WO2022056971A1 - 一种三轴光栅尺 - Google Patents

一种三轴光栅尺 Download PDF

Info

Publication number
WO2022056971A1
WO2022056971A1 PCT/CN2020/120568 CN2020120568W WO2022056971A1 WO 2022056971 A1 WO2022056971 A1 WO 2022056971A1 CN 2020120568 W CN2020120568 W CN 2020120568W WO 2022056971 A1 WO2022056971 A1 WO 2022056971A1
Authority
WO
WIPO (PCT)
Prior art keywords
axis
measurement
light
diffraction grating
grating
Prior art date
Application number
PCT/CN2020/120568
Other languages
English (en)
French (fr)
Inventor
韦春龙
周常河
Original Assignee
中国科学院上海光学精密机械研究所
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 中国科学院上海光学精密机械研究所 filed Critical 中国科学院上海光学精密机械研究所
Publication of WO2022056971A1 publication Critical patent/WO2022056971A1/zh

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

Definitions

  • the invention belongs to the field of precision optical measuring instruments, in particular to a three-axis grating ruler used for displacement measurement of three degrees of freedom.
  • Grating ruler also known as optical encoder
  • optical encoder is widely used in displacement and angle measurement in the fields of precision motion table, precision optical machinery, and precision measuring instruments.
  • the grating scale based on the high-density diffraction grating has higher precision and resolution than the grating scale based on the low-density ordinary geometric grating, and can reach the sub-nanometer level.
  • US Patent US5098190 provides another grating structure based on diffraction grating. It is characterized in that the light source emits a collimated laser beam to the surface of the measurement grating, and the diffracted positive and negative first-order diffracted lights are focused on the phase grating through a lens, generating three interference beams with a phase shift of 120°. After the photoelectric conversion of the detector and the processing by the signal processor, the corresponding measurement grating displacement information can be obtained.
  • This patent also has the problem that the grating reading head is sensitive to the measuring grating distance and is prone to errors.
  • the optical path is essentially a Mach-Zehnder interferometer. Therefore, the measurement signal of two degrees of freedom is an optical differential signal based on the Doppler frequency shift, which is more accurate than the electronic differential of individual displacement measurement.
  • the two-degree-of-freedom measuring grating scale proposed by Kao et al. uses the Littrow self-collimation angle
  • the incident measurement grating makes the installation tolerance of the grating scale reading head larger, but it is essentially two independent one-dimensional optical path structures, which are complex, difficult to manufacture, and prone to Abbe errors.
  • the three-degree-of-freedom measurement extension is more complex. Its optical path is also a Mach-Zeder interferometer in essence.
  • Gao's research group proposed three degrees of freedom (A. Kimura, Wei Gao, W. Kim et.al, A sub-nanometric three-axis surface encoder with short-period planar gratings for stage motion measurement, Precision Engineering 36 (2013), 771-781), six degrees 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 ) measuring three-axis and six-axis grating scales.
  • Chinese patents CN103307986A and CN103322927B respectively provide a two-axis grating ruler for measurement with two degrees of freedom and a three-axis grating ruler for measurement with three degrees of freedom.
  • the optical path is essentially a Michelson interferometer without optical subdivision function, that is, the resolution is relatively reduced by half; error problem.
  • each degree of freedom signal is an electronic differential signal. Compared with optical difference, the accuracy is not high.
  • Chinese patent CN10862709913 presents a five-axis grating ruler for five-degree-of-freedom measurement.
  • Littrow self-collimating incident grating is used to improve installation tolerance, the structure is stacked, manufacturing is difficult, and it is still deformed for the Michelson interferometer. form, the displacement signal of each degree of freedom is still obtained by electronic differential, and there is no optical subdivision function, that is, the resolution is relatively reduced by half.
  • Chinese patent CN106017308B provides a six-axis grating ruler for six-degree-of-freedom measurement.
  • the reading head is formed by overlapping three grating reading heads and three heterodyne laser reading heads.
  • the measuring grating array is composed of three measuring grating components. It is cross-stacked with three heterodyne laser mirrors, which is more complicated and difficult to manufacture, and the X, Y, and Z axes are separated, which is likely to cause Abbe errors.
  • the three-axis grating ruler of the present invention includes: a three-axis measurement beam generation unit, an X-axis measurement beam detection unit, a Y-axis measurement beam detection unit, a Z-axis measurement beam detection unit and a signal acquisition and processing unit; the three-axis measurement beam
  • the generating unit generates an X-axis measurement beam, a Y-axis measurement beam and a Z-axis measurement beam; along the X-axis measurement beam direction, the X-axis measurement beam detection unit is provided, along the Y-axis measurement beam direction
  • the Y-axis measurement beam detection unit is provided, and the Z-axis measurement beam detection unit is provided along the Z-axis measurement beam direction;
  • the three-axis measurement beam generating unit includes: a polarization collimation laser light source, a two-dimensional diffraction grating for beam splitting, a first collimating objective lens, a polarizing prism assembly, a second collimating objective lens, and a two-dimensional diffraction grating for measurement; the 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 pitch is equal.
  • the X-axis measurement beam detection unit includes: a third collimating objective lens, a first phase-shift grating, a first detector, a second detector, and a third detector.
  • the Y-axis measurement beam detection unit includes: a second total reflection mirror, a third collimating objective lens, a second phase-shift grating, a fourth detector, a fifth detector, and a sixth detector.
  • the Z-axis measurement beam detection unit includes a third total reflection 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, corresponding to the polarizing prism assembly, comprising: a first linear polarizer, a first total reflection mirror, a first quarter wave plate, a polarizing prism, a second quarter wave A wave plate.
  • the polarization collimation laser light source is in the P polarization state
  • the three-axis measurement beam generating unit optical path and the three-axis grating ruler measurement principle are as follows: take the polarization prism as the polarization state reference object: the polarization collimation laser light source emits a P-polarized beam
  • the transmission type beam splitting uses a two-dimensional diffraction grating to divide the left beam, the right beam, the front beam, the rear beam and the middle beam into five beams, and the left beam and the right beam are symmetrical with the middle beam axis in the plane composed of the middle beam.
  • the beam and the rear beam are symmetrical about the axis of the middle beam in the plane formed by the middle beam.
  • the middle beam passes through the first linear polarizer that rotates 45° relative to the polarization axis of the P light, so that the polarization axis of the middle beam rotates by 45°, and has two components of P light and S light.
  • the P light and the other four beams pass through the polarizing prism, and then pass through the second quarter-wave plate and the second collimating lens to converge and incident on the surface of the two-dimensional diffraction grating for measurement.
  • the left beam and the right beam are incident at the Littrow self-collimation angle to form the X-axis retroreflected beam; the front beam and the rear beam are respectively incident at the Littrow self-collimation angle to form the Y-axis retroreflection beam; the P light component of the middle beam Normal incidence and retroreflection to form the P light component of the Z-axis retroreflected beam.
  • the P light components of the left beam, the right beam, the front beam, the rear beam, and the middle beam converge to one point.
  • the retroreflected beams of the P light components of the left beam, right beam, front beam, rear beam, and middle beam are self-collimated and retroreflected, they are converted into S-polarized beams by the second quarter-wave plate, and passed through a polarizing prism.
  • the lower and upper beams corresponding to the left and right beams are obtained by reflection, the outer and inner beams corresponding to the front and rear two beams respectively, and the central beam corresponding to the middle beam, thus forming the X-axis, Y-axis and Z-axis measurement
  • the signal beam is shifted with a two-dimensional diffraction grating with positive and negative Doppler shifted signals, respectively.
  • the S component of the intermediate beam is reflected by the polarizing prism and then reflected by the first quarter-wave plate and the first total reflection mirror, and then passes through the first quarter-wave plate again and then changes to the P polarization state, and directly passes through the polarization state.
  • the prism exit coincides with the S component of the intermediate beam.
  • P-light and S-light signal beams for Z-axis displacement of the two-dimensional diffraction grating for measurement are formed.
  • the upper beam and the lower beam are focused on the first phase grating by the third collimating lens and then diffracted to form three interference beams.
  • the phase difference of the three diffraction interference beams is preferably 120°.
  • a total of three detectors are detected separately. After photoelectric conversion, the X-axis displacement of the two-dimensional diffraction grating for measurement can be obtained through signal acquisition and processor processing and calculation.
  • the inner beam and the outer beam are reflected by the second total reflection mirror and the fourth collimating lens is focused on the second phase grating and then diffracted to form three interference beams.
  • the phase difference of the three diffraction interference beams is preferably 120°.
  • the fourth, fifth and sixth detectors detect respectively. After photoelectric conversion, the Y-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained through signal acquisition and processor processing and calculation.
  • the central beam contains two parts of P light and S light components, which are reflected by the second total reflection mirror and then diffracted through the second linear polarizer and the third phase grating placed at a polarization axis of 45° to form three interference beams.
  • the three interference beams The preferred angle of phase difference from each other is 120°, which are detected by the seventh, eighth, and ninth detectors respectively.
  • the Z-axis displacement of the two-dimensional diffraction grating for measurement can be obtained through signal acquisition and processor processing and calculation.
  • the three-axis measurement beam generating unit has a second optical path structure, which is different from the first one described above in that an S-polarized polarized collimated laser light source with opposite polarizing prisms is used.
  • an S-polarized polarized collimated laser light source with opposite polarizing prisms is used.
  • the overall positions of the first quarter-wave plate and the first total reflection mirror, the second quarter-wave plate, the second collimating objective, and the two-dimensional diffraction grating for measurement are reversed.
  • the center The beam polarization axes are still P and S, while the other beams are changed to P light.
  • the three-axis measurement beam generating unit has a third optical path structure, which is different from the first one described above in that: the S-polarized polarized collimated laser light source using a relative polarizing prism is used, but the polarized collimated laser light source, the beam splitting The overall positions of the two-dimensional diffraction grating, the first collimating lens, and the first linear polarizer are aligned with the overall positions of the first quarter-wave plate and the first total reflection mirror. Ultimately, the polarization states of the five outgoing beams are still the same as in the first case.
  • the three-axis measurement beam generating unit has a fourth optical path structure, which is different from the first one above in that the polarization collimated laser light source adopts a polarization state that forms a certain angle with respect to the P light and the S light of the polarizing prism.
  • the two-dimensional diffraction grating for beam splitting is a reflection type. Relative to the first case, the first quarter-wave plate is displaced to replace the first linear polarizer, allowing all beams to pass through, and the polarized collimated laser light source is displaced to replace the first total reflection mirror and the first quarter-wave piece.
  • the polarization states of the five outgoing beams are consistent with the first case.
  • the three-axis measurement beam generating unit has a fifth optical path structure, which is different from the first one described above in that the polarization collimated laser light source adopts a polarization state that forms a certain angle with respect to the P light and the S light of the polarizing prism, and the beam splits.
  • a two-dimensional diffraction grating is used as a reflection type.
  • the polarized collimated laser light source is shifted to replace the second quarter wave plate, the second collimation lens and the measurement of the overall position of the two-dimensional diffraction grating, while the second quarter wave plate, the second collimation lens and the measurement of the two-dimensional diffraction grating
  • the entirety of the diffraction grating replaces the entire position of the first total reflection mirror and the first quarter-wave plate.
  • the first quarter wave plate takes the place of the first linear polarizer and lets all beams pass through. Among the five outgoing beams, the polarization state of the central beam remains unchanged, and the others all change to the P polarization state.
  • homodyne interferometer the optical path of the Z-axis measurement beam and the optical path of the Z-axis measurement beam detection unit constitute a one-dimensional Michelson (Michelson) homodyne interferometer or a one-dimensional Mach-Zehnder (Mach-Zehnder) homodyne interferometer; thus An integrated three-dimensional displacement measurement homodyne grating interferometer; only one polarizing prism component is used in the optical element used, and the structure is compact and the cost is low.
  • Michelson Michelson
  • Mach-Zehnder Mach-Zehnder
  • the X and Y axis optical paths have 2x optical subdivision and optical differential signals, with high precision; the X axis and Y axis measurement beams are incident at the Littrow self-collimation angle to measure the two-dimensional diffraction grating, so they are not sensitive to Z axis displacement, and the installation capacity big difference.
  • the straight lines projected on the two-dimensional diffraction grating for measurement in the optical paths of the X-axis, Y-axis, and Z-axis measurement beams are orthogonal to each other and have common intersection points, corresponding to the corresponding measurement axes, avoiding the occurrence of different intersection points of the measurement axes. Abbe error and cosine error due to non-orthogonal measurement axes.
  • the two-dimensional diffraction grating for beam splitting may be a Dammann grating, or may be 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 may also be two-dimensional diffraction gratings.
  • a three-axis grating ruler composed of a three-dimensional Mach-Zehnder interferometer or a two-dimensional Mach-Zehnder interferometer and a one-dimensional Michelsion interferometer is proposed.
  • the optical path structure of the Littrow self-collimated incident measurement grating with large installation tolerance is obtained, and at the same time, the optical differential high-precision signal of the two axes (x, y) and the 2-fold optical precision signal are obtained.
  • Sub-function and large-scale Z-axis displacement measurement are obtained.
  • the three axes of the beams incident on the measurement grating intersect at one point, avoiding Abbe and cosine errors.
  • the homodyne interference technology which is different from heterodyne interference, is simple in structure, easy to manufacture and low in cost.
  • Fig. 1 is the schematic diagram of the optical system of the three-axis grating ruler of the present invention
  • FIG. 2 is a schematic diagram of a second three-axis measurement beam generating unit of the present invention.
  • FIG. 3 is a schematic diagram of a third three-axis measurement beam generating unit of the present invention.
  • FIG. 4 is a schematic diagram of a fourth three-axis measurement beam generating unit of the present invention.
  • FIG. 5 is a schematic diagram of a fifth three-axis measurement beam generating unit of the present invention.
  • FIG. 6 is a schematic diagram of the derivation of formulas (1), (2) and (3).
  • FIG. 1 is a schematic diagram of the optical system of the three-axis grating ruler of the present invention, including: a three-axis measurement beam generation unit 101, an X-axis measurement beam detection unit 104, a Y-axis measurement beam detection unit 103, a Z-axis measurement beam detection unit 102 and a signal acquisition unit and the processing unit 38; the three-axis measurement beam generation unit 101 generates an X-axis measurement beam, a Y-axis measurement beam and a Z-axis measurement beam, and along the X-axis measurement beam direction, the X-axis measurement beam is provided
  • the detection unit 104 is provided with the Y-axis measurement beam detection unit 103 along the Y-axis measurement beam direction, and the Z-axis measurement beam detection unit 102 is provided along the Z-axis measurement beam direction;
  • the three-axis measurement beam generating unit 101 includes: a polarized collimating laser light source 1, a two-dimensional diffraction grating 2 for beam splitting, a first collimating objective lens 8, a polarizing prism assembly 1011, a second collimating objective lens 14, and two measuring The two-dimensional diffraction grating 15; the two-dimensional diffraction grating 2 for beam splitting and the two-dimensional diffraction grating 15 for measurement are two-dimensional orthogonal symmetry, and the two-dimensional grating pitch is equal.
  • the grating distance d 1 of the two-dimensional diffraction grating 2 for beam splitting and the grating distance d 2 of the two-dimensional diffraction grating 15 for measurement, the focal length f 1 of the collimating objective lens 8 , and the focal length f 2 of the focusing and collimating objective lens 14 satisfy the relational formula (1).
  • the X-axis measurement beam detection unit 104 includes: a third collimating objective lens 33 , a first phase shift grating 34 , a first detector 35 , a second detector 36 , and a third detector 37 .
  • the focal length f 3 of the third collimating objective lens 33 and the grating pitch d 3 of the first phase shift grating 34 and the two-dimensional diffraction grating 2 grating pitch d 1 in the three-axis measurement beam generating unit 101 are the same as those of the first collimator.
  • the Y-axis measurement beam detection unit 103 includes: a second total reflection mirror 27 , a fourth collimating objective lens 28 , a second phase-shift grating 29 , a fourth detector 30 , a fifth detector 31 , and a sixth detector 32 .
  • the focal length f 1 of the straight objective lens 8 satisfies the relational expression (3).
  • the Z-axis measurement beam detection unit 102 includes 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 .
  • 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, corresponding to the polarizing prism assembly 1011 , comprising: a second linear polarizer 9 , a first total reflection mirror 12 , a first quarter-wave plate 11 , and a polarizing prism 10 , the second quarter wave plate 13 .
  • the polarized collimated laser light source 1 is in a P-polarized state.
  • the measurement principle of the optical path of the three-axis measurement beam generating unit 101 and the optical system of the three-axis grating ruler is as follows: take the polarizing prism 10 as the polarization state reference: the polarization collimated laser light source 1 emits a P-polarized beam, and the two-dimensional beam is transmitted through the transmission type beam splitting.
  • the diffraction grating 2 is divided into five beams, a left beam 3, a right beam 5, a front beam 7, a rear beam 4 and a middle beam 6, and the left beam 3 and the right beam 5 are in the plane formed by the middle beam 6 and the middle beam 6 axis.
  • Symmetric, 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 middle beam 6 passes through the first linear polarizer 9 which is rotated by 45° relative to the polarization axis of the P light, so that the polarization axis of the middle beam 6 is rotated by 45°.
  • the left beam 3 and the right beam 5 are respectively incident at the Littrow self-collimation angle to form the X-axis retroreflected beam; the rear beam 4 and the front beam 7 are respectively incident at the Littrow self-collimation angle to form the Y-axis retroreflected beam; the middle beam
  • the P light component of 6 is normally incident and retroreflected, forming the P light component of the Z-axis retroreflected beam.
  • the retroreflected beams of the P light components of the left beam 3, the right beam 5, the front beam 7, the rear beam 4 and the middle beam 6 are self-collimated by the second collimating lens 14, and then passed through the second quarter wave.
  • the plate 13 is converted into an S-polarized light beam, and is reflected by the polarizing prism 10 to obtain the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5 respectively, and the outer beam 20 and the inner beam corresponding to the front beam 7 and the rear two beams 4 respectively. 19, and the central beam 18 corresponding to the intermediate beam 6, thereby forming a two-dimensional diffraction grating 15 displacement signal beam for X-axis and Y-axis measurement, with positive and negative Doppler frequency shift signals respectively;
  • the S-polarized light beam of the intermediate beam 6 is reflected by the first quarter-wave plate 11 and the first total reflection mirror 12 after being reflected by the polarizing prism 10, and then converted into the second quarter-wave plate 11 after being reflected.
  • the P-polarized state directly exits through the polarizing prism and coincides with the central beam 18 to form the P-light and S-light signal beams of the Z-axis displacement of the two-dimensional diffraction grating for measurement.
  • the three-axis measurement beam generating unit 101 of the X-axis, the Y-axis, and the Z-axis is formed.
  • the upper beam 16 and the lower beam 17 are focused on the first phase grating 34 by the third collimating lens 33 and diffracted to form three interference beams.
  • the second detector 36 and the third detector 37 respectively detect.
  • the X-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained through signal acquisition and processing and calculation by the processor 38 .
  • the inner beam 19 and the outer beam 20 are reflected by the second total reflection mirror 27 and focused by the fourth collimating lens 28 on the second phase grating 29 and diffracted to form three interference beams.
  • the phase difference of the three diffraction interference beams is preferably 120°. °, respectively detected by the fourth detector 30, the fifth detector 31, and the sixth detector 32.
  • the Y-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained through signal acquisition and processing and calculation by the processor 38 .
  • the central beam 18 contains two parts of the P polarization state and the S polarization state. After being reflected by the second total reflection mirror, it is diffracted by the second linear polarizer 22 and the third phase grating 23 with the polarization axis at 45° to form three interference beams.
  • the interfering beams are preferably out of phase with each other by an angle of 120°, which are detected by the seventh detector 24 , the eighth detector 25 , and the ninth detector 26 , respectively.
  • the Z-axis displacement of the two-dimensional diffraction grating 15 for measurement can be obtained after signal acquisition and processing and calculation by the processor 38 .
  • Fig. 2 is a second scheme different from the optical path of the three-axis measurement beam generating unit 101 described above:
  • the polarized collimated laser light source 1 is in the S polarization state.
  • the polarized collimated laser light source 1 emits an S-polarized beam, which is divided into a left beam 3, a right beam 5, a front beam 7, a rear beam 4 and a middle beam by a two-dimensional diffraction grating 2 through the transmission type beam splitting.
  • the beam 6 has five beams in total, and the left beam 3 and the right beam 5 are axially symmetrical with the middle beam 6 in the plane formed by the middle beam 6, and the front beam 7 and the rear beam 4 are in the plane formed by the middle beam 6. 6-axis symmetry;
  • the middle beam 6 passes through the first linear polarizer 9 which is rotated by 45° relative to the polarization axis of the P light, so that the polarization axis of the middle beam 6 is rotated by 45°.
  • the left beam 3 and the right beam 5 are respectively incident at the Littrow self-collimation angle to form the X-axis retroreflected beam; the rear beam 4 and the front beam 7 are respectively incident at the Littrow self-collimation angle to form the Y-axis retroreflected beam; the middle beam
  • the S light component of 6 is normally incident and retroreflected, forming the S light component of the Z-axis retroreflected beam.
  • 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 converge at one point, avoiding Abbe errors caused by the separation of the measurement axes X, Y, and Z.
  • the retroreflected beams of the S component 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 retroreflected by the second collimating lens 14, and then pass through the second quarter wave.
  • the plate is transformed into a P-polarized light beam, and the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5 are obtained respectively through the polarizing prism 10, and the outer beam 20 and the inner beam 19 corresponding to the front beam 7 and the rear beam 4 respectively, And the center beam 18 corresponding to the intermediate beam 6, thereby forming the X-axis and the Y-axis measurement with the two-dimensional diffraction grating 15 displacement signal beam, respectively with positive and negative Doppler frequency shift signals;
  • the P-polarized beam of the intermediate beam 6 passes through the polarizing prism 10 and the first quarter-wave plate 11, is reflected by the first total reflection mirror 12, and is converted after passing through the second quarter-wave plate 11 for the second time. It is in the S-polarized state, and is then reflected by the polarizing prism to coincide with the beam 18.
  • P-light and S-light signal beams for Z-axis displacement of the two-dimensional diffraction grating for measurement are formed.
  • the X-axis and Y-axis and Z-axis measurement beam detection optical paths are all consistent with the first case.
  • Fig. 3 is a third scheme different from the optical path of the three-axis measurement beam generating unit 101 described above:
  • the polarized collimated laser light source 1 is in the S polarization state.
  • the polarized collimated laser light source 1 emits an S-polarized beam, which is divided into a left beam 3, a right beam 5, a front beam 7, a rear beam 4 and a middle beam by a two-dimensional diffraction grating 2 through the transmission type beam splitting.
  • the beam 6 has five beams in total, and the left beam 3 and the right beam 5 are axially symmetrical with the middle beam 6 in the plane formed by the middle beam 6, and the front beam 7 and the rear beam 4 are in the plane formed by the middle beam 6. 6-axis symmetry;
  • the middle beam 6 passes through the first linear polarizer 9 which is rotated by 45° relative to the polarization axis of the P light, so that the polarization axis of the middle beam 6 is rotated by 45°.
  • Two components of light in which the S light is reflected by the polarizing prism 10 together with the other four beams, passes through the first quarter wave plate 11 together and is reflected by the first total reflection mirror 12, and passes through the first quarter twice A wave plate 11, the polarization states of the five beams are converted to P polarization state, directly pass through the polarizing prism 10, and then pass through the second quarter wave plate 13 and the second collimating lens 14 to converge and incident on the reflection type measurement 15 surfaces with a two-dimensional diffraction grating.
  • the left beam 3 and the right beam 5 are respectively incident at the Littrow self-collimation angle to form the X-axis retroreflected beam; the rear beam 4 and the front beam 7 are respectively incident at the Littrow self-collimation angle to form the Y-axis retroreflected beam; the middle beam
  • the S light component of 6 is normally incident and retroreflected, forming the S light component of the Z-axis retroreflected beam.
  • 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 converge at one point, avoiding Abbe errors caused by the separation of the measurement axes X, Y, and Z.
  • the retroreflected beams of the S component 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 retroreflected by the second collimating lens 14, and then pass through the second quarter wave.
  • the plate 13 is converted into an S-polarized light beam, and is reflected by the polarizing prism 10 to obtain the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5 respectively, and the outer beam 20 and the inner beam corresponding to the front beam 7 and the rear two beams 4 respectively. 19, and the central beam 18 corresponding to the intermediate beam 6, thereby forming a two-dimensional diffraction grating 15 displacement signal beam for X-axis and Y-axis measurement, with positive 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 directly exits to coincide with the central light beam 18 .
  • P-light and S-light signal beams for Z-axis displacement of the two-dimensional diffraction grating for measurement are formed.
  • the X-axis and Y-axis and Z-axis measurement beam detection optical paths are all consistent with the first case.
  • Fig. 4 is a fourth scheme different from the optical path of the three-axis measurement beam generating unit 101 described above:
  • the two-dimensional diffraction grating 2 for beam splitting is a reflective type, and correspondingly, the polarizing prism assembly 1011 is only composed of a first quarter-wave plate 11 , a polarizing prism 10 and a second quarter-wave plate 13 .
  • the polarized collimated laser light source 1 is linearly polarized light at a certain angle with the P light and the S light, and thus has both the P light and the S light polarization components.
  • the polarized collimated laser light source 1 emits a polarized beam with P light and S light polarization components, and the S light component beam is reflected by the polarizing prism 10, and then passes through the first quarter-wave plate.
  • 11 and the first collimating lens 8, which are normally incident on the reflective beam splitting two-dimensional diffraction grating 2 are divided into five beams of left beam 3, right beam 5, front beam 7, rear beam 4 and middle beam 6, and the left beam 3.
  • the right beam 5 is axisymmetric with the middle beam 6 in the plane formed by the middle beam 6, and the front beam 7 and the rear beam 4 are axisymmetric with the middle beam 6 in the plane formed by the middle beam 6;
  • the five beams are collimated by the first collimating lens 8, they pass through the first quarter-wave plate 11 together, and the polarization states are all converted into P polarization states, directly pass through the polarizing prism 10, and then pass through the second quarter of A wave plate 13 and a second collimating lens 14 are condensed and incident on the surface of the reflection-type measurement two-dimensional diffraction grating 15 .
  • the left beam 3 and the right beam 5 are respectively incident at the Littrow self-collimation angle to form the X-axis retroreflected beam; the rear beam 4 and the front beam 7 are respectively incident at the Littrow self-collimation angle to form the Y-axis retroreflected beam; the middle beam
  • the S light component of 6 is normally incident and retroreflected, forming the S light component of the Z-axis retroreflected beam.
  • 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 converge at one point, avoiding Abbe errors caused by the separation of the measurement axes X, Y, and Z.
  • the left beam 3, the right beam 5, the rear beam 4, the front beam 7, and all the retroreflected beams corresponding to the S component of the middle beam 6 are collimated and retroreflected by the second collimating lens 14, and then pass through the second
  • the quarter-wave plate 13 is converted into an S-polarized beam, which is reflected by the 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, corresponding to the front beam 7 and the outer beams of the latter two beams 4.
  • the P-polarized light beam of the intermediate light beam 6 directly exits through the polarizing prism 10 and coincides with the central light beam 18 .
  • P-light and S-light signal beams for Z-axis displacement of the two-dimensional diffraction grating for measurement are formed.
  • the X-axis and Y-axis and Z-axis measurement beam detection optical paths are all consistent with the first case.
  • Fig. 5 is a fifth scheme different from the optical path of the above-mentioned three-axis measurement beam generating unit 101:
  • the two-dimensional diffraction grating 2 for beam splitting is a reflective type, and correspondingly, the polarizing prism assembly 1011 is only composed of a first quarter-wave plate 11 , a polarizing prism 10 and a second quarter-wave plate 13 .
  • the polarized collimated laser light source 1 is linearly polarized light at a certain angle with the P light and the S light, and thus has both the P light and the S light polarization components. Taking the polarizing prism 10 as the polarization state reference, the polarized collimated laser light source 1 emits a polarized beam with polarization components of P light and S light, and the P light component beam passes through the polarizing prism 10 and the first quarter-wave plate 11 and the first quarter-wave plate 11.
  • a collimating lens 8 which is normally incident on the reflection type beam splitting two-dimensional diffraction grating 2, is divided into five beams: left beam 3, right beam 5, front beam 7, rear beam 4 and middle beam 6, and left beam 3, right beam 6
  • the beam 5 is axisymmetric with the middle beam 6 in the plane formed with the middle beam 6, and the front beam 7 and the rear beam 4 are axisymmetric with the middle beam 6 in the plane formed by the middle beam 6;
  • the five beams are collimated by the first collimating lens 8, they pass through the first quarter-wave plate 11, and their polarization states are all converted into S-polarization states. After being reflected by the polarizing prism 10, they pass through the second quarter A wave plate 13 and a second collimating lens 14 are condensed and incident on the surface of the reflection-type measurement two-dimensional diffraction grating 15 .
  • the left beam 3 and the right beam 5 are respectively incident at the Littrow self-collimation angle to form the X-axis retroreflected beam; the rear beam 4 and the front beam 7 are respectively incident at the Littrow self-collimation angle to form the Y-axis retroreflected beam; the middle beam
  • the P light component of 6 is normally incident and retroreflected, forming the P light component of the Z-axis retroreflected beam.
  • the P light components of the left beam 3, the right beam 5, the rear beam 4, the front beam 7, and the middle beam 6 converge at one point, avoiding Abbe errors caused by the separation of the measurement axes X, Y, and Z.
  • the retroreflected beams of the P light 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 retroreflected by the second collimating lens 14, and then pass through the second
  • the half-wave plate 13 is converted into a P-polarized light beam, which is directly emitted through the polarizing prism 10 to obtain the lower beam 17 and the upper beam 16 corresponding to the left beam 3 and the right beam 5 respectively, corresponding to the front beam 7 and the outer beams of the latter two beams 4 respectively.
  • the S-polarized light beam of the intermediate light beam 6 is reflected by the polarizing prism 10 and exits to coincide with the light beam 18 .
  • P-light and S-light signal beams for Z-axis displacement of the two-dimensional diffraction grating for measurement are formed.
  • the X-axis and Y-axis and Z-axis measurement beam detection optical paths are all consistent with the first case.
  • the polarized collimated laser light source 1 obtains the left beam 3 and the right beam 5 after beam splitting, and the optical path that is diffracted and exited by the first phase grating 34 is essentially an X-axis Mach-Zehnder interferometer, and the first detector 35
  • the signals obtained by the second detector 36 and the third detector 37 are actually the X-axis Doppler frequency-shifted optical differential signals of the measurement of the two-dimensional diffraction grating 15, which have 2-fold optical subdivision characteristics, and have higher accuracy than electronic differential signals. .
  • the polarized collimated laser light source 1 obtains a back beam 4 and a front beam 7 after beam splitting until it is diffracted by the second phase grating 29 and the light path is essentially a Y-axis Mach-Zehnder Mach-Zehnder interferometer, and the fourth
  • the signals obtained by the detector 30 , the fifth detector 31 , and the sixth detector 32 are actually the Y-axis Doppler frequency-shifted optical differential signals of the two-dimensional diffraction grating 15 for measurement, which have 2-fold optical subdivision characteristics. , with higher precision.
  • the X-axis Mach-Zehnder Mach-Zehnder interferometer and the Y-axis Mach-Zehnder Mach-Zehnder interferometer constitute a two-dimensional Mach-Zehnder Mach-Zehnder interferometer.
  • the polarized collimated laser light source 1 obtains an intermediate beam 6 after beam splitting until it is diffracted and exited by the third phase grating 23.
  • the light path is essentially a Z-axis Michelson Michelson interferometer; Figs. 4 and 4, In Fig. 5, the polarized collimated laser light source 1 is split to obtain an intermediate beam 6 until it is diffracted by the third phase grating 23 and the light path is essentially a Z-axis Mach-Zehnder Mach-Zehnder interferometer, thus forming a three-dimensional Mach-Zehnder interferometer.
  • -Zehnder Mach-Zehnder interferometer the signals obtained by the seventh detector 24 , the eighth detector 25 , and the ninth detector 26 are actually the Z-axis displacement signals of the two-dimensional diffraction grating 15 measured.
  • the straight lines projected on the measurement two-dimensional diffraction grating 15 in the optical paths of the X-axis, Y-axis, and Z-axis measurement beams are orthogonal and have a common intersection point, corresponding to the corresponding measurement axes. Abbe errors caused by different intersection points of measurement axes and cosine errors caused by non-orthogonal measurement axes are avoided.
  • the three-dimensional Mach-Zehnder Mach-Zehnder interferometer or the two-dimensional Mach-Zehnder Mach-Zehnder interferometer and the one-dimensional Michelson Michelson interferometer constitute a three-dimensional displacement measurement homodyne grating interferometer, which is composed of a signal acquisition and processor 38
  • the three-axis grating ruler of the present invention Compact structure, low cost, X, Y axis optical path has 2 times optical subdivision and optical differential signal, high precision and large installation tolerance.
  • FIG. 6 is a schematic diagram of formula 1 derivation.
  • G1 represents the two-dimensional diffraction grating 2 for beam splitting, the grating distance is d 1 ;
  • L1 represents the first collimating lens 8, the focal length is f 1 ;
  • L2 represents the second collimating lens 14, the focal length is f 2 , and
  • G2 represents the measuring two A three-dimensional diffraction grating 15 with a grating pitch of d 2 is provided.
  • ⁇ 1 is the diffraction angle of the ⁇ 1st-order G 1 grating diffraction beam splitting, which satisfies:
  • ⁇ 2 is the Littrow self-collimating incident angle of G 2 , which satisfies:
  • L2 represents the third collimating lens 33
  • the focal length is f 3
  • G2 represents the first phase grating 34
  • the grating distance is d3
  • the upper beam 16 and the lower beam 17 are focused on the first phase grating through the third collimating lens 33 34 diffracted to form three interference beams, such as the dashed outgoing beams D1, D2, and D3 in Figure 6.
  • the three diffracted interference beams are preferably out of phase with each other by an angle of 120°, which are detected by the first detector 35 , the second detector 36 and the third detector 37 respectively. From this, the relation (2) is derived.
  • L2 represents the fourth collimating lens 28, the focal length is f4 , G2 represents the second phase grating 29, the grating distance is d4, the inner beam 19 and the outer beam 20 are focused on the second phase grating through the fourth collimating lens 28 29 diffracted to form three interfering beams, such as the dashed outgoing beams D1, D2, and D3 in Figure 6.
  • the three diffracted interference beams are preferably out of phase with each other by a preferred angle of 120°, and are detected by the fourth detector 30 , the fifth detector 31 , and the sixth detector 32 respectively. From this, the relation (3) is derived.
  • the two-dimensional diffraction grating 2 for beam splitting may be a Dammann grating, or may be a combination of two one-dimensional diffraction gratings.
  • the first phase shift grating 34 , the second phase grating 29 , and the third phase grating 23 are one-dimensional diffraction gratings, and may also be two-dimensional diffraction gratings.

Landscapes

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

Abstract

三轴光栅尺，包括三轴测量光束产生单元（101）、X轴测量光束探测单元（104）、Y轴测量光束探测单元（103）、Z轴测量光束探测单元（102）和信号采集及处理单元（38）。三轴测量光束产生单元（101），包括偏振准直激光光源（1）、分束用二维衍射光栅（2）、第一准直物镜（8）、偏振棱镜组件（1011）、第二准直物镜（14）和测量用二维衍射光栅（15）。分束用二维衍射光栅（2）和测量用二维衍射光栅（15）是二维正交对称，各自两维度栅距相等。X，Y轴测量光束产生光路具有2倍光学细分及光学差分特性，精度高，安装容差大；测量光束产生单元光路与测量光束探测单元光路共同构成一体的三维位移测量零差光栅干涉仪，结构紧凑，成本低，并且避免了不满足正交和共交点所导致的阿贝误差和余弦误差。

Description

一种三轴光栅尺 技术领域
本发明属于精密光学测量仪器领域，特别涉及一种用于三自由度位移测量的三轴光栅尺。
背景技术
光栅尺又称光学编码器，广泛应用于精密运动台、精密光学机械、精密测量仪器等领域的位移和角度测量。其中，基于高密度衍射光栅的光栅尺相比基于低密度普通几何光栅的光栅尺，具有更高精度和分辨率，可达到亚纳米级。世界上最精密的设备——光刻机已采用此类仪器进行高精密位移和角度测量。
随着精密制造技术的发展，尤其是光刻机技术的推动，多自由度的位移测量需求不断涌现。因此，迫切需要面向三自由度乃至更多自由度的位移测量光栅尺的研发。
国际市场上，德国海德汉最早推出了基于衍射光栅的光栅尺，已开发出了用于二自由度位移测量的二轴光栅尺。其原理是基于其专利US4776701。这一专利所给出的光学光路及其实际产品使用效果表明，相对于固定在被测量物体表面的测量衍射光栅，读数头的安装距离要求严格，稍有前后移动便会导致其探测器上的光斑横向移动，产生误差。此外，其三自由位移测量的扩展较为困难，尚未设计出相应的三轴光栅尺。
美国专利US5098190给出了另外一种基于衍射光栅的光栅尺结构。其特征是，光源发出准直激光束至测量光栅表面，经其衍射后的正、负一级衍射光通过透镜聚焦于相位光栅，产生三束彼此相移120°的干涉光束。再由探测器光电转换及信号处理器处理后，可得出相应的测量光栅位移信息。此专利同样存在光栅读数头相对于测量光栅距离敏感，容易产生误差的问题。上面所述两个专利，其光路本质上是马赫-泽德(Mach-Zehnder)干涉仪。因此，两自由度的测量信号是基于多普勒频移的光学差分信号，相对单独位移测量的电子差分，精度更高。
Kao等提出的二自由度测量光栅尺(C.F.KAO,S.H.LU，et.al.,Diffractive Laser Encoder with a Grating in Littrow Configuration,Jpn.J.Appl.Phys.47.1833-1837)采用Littrow自准直角度入射测量光栅，使得光栅尺读数头安装容差变得较大，但本质上是两个独立的一维光路结构，复杂，不易制作，容易产生阿贝误差。此外，三自由度测量扩展更为复杂。其光路本质上亦是马赫-泽德干涉仪。
Gao研究小组提出了三自由度(A.Kimura,Wei Gao,W.Kim et.al,A sub-nanometric three-axis surface encoder with short-period planar gratings for stage motion measurement,Precision Engineering 36(2013),771-781)、六自由度(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)测量的三轴、六轴光栅尺。中国专利CN103307986A，CN103322927B分别给出了一种二自由度测量的二轴光栅尺和一种三自由度测量的三轴光栅尺。上面所述文献和专利，其光路本质上是迈克尔逊(Michelsion)干涉仪，无光学细分功能，亦即分辨率相对降低一半；此外，同样存在光栅读数头相对于测量光栅距离敏感，容易产生误差的问题。而且，各自由度信号是电子差分信号。相对光学差分，精度不高。
中国专利CN10862709913给出了一种五自由度测量的五轴光栅尺，尽管利用了Littrow自准直入射测量光栅，改善了安装容差，但是结构堆叠，制造困难，并且仍为迈克尔逊干涉仪变形形式，各自由度位移信号仍采用电子差分获得，无光学细分功能，亦即分辨率相对降低一半。
中国专利CN106017308B给出了一种六自由度测量的六轴光栅尺，读数头由三个光栅读数头和三个外差激光读数表头交叉叠放而成，测量光栅阵列由三个测量光栅组件和三个外差激光反射镜交叉叠放而成，较为复杂，不易制造，并且X、Y、Z轴是分离的，容易造成阿贝误差。
发明内容
本发明三轴光栅尺，包括：三轴测量光束产生单元、X轴测量光束探测单元、Y轴测量光束探测单元、Z轴测量光束探测单元和信号采集及处理单元；所述的三轴测量光束产生单元产生X轴测量光束、Y轴测量光束和Z轴测量光束；沿所述的X轴测量光束方向，设有所述的X轴测量光束探测单元，沿所述的Y轴测量光束方向设有所述的Y轴测量光束探测单元，沿所述的Z轴测量光束方向设有Z轴测量光束探测单元；
所述三轴测量光束产生单元，包括：偏振准直激光光源，分束用二维衍射光栅，第一准直物镜，偏振棱镜组件，第二准直物镜，测量用二维衍射光栅；所述分束用二维衍射光栅和测量用二维衍射光栅是二维正交对称，各自两维度栅距相等。所述分束用二维衍射光栅栅距d 1与测量用二维衍射光栅栅距d 2，第一准直物镜焦距f 1，第二准直物镜焦距f 2满足如下关系式(1),其中λ为偏振准直激光光源波长，优化情形是：d 1＝2d 2，f 1＝f 2。
所述X轴测量光束探测单元，包括：第三准直物镜，第一相移光栅，第一探测器，第二探测器，第三探测器。所述第三准直物镜焦距f 3和第一相移光栅栅距d 3与所述三轴测量光束产生单元中的分束用二维衍射光栅栅距d 1和第一准直物镜焦距f 1，满足如下关系式(2),其中λ为偏振准直激光光源波长，优化情形是：d 1＝d 3，f 1＝f 3。
所述Y轴测量光束探测单元，包括：第二全反镜，第三准直物镜，第二相移光栅，第四探测器，第五探测器，第六探测器。所述第三准直物镜焦距f 4和第二相移光栅栅距d 4与所述三轴测量光束产生单元中的分束用二维衍射光栅栅距d 1和准直物镜焦距f 1，满足如下关系式(3),其中λ为偏振准直激光光源波长，优化情形是：d 1＝d 4，f 1＝f 4。
所述Z轴测量光束探测单元，包括第三全反镜，第二线偏振片，第三相移光栅，第七探测器，第八探测器，第九探测器。
所述测量用二维衍射光栅是反射型。所述分束用二维衍射光栅是透射型，相应所述偏振棱镜组件，包含：第一线偏振片，第一全反镜，第一四分之一波片，偏振棱镜，第二四分之一波片。
所述偏振准直激光光源为P偏振态，所述三轴测量光束产生单元光路及三轴光栅尺测量原理如下：以偏振棱镜为偏振态参考物：偏振准直激光光源发出P偏振光束，经透射型分束用二维衍射光栅分成左光束、右光束、前光束、后光束及中间光束共五束光束,且左光束、右光束在与中间光束组成的平面内以中间光束轴对称，前光束、后光束在与中间光束组成的平面内以中间光束轴对称。
五束光束由第一准直透镜准直后，仅中间光束通过相对P光偏振轴旋转45°的第一线偏振片，使中间光束偏振轴旋转45°，具备P光和S光两个分量，其中P光与其它四束光束一起通过偏振棱镜，再一起经过第二四分之一波片及第二准直透镜会聚入射于测量用二维衍射光栅表面。其中，左光束、右光束分别以Littrow自准直角度入射，形成X轴回射光束；前光束、后光束分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束的P光分量正入射并回射，形成Z轴回射光束P光分量。
所述左光束、右光束、前光束、后光束、中间光束的P光分量会聚与一点。所述左光束、右光束、前光束、后光束、中间光束的P光分量的回射光束自准直回射后，经第二四分之一波片转变为S偏振态光束，通过偏振棱镜反射分别得到对应左光束和右光束的下光束和上光束，分别对应前光束和后两束的外光束和里光束，以及对应中间光束的中心光束，从而形成X轴和Y轴及Z轴测量用二维衍射光栅位移信号光束，分别带有正、负多普勒频移信号。
所述中间光束的S分量经偏振棱镜反射后由第一四分之一波片和第一全反镜反射后，再次通过第一四分之一波片后转变为P偏振态，直接通过偏振棱镜出射与中间光束S分量重合。形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
上光束、下光束经过第三准直透镜聚焦于第一相位光栅后衍射形成三束干涉光束，所述三束衍射干涉光束彼此相位相差优选角度是120°，由第一、第二、第三共三个探测器分别探测。经光电转换后通过信号采集及处理器处理和计算后可获得测量用二维衍射光栅的X轴位移量。
里光束、外光束经过第二全反镜反射及第四准直透镜聚焦于第二相位光栅后衍射形成三束干涉光束，所述三束衍射干涉光束彼此相位相差优选角度是120°，由第四、第五、第六三个探测器分别探测。经光电转换后通过信号采集及处理器处理和计算后可获得测量用二维衍射光栅15的Y轴位移量。
中心光束含有P光和S光分量两部分，经第二全反镜反射后通过偏振轴45°放置的第二线偏振片及第三相位光栅后衍射形成三束干涉光束，所述三束干涉光束彼此相位相差优选角 度是120°，由第七、第八、第九三个探测器分别探测。经光电转换后通过信号采集及处理器处理和计算后可获得测量用二维衍射光栅的Z轴位移量。
所述三轴测量光束产生单元具有第二种光路结构，其与上面所述第一种不同在于：采用相对偏振棱镜的S偏振态偏振准直激光光源。但第一四分之一波片及第一全反镜整体与第二四分之一波片和第二准直物镜、测量用二维衍射光栅整***置对调，最终五束出射光束中，中心光束偏振轴仍为P和S，而其它光束改变为P光。
所述三轴测量光束产生单元具有第三种光路结构，其与上面所述第一种不同在于：采用相对偏振棱镜的S偏振态偏振准直激光光源，但偏振准直激光光源、分束用二维衍射光栅、第一准直透镜、第一线偏振片整***置与第一四分之一波片及第一全反镜整***置对调。最终，五束出射光束偏振态仍与第一种情形相同。
所述三轴测量光束产生单元具有第四种光路结构，其与上面所述第一种不同在于：偏振准直激光光源采用相对偏振棱镜的P光和S光成一定角度的偏振态。分束用二维衍射光栅为反射型。相对第一种情形，第一四分之一波片移位替代第一线偏振片，并让所有光束通过，偏振准直激光光源移位替代第一全反镜和第一四分之一波片。五束出射光束偏振态与第一种情形一致。
所述三轴测量光束产生单元具有第五种光路结构，其与上面所述第一种不同在于：偏振准直激光光源采用相对偏振棱镜的P光和S光成一定角度的偏振态，分束用二维衍射光栅为反射型。偏振准直激光光源移位替代第二四分之一波片，第二准直透镜及测量二维衍射光栅整***置，而第二四分之一波片，第二准直透镜及测量二维衍射光栅整体替代第一全反镜和第一四分之一波片整***置。第一四分之一波片替代第一线偏振片位置，并让所有光束通过。五束出射光束中，中心光束偏振态不变，其他皆变为P偏振态。
所述三轴测量光束产生单元中，X轴测量光束光路与X轴测量光束探测单元光路，Y轴测量光束光路与Y轴测量光束探测单元光路，共同构成两维Mach-Zehnder(马赫-泽德)零差干涉仪；Z轴测量光束光路与Z轴测量光束探测单元光路构成一维Michelson(迈克尔逊)零差干涉仪或一维Mach-Zehnder(马赫-泽德)零差干涉仪；由此构成一体的三维位移测量零差光栅干涉仪；所采用的光学元件中仅有一个偏振棱镜组件，结构紧凑，成本低。X，Y轴光路具有2倍光学细分及光学差分信号，精度高；X轴、Y轴测量光束以Littrow自准直角度入射测量二维衍射光栅，因此对Z轴向位移不敏感，安装容差大。所述X轴、Y轴、Z轴测量光束产生光路中，投影于测量用二维衍射光栅上的直线，两两正交且共交点，对应为相应测量轴，避免了测量轴交点不同导致的阿贝误差以及测量轴非正交导致的余弦误差。
所述分束用二维衍射光栅可以是Dammann(达曼)光栅，亦可以是两个一维衍射光栅组合。
所述第一相移光栅、第二相移光栅、第三相移光栅是一维衍射光栅，亦可是二维衍射光栅。
与现有技术相比，本发明的有益效果是：
1)提出一种由三维马赫-泽德(Mach-Zehnder)干涉仪或两维马赫-泽德(Mach-Zehnder)干涉仪和一维迈克尔逊(Michelsion)干涉仪组成的三轴光栅尺。通过光路中光学元件间相关参数特定设计，获得大的安装容差的Littrow自准直入射测量光栅的光路结构，同时，获得两轴(x，y)的光学差分高精度信号和2倍光学细分功能以及大范围Z轴位移测量。此外，入射测量光栅的光束三轴交于一点，避免了阿贝误差和余弦误差。采用不同于外差干涉的零差干涉技术，其结构简单，易于制造，成本低。
2)采用三维马赫-泽德(Mach-Zehnder)干涉仪或两维马赫-泽德(Mach-Zehnder)干涉仪和一维迈克尔逊(Michelsion)干涉仪的一体化有效组合及其光路的特定设计，较全面解决了已有技术的缺陷和不足；进而可以获得本领域研发人员长期渴望得到的较全面优良性能的三轴光栅尺。
附图说明
图1为本发明三轴光栅尺光学***示意图；
图2为本发明第二种三轴测量光束产生单元示意图；
图3为本发明第三种三轴测量光束产生单元示意图；
图4为本发明第四种三轴测量光束产生单元示意图；
图5为本发明第五种三轴测量光束产生单元示意图；
图6为公式(1)、(2)、(3)推导示意图。
具体实施方式
下面结合实施例对本发明作进一步详细的描述，但本发明的实施方式不限于此。
如图1为本发明三轴光栅尺光学***示意图，包括：三轴测量光束产生单元101、X轴测量光束探测单元104、Y轴测量光束探测单元103、Z轴测量光束探测单元102和信号采集及处理单元38；所述的三轴测量光束产生单元101产生X轴测量光束、Y轴测量光束和Z轴测量光束，沿所述的X轴测量光束方向，设有所述的X轴测量光束探测单元104，沿所述的Y轴测量光束方向设有所述的Y轴测量光束探测单元103，沿所述的Z轴测量光束方向设有Z轴测量光束探测单元102；
所述三轴测量光束产生单元101，包括：偏振准直激光光源1，分束用二维衍射光栅2，第一准直物镜8，偏振棱镜组件1011，第二准直物镜14，测量用二维衍射光栅15；所述分束用二维衍射光栅2和测量用二维衍射光栅15是二维正交对称，各自两维度栅距相等。所述分束用二维衍射光栅2栅距d 1与测量用二维衍射光栅15栅距d 2，准直物镜8焦距f 1，聚焦准直物镜14焦距f 2满足关系式(1)。
其中λ为偏振准直激光光源波长，优化情形是：d 1＝2d 2，f 1＝f 2。
所述X轴测量光束探测单元104，包括：第三准直物镜33，第一相移光栅34，第1探测器35，第2探测36，第3探测器37。所述第三准直物镜33焦距f 3和第一相移光栅34栅距d 3与所述三轴测量光束产生单元101中的分束用二维衍射光栅2栅距d 1与第一准直物镜8焦距f 1，满足关系式(2).其中λ为偏振准直激光光源1波长，优化情形是：d 1＝d 3，f 1＝f 3。
所述Y轴测量光束探测单元103，包括：第二全反镜27，第四准直物镜28，第二相移光栅29，第4探测器30，第5探测31，第6探测器32。所述第四准直物镜28焦距f 4和第二相移光栅29栅距d 4与所述三轴测量光束产生单元101中的分束用二维衍射光栅2栅距d 1与第一准直物镜8焦距f 1，满足关系式(3)。其中λ为偏振准直激光光源波长，优化情形是：d 1＝d 4，f 1＝f 4。
所述Z轴测量光束探测单元102，包括第三全反镜21，第二线偏振片22，第三相移光栅23，第7探测器24，第8探测器25，第9探测器26。
所述测量用二维衍射光栅15是反射型。所述分束用二维衍射光栅2是透射型，相应所述偏振棱镜组件1011，包含：第二线偏振片9，第一全反镜12，第一四分之一波片11，偏振棱镜10，第二四分之一波片13。
所述偏振准直激光光源1为P偏振态。
所述三轴测量光束产生单元101光路及三轴光栅尺光学***测量原理如下：以偏振棱镜10为偏振态参考物：偏振准直激光光源1发出P偏振光束，经透射型分束用二维衍射光栅2分成左光束3、右光束5、前光束7、后光束4及中间光束6共五束光束，且左光束3、右光束5在与中间光束6组成的平面内以中间光束6轴对称，前光束7、后光束4在与中间光束6组成的平面内以中间光束6轴对称；
五束光束由第一准直透镜8准直后，仅中间光束6通过相对P光偏振轴旋转45°的第一线偏振片9，使中间光束6偏振轴旋转45°，具备P光和S光两个分量，其中P光与其它四束光束一起通过偏振棱镜10，再一起经过第二四分之一波片13及第二准直透镜14会聚入射于测量用二维衍射光栅15表面。其中，左光束3和右光束5分别以Littrow自准直角度入射，形成X轴回射光束；后光束4和前光束7分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束6的P光分量正入射并回射，形成Z轴回射光束P光分量。所述左光束3、右光束5、前光束7、后光束4和中间光束6的P光分量的回射光束再由第二准直透 镜14自准直后，经第二四分之一波片13转变为S偏振态光束，通过偏振棱镜10反射得到分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18，从而形成X轴和Y轴测量用二维衍射光栅15位移信号光束，分别带有正、负多普勒频移信号；
所述中间光束6的S偏振态光束经偏振棱镜10反射后由第一四分之一波片11和第一全反镜12反射后，再通过第二四分之一波片11后转变为P偏振态，直接通过偏振棱镜出射与中心光束18重合，形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
至此，形成了X轴、Y轴、Z轴的三轴测量光束产生单元101。
上光束16、下光束17经过第三准直透镜33聚焦于第一相位光栅34衍射形成三束干涉光束，所述三束衍射干涉光束彼此相位相差优选角度是120°，由第一探测器35、第二探测器36、第三探测器37分别探测。经光电转换后通过信号采集及处理器38处理和计算后可获得测量用二维衍射光栅15的X轴位移量。
里光束19、外光束20经过第二全反镜27反射及第四准直透镜28聚焦于第二相位光栅29衍射形成三束干涉光束，所述三束衍射干涉光束彼此相位相差优选角度是120°，由第四探测器30、第五探测器31、第六探测器32分别探测。经光电转换后通过信号采集及处理器38处理和计算后可获得测量用二维衍射光栅15的Y轴位移量。
中心光束18含有P偏振态和S偏振态两部分，经第二全反镜反射后通过偏振轴45°放置的第二线偏振片22及第三相位光栅23衍射形成三束干涉光束，所述三束干涉光束彼此相位相差优选角度是120°，由第七探测器24、第八探测器25、第九探测器26分别探测。经光电转换后通过信号采集及处理器38处理和计算后可获得测量用二维衍射光栅15的Z轴位移量。
图2为不同于上面所述三轴测量光束产生单元101光路的第二种方案：
所述偏振准直激光光源1为S偏振态。
以偏振棱镜10为偏振态参考物：偏振准直激光光源1发出S偏振光束，经透射型分束用二维衍射光栅2分成左光束3、右光束5、前光束7、后光束4及中间光束6共五束光束，且左光束3、右光束5在与中间光束6组成的平面内以中间光束6轴对称，前光束7、后光束4在与中间光束6组成的平面内以中间光束6轴对称；
五束光束由第一准直透镜8准直后，仅中间光束6通过相对P光偏振轴旋转45°的第一线偏振片9，使中间光束6偏振轴旋转45°，具备P光和S光两个分量，其中S光与其它四束光束一起经偏振棱镜10反射，再一起通过第二四分之一波片13及第二准直透镜14会聚入射于反射型测量用二维衍射光栅15表面。其中，左光束3和右光束5分别以Littrow自准直角度入射，形成X轴回射光束；后光束4和前光束7分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束6的S光分量正入射并回射，形成Z轴回射光束S光分量。
所述左光束3、右光束5、后光束4、前光束7、中间光束6之S分量会聚于一点，避免了由于测量轴X、Y、Z分离导致的阿贝误差。所述左光束3、右光束5、后光束4、前光束7、中间光束6之S分量的回射光束再由第二准直透镜14准直回射后，经第二四分之一波片转变为P偏振态光束，通过偏振棱镜10出射得到分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后光束4的外光束20和里光束19，以及对应中间光束6的中心光束18，从而形成X轴和Y轴测量用二维衍射光栅15位移信号光束，分别带有正、负多普勒频移信号；
所述中间光束6的P偏振态光束通过偏振棱镜10和第一四分之一波片11后，由第一全反镜12反射，第二次通过第二四分之一波片11后转变为S偏振态，再通过偏振棱镜反射与光束18重合。形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
针对所述分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18的X轴和Y轴及Z轴测量光束探测光路皆与第一种情形一致。
图3为不同于上面所述三轴测量光束产生单元101光路的第三种方案：
所述偏振准直激光光源1为S偏振态。
以偏振棱镜10为偏振态参考物：偏振准直激光光源1发出S偏振光束，经透射型分束用二维衍射光栅2分成左光束3、右光束5、前光束7、后光束4及中间光束6共五束光束，且左光束3、右光束5在与中间光束6组成的平面内以中间光束6轴对称，前光束7、后光束4在与中间光束6组成的平面内以中间光束6轴对称；
五束光束由第一准直透镜8准直后，仅中间光束6通过相对P光偏振轴旋转45°的第一线偏振片9，使中间光束6偏振轴旋转45°，具备P光和S光两个分量，其中S光与其它四束光束一起经偏振棱镜10反射，一起通过第一四分之一波片11并由及第一全反镜12反射，二次通过第一四分之一波片11，所述五束光束偏振态皆转变为P偏振态，直接通过偏振棱镜10，再一起通过第二四分之一波片13及第二准直透镜14会聚入射于反射型测量用二维衍射光栅15表面。其中，左光束3和右光束5分别以Littrow自准直角度入射，形成X轴回射光束；后光束4和前光束7分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束6的S光分量正入射并回射，形成Z轴回射光束S光分量。
所述左光束3、右光束5、后光束4、前光束7、中间光束6之S分量会聚于一点，避免了由于测量轴X、Y、Z分离导致的阿贝误差。所述左光束3、右光束5、后光束4、前光束7、中间光束6之S分量的回射光束再由第二准直透镜14准直回射后，经第二四分之一波片13转变为S偏振态光束，通过偏振棱镜10反射得到分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18，从而形成X轴和Y轴测量用二维衍射光栅15位移信号光束，分别带有正、负多普勒频移信号；
所述中间光束6的P偏振态光束通过偏振棱镜10后直接出射与中心光束18重合。形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
针对所述分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18的X轴和Y轴及Z轴测量光束探测光路皆与第一种情形一致。
图4为不同于上面所述三轴测量光束产生单元101光路的第四种方案：
所述分束用二维衍射光栅2是反射型，相应所述偏振棱镜组件1011仅由第一四分之一波片11，偏振棱镜10，第二四分之一波片13组成。
所述偏振准直激光光源1为与P光和S光成一定角度的线偏光，因而同时具有P光和S光偏振分量。以偏振棱镜10为偏振态参考物，偏振准直激光光源1发出具有P光和S光偏振分量的偏振光束，其S光分量光束经偏振棱镜10反射，再通过第一四分之一波片11和第一准直透镜8，正入射于反射型分束用二维衍射光栅2分成左光束3、右光束5、前光束7、后光束4及中间光束6共五束光束，且左光束3、右光束5在与中间光束6组成的平面内以中间光束6轴对称，前光束7、后光束4在与中间光束6组成的平面内以中间光束6轴对称；
五束光束再由第一准直透镜8准直后，一起通过第一四分之一波片11，偏振态皆转变为P偏振态，直接通过偏振棱镜10，再一起经过第二四分之一波片13及第二准直透镜14会聚入射于反射型测量用二维衍射光栅15表面。其中，左光束3和右光束5分别以Littrow自准直角度入射，形成X轴回射光束；后光束4和前光束7分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束6的S光分量正入射并回射，形成Z轴回射光束S光分量。
所述左光束3、右光束5、后光束4、前光束7、中间光束6之S分量会聚于一点，避免了由于测量轴X、Y、Z分离导致的阿贝误差。所述左光束3、右光束5、后光束4、前光束7、对应中间光束6之S分量的所有回射光束再由第二准直透镜14准直回射后，第二次经第二四分之一波片13转变为S偏振态光束，通过偏振棱镜10反射得到分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18，从而形成X轴和Y轴测量用二维衍射光栅15位移信号光束，分别带有正、负多普勒频移信号；
所述中间光束6的P偏振态光束直接通过偏振棱镜10出射与中心光束18重合。形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
针对所述分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18的X轴和Y轴及Z轴测量光束探测光路皆与第一种情形一致。
图5为不同于上面所述三轴测量光束产生单元101光路的第五种方案：
所述分束用二维衍射光栅2是反射型，相应所述偏振棱镜组件1011仅由第一四分之一波片11，偏振棱镜10，第二四分之一波片13组成。
所述偏振准直激光光源1为与P光和S光成一定角度的线偏光，因而同时具有P光和S光偏振分量。以偏振棱镜10为偏振态参考物，偏振准直激光光源1发出具有P光和S光偏振分量的偏振光束，其P光分量光束通过偏振棱镜10和第一四分之一波片11及第一准直透镜8，正入射于反射型分束用二维衍射光栅2分成左光束3、右光束5、前光束7、后光束4及中间光束6共五束光束，且左光束3、右光束5在与中间光束6组成的平面内以中间光束6轴对称，前光束7、后光束4在与中间光束6组成的平面内以中间光束6轴对称；
五束光束再由第一准直透镜8准直后，通过第一四分之一波片11，偏振态皆转变为S偏振态，一起经偏振棱镜10反射后，再经过第二四分之一波片13及第二准直透镜14会聚入射于反射型测量用二维衍射光栅15表面。其中，左光束3和右光束5分别以Littrow自准直角度入射，形成X轴回射光束；后光束4和前光束7分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束6的P光分量正入射并回射，形成Z轴回射光束P光分量。
所述左光束3、右光束5、后光束4、前光束7、中间光束6之P光分量会聚于一点，避免了由于测量轴X、Y、Z分离导致的阿贝误差。所述左光束3、右光束5、后光束4、前光束7、中间光束6之P光分量的回射光束再由第二准直透镜14准直回射后，第二次经第二四分之一波片13转变为P偏振态光束，直接通过偏振棱镜10出射得到分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18，从而形成X轴和Y轴测量用二维衍射光栅15位移信号光束，分别带有正、负多普勒频移信号；
所述中间光束6的S偏振态光束通过偏振棱镜10反射出射与光束18重合。形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
针对所述分别对应左光束3和右光束5的下光束17和上光束16，分别对应前光束7和后两束4的外光束20和里光束19，以及对应中间光束6的中心光束18的X轴和Y轴及Z轴测量光束探测光路皆与第一种情形一致。
所述偏振准直激光光源1经分束后得到左光束3、右光束5直至经第一相位光栅34衍射出射之光路本质为X轴Mach-Zehnder马赫-泽德干涉仪，第一探测器35、第二探测器36、第三探测器37所得信号实为测量二维衍射光栅15的X轴多普勒频移光学差分信号，具有2倍光学细分特征，相比电子差分，精度更高。
类似地，所述偏振准直激光光源1经分束后得到后光束4、前光束7直至经第二相位光栅29衍射出射之光路本质为Y轴Mach-Zehnder马赫-泽德干涉仪，第四探测器30、第五探测器31、第六探测器32所得信号实为测量用二维衍射光栅15的Y轴多普勒频移光学差分信号，具有2倍光学细分特征，相比电子差分，精度更高。
所述X轴Mach-Zehnder马赫-泽德干涉仪和Y轴Mach-Zehnder马赫-泽德干涉仪构成两维Mach-Zehnder马赫-泽德干涉仪。
图一、图二、图三中，所述偏振准直激光光源1经分束后得到中间光束6直至经第三相位光栅23衍射出射之光路本质为Z轴Michelson迈克尔逊干涉仪；图四、图五中，所述偏振准直激光光源1经分束后得到中间光束6直至经第三相位光栅23衍射出射之光路本质为Z轴Mach-Zehnder马赫-泽德干涉仪，由此构成三维Mach-Zehnder马赫-泽德干涉仪；第七探测器24、第八探测器25、第九探测器26所得信号实为测量二维衍射光栅15的Z轴位移信号。
所述X轴、Y轴、Z轴测量光束产生光路中，投影于测量用二维衍射光栅15上的直线，两两正交且共交点，对应为相应测量轴。避免了测量轴交点不同导致的阿贝误差以及测量轴非正交导致的余弦误差。
所述三维Mach-Zehnder马赫-泽德干涉仪或两维Mach-Zehnder马赫-泽德干涉仪与一维Michelson迈克尔逊干涉仪构成三维位移测量零差光栅干涉仪，与信号采集及处理器38组成本发明的三轴光栅尺。结构紧凑，成本低，X，Y轴光路具有2倍光学细分及光学差分信号，精度高，大安装容差特征。
图6为公式1推导示意图。G1代表分束用二维衍射光栅2，栅距为d 1；L1代表第一准直透镜8，焦距为f 1；L2代表第二准直透镜14，焦距为f 2，G2代表测量用二维衍射光栅15，栅距为d 2。
θ 1为±1级G 1光栅衍射分束衍射角，满足：
d 1sinθ 1＝λ         (4)
R＝f 1t gθ 1         (5)
θ 2为G 2的Littrow自准直入射角，满足：
2d 2sinθ 2＝λ          (6)
R＝f 2t gθ 2          (7)
联立(4)----(7)式可推得关系式(1)。
类似地，L2代表第三准直透镜33，焦距为f 3，G2代表第一相位光栅34，栅距为d3，上光束16、下光束17经过第三准直透镜33聚焦于第一相位光栅34衍射形成三束干涉光束，如图6中虚线出射光束D1、D2、D3。所述三束衍射干涉光束彼此相位相差优选角度是120°，由第一探测器35、第二探测器36、第三探测器37分别探测。由此推得关系式(2)。满足关系式(2)的所述三束干涉光束，其中每束由两束入射光衍射后完全重合形成，对比度最大，信号最佳。
类似地，L2代表第四准直透镜28，焦距为f 4，G2代表第二相位光栅29，栅距为d4，里光束19、外光束20经过第四准直透镜28聚焦于第二相位光栅29衍射形成三束干涉光束，如图6中虚线出射光束D1、D2、D3。所述三束衍射干涉光束彼此相位相差优选角度是120°，由第四探测器30、第五探测器31、第六探测器32分别探测。由此推得关系式(3)。满足关系式(3)的所述三束干涉光束，其中每束由两束入射光衍射后完全重合形成，对比度最大，信号最佳。
所述分束用二维衍射光栅2可以是Dammann达曼光栅，亦可以是两个一维衍射光栅组合。
所述第一相移光栅34、第二相位光栅29、第三相位光栅23是一维衍射光栅，亦可是二维衍射光栅。

Claims (10)

  1. 一种三轴光栅尺，包括：三轴测量光束产生单元(101)、X轴测量光束探测单元(104)、Y轴测量光束探测单元(103)、Z轴测量光束探测单元(102)和信号采集及处理单元(38)；其特征在于：所述的三轴测量光束产生单元(101)产生X轴测量光束、Y轴测量光束和Z轴测量光束，沿所述的X轴测量光束方向，设有所述的X轴测量光束探测单元(104)，沿所述的Y轴测量光束方向设有所述的Y轴测量光束探测单元(103)，沿所述的Z轴测量光束方向设有Z轴测量光束探测单元(102)；
    所述三轴测量光束产生单元(101)，包括：偏振准直激光光源(1)、分束用二维衍射光栅(2)、第一准直物镜(8)、偏振棱镜组件(1011)、第二准直物镜(14)和测量用二维衍射光栅(15)；所述分束用二维衍射光栅(2)和测量用二维衍射光栅(15)是二维正交对称，且各自两维度栅距相等，所述分束用二维衍射光栅(2)栅距d 1、测量用二维衍射光栅(15)栅距d 2，第一准直物镜(8)焦距f 1，第二准直物镜(14)焦距f 2满足如下关系式：
    Figure PCTCN2020120568-appb-100001
    其中，λ为偏振准直激光光源(1)波长；
    所述X轴测量光束探测单元(104)，包括：第三准直物镜(33)、第一相移光栅(34)、第一探测器(35)、第二探测器(36)和第三探测器(37)，所述第三准直物镜(33)焦距f 3、第一相移光栅(34)栅距d 3、所述分束用二维衍射光栅(2)栅距d 1、第一准直物镜(2)焦距f 1，满足如下关系式：
    Figure PCTCN2020120568-appb-100002
    所述Y轴测量光束探测单元(103)，包括：第二全反镜(27)、第四准直物镜(28)、第二相移光栅(29)、第四探测器(30)、第五探测(31)和第六探测器(32)；所述第四准直物镜(28)焦距f 4、第二相移光栅(29)栅距d 4、所述分束用二维衍射光栅(2)栅距d 1、第一准直物镜(8)焦距f 1，满足如下关系式：
    Figure PCTCN2020120568-appb-100003
    所述Z轴测量光束探测单元(102)，包括第三全反镜(21)、第二线偏振片(22)、第三相移光栅(23)、第七探测器(24)、第八探测器(25)和第九探测器(26)；
    所述三轴测量光束产生单元(101)中，偏振准直激光光源(1)发出偏振准直光束，经由分束用二维衍射光栅(2)分成五束光束，通过第一准直物镜(8)准直及偏振棱镜组件(1011)及第二准直物镜(14)会聚入射于测量用二维衍射光栅(15)衍射后再由第二准直物镜(14)准直后回射，经由偏振棱镜组件(1011)出射，形成X、Y、Z三轴测量光束；进而由所述X轴测量光束探测单元(104)、所述Y轴测量光束探测单元(103)、所述Z轴测量光束探测单元(102)探测并经光电转换后通过信号采集及处理器(38)处理和计算后可获得测量用二维衍射光栅(15)的X、Y、Z轴位移量。
  2. 根据权利要求1所述的三轴光栅尺，其特征在于，通过偏振棱镜(10)右方出射的五束光束，其中上、下二束经过第三准直透镜(33)聚焦于第一相位光栅(34)后衍射形成三束干涉光束，由第一探测器(35)、第二探测器(36)、第三探测器(37)分别探测，经光电转换后通过信号采集及处理器(38)处理和计算后可获得测量用二维衍射光栅(15)的X轴位移量；另外前、后二束经过第二全反镜(27)反射及第四准直透镜(28)聚焦于第二相位光栅(29)后衍射形成三束干涉光束，由第四探测器(30)、第五探测器(31)、第六探测器(32)分别探测，经光电转换后通过信号采集及处理器(38)处理和计算后可获得测量用二维衍射光栅(15)的Y轴位移量；最后中间一束经第三全反镜(21)反射后通过偏振轴45°放置的第二线偏振片(22)及第三相位光栅(23)后衍射形成三束干涉光束，由第七探测器(24)、第八探测器(25)、第九探测器(26)分别探测，经光电转换后通过信号采集及处理器(38)处理和计算后可获得测量用二维衍射光栅(15)的Z轴位移量。
  3. 根据权利要求1或2所述的三轴光栅尺，其特征在于，所述测量用二维衍射光栅(15)是反射型，且所述分束用二维衍射光栅(2)是透射型，所述偏振棱镜组件(1011)包含：第一线偏振片(9)，第一全反镜(12)，第一四分之一波片(11)，偏振棱镜(10)和第二四分之一波片(13)；
    所述三轴测量光束产生单元(101)光路如下:
    以偏振棱镜(10)为偏振态参考物，偏振准直激光光源(1)发出P偏振光束，经透射型分束用二维衍射光栅(2)分成左光束(3)、右光束(5)、前光束(7)、后光束(4)及中间光束(6)共五束光束，且左光束(3)、右光束(5)在与中间光束(6)组成的平面内以中间光束(6)轴对称，前光束(7)、后光束(4)在与中间光束(6)组成的平面内以中间光束(6)轴对称；
    五束光束由第一准直透镜(8)准直后，仅中间光束(6)通过相对P光偏振轴旋转45°的第一线偏振片(9)，使中间光束(6)偏振轴旋转45°，具备P光和S光两个分量，其中，中间光束(6)的P光分量与其它四束光束一起通过偏振棱镜(10)，再一起经过第二四分之一波片(13)及第二准直透镜(14)汇聚一点，并照射在测量用二维衍射光栅(15)表面，其中，左光束(3)和右光束(5)光束分别以Littrow自准直角度入射，形成X轴回射光束；前光束(7)和后光束(4)分别以Littrow自准直角度入射，形成Y轴回射光束；中 间光束(6)的P光分量正入射并回射，形成Z轴回射光束P光分量；所述左光束(3)、右光束(5)、前光束(7)、后光束(4)和中间光束(6)的P光分量的回射光束再由第二准直透镜(14)自准直后，经第二四分之一波片(13)转变为S偏振态光束，通过偏振棱镜(10)反射得到分别对应左光束(3)和右光束(5)的下光束(17)和上光束(16)，分别对应前光束(7)和后两束(4)的外光束(20)和里光束(19)，以及对应中间光束(6)的中心光束(18)，从而形成X轴和Y轴测量用二维衍射光栅(15)位移信号光束，分别带有正、负多普勒频移信号；
    所述中间光束(6)的S分量经偏振棱镜(10)反射后通过第一四分之一波片(11)且由第一全反镜(12)反射后，再次通过第一四分之一波片(11)后转变为P偏振态，直接通过偏振棱镜(10)出射与中间光束(6)的所述由P分量转变而来的S分量重合,形成测量用二维衍射光栅(15)Z轴位移的P光和S光信号光束。
  4. 根据权利要求1或2所述的三轴光栅尺，其特征在于：所述测量用二维衍射光栅(15)是反射型，且所述分束用二维衍射光栅(2)是透射型，所述偏振棱镜组件(1011)包含：第一线偏振片(9)，第一全反镜(12)，第一四分之一波片(11)，偏振棱镜(10)和第二四分之一波片(13)；
    所述三轴测量光束产生单元(101)光路如下:
    以偏振棱镜(10)为偏振态参考物：偏振准直激光光源(1)发出S偏振光束，经透射型分束用二维衍射光栅(2)分成左光束(3)、右光束(5)、前光束(7)、后光束(4)及中间光束(6)共五束光束，且左光束(3)、右光束(5)在与中间光束(6)组成的平面内以中间光束(6)轴对称，前光束(7)、后光束(4)在与中间光束(6)组成的平面内以中间光束(6)轴对称；
    五束光束由第一准直透镜(8)准直后，仅中间光束(6)通过相对P光偏振轴旋转45°的第一线偏振片(9)，使中间光束(6)偏振轴旋转45°，具备P光和S光两个分量，其中S光与其它四束光束一起经偏振棱镜(10)反射，再一起通过第二四分之一波片(13)及第二准直透镜(14)会聚入射于反射型测量用二维衍射光栅(15)表面，其中，左光束(3)和右光束(5)分别以Littrow自准直角度入射，形成X轴回射光束；后光束(4)和前光束(7)分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束(6)的S光分量正入射并回射，形成Z轴回射光束S光分量；
    所述左光束(3)、右光束(5)、后光束(4)、前光束(7)、以及中间光束(6)的S分量的回射光束再由第二准直透镜(14)准直回射后，经第二四分之一波片转变为P偏振态光束，直接通过偏振棱镜(10)出射得到分别对应左光束(3)和右光束(5)的下光束(17)和上光束(16)，分别对应前光束(7)和后两束(4)的外光束(20)和里光束(19)，以及对应中间光束(6)的中心光束(18)，从而形成X轴和Y轴测量用二维衍射光栅(15)位移信号光束，分别带有正、负多普勒频移信号；
    所述中间光束(6)的P偏振态光束通过偏振棱镜(10)和第一四分之一波片(11)后，由第一全反镜(12)反射，第二次通过第二四分之一波片(11)后转变为S偏振态，再通过偏振棱镜反射与中心光束(18)重合，形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
  5. 根据权利要求1或2所述的三轴光栅尺，其特征在于：所述测量用二维衍射光栅(15)是反射型，且所述分束用二维衍射光栅(2)是透射型，所述偏振棱镜组件(1011)包含：第一线偏振片(9)，第一全反镜(12)，第一四分之一波片(11)，偏振棱镜(10)和第二四分之一波片(13)；
    所述三轴测量光束产生单元(101)光路如下:
    以偏振棱镜(10)为偏振态参考物：偏振准直激光光源(1)发出S偏振光束，经透射型分束用二维衍射光栅(2)分成五束光束，分别为左光束(3)、右光束(5)、前光束(7)、后光束(4)及中间光束(6)，且左光束(3)、右光束(5)在与中间光束(6)组成的平面内以中间光束(6)轴对称，前光束(7)、后光束(4)在与中间光束(6)组成的平面内以中间光束(6)轴对称；
    五束光束由第一准直透镜(8)准直后，仅中间光束(6)通过相对P光偏振轴旋转45°的第一线偏振片(9)，使中间光束(6)偏振轴旋转45°，具备P光和S光两个分量，其中S光与其它四束光束一起经偏振棱镜(10)反射，一起通过第一四分之一波片(11)并由及第一全反镜(12)反射，二次通过第一四分之一波片(11)，所述五束光束偏振态皆转变为P偏振态，直接通过偏振棱镜(10)，再一起通过第二四分之一波片(13)及第二准直透镜(14)会聚入射于反射型测量用二维衍射光栅(15)表面，其中，左光束(3)和右光束(5)分别以Littrow自准直角度入射，形成X轴回射光束；后光束(4)和前光束(7)分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束(6)的S光分量正入射并回射，形成Z轴回射光束S光分量；
    所述左光束(3)、右光束(5)、后光束(4)、前光束(7)、中间光束(6)之S分量的回射光束再由第二准直透镜(14)准直回射后，经第二四分之一波片(13)转变为S偏振态光束，通过偏振棱镜(10)反射得到分别对应左光束(3)和右光束(5)的下光束(17)和上光束(16)，分别对应前光束(7)和后两束(4)的外光束(20)和里光束(19)，以及对应中间光束(6)的中心光束(18)，从而形成X轴和Y轴测量用二维衍射光栅(15)位移信号光束，分别带有正、负多普勒频移信号；
    所述中间光束(6)的P偏振态光束通过偏振棱镜(10)后直接出射与中心光束(18)重合。形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
  6. 根据权利要求1或2所述的三轴光栅尺，其特征在于：所述测量用二维衍射光栅(15)是反射型，且所述分束用二维衍射光栅(2)是反射型，所述偏振棱镜组件(1011)仅包含：第一四分之一波片(11)，偏振棱镜(10)，第二四分之一波片(13)；
    所述三轴测量光束产生单元(101)光路如下:
    以偏振棱镜(10)为偏振态参考物，偏振准直激光光源(1)发出具有P光和S光偏振分量的线偏振光束，其S光分量光束经偏振棱镜(10)反射，再通过第一四分之一波片(11)和第一准直透镜(8)，正入射于反射型分束用二维衍射光栅(2)分成左光束(3)、右光束(5)、前光束(7)、后光束(4)及中间光束(6)共五束光束，且左光束(3)、右光束(5)在与中间光束(6)组成的平面内以中间光束(6)轴对称，前光束(7)、后光束(4)在与中间光束(6)组成的平面内以中间光束(6)轴对称；
    五束光束再由第一准直透镜(8)准直后，一起通过第一四分之一波片(11)，偏振态皆转变为P偏振态，直接通过偏振棱镜(10)，再一起经过第二四分之一波片(13)及第二准直透镜(14)会聚入射于反射型测量用二维衍射光栅(15)表面。其中，光束(3)和光束(5)分别以Littrow自准直角度入射，形成X轴回射光束；光束(4)和光束(7)分别以Littrow自准直角度入射，形成Y轴回射光束；光束(6)的S光分量正入射并回射，形成Z轴回射光束S光分量；
    所述左光束(3)、右光束(5)、后光束(4)、前光束(7)、对应中间光束(6)之S分量的所有回射光束再由第二准直透镜(14)准直回射后，第二次经第二四分之一波片(13)转变为S偏振态光束，通过偏振棱镜(10)反射得到分别对应左光束(3)和右光束(5)的下光束(17)和上光束(16)，分别对应前光束(7)和后两束(4)的外光束(20)和里光束(19)，以及对应中间光束(6)的中心光束(18)，从而形成X轴和Y轴测量用二维衍射光栅(15)位移信号光束，分别带有正、负多普勒频移信号；
    所述中间光束(6)的P偏振态光束直接通过偏振棱镜(10)出射与中心光束(18)重合。形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
  7. 根据权利要求1或2所述的三轴光栅尺，其特征在于：所述测量用二维衍射光栅(15)是反射型，且所述分束用二维衍射光栅(2)是反射型，所述偏振棱镜组件(1011)仅包含：第一四分之一波片(11)，偏振棱镜(10)，第二四分之一波片(13)；
    所述三轴测量光束产生单元(101)光路如下:
    以偏振棱镜(10)为偏振态参考物，偏振准直激光光源(1)发出具有P光和S光偏振分量的线偏振光束，其P光分量光束通过偏振棱镜(10)和第一四分之一波片(11)及第一准直透镜(8)，正入射于反射型分束用二维衍射光栅(2)分成左光束(3)、右光束(5)、前光束(7)、后光束(4)及中间光束(6)共五束光束，且左光束(3)、右光束(5)在与中间光束(6)组成的平面内以中间光束(6)轴对称，前光束(7)、后光束(4)在与中间光束(6)组成的平面内以中间光束(6)轴对称；
    五束光束再由第一准直透镜(8)准直后，通过第一四分之一波片(11)，偏振态皆转变为S偏振态，一起经偏振棱镜(10)反射后，再经过第二四分之一波片(13)及第二准直透镜(14)会聚入射于反射型测量用二维衍射光栅(15)表面。其中，左光束(3)和右光束(5)分别以Littrow自准直角度入射，形成X轴回射光束；后光束(4)和前光束(7) 分别以Littrow自准直角度入射，形成Y轴回射光束；中间光束(6)的P光分量正入射并回射，形成Z轴回射光束P光分量；
    所述左光束(3)、右光束(5)、后光束(4)、前光束(7)、中间光束(6)之P光分量的回射光束再由第二准直透镜(14)准直回射后，第二次经第二四分之一波片(13)转变为P偏振态光束，直接通过偏振棱镜(10)出射得到分别对应左光束(3)和右光束(5)的下光束(17)和上光束(16)，分别对应前光束(7)和后两束(4)的外光束(20)和里光束(19)，以及对应中间光束(6)的中心光束(18)，从而形成X轴和Y轴测量用二维衍射光栅(15)位移信号光束，分别带有正、负多普勒频移信号；
    所述中间光束(6)的S偏振态光束直接通过偏振棱镜(10)反射与光束(18)重合，形成测量用二维衍射光栅Z轴位移的P光和S光信号光束。
  8. 根据权利要求项1所述三轴光栅尺，其特征在于：所述三轴测量光束产生单元(101)中X轴测量光束的光路与X轴测量光束探测单元(104)光路，Y轴测量光束的光路与Y轴测量光束探测单元(103)光路，共同构成两维Mach-Zehnder(马赫-泽德)零差干涉仪；Z轴测量光束的光路与Z轴测量光束探测单元(102)光路构成一维Michelson(迈克尔逊)或一维Mach-Zehnder(马赫-泽德)零差干涉仪；由此构成一体的三维位移测量零差光栅干涉仪；X，Y轴光路具有2倍光学细分及光学差分信号。
  9. 根据权利要求项1所述三轴光栅尺，其特征在于：所述分束用二维衍射光栅(2)是Dammann(达曼)光栅，或者两个一维衍射光栅组合。
  10. 根据权利要求项1所述三轴光栅尺，其特征在于：所述第一相移光栅(34)、第二相移光栅(29)、第三相移光栅(23)是一维衍射光栅，或二维衍射光栅。
PCT/CN2020/120568 2020-09-17 2020-10-13 一种三轴光栅尺 WO2022056971A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202010978240.4 2020-09-17
CN202010978240.4A CN113701640B (zh) 2020-09-17 2020-09-17 一种三轴光栅尺

Publications (1)

Publication Number Publication Date
WO2022056971A1 true WO2022056971A1 (zh) 2022-03-24

Family

ID=78646603

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2020/120568 WO2022056971A1 (zh) 2020-09-17 2020-10-13 一种三轴光栅尺

Country Status (2)

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

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114754685A (zh) * 2022-06-13 2022-07-15 探维科技(北京)有限公司 探测信号处理方法、装置、介质、设备及光栅尺
CN115218823A (zh) * 2022-07-21 2022-10-21 北方工业大学 一种测量干涉图像相位分布的五步相移信号处理光路
CN115236865A (zh) * 2022-07-21 2022-10-25 中国科学院精密测量科学与技术创新研究院 一种基于伺服反馈电动调焦透镜的冷原子长距离转移装置

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117091513B (zh) * 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 一种基于大尺寸光斑的光栅干涉测量装置及测量方法
CN117948897B (zh) * 2024-03-27 2024-06-04 中国科学院长春光学精密机械与物理研究所 一种混合位移测量装置

Citations (8)

* 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
CN103307986A (zh) * 2013-06-19 2013-09-18 清华大学 一种二自由度外差光栅干涉仪位移测量***
CN103322927A (zh) * 2013-06-19 2013-09-25 清华大学 一种三自由度外差光栅干涉仪位移测量***
CN103644848A (zh) * 2013-12-12 2014-03-19 哈尔滨工业大学 一种使用双频激光的三维光栅位移测量***
CN106017308A (zh) * 2016-07-22 2016-10-12 清华大学 一种六自由度干涉测量***及方法
CN106247947A (zh) * 2016-08-11 2016-12-21 哈尔滨工业大学 一种外差式二/三维光栅位移粗/细测量***
CN108627099A (zh) * 2018-07-02 2018-10-09 清华大学 五自由度外差光栅干涉测量***
CN108775869A (zh) * 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 实现长行程三维位移测量的光栅位移测量***及方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6654128B2 (en) * 1997-06-30 2003-11-25 Canon Kabushiki Kaisha Displacement information detecting apparatus
CN103673891B (zh) * 2013-11-21 2016-05-18 清华大学 一种光栅外差干涉自准直测量装置
CN104949616A (zh) * 2014-03-25 2015-09-30 上海微电子装备有限公司 回射式光栅尺测量***及其应用
CN104596425B (zh) * 2015-01-09 2017-05-17 哈尔滨工业大学 一种基于衍射光栅的三维位移测量装置
CN110285761B (zh) * 2019-07-03 2021-02-23 哈尔滨工业大学 一种结构紧凑的光栅三维位移测量装置

Patent Citations (8)

* 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
CN103307986A (zh) * 2013-06-19 2013-09-18 清华大学 一种二自由度外差光栅干涉仪位移测量***
CN103322927A (zh) * 2013-06-19 2013-09-25 清华大学 一种三自由度外差光栅干涉仪位移测量***
CN103644848A (zh) * 2013-12-12 2014-03-19 哈尔滨工业大学 一种使用双频激光的三维光栅位移测量***
CN106017308A (zh) * 2016-07-22 2016-10-12 清华大学 一种六自由度干涉测量***及方法
CN106247947A (zh) * 2016-08-11 2016-12-21 哈尔滨工业大学 一种外差式二/三维光栅位移粗/细测量***
CN108775869A (zh) * 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 实现长行程三维位移测量的光栅位移测量***及方法
CN108627099A (zh) * 2018-07-02 2018-10-09 清华大学 五自由度外差光栅干涉测量***

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114754685A (zh) * 2022-06-13 2022-07-15 探维科技(北京)有限公司 探测信号处理方法、装置、介质、设备及光栅尺
CN114754685B (zh) * 2022-06-13 2022-09-02 探维科技(北京)有限公司 探测信号处理方法、装置、介质、设备及光栅尺
CN115218823A (zh) * 2022-07-21 2022-10-21 北方工业大学 一种测量干涉图像相位分布的五步相移信号处理光路
CN115236865A (zh) * 2022-07-21 2022-10-25 中国科学院精密测量科学与技术创新研究院 一种基于伺服反馈电动调焦透镜的冷原子长距离转移装置
CN115236865B (zh) * 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 一种基于伺服反馈电动调焦透镜的冷原子长距离转移装置
CN115218823B (zh) * 2022-07-21 2024-06-11 北方工业大学 一种测量干涉图像相位分布的五步相移信号处理光路

Also Published As

Publication number Publication date
CN113701640A (zh) 2021-11-26
CN113701640B (zh) 2023-01-20

Similar Documents

Publication Publication Date Title
WO2022056971A1 (zh) 一种三轴光栅尺
TWI784265B (zh) 位移測量裝置、位移測量方法及光刻設備
JP6732543B2 (ja) 変位検出装置
US20160138903A1 (en) Two-dof heterodyne grating interferometer displacement measurement system
US5369488A (en) High precision location measuring device wherein a position detector and an interferometer are fixed to a movable holder
WO2014071807A1 (zh) 一种外差光栅干涉仪位移测量***
CN102506764B (zh) 用于位移直线度测量的激光干涉***
JPH073344B2 (ja) エンコ−ダ−
CN109883362B (zh) 一种基于光栅干涉原理的直线度测量***
CN105180845A (zh) 一种基于闪耀光栅的高精度滚转角干涉测量装置
CN108775878B (zh) 光栅外差干涉***及其滚转角测量方法
US20230366667A1 (en) Heterodyne grating interferometry system based on secondary diffraction
CN1979086A (zh) 低走离干涉仪
JPS63277926A (ja) 測長装置
WO2022095128A1 (zh) 一种六自由度测量光栅尺
CN109781034B (zh) 微小滚转角与直线度同步高精度测量干涉仪以及测量方法
US4836678A (en) Double-path interferometer
US20050062981A1 (en) Apparatus for measuring two-dimensional displacement
CN116086310A (zh) 基于kb镜纳米实验***的高精度定位测量方法及装置
WO2023070757A1 (zh) 一种三轴高光学细分光栅尺
CN108931190B (zh) 位移检测装置
US10451401B2 (en) Displacement detecting device with controlled heat generation
CN104613902A (zh) 用于位移直线度测量的激光干涉***
Chen et al. Multi-DOF incremental optical encoder with laser wavelength compensation
JP2675317B2 (ja) 移動量測定方法及び移動量測定装置

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 20953828

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 20953828

Country of ref document: EP

Kind code of ref document: A1