G2 represents the second phase-shift grating 29 with a grating pitch D4, and the inner beam 19 and the outer beam 20 are focused on the second phase-shift grating 29 by the fourth collimator objective lens 28 to be diffracted into three interference beams, such as the outgoing beams D1, D2, and D3 shown by the dotted lines in fig. 6. The three diffracted interfering beams are phase-shifted from each other by a preferred angle of 120 deg., and are detected by a fourth detector 30, a fifth detector 31, and a sixth detector 32, respectively. Thereby, relation (3) is derived. The three interference beams satisfying the relation (3) are formed by completely superposing two incident beams after diffraction, the contrast is maximum, and the signal is optimal.
The two-dimensional diffraction grating 2 for beam splitting may be a Dammann grating or a combination of two one-dimensional diffraction gratings.
The first phase shift grating 34, the second phase shift grating 29, and the third phase shift grating 23 may be one-dimensional diffraction gratings or two-dimensional diffraction gratings.

Claims (10)

1. A three-axis grating scale comprising: the device comprises a three-axis measuring beam generating unit (101), an X-axis measuring beam detecting unit (104), a Y-axis measuring beam detecting unit (103), a Z-axis measuring beam detecting unit (102) and a signal acquisition and processor (38); the method is characterized in that: the three-axis measuring beam generating unit (101) generates an X-axis measuring beam, a Y-axis measuring beam and a Z-axis measuring beam, the X-axis measuring beam detecting unit (104) is arranged along the direction of the X-axis measuring beam, the Y-axis measuring beam detecting unit (103) is arranged along the direction of the Y-axis measuring beam, and the Z-axis measuring beam detecting unit (102) is arranged along the direction of the Z-axis measuring beam;
the three-axis measuring beam generating unit (101) comprises: the device comprises a polarization collimation laser light source (1), a two-dimensional diffraction grating (2) for beam splitting, a first collimation objective (8), a polarization prism assembly (1011), a second collimation objective (14) and a two-dimensional diffraction grating (15) for measurement; the two-dimensional diffraction grating (2) for beam splitting and the two-dimensional diffraction grating (15) for measurement are two-dimensionally and orthogonally symmetrical, the two-dimensional grating distances are equal, and the grating distance d of the two-dimensional diffraction grating (2) for beam splitting 1 And a two-dimensional diffraction grating (15) for measurement, the pitch d of which is set to be equal to the pitch of the grating 2 Focal length of the first collimating objective lens (8)f 1 The focal length f of the second collimator objective (14) 2 Satisfies the following relation:
Figure FDA0003810647760000011
wherein, lambda is the wavelength of the polarized collimation laser light source (1);
the X-axis measuring beam detection unit (104) comprising: a third collimator objective (33), a first phase-shift grating (34), a first detector (35), a second detector (36) and a third detector (37), wherein the third collimator objective (33) has a focal length f 3 The first phase shift grating (34) has a grating pitch d 3 The two-dimensional diffraction grating (2) for beam splitting has a grating pitch d 1 The focal length f of the first collimating objective lens (8) 1 And satisfies the following relation:
Figure FDA0003810647760000012
the Y-axis measuring beam detecting unit (103) includes: a second total reflection mirror (27), a fourth collimating objective (28), a second phase-shift grating (29), a fourth detector (30), a fifth detector (31) and a sixth detector (32); the focal length f of the fourth collimating objective lens (28) 4 A second phase shift grating (29) having a grating pitch d 4 The two-dimensional diffraction grating (2) for beam splitting has a grating pitch d 1 The focal length f of the first collimating objective lens (8) 1 The following relational expression is satisfied:
Figure FDA0003810647760000013
the Z-axis measuring beam detection unit (102) comprises a third total reflection mirror (21), a second linear polarizer (22), a third phase-shift grating (23), a seventh detector (24), an eighth detector (25) and a ninth detector (26);
in the triaxial measuring beam generating unit (101), a polarized collimated laser source (1) emits a polarized collimated beam, the polarized collimated beam is divided into five beams by a two-dimensional diffraction grating (2) for beam splitting, the five beams are converged and incident by a first collimating objective lens (8), a polarizing prism assembly (1011) and a second collimating objective lens (14), are diffracted by a two-dimensional diffraction grating (15) for measurement, are collimated by the second collimating objective lens (14) and are reflected back, and the beams are emitted by the polarizing prism assembly (1011) to form triaxial measuring beams of X, Y and Z axes; and the X-axis measuring beam detection unit (104), the Y-axis measuring beam detection unit (103) and the Z-axis measuring beam detection unit (102) are used for detecting, performing photoelectric conversion, and then processing and calculating through a signal acquisition and processor (38) to obtain X-axis, Y-axis and Z-axis displacement of the two-dimensional diffraction grating (15) for measurement.
2. The three-axis grating ruler of claim 1, wherein five beams are emitted from the right of the polarizing prism (10), wherein the upper and lower beams are focused on the first phase shift grating (34) by the third collimating objective lens (33) and then diffracted to form three interference beams, which are respectively detected by the first detector (35), the second detector (36) and the third detector (37), and after photoelectric conversion, the three interference beams are processed and calculated by the signal acquisition and processor (38), so as to obtain the X-axis displacement of the two-dimensional diffraction grating (15) for measurement; in addition, the front beam and the rear beam are reflected by a second total reflection mirror (27) and focused on a second phase shift grating (29) by a fourth collimating objective lens (28) to form three interference beams through diffraction, the three interference beams are respectively detected by a fourth detector (30), a fifth detector (31) and a sixth detector (32), and the three interference beams are processed and calculated by a signal acquisition and processor (38) after photoelectric conversion to obtain the Y-axis displacement of the two-dimensional diffraction grating (15) for measurement; and finally, the middle beam is reflected by a third total reflection mirror (21), passes through a second linear polarizer (22) and a third phase shift grating (23) which are arranged at an angle of 45 degrees in a polarization axis and is diffracted to form three interference beams, the three interference beams are respectively detected by a seventh detector (24), an eighth detector (25) and a ninth detector (26), and are subjected to photoelectric conversion, processed and calculated by a signal acquisition and processor (38) to obtain the Z-axis displacement of the two-dimensional diffraction grating (15) for measurement.
3. Three-axis grating scale according to claim 1 or 2, wherein the measuring two-dimensional diffraction grating (15) is of a reflective type and the beam-splitting two-dimensional diffraction grating (2) is of a transmissive type, and the polarizing prism assembly (1011) comprises: a first linear polarizer (9), a first total reflection mirror (12), a first quarter-wave plate (11), a polarizing prism (10) and a second quarter-wave plate (13);
the optical path of the triaxial measuring beam generating unit (101) is as follows:
the polarization collimation laser source (1) emits P polarized light beams by taking a polarization prism (10) as a polarization state reference object, the P polarized light beams are divided into five light beams including a left light beam (3), a right light beam (5), a front light beam (7), a rear light beam (4) and a middle light beam (6) through a transmission type beam splitting two-dimensional diffraction grating (2), the left light beam (3) and the right light beam (5) are axially symmetrical with the middle light beam (6) in a plane formed by the middle light beam (6), and the front light beam (7) and the rear light beam (4) are axially symmetrical with the middle light beam (6) in a plane formed by the middle light beam (6);
after the five beams are collimated by a first collimating objective lens (8), only the middle beam (6) passes through a first linear polarizer (9) which rotates 45 degrees relative to the polarization axis of the P light, so that the polarization axis of the middle beam (6) rotates 45 degrees, and the middle beam has two components of the P light and the S light, wherein the P light component of the middle beam (6) and other four beams pass through a polarizing prism (10) together, then pass through a second quarter-wave plate (13) and a second collimating objective lens (14) together to be converged to one point, and irradiate the point on the surface of a two-dimensional diffraction grating (15) for measurement, wherein the beams of the left beam (3) and the right beam (5) are respectively incident at a Littrow self-collimation angle to form an X-axis retroreflection beam; the front light beam (7) and the rear light beam (4) are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the P light component of the intermediate beam (6) is normally incident and retroreflected to form a Z-axis retroreflected beam P light component; the reflected light beams of the P light components of the left light beam (3), the right light beam (5), the front light beam (7), the rear light beam (4) and the middle light beam (6) are self-collimated by a second collimating objective lens (14), converted into S-polarized light beams by a second quarter wave plate (13), reflected by a polarizing prism (10) to obtain a lower light beam (17) and an upper light beam (16) respectively corresponding to the left light beam (3) and the right light beam (5), an outer light beam (20) and an inner light beam (19) respectively corresponding to the front light beam (7) and the rear light beam (4) and a central light beam (18) corresponding to the middle light beam (6), so that two-dimensional diffraction grating (15) displacement signal beams for measuring the X axis and the Y axis are formed and respectively have positive and negative Doppler frequency shift signals;
the S light component of the intermediate light beam (6) is reflected by the polarizing prism (10), passes through the first quarter wave plate (11), is reflected by the first total reflection mirror (12), then passes through the first quarter wave plate (11) again and is converted into a P polarization state, and directly exits through the polarizing prism (10) to coincide with the S light component of the intermediate light beam (6) converted from the P light component, so that a P light signal light beam and an S light signal light beam which are used for measuring the Z-axis displacement of the two-dimensional diffraction grating (15) are formed.
4. The three-axis grating scale of claim 1 or 2, wherein: the two-dimensional diffraction grating (15) for measurement is a reflection type, and the two-dimensional diffraction grating (2) for beam splitting is a transmission type, and the polarizing prism assembly (1011) includes: a first linear polarizer (9), a first total reflection mirror (12), a first quarter-wave plate (11), a polarizing prism (10) and a second quarter-wave plate (13);
the optical path of the triaxial measuring beam generating unit (101) is as follows:
taking a polarizing prism (10) as a polarization state reference: the polarization collimation laser light source (1) emits S polarization light beams, the S polarization light beams are divided into five light beams including a left light beam (3), a right light beam (5), a front light beam (7), a rear light beam (4) and a middle light beam (6) through a transmission type beam splitting two-dimensional diffraction grating (2), the left light beam (3) and the right light beam (5) are axially symmetrical through the middle light beam (6) in a plane formed by the left light beam and the right light beam (6), and the front light beam (7) and the rear light beam (4) are axially symmetrical through the middle light beam (6) in a plane formed by the middle light beam (6);
after the five beams are collimated by a first collimating objective lens (8), only the middle beam (6) passes through a first linear polarizer (9) which rotates 45 degrees relative to the polarization axis of the P light, so that the polarization axis of the middle beam (6) rotates 45 degrees, and the middle beam has two components of the P light and the S light, wherein the S light and other four beams are reflected by a polarizing prism (10) together, and then are converged and incident on the surface of a two-dimensional diffraction grating (15) for reflection type measurement through a second quarter-wave plate (13) and a second collimating objective lens (14) together, wherein the left beam (3) and the right beam (5) are incident at a Littrow self-collimation angle respectively to form an X-axis retroreflection beam; the rear light beam (4) and the front light beam (7) are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the S light component of the intermediate beam (6) is normally incident and retroreflected to form a Z-axis retroreflected beam S light component;
the reflected light beams of the S light components of the left light beam (3), the right light beam (5), the rear light beam (4), the front light beam (7) and the middle light beam (6) are collimated and reflected by a second collimating objective lens (14), converted into P polarized light beams through a second quarter wave plate, and directly emitted through a polarizing prism (10) to obtain a lower light beam (17) and an upper light beam (16) which respectively correspond to the left light beam (3) and the right light beam (5), an outer light beam (20) and an inner light beam (19) which respectively correspond to the front light beam (7) and the rear light beam (4), and a central light beam (18) which corresponds to the middle light beam (6), so that two-dimensional diffraction grating (15) displacement signal beams for measuring the X axis and the Y axis are formed and respectively have positive Doppler frequency shift signals and negative Doppler frequency shift signals;
the P polarized light beam of the intermediate light beam (6) passes through the polarizing prism (10) and the first quarter-wave plate (11), is reflected by the first total reflection mirror (12), passes through the first quarter-wave plate (11) for the second time, is converted into an S polarized state, and is reflected by the polarizing prism to coincide with the central light beam (18), so that the P light and S light signal light beam for measuring the Z-axis displacement of the two-dimensional diffraction grating is formed.
5. The three-axis grating scale of claim 1 or 2, wherein: the two-dimensional diffraction grating (15) for measurement is a reflection type, the two-dimensional diffraction grating (2) for beam splitting is a transmission type, and the polarizing prism assembly (1011) includes: a first linear polarizer (9), a first total reflection mirror (12), a first quarter-wave plate (11), a polarizing prism (10) and a second quarter-wave plate (13);
the optical path of the triaxial measuring beam generating unit (101) is as follows:
taking a polarizing prism (10) as a polarization state reference: the polarization collimation laser light source (1) emits S polarization light beams, the S polarization light beams are divided into five light beams through the transmission type beam splitting two-dimensional diffraction grating (2), the five light beams are respectively a left light beam (3), a right light beam (5), a front light beam (7), a rear light beam (4) and a middle light beam (6), the left light beam (3) and the right light beam (5) are axially symmetrical through the middle light beam (6) in a plane formed by the left light beam and the right light beam (6), and the front light beam (7) and the rear light beam (4) are axially symmetrical through the middle light beam (6) in a plane formed by the middle light beam (6);
after five beams are collimated by a first collimating objective lens (8), only the middle beam (6) passes through a first linear polarizer (9) which rotates 45 degrees relative to the polarization axis of the P light, the polarization axis of the middle beam (6) is rotated 45 degrees, and the middle beam has two components of the P light and the S light, wherein the S light and other four beams are reflected by a polarizing prism (10), pass through a first quarter-wave plate (11) and are reflected by a first full-reflecting mirror (12), pass through the first quarter-wave plate (11) for the second time, the polarization states of the five beams are converted into the P polarization state, directly pass through the polarizing prism (10), and then pass through a second quarter-wave plate (13) and a second collimating objective lens (14) together to be converged and incident on the surface of a two-dimensional diffraction grating (15) for reflection type measurement, wherein the left beam (3) and the right beam (5) are respectively incident at a Littrow self-collimation angle to form an X-axis reflected beam; the rear light beam (4) and the front light beam (7) are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the S light component of the intermediate beam (6) is normally incident and retroreflected to form a Z-axis retroreflected beam S light component;
the reflected light beams of the S light components of the left light beam (3), the right light beam (5), the rear light beam (4), the front light beam (7) and the middle light beam (6) are collimated and reflected by a second collimating objective lens (14), converted into S polarized light beams through a second quarter-wave plate (13), reflected by a polarizing prism (10) to obtain a lower light beam (17) and an upper light beam (16) which respectively correspond to the left light beam (3) and the right light beam (5), an outer light beam (20) and an inner light beam (19) which respectively correspond to the front light beam (7) and the rear light beam (4) and a central light beam (18) which corresponds to the middle light beam (6), so that two-dimensional diffraction grating (15) displacement signal beams for measuring the X axis and the Y axis are formed and respectively have positive Doppler frequency shift signals and negative Doppler frequency shift signals;
the P polarized light beam of the intermediate light beam (6) passes through the polarizing prism (10) and then directly exits to coincide with the central light beam (18) to form P light and S light signal beams for measuring the Z-axis displacement of the two-dimensional diffraction grating.
6. The three-axis grating scale of claim 1 or 2, wherein: the two-dimensional diffraction grating for measurement (15) is a reflection type, and the two-dimensional diffraction grating for beam splitting (2) is a reflection type, the polarizing prism assembly (1011) includes only: a first quarter-wave plate (11), a polarizing prism (10), a second quarter-wave plate (13);
the optical paths of the three-axis measuring beam generating unit (101) are as follows:
the polarization collimation laser source (1) emits linearly polarized light beams with P light and S light polarization components by taking a polarization prism (10) as a polarization state reference object, the S light component beams are reflected by the polarization prism (10), and then pass through a first quarter-wave plate (11) and a first collimation objective lens (8), the normally incident two-dimensional diffraction grating (2) for reflection type beam splitting is divided into five beams including a left beam (3), a right beam (5), a front beam (7), a rear beam (4) and a middle beam (6), the left beam (3) and the right beam (5) are axially symmetrical by the middle beam (6) in a plane formed by the middle beam (6), and the front beam (7) and the rear beam (4) are axially symmetrical by the middle beam (6) in a plane formed by the middle beam (6);
the five beams of light are collimated by a first collimating objective lens (8), pass through a first quarter-wave plate (11) together, are converted into a P polarization state, directly pass through a polarizing prism (10), and then pass through a second quarter-wave plate (13) and a second collimating objective lens (14) together to be converged and incident on the surface of a two-dimensional diffraction grating (15) for reflection type measurement, wherein a left beam (3) and a right beam (5) are incident at a Littrow auto-collimation angle respectively to form an X-axis retroreflection beam; the rear light beam (4) and the front light beam (7) are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the S light component of the intermediate beam (6) is normally incident and retroreflected to form a Z-axis retroreflected beam S light component;
all the reflected light beams of the left light beam (3), the right light beam (5), the rear light beam (4), the front light beam (7) and the S light component corresponding to the middle light beam (6) are collimated and reflected by a second collimating objective lens (14), are converted into S polarized light beams through a second quarter-wave plate (13) for the second time, and are reflected by a polarizing prism (10) to obtain a lower light beam (17) and an upper light beam (16) corresponding to the left light beam (3) and the right light beam (5) respectively, an outer light beam (20) and an inner light beam (19) corresponding to the front light beam (7) and the rear light beam (4) respectively, and a central light beam (18) corresponding to the middle light beam (6), so that two-dimensional diffraction grating (15) displacement signal beams for measuring the X axis and the Y axis are formed, and are respectively provided with positive and negative Doppler frequency shift signals;
the P polarized light beam of the intermediate light beam (6) directly passes through the polarizing prism (10) to be emitted and superposed with the central light beam (18) to form P light and S light signal light beams for measuring the Z-axis displacement of the two-dimensional diffraction grating.
7. The three-axis grating scale of claim 1 or 2, wherein: the two-dimensional diffraction grating for measurement (15) is a reflection type, and the two-dimensional diffraction grating for beam splitting (2) is a reflection type, the polarizing prism assembly (1011) includes only: a first quarter-wave plate (11), a polarizing prism (10), a second quarter-wave plate (13);
the optical path of the triaxial measuring beam generating unit (101) is as follows:
the polarization collimation laser source (1) emits linearly polarized light beams with P light and S light polarization components by taking a polarization prism (10) as a polarization state reference object, the P light component beams pass through the polarization prism (10), a first quarter-wave plate (11) and a first collimation objective lens (8), are normally incident on a reflection type beam splitting two-dimensional diffraction grating (2) to be divided into five beams including a left beam (3), a right beam (5), a front beam (7), a rear beam (4) and a middle beam (6), the left beam (3) and the right beam (5) are axially symmetrical by the middle beam (6) in a plane formed by the left beam (3) and the middle beam (6), and the front beam (7) and the rear beam (4) are axially symmetrical by the middle beam (6) in a plane formed by the middle beam (6);
the five beams of light are collimated by a first collimating objective lens (8), pass through a first quarter-wave plate (11), are converted into S polarization states, are reflected by a polarizing prism (10), pass through a second quarter-wave plate (13) and a second collimating objective lens (14), are converged and are incident on the surface of a two-dimensional diffraction grating (15) for reflection type measurement, wherein a left beam (3) and a right beam (5) are incident at a Littrow auto-collimation angle respectively to form an X-axis retroreflection beam; the rear light beam (4) and the front light beam (7) are respectively incident at a Littrow auto-collimation angle to form a Y-axis retroreflection light beam; the P light component of the intermediate beam (6) is normally incident and retroreflected to form a Z-axis retroreflected beam P light component;
the reflected light beams of the P light components of the left light beam (3), the right light beam (5), the rear light beam (4), the front light beam (7) and the middle light beam (6) are collimated and reflected by a second collimating objective lens (14), are converted into P polarized light beams through a second quarter-wave plate (13) for the second time, and are directly emitted through a polarizing prism (10) to obtain a lower light beam (17) and an upper light beam (16) which respectively correspond to the left light beam (3) and the right light beam (5), an outer light beam (20) and an inner light beam (19) which respectively correspond to the front light beam (7) and the rear light beam (4), and a central light beam (18) which corresponds to the middle light beam (6), so that two-dimensional diffraction grating (15) displacement signal beams for measuring the X axis and the Y axis are formed and respectively have positive Doppler frequency shift signals and negative Doppler frequency shift signals;
and the S polarized light beam of the intermediate light beam (6) is directly reflected by the polarizing prism (10) to coincide with the central light beam (18) to form a P light signal beam and an S light signal beam for measuring the Z-axis displacement of the two-dimensional diffraction grating.
8. The three-axis grating scale of claim 1, wherein: the optical path of the X-axis measuring beam in the three-axis measuring beam generating unit (101) and the optical path of the X-axis measuring beam detecting unit (104), and the optical path of the Y-axis measuring beam detecting unit (103) jointly form a two-dimensional Mach-Zehnder (Mach-Zehnder) homodyne interferometer; the optical path of the Z-axis measuring beam and the optical path of the Z-axis measuring beam detection unit (102) form a one-dimensional Michelson or Mach-Zehnder homodyne interferometer; thereby forming an integrated three-dimensional displacement measurement homodyne grating interferometer; the X-axis and Y-axis optical paths have 2 times optical subdivision and optical differential signals.
9. The three-axis grating scale of claim 1, wherein: the two-dimensional diffraction grating (2) for beam splitting is a Dammann grating or a combination of two one-dimensional diffraction gratings.
10. The three-axis grating scale of claim 1, wherein: the first phase-shift grating (34), the second phase-shift grating (29) and the third phase-shift grating (23) are one-dimensional diffraction gratings or two-dimensional diffraction gratings.
CN202010978240.4A 2020-09-17 2020-09-17 Three-axis grating ruler Active CN113701640B (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
CN202010978240.4A CN113701640B (en) 2020-09-17 2020-09-17 Three-axis grating ruler
PCT/CN2020/120568 WO2022056971A1 (en) 2020-09-17 2020-10-13 Three-axis grating ruler

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010978240.4A CN113701640B (en) 2020-09-17 2020-09-17 Three-axis grating ruler

Publications (2)

Publication Number Publication Date
CN113701640A CN113701640A (en) 2021-11-26
CN113701640B true CN113701640B (en) 2023-01-20

Family

ID=78646603

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010978240.4A Active CN113701640B (en) 2020-09-17 2020-09-17 Three-axis grating ruler

Country Status (2)

Country Link
CN (1) CN113701640B (en)
WO (1) WO2022056971A1 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114754685B (en) * 2022-06-13 2022-09-02 探维科技(北京)有限公司 Detection signal processing method, device, medium, equipment and grating ruler
CN115236865B (en) * 2022-07-21 2023-04-14 中国科学院精密测量科学与技术创新研究院 Cold atom long distance transfer device based on servo feedback electric focusing lens
CN117091513B (en) * 2023-10-19 2024-01-02 中国科学院长春光学精密机械与物理研究所 Grating interferometry device and measurement method based on large-size light spots

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0889303A2 (en) * 1997-06-30 1999-01-07 Canon Kabushiki Kaisha Displacement information detecting apparatus
CN103322927A (en) * 2013-06-19 2013-09-25 清华大学 Three-degree of freedom heterodyne grating interferometer displacement measurement system
CN103673891A (en) * 2013-11-21 2014-03-26 清华大学 Grating heterodyne interference auto-collimation measuring device
CN104596425A (en) * 2015-01-09 2015-05-06 哈尔滨工业大学 Three-dimensional displacement measurement device based on diffraction grating
CN104949616A (en) * 2014-03-25 2015-09-30 上海微电子装备有限公司 Retro-reflection grating scale measurement system and application thereof
CN110285761A (en) * 2019-07-03 2019-09-27 哈尔滨工业大学 A kind of compact-sized diffraction grating three-D displacement measuring device

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5098190A (en) * 1989-08-07 1992-03-24 Optra, Inc. Meterology using interferometric measurement technology for measuring scale displacement with three output signals
CN103307986B (en) * 2013-06-19 2016-03-30 清华大学 A kind of two degrees of freedom heterodyne grating interferometer displacement measurement system
CN103644848B (en) * 2013-12-12 2016-02-03 哈尔滨工业大学 A kind of three dimensional grating displacement measurement system using double-frequency laser
CN106017308B (en) * 2016-07-22 2019-01-04 清华大学 A kind of six degree of freedom interferometer measuration system and method
CN106247947B (en) * 2016-08-11 2018-10-12 哈尔滨工业大学 A kind of thick/thin measuring system of two/three-dimensional grating of heterodyne system displacement
CN108775869A (en) * 2018-03-23 2018-11-09 中国科学院长春光学精密机械与物理研究所 Realize the grating displacement measuring system and method that long stroke three-D displacement measures
CN108627099B (en) * 2018-07-02 2020-03-20 清华大学 Five-degree-of-freedom heterodyne grating interferometry system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0889303A2 (en) * 1997-06-30 1999-01-07 Canon Kabushiki Kaisha Displacement information detecting apparatus
CN103322927A (en) * 2013-06-19 2013-09-25 清华大学 Three-degree of freedom heterodyne grating interferometer displacement measurement system
CN103673891A (en) * 2013-11-21 2014-03-26 清华大学 Grating heterodyne interference auto-collimation measuring device
CN104949616A (en) * 2014-03-25 2015-09-30 上海微电子装备有限公司 Retro-reflection grating scale measurement system and application thereof
CN104596425A (en) * 2015-01-09 2015-05-06 哈尔滨工业大学 Three-dimensional displacement measurement device based on diffraction grating
CN110285761A (en) * 2019-07-03 2019-09-27 哈尔滨工业大学 A kind of compact-sized diffraction grating three-D displacement measuring device

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
二维光栅纳米位移测量***的设计与分析;李帅;《现代显示》;20120430;第19-23页 *

Also Published As

Publication number Publication date
CN113701640A (en) 2021-11-26
WO2022056971A1 (en) 2022-03-24

Similar Documents

Publication Publication Date Title
CN113701640B (en) Three-axis grating ruler
TWI784265B (en) Displacement measuring device, displacement measuring method and photolithography equipment
US7561280B2 (en) Displacement measurement sensor head and system having measurement sub-beams comprising zeroth order and first order diffraction components
US7573581B2 (en) Position-measuring device
JP6732543B2 (en) Displacement detection device
CN101691998B (en) Two-dimensional laser autocollimator
JP6765497B2 (en) Diffraction grating measuring device
CN108627099B (en) Five-degree-of-freedom heterodyne grating interferometry system
US5369488A (en) High precision location measuring device wherein a position detector and an interferometer are fixed to a movable holder
WO2020133820A1 (en) Method and system for measuring interference of two-degree-of-freedom heterodyne optical grating having high tolerance
CN108775878B (en) Grating heterodyne interference system and roll angle measuring method thereof
CN105180845A (en) High-precision roll angle interferometric measuring device based on blazed grating
US20230366667A1 (en) Heterodyne grating interferometry system based on secondary diffraction
WO2022095128A1 (en) Six-degree-of-freedom measuring grating scale
CN116086310A (en) High-precision positioning measurement method and device based on KB mirror nano experiment system
Chen et al. Multi-DOF incremental optical encoder with laser wavelength compensation
CN114111587B (en) Triaxial high-optical subdivision grating ruler
CN110068272B (en) Two-dimensional straightness error and position simultaneous measurement device and method
JP2675317B2 (en) Moving amount measuring method and moving amount measuring device
TWI414747B (en) A five - degree - of - freedom optical system
CN114353671B (en) Dual-wavelength diffraction interference system and method for realizing synchronous measurement of displacement and angle
JPH0799325B2 (en) Minute displacement measuring method and minute displacement measuring device
JP2023097776A (en) Multiaxial displacement measuring device and multiaxial displacement measuring method
JP3064613B2 (en) High precision coordinate measuring device
TW479125B (en) Two dimensional displacement measurement method with conjugate optical paths

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant