CN112747667B - Differential interferometer apparatus - Google Patents
Differential interferometer apparatus Download PDFInfo
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- CN112747667B CN112747667B CN201911052228.4A CN201911052228A CN112747667B CN 112747667 B CN112747667 B CN 112747667B CN 201911052228 A CN201911052228 A CN 201911052228A CN 112747667 B CN112747667 B CN 112747667B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02015—Interferometers characterised by the beam path configuration
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Abstract
The invention provides a differential interferometer apparatus, comprising a light source; the light splitting prism is used for splitting incident light to split the incident light into at least two light beams, and the first light splitting prism is provided with a first surface and a second surface which are opposite; the first wave plate and the first reflector are used for receiving the light beam emitted from the first surface in a first direction, and the first direction is the reflection direction of the first light splitting prism for the incident light; a second wave plate and a second mirror for receiving the light beam emitted from the second surface in the second direction; and the third wave plate and the measuring mirror are used for receiving the light beam emitted from the second surface in the third direction, and the at least two light beams are irradiated onto the measuring mirror based on the arrangement of the first wave plate, the second wave plate, the third wave plate, the first reflecting mirror and the second reflecting mirror. The differential interferometer device provided by the invention has the advantages of less occupied space, lower cost, higher integration level and lower debugging difficulty.
Description
Technical Field
The invention relates to a laser interferometer, in particular to a differential interferometer device.
Background
The differential interferometer can be used as ultra-precise non-contact measuring equipment for high-speed and high-precision displacement measurement, and has very wide application in the fields of semiconductor manufacturing, precision machine tool machining, military, aerospace, automobile manufacturing, coordinate measurement and the like.
In the related art, it is generally required that the differential interferometer has a vertical displacement measurement function or a rotational displacement measurement function. However, the differential interferometer with the vertical displacement and rotational displacement measurement functions in the related art has a large size, occupies a large space, and is high in cost.
Disclosure of Invention
The invention aims to provide a differential interferometer device to solve the problems of large occupied space, high cost, low debugging difficulty and low integration level of the conventional differential interferometer device.
To solve the above technical problem, the present invention provides a differential interferometer apparatus, comprising:
a light source for emitting incident light;
the light splitting prism is used for receiving incident light emitted by a light source and splitting the incident light so as to split the incident light into at least two light beams, and the light splitting prism is provided with a first surface and a second surface which are opposite;
the first wave plate and the first reflecting mirror are used for receiving the light beam emitted from the first surface in a first direction, and the first direction is the reflecting direction of the first light splitting prism for the incident light;
the second wave plate and the second reflector are used for receiving the light beam emitted from the second surface in a second direction, and the second direction is opposite to the first direction;
the third wave plate and the measuring mirror are used for receiving the light beam emitted from the second surface in a third direction, and the third direction is the transmission direction of the first light splitting prism for the incident light;
the first wave plate, the second wave plate and the third wave plate are used for deflecting the polarization direction of the light beam, and the first reflecting mirror and the second reflecting mirror are used for reflecting the light beam; and based on the arrangement of the first wave plate, the second wave plate, the third wave plate, the first reflecting mirror and the second reflecting mirror, the at least two light beams are irradiated onto the measuring mirror.
Optionally, the incident light emitted by the light source irradiates the incident point of the first beam splitter prism and is split;
wherein a first light beam of the incident light having a polarization direction perpendicular to an incident plane is reflected to the first wave plate and the first mirror in the first direction via the first surface of the first beam splitter prism to deflect the polarization direction of the first light beam by 90 ° by the first wave plate and to reflect the first light beam back to the first surface in the second direction by the first mirror, and the first light beam reflected by the first mirror passes from the first surface to the second surface and is irradiated from the second surface to the second wave plate and the second mirror in the second direction to deflect the polarization direction of the first light beam by 90 ° by the second wave plate and to reflect the first light beam back to the second surface by the second mirror and to reflect the first light beam reflected by the second mirror in the third direction by the second surface to the third wave plate and the measuring mirror, deflecting the polarization direction of the first light beam by 90 degrees through the third wave plate, reflecting the first light beam back to the second surface through the measuring mirror, and enabling the first light beam reflected by the measuring mirror to pass through the second surface to the first surface so as to enable the first light beam to be emitted from the exit point of the first light splitting prism;
wherein the first and second beams pass through the first or second mirror to shift the exit point relative to the point of incidence.
Optionally, the incident light emitted by the light source irradiates the incident point of the first beam splitter prism and is split;
wherein a second light beam of the incident light having a polarization direction parallel to the incident plane passes through the first surface to the second surface of the first beam splitter prism and is transmitted from the second surface to the third wave plate and the measurement mirror in the third direction to deflect the polarization direction of the second light beam by 90 ° by the third wave plate and reflect the second light beam back to the second surface by the measurement mirror, and the second light beam reflected back by the measurement mirror is reflected to the second wave plate and the second mirror in the second direction via the second surface to deflect the polarization direction of the second light beam by 90 ° by the second wave plate and reflect the second light beam to the second surface in the first direction by the second mirror, and the second light beam reflected back by the second mirror passes through the second surface to the first surface and is projected from the first surface to the first wave plate and the first mirror in the first direction, deflecting the polarization direction of the second light beam by 90 degrees through the first wave plate, reflecting the second light beam to the first surface through the first reflecting mirror, and reflecting the second light beam out of the exit point of the first light splitting prism through reflection of the first surface;
wherein the first and second beams pass through the first or second mirror to shift the exit point relative to the point of incidence.
Optionally, the measuring mirror is fixed on the object to be measured, so as to determine the displacement of the object to be measured by measuring the displacement of the measuring mirror.
Optionally, the third wave plate is a quarter wave plate, and when the light beam passes through the quarter wave plate twice, the polarization direction of the light beam changes by 90 °.
Optionally, the first mirror or the second mirror is a corner cube, the corner cube includes a first mirror surface and a second mirror surface, the light beam irradiates onto the first mirror surface in a predetermined direction, is reflected by the first mirror surface onto the second mirror surface, and is further reflected by the second mirror surface, wherein the light beam irradiating onto the first mirror surface and the light beam reflected by the second mirror surface are offset by a predetermined size in a direction perpendicular to the predetermined direction.
Optionally, the first reflector is the corner cube prism;
the first wave plate is a half wave plate, and one of the light beam irradiated to the first reflecting mirror and the light beam reflected by the first reflecting mirror passes through the first wave plate; or, the first wave plate is a quarter wave plate, and both the light beam irradiated to the first reflecting mirror and the light beam reflected by the first reflecting mirror pass through the first wave plate.
Optionally, the second reflecting mirror is a corner cube prism;
the second wave plate is a half wave plate, and one of the light beam irradiated to the second reflector and the light beam reflected by the second reflector passes through the second wave plate; or, the second wave plate is a quarter wave plate, and both the light beam irradiated to the second reflector and the light beam reflected by the second reflector pass through the second wave plate.
Optionally, the first surface and the second surface of the first light splitting prism are parallel, and the first direction, the second direction and the third direction form an included angle of 45 degrees with the first surface.
Optionally, the measuring mirror comprises a first measuring mirror and a second measuring mirror;
wherein a part of the light beam emitted from the second surface in the third direction is irradiated to the first measuring mirror, another part is irradiated to the second measuring mirror, and the light beam is retroreflected to the second surface by the first measuring mirror and the second measuring mirror.
Optionally, the measuring mirrors include a third measuring mirror, a fourth measuring mirror, and a fifth measuring mirror;
the extending direction of the third measuring mirror is perpendicular to the third direction, the fourth measuring mirror is located between the third wave plate and the third measuring mirror, is connected with the third measuring mirror and is not perpendicular to the third measuring mirror, and the fifth measuring mirror is arranged on one side of a reflecting mirror surface of the fourth measuring mirror;
in the light beam emitted from the second surface in the third direction, part of the light beam irradiates the third measuring mirror, and the other part of the light beam irradiates the fourth measuring mirror; wherein the light beam irradiated to the third measuring mirror is retro-reflected to a second surface by the third measuring mirror, the light beam irradiated to the fourth measuring mirror is reflected to the fifth measuring mirror by the fourth measuring mirror and is re-reflected back to the fourth measuring mirror by the fifth measuring mirror, and the re-reflected light beam is retro-reflected to the second surface by the fourth measuring mirror.
Optionally, the second reflecting mirror is a corner cube prism;
the device also comprises a second beam splitter prism, the second beam splitter prism is positioned between the second reflecting mirror and the first beam splitter prism, and the first beam splitter prism comprises two beam splitters and a plane mirror which are arranged in parallel;
wherein the beam emitted from the second surface in the second direction is irradiated to the beam splitter, so that part of the beam is transmitted out of the beam splitter, and the other part of the beam is reflected to the plane mirror by the beam splitter and reflected to the second wave plate and the second reflecting mirror by the plane mirror.
Optionally, the plane mirror is a spectroscope or a reflecting mirror.
Optionally, the portion of the light beam transmitted from the beam splitter is used to form the first test light.
Optionally, the other light beam reflected by the beam splitter is used to exit from the exit point of the first beam splitter prism to form the second test light.
In summary, in the differential interferometer apparatus provided by the present invention, the light beam emitted from the first surface of the first beam splitter prism in the first direction is irradiated to the first wave plate and the first reflection mirror, the light beam emitted from the second surface of the first beam splitter prism in the second direction is irradiated to the second wave plate and the second reflection mirror, and the light beam emitted from the second surface in the third direction is irradiated to the third wave plate and the measurement mirror, and the first direction is a reflection direction of the first beam splitter prism with respect to the incident light, the second direction is an opposite direction of the first direction, and the third direction is a transmission direction of the first beam splitter with respect to the incident light.
Therefore, when the incident light irradiates the first beam splitter prism and is split into two beams, the beam transmitted by the first beam splitter prism directly irradiates the measuring mirror, and the beam reflected by the first beam splitter prism is reflected to the first wave plate and the first measuring mirror along the first direction, then reflected back to the first beam splitter prism along the second direction by the first measuring mirror, passes through the first beam splitter prism to reach the second wave plate and the second measuring mirror, is reflected to the first beam splitter prism along the first direction again by the second measuring mirror, and then is reflected to the measuring mirror by the first beam splitter prism. It can be known that, in the present invention, after the incident light is split into two beams by the first beam splitter prism, the two beams can respectively irradiate to different positions of the measuring mirror, that is, the differential interferometer apparatus in the present invention can realize the measurement of the rotational displacement and the vertical displacement of the measuring mirror.
That is, in this embodiment, the differential interferometer apparatus only needs one beam splitter prism (i.e., the first beam splitter prism), three wave plates (i.e., the first wave plate, the second wave plate, and the third wave plate), two mirrors (i.e., the first mirror and the second mirror), and the measurement mirror, and can achieve the measurement of the rotational displacement and the vertical displacement. The required components are fewer, and the size of the measuring mirror does not need to be too large because the number of light spots irradiated on the measuring mirror is fewer and only two, so that the differential interferometer device for measuring the vertical displacement and the rotary displacement is lower in cost and smaller in occupied space.
In addition, the differential interferometer device has less components, so that the debugging difficulty is lower, and meanwhile, the interferometer in the invention is a multi-axis interferometer, so that the integration level is higher.
Drawings
FIG. 1 is a schematic diagram of a differential interferometer apparatus of the prior art;
FIG. 2 is a schematic diagram of a prior art differential interferometer apparatus for measuring rotational displacement;
FIG. 3 is a schematic diagram of a prior art differential interferometer apparatus for measuring vertical displacement;
FIG. 4 is a schematic structural diagram of a differential interferometer apparatus according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a corner cube prism according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of another differential interferometer apparatus according to an embodiment of the present invention;
FIGS. 7 and 8 are schematic diagrams of the paths of a first light beam and a second light beam in the apparatus shown in FIG. 4, respectively, according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of an interferometer apparatus for measuring rotational displacement using the apparatus of FIG. 4 according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of an interferometer apparatus for measuring vertical displacement using the apparatus of FIG. 4 according to an embodiment of the present invention;
FIG. 11 is a schematic structural diagram of a differential interferometer apparatus for simultaneously measuring horizontal displacement and vertical displacement according to an embodiment of the present invention;
fig. 12 is a schematic structural diagram of an interferometer apparatus for measuring horizontal displacement according to an embodiment of the present invention, where the apparatus of fig. 4 is used.
Detailed Description
As described in the background, a differential interferometer apparatus in the related art is shown in fig. 1. Wherein, the device mainly includes: the device comprises a light source 01, a beam splitter prism 02, a first wave plate 03, a first reflector 04, a third wave plate 05, a corner cube 06 and a measuring mirror 07. The beam splitter prism is used for splitting a light beam, the light beam with the polarization direction perpendicular to the incident plane is reflected by the beam splitter prism, and the light beam with the polarization direction parallel to the incident plane is transmitted by the beam splitter prism.
Specifically, in the interferometer apparatus shown in fig. 1, the light beam emitted from the light source 01 is irradiated onto the spectroscopic surface 021 of the spectroscopic prism 02 and is divided into the first light beam f1 and the second light beam f 2.
The first light beam f1 (indicated by a solid line in fig. 1) with a polarization direction perpendicular to the incident plane (i.e., a plane formed by the incident light and the reflected light) is reflected by the splitting plane 021 to the first wave plate 03 and the first mirror 04, and the first wave plate 03 deflects the polarization direction of the first light beam f1 by 90 °, and is reflected by the first mirror 04 to the splitting plane 021. The polarization direction of the first light beam f1 reflected back by the first reflector 04 is already deflected by 90 °, then the first light beam f1 passes through the splitting surface 021 and irradiates onto the corner cube 06, the corner cube 06 deflects the first light beam f1 for a certain distance and then retroreflects back to the splitting surface 021 again, the first light beam f1 retroreflected by the corner cube 06 passes through the splitting surface 021 and then abuts against the first wave plate 03 and the first reflector 04 again, the first wave plate 03 deflects the polarization direction of the first light beam f1 for another 90 °, and the first light beam f1 is reflected back to the splitting surface 021 by the first reflector 04, and at this time, the splitting surface 021 reflects the first light beam f1 out.
Meanwhile, a second light beam f2 (shown by a dotted line in fig. 1) with a polarization direction parallel to the incident plane passes through the splitting plane 021 and is abutted to the third wave plate 05 and the measuring mirror 07, and the third wave plate 05 deflects the polarization direction of the second light beam f2 by 90 ° and is reflected back to the splitting plane 021 through the measuring mirror 07. The polarization direction of the second light beam f2 reflected back by the measuring mirror 07 is already deflected by 90 °, and then it is reflected by the splitting plane 021 onto the corner cube 06, the corner cube 06 deflects the second light beam f2 by a certain displacement and then retroreflects to the splitting plane 021 again, the second light beam f2 retroreflected by the corner cube 06 is reflected to the third wave plate 05 and the measuring mirror 07 again, and the third wave plate 05 deflects the polarization direction of the second light beam f2 by 90 °, and then reflects back to the splitting plane 021 again by the measuring mirror 07. The second light beam f2 reflected back again by the measuring mirror 07 is emitted through the spectroscopic surface 021.
It should be noted that the first light beam f1 and the second light beam f2 are emitted from the beam splitter prism 02 in a coincident manner, and the emitted first light beam and second light beam can be received by a detector (not shown).
Further, by comparing the optical paths of the first light beam f1 and the second light beam f2, it can be determined that the optical paths of the first light beam f1 and the second light beam f2 are different, and an optical path difference exists, so that a phase difference exists between the first light beam f1 and the second light beam f2, and an interference phenomenon is generated, so that interference fringes are formed. In this way, after the first light beam f1 and the second light beam f2 are received by the detector, interference fringe patterns of the first light beam and the second light beam are acquired, and the optical path difference between the first light beam and the second light beam can be determined by analyzing and calculating the interference fringe patterns. Based on this, on the basis of the device shown in fig. 1, by making the optical path difference of different light beams be the displacement to be measured, the specific displacement value of the displacement to be measured can be calculated by analyzing and calculating the interference fringe pattern shown by the detector, thereby realizing the measurement of the rotational displacement and the vertical displacement.
Specifically, referring to fig. 2 and 3, fig. 2 is a schematic structural diagram of an interferometer apparatus for measuring rotational displacement in the prior art, and fig. 3 is a schematic structural diagram of an interferometer apparatus for measuring vertical displacement in the prior art. As shown in fig. 2 and 3, the devices each comprise two sets of interferometer devices as shown in fig. 1. As can be seen from fig. 2, the optical paths of the first light beams emitted by the two light sources 01 in fig. 2 are the same, and there is no optical path difference, but the optical paths of the second light beams emitted by the two light sources 01 are different due to the rotation angle of the measuring mirror, and there is an optical path difference, and the optical path difference is related to the rotational displacement of the measuring mirror. The optical path difference of the second light beams f2 of the two light sources in fig. 2 can be determined by comparing and analyzing the interference fringe patterns respectively received by the two detectors in fig. 2, and the rotational displacement of the measuring mirror can be further determined.
Meanwhile, with further reference to fig. 3, the apparatus in fig. 3 further includes a first reflecting mirror 08 and a second reflecting mirror 09, wherein the third reflecting mirror is configured to receive the second light beam f2 emitted from one of the two beam splitting prisms shown in fig. 3 toward the measuring mirror, and reflect the second light beam f2 to the second reflecting mirror 09, so that the second reflecting mirror 09 reflects the second light beam back to the first reflecting mirror 08, and the first reflecting mirror 08 reflects the retro-reflected second light beam f2 to the splitting plane 021. Referring to fig. 3, it can be seen that the optical paths of the first light beams emitted by the two light sources in the apparatus of fig. 3 are the same, and the optical paths of the second light beams are different, and there is an optical path difference, where the optical path of the second light beam emitted by one light source includes the round trip distance of the first mirror 07 and the second mirror 08, and the optical path of the second light beam emitted by one light source is not included. Therefore, by comparing and analyzing the interference fringe patterns respectively received by the two detectors in fig. 3, the optical path difference of the second light beams f2 of the two light sources in fig. 3 can be determined, and thus the vertical displacement of the measuring mirror can be determined.
It can be understood from the above that, since the interferometer apparatus in the prior art (i.e. fig. 1) can only irradiate the same light beam (e.g. the second light beam) onto the measuring mirror, it is not able to irradiate two different light beams (e.g. the first light beam and the second light beam) onto different positions of the measuring mirror. Therefore, when the prior art needs to measure the vertical displacement and the rotational displacement, two sets of devices shown in fig. 1 need to be arranged to irradiate different light beams to different positions of the measuring mirror respectively, and the optical path difference of the different light beams is the vertical displacement or the rotational displacement to be measured, so that the calculation of the vertical displacement and the rotational displacement is realized, and more components are needed. In addition, in the prior art, the number of light spots projected onto the measuring mirror is more than four, so that the side size of the measuring mirror is larger. This results in a relatively expensive and space-consuming interferometer for measuring rotational and vertical displacements.
Based on this, the invention provides a differential interferometer device to solve the technical problems existing in the prior art.
The differential interferometer apparatus of the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
Fig. 4 is a schematic structural diagram of a differential interferometer apparatus for measuring rotational displacement according to an embodiment of the present invention, and as shown in fig. 4, the apparatus may include:
the light source 1 is used for emitting incident light, and the light source can be a helium-neon double-frequency laser, for example, and the incident light emitted by the light source comprises at least two coincident linear polarized lights.
The first beam splitter prism 21 is configured to receive an incident light emitted from the light source 1 and split the incident light to split the incident light into at least two light beams with different frequencies (in this embodiment, the splitting into two light beams is taken as an example for description), and the first beam splitter prism 21 has a first surface 211 and a second surface 212 which are opposite to each other, and the incident light is irradiated onto the first surface 211. In addition, the light beam having the polarization direction perpendicular to the incident surface of the incident light is reflected by the first beam splitter prism 21, and the light beam having the polarization direction parallel to the incident surface is transmitted by the first beam splitter prism 21. The first surface 211 further includes an incident point and an exit point, the incident light irradiates the incident point and is split to form at least two light beams, and the split at least two light beams are re-coincided and emitted from the exit point.
And a first wave plate 22 and a first reflecting mirror 23 which are disposed on a side of the first beam splitter prism 21 corresponding to the first surface 211, and to which the light beam emitted from the first surface in the first direction is irradiated. The first direction may be a reflection direction of the first light splitting prism 21 with respect to a light beam having a polarization direction perpendicular to the incident surface among the incident lights, and for example, the first direction may be a direction a in fig. 4. And the first wave plate 22 is mainly used for changing the polarization direction of the light beam, and the first wave plate may be a half wave plate or a quarter wave plate. The first mirror 23 is used to retroreflect the light beam back to the first beam splitting prism 21.
And a second wave plate 24 and a second reflecting mirror 25 which are disposed on a side of the first beam splitter prism corresponding to the second surface 212, and to which the light beam emitted from the second surface in the second direction is irradiated. The second direction is opposite to the first direction, for example, the second direction may be a direction B shown in fig. 4. And the second wave plate 24 is mainly used for changing the polarization direction of the light beam, and the second wave plate may be a half wave plate or a quarter wave plate. The second mirror 25 is used to retroreflect the light beam back to the first beam splitting prism 21.
And a third wave plate 26 and a measuring mirror 3 which are disposed on a side of the first beam splitter prism 21 corresponding to the second surface 212, and to which the light beam emitted from the second surface 212 in the third direction is irradiated. The third direction may be a transmission direction of the first light splitting prism 21 with respect to a light beam of which polarization direction is parallel to the incident surface in the incident light, that is, the third direction coincides with the incident direction of the incident light, for example, the third direction may be a direction C in fig. 4. And the third wave plate 22 is mainly used for changing the polarization direction of the light beam, and may be, for example, a quarter wave plate. The measuring mirror 3 is used to retroreflect the light beam back to the first beam splitting prism 21.
In this embodiment, the first surface 211 and the second surface 212 are parallel to each other, and the first surface 211 and the second surface 212 may form an included angle of 45 degrees with the horizontal direction, and the first direction, the second direction and the third direction may form an included angle of 45 degrees with the first surface.
Further, it should be noted that one of the first mirror and the second mirror is a corner cube prism, so that the light beam is offset, so that the incident point and the exit point of the light beam do not coincide with each other, and there is an offset, so that a corresponding measurement (for example, displacement measurement) can be performed based on the light beam emitted from the exit point in the following.
Specifically, the corner cube (refer to fig. 5) may include a first mirror 251 and a second mirror 252 connected to each other, and an included angle between the first mirror 251 and the second mirror 252 is an acute angle, and a light beam is irradiated to the first mirror 251 in a predetermined direction, reflected by the first mirror 251 to the second mirror 252, and further reflected by the second mirror 252. As can be seen from fig. 5, the light beam irradiated to the first mirror 251 and the light beam reflected by the second mirror 251 are shifted in a direction perpendicular to the predetermined direction, so that the light beam irradiated to the corner cube is not returned as it is, but is reflected after being shifted by a certain distance, and thus, both the incident point and the exit point of the light beam can be shifted, so as to perform corresponding measurement in the following.
And the first wave plate 22, the second wave plate 24 and the third wave plate 26 are all used for changing the polarization direction of the light beam. In this embodiment, it is necessary to change the polarization direction of the light beam by 90 °. The third wave plate may be a quarter-wave plate, and specifically, after the light beam passes through the quarter-wave plate twice, the polarization direction of the light beam may be changed by 90 °. The first wave plate and the second wave plate can be a half wave plate or a quarter wave plate, wherein the polarization direction of the light beam can be changed by 90 degrees after the light beam passes through the half wave plate once.
Further, in this embodiment, when the first reflecting mirror 23 is a pyramid prism and the second reflecting mirror 25 is a plane mirror, the second wave plate 24 can only be a quarter wave plate, and the first wave plate 22 can be a half wave plate or a quarter wave plate; when the first wave plate 22 is a half wave plate, one of the light beam irradiated to the first reflecting mirror 23 and the light beam reflected by the first reflecting mirror 23 passes through the first wave plate 22; when the first wave plate 22 is a quarter wave plate, the light beam irradiated to the first reflecting mirror 23 and the light beam reflected by the first reflecting mirror 23 both pass through the first wave plate 22 to deflect the polarization direction of the light beam by 90 °.
And when the second reflecting mirror 25 is a pyramid prism and the first reflecting mirror 23 is a plane mirror, the first wave plate 22 can only be a quarter wave plate, and the second wave plate 24 can be a half wave plate or a quarter wave plate. Specifically, reference may be made to fig. 4 and 6, wherein the second reflecting mirror 25 is a corner cube prism and the second wave plate 24 is a half wave plate in the apparatus shown in fig. 4, and the second reflecting mirror 25 is a corner cube prism and the second wave plate 24 is a quarter wave plate in the apparatus shown in fig. 6; further, it should be noted that, on the premise that the second reflecting mirror 25 is a corner cube prism, when the second wave plate 24 is a half wave plate, one of the light beam irradiated to the second reflecting mirror 25 and the light beam reflected by the second reflecting mirror 25 passes through the second wave plate (specifically, refer to fig. 4); when the second wave plate 24 is a quarter wave plate, the light beam irradiated to the second mirror 25 and the light beam reflected by the second mirror 25 both pass through the second wave plate 24 (refer to fig. 6 in particular), so that the polarization direction of the light beam can be deflected by 90 ° based on the second wave plate.
In the present embodiment, the second reflecting mirror 25 is mainly used as a corner cube prism, the first wave plate 22 is a quarter wave plate, and the second wave plate 24 is a half wave plate. As shown in fig. 4, the second mirror 25 includes a first mirror 251 and a second mirror 252 for shifting the light beam by a certain distance.
And, further, for the apparatus shown in fig. 4, the incident light emitted from the light source 1 is irradiated to the incident point of the first beam splitter prism for splitting, and is split into a first light beam f1 and a second light beam f2, the polarization directions of the first light beam f1 and the second light beam f2 are orthogonal and have a frequency difference of 4-20MHz, and the polarization direction of the first light beam f1 is perpendicular to the incident plane, and the polarization direction of the second light beam f2 is parallel to the incident plane, based on which, fig. 7 and 8 are schematic optical path diagrams of the first light beam f1 and the second light beam f2 in the apparatus shown in fig. 4 provided by the embodiment of the present invention, respectively.
Referring to fig. 7, a first light beam f1 with a polarization direction perpendicular to the incident plane is reflected to the first wave plate 22 and the first reflection mirror 23 via the first surface 211 of the first beam splitter prism 21 in the first direction a, so that the polarization direction of the first light beam f1 is deflected by 90 ° by the first wave plate 22, and the first light beam is reflected back to the first surface 211 in the second direction B by the first reflection mirror 23. Specifically, the first light beam f1 is reflected by the first surface 211 to the first wave plate 22, passes through the first wave plate 22 and reaches the first reflecting mirror 23, and then the first light beam f1 is reflected by the first reflecting mirror 23 to the first wave plate 22 again, and passes through the first wave plate 22 again and reaches the first surface 211, at this time, the first light beam f1 passes through the first wave plate 22 twice, the polarization direction thereof changes by 90 °, and then the first light beam f1 reflected by the first reflecting mirror 23 passes through the first surface 021 and reaches the second surface 022. Thereafter, the first light beam f1 will be irradiated from the second surface 022 to the second wave plate 24 and the second mirror 25 in the second direction B, so as to deflect the polarization direction of the first light beam f1 by 90 ° through the second wave plate 24, and reflect the first light beam f1 back to the second surface 212 through the second mirror 25. Specifically, the first light beam f1 irradiated from the second surface 022 in the second direction B passes through the second wave plate 24, and reaches the first mirror 251 of the second mirror 25, and is reflected by the first mirror 251 to the second mirror 252, and then the second mirror 252 reflects the first light beam f1 back to the second surface 212 again. Since the first light beam f1 passes through the first-order second wave plate 24, its polarization direction is deflected by 90 °, when the second light beam f2 reflected by the second mirror surface reaches the second surface 212, it is reflected by the second surface in the third direction C to the third wave plate 26 and the measuring mirror 3, so that the polarization direction of the first light beam is deflected by 90 ° by the third wave plate 26, and the first light beam is reflected back to the second surface 212 by the measuring mirror 3, and the first light beam reflected back by the measuring mirror 3 passes through the second surface to the first surface 211, so that the first light beam f1 exits from the exit point of the first beam splitter prism 21 (i.e. exits along out in fig. 4).
Similarly, referring to fig. 8, the second light beam f2 with the polarization direction parallel to the incident plane passes through the first surface 211 to the second surface 212 of the first beam splitter prism 21, and is projected from the second surface 212 to the third wave plate 24 and the measuring mirror 3 in the third direction C, so that the polarization direction of the second light beam f2 is deflected by 90 ° by the third wave plate 26, and the second light beam f2 is reflected back to the second surface 212 by the measuring mirror 3. And the second light beam f2 reflected by the measuring mirror 3 is reflected via the second surface 212 to the second wave plate 24 and the second mirror 25 in the second direction B to deflect the polarization direction of the second light beam f2 by 90 ° by the second wave plate 24 and to reflect the second light beam f2 in the first direction a to the second surface 212 by the second mirror 25. And the second light beam f2 reflected by the second mirror 25 passes through the second surface 212 to the first surface 211 and is projected from the first surface 211 to the first wave plate 22 and the first mirror 23 in the first direction a, so as to deflect the polarization direction of the second light beam f2 by 90 ° through the first wave plate 22, and reflect the second light beam f2 to the first surface 211 through the first mirror 23, and is reflected by the first surface 211, so that the second light beam f2 is reflected from the exit point of the first beam splitter prism 21 (i.e., exits at out in fig. 4).
And, in this embodiment, the apparatus further includes a detector (not shown in the figure) disposed at the exit point of the first beam splitter prism 21, for receiving the first and second light beams emitted from the exit point.
As can be seen from the above, in the apparatus shown in fig. 4, compared with the apparatus in the prior art (refer to fig. 1), the second wave plate 24 is disposed between the second reflecting mirror 25 and the first beam splitter prism 21 to change the polarization direction of the light beam emitted from the first beam splitter prism 21 along the second direction, so that the two light beams split by the first beam splitter prism 21 (i.e. the first light beam f1 and the second light beam f2) are both irradiated onto the measuring mirror, and the optical paths of the two light beams are the same, thereby realizing the measurement of the rotational displacement and the vertical displacement.
Specifically, fig. 9 is a schematic structural diagram of an interferometer apparatus for measuring rotational displacement by using the apparatus in fig. 4 according to an embodiment of the present invention, as shown in fig. 9, when the measuring mirror 7 rotates by a certain angle to generate rotational displacement, optical paths of the first light beam f1 and the second light beam f2 are different, and an optical path difference exists, so that a phase difference exists between the first light beam and the second light beam, and an interference phenomenon occurs. At this time, when the detector receives the first and second light beams, an interference fringe pattern of the first and second light beams is generated. And then, the optical path difference between the first light beam and the second light beam can be determined by analyzing the interference fringe pattern of the first light beam and the second light beam shown by the detector, and further the rotational displacement of the measuring mirror can be determined, so that the rotational displacement of the object to be measured can be measured when the object to be measured is fixed on the measuring mirror.
As can be seen from comparing fig. 2 and fig. 9, the interferometer apparatus in this embodiment only needs one beam splitter prism (i.e., the first beam splitter prism), three wave plates (i.e., the first wave plate, the second wave plate, and the third wave plate), and three mirrors (i.e., the first mirror, the second mirror, and the measurement mirror), so as to implement the measurement of the rotational displacement, and the number of required components is small, and since the number of light spots irradiated onto the measurement mirror is also small, and is only two, the size of the measurement mirror is also small, thereby saving space and reducing cost.
Further, fig. 10 is a schematic structural diagram of an interferometer apparatus for measuring vertical displacement by using the apparatus of fig. 4 according to an embodiment of the present invention, and as shown in fig. 10, the measuring mirror 3 includes a third measuring mirror 33, a fourth measuring mirror 34, and a fifth measuring mirror 35. Wherein, the extending direction of third measuring mirror 33 with third party C is perpendicular, fourth measuring mirror 34 is located between third wave piece 26 and the third measuring mirror 33, with third measuring mirror 33 is connected, and with third measuring mirror 33 non-perpendicular setting, the example, third measuring mirror 33 with fourth measuring mirror 34 can be 45 contained angles and set up, and fifth measuring mirror 35 sets up one side of the reflecting mirror surface of fourth measuring mirror 34.
Based on this, of the light beams emitted from the second surface 212 in the third direction C, a part of the light beams is irradiated to the third measuring mirror 33, and the other part of the light beams is irradiated to the fourth measuring mirror 34. And, the light beam irradiated to the third measuring mirror 33 is reflected back to the second surface 212 through the third measuring mirror 33, the light beam irradiated to the fourth measuring mirror 34 is reflected to the fifth measuring mirror 35 by the fourth measuring mirror 34 and is reflected back to the fourth measuring mirror 34 again by the fifth measuring mirror 35, and the light beam reflected back again is reflected back to the second surface 212 by the fourth measuring mirror 34 and is emitted from the exit point.
For example, in the present embodiment, the first light beam f1 emitted from the second surface 212 in the third direction C may be made to impinge on the fourth measuring mirror 34, so that the second light beam f2 emitted from the second surface 212 in the third direction C may be made to impinge on the third measuring mirror 33 (refer to fig. 10). The third measuring mirror 33 reflects the second light beam f2 back to the second surface 212, the fourth measuring mirror 34 reflects the first light beam f1 to the fifth measuring mirror 35 to reflect the first light beam f1 back to the fourth measuring mirror 34 again with the fifth measuring mirror 35, and the reflected first light beam f1 back to the second surface 212 is reflected by the fourth measuring mirror 34 again.
Referring to fig. 10, there is an optical path difference between the first light beam f1 and the second light beam f2 in fig. 10, which is twice the vertical displacement between the fourth measuring mirror and the fifth measuring mirror. At the moment, the optical path difference of the first light beam and the second light beam can be determined by analyzing and calculating the interference fringe pattern shown by the detector, and then the vertical displacement between the fourth measuring mirror and the fifth measuring mirror can be determined, so that the vertical displacement of the two objects to be measured can be determined when the objects to be measured are respectively fixed on the fourth measuring mirror and the fifth measuring mirror.
As can be seen from comparing fig. 3 and fig. 10, the interferometer apparatus for measuring vertical displacement according to the present invention only includes one beam splitter prism (i.e., the first beam splitter prism), three wave plates (i.e., the first wave plate, the second wave plate, and the third wave plate), and five mirrors (i.e., the first mirror, the second mirror, the third measuring mirror, the fourth measuring mirror, and the fifth measuring mirror), so as to measure vertical displacement. Compared with the interferometer device for measuring vertical displacement in the prior art, the interferometer device has fewer required components and fewer measurement mirrors, thereby saving space and reducing cost.
Still further, fig. 11 is a schematic structural diagram of a differential interferometer apparatus for simultaneously measuring horizontal displacement and vertical displacement according to an embodiment of the present invention, wherein, with reference to fig. 10 and 11, on the basis of the apparatus shown in fig. 10, the apparatus shown in fig. 11 further includes a second beam splitter prism 4, the second beam splitter prism 4 is located between the second reflecting mirror 25 and the first beam splitter prism 21, and the first beam splitter prism 4 includes two beam splitters 41 and a plane mirror 42 which are arranged in parallel. The beam splitter 41 is mainly used for splitting light, when a light beam irradiates on the beam splitter 41, a part of the light beam will be transmitted from the beam splitter, and another part of the light beam will be reflected by the beam splitter, in this embodiment, the beam splitter may be a fifty-percent mirror. And, the plane mirror 42 may be a beam splitter or a reflecting mirror, and is used for reflecting the light beam reflected by the beam splitter 41 to the second wave plate 24 and the second reflecting mirror 25.
In the present embodiment, the light beam emitted from the second surface 212 in the second direction B is irradiated onto the beam splitter 41, so that part of the light beam is transmitted out of the beam splitter 41 to form a first test light, the first test light is used for implementing the measurement of the horizontal displacement, and another part of the light beam is reflected by the beam splitter to the plane mirror and reflected by the plane mirror to the second wave plate and the second reflecting mirror, so as to be emitted from the exit point of the first beam splitter prism subsequently to form a second test light, and the second test light is used for measuring the vertical displacement.
Specifically, referring to fig. 11, the first light beam f1 emitted from the second surface 212 in the second direction B is irradiated onto the beam splitter 41 and is split into a first sub-light beam f11 and a second sub-light beam f12, wherein the first sub-light beam f11 is transmitted from the beam splitter 41, the second sub-light beam f12 is reflected by the beam splitter 4 to the plane mirror 42, and is reflected by the plane mirror 42 to the second reflecting mirror 25, so that the second reflecting mirror 25 reflects the second sub-light beam back to the second surface 212. And, the second light beam f2 emitted from the second surface 212 in the second direction B is irradiated onto the beam splitter 41 and is split into a third sub-light beam f21 and a fourth sub-light beam f22, wherein the third sub-light beam f21 is transmitted from the beam splitter 41, the fourth sub-light beam f22 is reflected by the beam splitter 4 to the plane mirror 42, and is reflected by the plane mirror 42 to the second reflecting mirror 25, so that the second reflecting mirror 25 reflects the fourth sub-light beam f22 back to the second surface 212.
Wherein the first sub-beam f11 and the third sub-beam f21 are transmitted from the beam splitter 41 (i.e. emitted out1 in fig. 11) in superposition, and constitute a first test light. The second sub-beam f12 and the fourth sub-beam f22 are reflected to the second wave plate and the second reflector, and then reflected back to the second surface 252, and then emitted from the exit point of the first beam splitter prism (i.e. emitted out in fig. 11), so as to form a second test light.
It should be noted that, at out and at out1, a detector is provided for receiving the first test light and the second test light, respectively.
As can be seen from fig. 11, an optical path difference exists between the first sub-beam f11 and the third sub-beam f21, which is twice the horizontal displacement of the measuring mirror relative to the first beam splitter prism 21, and an optical path difference also exists between the second test light f12 and the fourth test light f22, which is twice the vertical displacement between the fourth measuring mirror 34 and the fifth measuring mirror 35. So, through the interference fringe picture of analysis and calculation first test light, can determine the measuring mirror for the horizontal displacement of second beam splitting prism, through the interference fringe picture of analysis and calculation second test light, can determine fourth measuring mirror 34 with vertical displacement between the fifth measuring mirror 35 to can realize measuring simultaneously to horizontal displacement and vertical displacement, and its required subassembly is less, and the size of third measuring mirror is less, makes the shared space of device is less, and the cost is lower.
In addition, with respect to the apparatus of fig. 4, it may also measure only the horizontal displacement, specifically, fig. 12 is a schematic structural diagram of an interferometer apparatus for measuring the horizontal displacement by using the apparatus of fig. 4 according to an embodiment of the present invention, and as shown in fig. 12, the measuring mirror 3 includes a first measuring mirror 31 and a second measuring mirror 32. Among the light beams emitted from the second surface 212 in the third direction C, a part of the light beams irradiates the first measuring mirror 31, another part of the light beams irradiates the second measuring mirror 32, and the light beams are reflected back to the second surface 212 by the first measuring mirror 31 and the second measuring mirror 32. For example, the first light beam f1 emitted from the second surface 212 in the third direction C may be irradiated to the first measuring mirror 31, and the second light beam f2 emitted from the second surface 212 in the third direction C may be irradiated to the first measuring mirror 32, so that the first measuring mirror 31 may retroreflect the first light beam f1 to the second surface 212, and the second measuring mirror 32 may retroreflect the second light beam f2 to the second surface 212.
As can be seen from fig. 12, when there is a horizontal displacement difference between the first measuring mirror and the second measuring mirror, there is an optical path difference between the first light beam f1 and the second light beam f2, which is twice the lateral horizontal displacement difference between the first measuring mirror and the second measuring mirror, and at this time, the horizontal displacement difference between the first measuring mirror 31 and the second measuring mirror 32 can be determined by analyzing the interference fringes shown in the detector, so that when an object to be measured is fixed on the first measuring mirror and the second measuring mirror respectively, the horizontal displacements of the two objects to be measured can be measured, thereby achieving the measurement of the horizontal displacement. In addition, the device shown in fig. 12 requires fewer components, and the first measuring mirror and the second measuring mirror are smaller in size, lower in cost and smaller in occupied space.
In summary, in the differential interferometer apparatus provided by the present invention, the light beam emitted from the first surface of the first beam splitter prism in the first direction is irradiated to the first wave plate and the first reflection mirror, the light beam emitted from the second surface of the first beam splitter prism in the second direction is irradiated to the second wave plate and the second reflection mirror, and the light beam emitted from the second surface in the third direction is irradiated to the third wave plate and the measurement mirror, and the first direction is a reflection direction of the first beam splitter prism with respect to the incident light, the second direction is an opposite direction of the first direction, and the third direction is a transmission direction of the first beam splitter with respect to the incident light.
Therefore, when the incident light irradiates the first beam splitter prism and is split into two beams, the beam transmitted by the first beam splitter prism directly irradiates the measuring mirror, and the beam reflected by the first beam splitter prism is reflected to the first wave plate and the first measuring mirror along the first direction, then reflected back to the first beam splitter prism along the second direction by the first measuring mirror, passes through the first beam splitter prism to reach the second wave plate and the second measuring mirror, is reflected to the first beam splitter prism along the first direction again by the second measuring mirror, and then is reflected to the measuring mirror by the first beam splitter prism. It can be known that, in the present invention, after the incident light is split into two beams by the first beam splitter prism, the two beams can respectively irradiate to different positions of the measuring mirror, that is, the differential interferometer apparatus in the present invention can realize the measurement of the rotational displacement and the vertical displacement of the measuring mirror.
That is, in this embodiment, the differential interferometer apparatus only needs one beam splitter prism (i.e., the first beam splitter prism), three wave plates (i.e., the first wave plate, the second wave plate, and the third wave plate), two mirrors (i.e., the first mirror and the second mirror), and the measurement mirror, and can achieve the measurement of the rotational displacement and the vertical displacement. The required components are fewer, and the size of the measuring mirror does not need to be too large because the number of light spots irradiated on the measuring mirror is fewer and only two, so that the differential interferometer device for measuring the vertical displacement and the rotary displacement is lower in cost and smaller in occupied space.
In addition, the differential interferometer device has less components, so that the debugging difficulty is lower, and meanwhile, the interferometer in the invention is a multi-axis interferometer, so that the integration level is higher.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (15)
1. A differential interferometer apparatus, characterized in that the apparatus comprises:
a light source for emitting incident light;
the light splitting prism is used for receiving incident light emitted by a light source and splitting the incident light so as to split the incident light into at least two light beams, and the light splitting prism is provided with a first surface and a second surface which are opposite;
the first wave plate and the first reflecting mirror are used for receiving the light beam emitted from the first surface in a first direction, and the first direction is the reflecting direction of the first light splitting prism for the incident light;
the second wave plate and the second reflector are used for receiving the light beam emitted from the second surface in a second direction, and the second direction is opposite to the first direction;
the third wave plate and the measuring mirror are used for receiving the light beam emitted from the second surface in a third direction, and the third direction is the transmission direction of the first light splitting prism for the incident light;
the first wave plate, the second wave plate and the third wave plate are used for deflecting the polarization direction of the light beam; at least one of the first reflector and the second reflector is a corner cube prism for reflecting the light beam and enabling an incidence point and an exit point of the light beam not to coincide; and based on the arrangement of the first wave plate, the second wave plate, the third wave plate, the first reflecting mirror and the second reflecting mirror, the at least two light beams are irradiated onto the measuring mirror; the polarization direction of the light beam back and forth through the first wave plate and the first reflecting mirror is changed by 90 degrees; the polarization direction of the light beam back and forth through the second wave plate and the second reflector is changed by 90 degrees; the polarization direction of the light beam back and forth through the third wave plate and the measuring mirror is changed by 90 degrees.
2. The differential interferometer apparatus of claim 1,
incident light emitted by the light source irradiates an incident point of the first light splitting prism and is split;
wherein a first light beam of the incident light having a polarization direction perpendicular to an incident plane is reflected to the first wave plate and the first mirror in the first direction via the first surface of the first beam splitter prism to deflect the polarization direction of the first light beam by 90 ° by the first wave plate and to reflect the first light beam back to the first surface in the second direction by the first mirror, and the first light beam reflected by the first mirror passes from the first surface to the second surface and is irradiated from the second surface to the second wave plate and the second mirror in the second direction to deflect the polarization direction of the first light beam by 90 ° by the second wave plate and to reflect the first light beam back to the second surface by the second mirror and to reflect the first light beam reflected by the second mirror in the third direction by the second surface to the third wave plate and the measuring mirror, deflecting the polarization direction of the first light beam by 90 degrees through the third wave plate, reflecting the first light beam back to the second surface through the measuring mirror, and enabling the first light beam reflected by the measuring mirror to pass through the second surface to the first surface so as to enable the first light beam to be emitted from the exit point of the first light splitting prism;
wherein the first beam of light passes through the first mirror or the second mirror to shift the exit point relative to the entrance point.
3. The differential interferometer apparatus of claim 1,
incident light emitted by the light source irradiates an incident point of the first light splitting prism and is split;
wherein a second light beam of the incident light having a polarization direction parallel to the incident plane passes through the first surface to the second surface of the first beam splitter prism and is transmitted from the second surface to the third wave plate and the measurement mirror in the third direction to deflect the polarization direction of the second light beam by 90 ° by the third wave plate and reflect the second light beam back to the second surface by the measurement mirror, and the second light beam reflected back by the measurement mirror is reflected to the second wave plate and the second mirror in the second direction via the second surface to deflect the polarization direction of the second light beam by 90 ° by the second wave plate and reflect the second light beam to the second surface in the first direction by the second mirror, and the second light beam reflected back by the second mirror passes through the second surface to the first surface and is projected from the first surface to the first wave plate and the first mirror in the first direction, deflecting the polarization direction of the second light beam by 90 degrees through the first wave plate, reflecting the second light beam to the first surface through the first reflecting mirror, and reflecting the second light beam out of the exit point of the first light splitting prism through reflection of the first surface;
wherein the second beam passes through the first mirror or the second mirror to shift the exit point relative to the entrance point.
4. The differential interferometer apparatus of claim 1, wherein the measurement mirror is fixed to an object to be measured to determine a displacement of the object to be measured by measuring a displacement of the measurement mirror.
5. The differential interferometer apparatus of claim 1, wherein the third wave plate is a quarter wave plate, and the polarization direction of the light beam changes by 90 ° when the light beam passes through the quarter wave plate twice.
6. The differential interferometer apparatus of claim 1, wherein the corner cube comprises a first mirror surface and a second mirror surface, the light beam impinging on the first mirror surface in a predetermined direction, being reflected by the first mirror surface to the second mirror surface, and being further reflected by the second mirror surface, wherein the light beam impinging on the first mirror surface and the light beam reflected by the second mirror surface are offset by a predetermined dimension in a direction perpendicular to the predetermined direction.
7. The differential interferometer apparatus of claim 1, wherein the first mirror is the corner cube;
the first wave plate is a half wave plate, and one of the light beam irradiated to the first reflecting mirror and the light beam reflected by the first reflecting mirror passes through the first wave plate; or, the first wave plate is a quarter wave plate, and both the light beam irradiated to the first reflecting mirror and the light beam reflected by the first reflecting mirror pass through the first wave plate.
8. The differential interferometer apparatus of claim 1, wherein the second mirror is a corner cube prism;
the second wave plate is a half wave plate, and one of the light beam irradiated to the second reflector and the light beam reflected by the second reflector passes through the second wave plate; or, the second wave plate is a quarter wave plate, and both the light beam irradiated to the second reflector and the light beam reflected by the second reflector pass through the second wave plate.
9. The differential interferometer apparatus of claim 1, wherein the first and second surfaces of the first beam splitting prism are parallel, and wherein the first, second, and third directions each include a 45 ° angle with the first surface.
10. The differential interferometer apparatus of claim 1, wherein the measurement mirror comprises a first measurement mirror and a second measurement mirror;
wherein a part of the light beam emitted from the second surface in the third direction is irradiated to the first measuring mirror, another part is irradiated to the second measuring mirror, and the light beam is retroreflected to the second surface by the first measuring mirror and the second measuring mirror.
11. The differential interferometer apparatus of claim 1, wherein the measurement mirrors include a third measurement mirror, a fourth measurement mirror, a fifth measurement mirror;
the extending direction of the third measuring mirror is perpendicular to the third direction, the fourth measuring mirror is located between the third wave plate and the third measuring mirror, is connected with the third measuring mirror and is not perpendicular to the third measuring mirror, and the fifth measuring mirror is arranged on one side of a reflecting mirror surface of the fourth measuring mirror;
in the light beam emitted from the second surface in the third direction, part of the light beam irradiates the third measuring mirror, and the other part of the light beam irradiates the fourth measuring mirror; wherein the light beam irradiated to the third measuring mirror is retro-reflected to a second surface by the third measuring mirror, the light beam irradiated to the fourth measuring mirror is reflected to the fifth measuring mirror by the fourth measuring mirror and is re-reflected back to the fourth measuring mirror by the fifth measuring mirror, and the re-reflected light beam is retro-reflected to the second surface by the fourth measuring mirror.
12. The differential interferometer apparatus of claim 11, wherein the second mirror is a corner cube prism;
the device also comprises a second beam splitter prism, the second beam splitter prism is positioned between the second reflecting mirror and the first beam splitter prism, and the first beam splitter prism comprises two beam splitters and a plane mirror which are arranged in parallel;
wherein the beam emitted from the second surface in the second direction is irradiated to the beam splitter, so that part of the beam is transmitted out of the beam splitter, and the other part of the beam is reflected to the plane mirror by the beam splitter and reflected to the second wave plate and the second reflecting mirror by the plane mirror.
13. The differential interferometer apparatus of claim 12, wherein the planar mirror is a beam splitter or a mirror.
14. The differential interferometer apparatus of claim 12, wherein the portion of the beam transmitted from the beam splitter is used to form the first test light.
15. The differential interferometer apparatus of claim 12, wherein the other beam reflected by the beam splitter is for exiting from the exit point of the first beam splitter prism to form the second test light.
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| WO1986006481A1 (en) * | 1985-04-24 | 1986-11-06 | Nauchno-Tekhnicheskoe Obiedinenie Akademii Nauk Ss | Interference polarization refractometer |
| JPH08327453A (en) * | 1995-05-29 | 1996-12-13 | Shimadzu Corp | Polarization interferometer |
| CN1431478A (en) * | 2003-02-14 | 2003-07-23 | 中国科学院上海光学精密机械研究所 | Micro displacement real time interferometry apparatus |
| US7196797B2 (en) * | 2004-05-28 | 2007-03-27 | Agilent Technologies, Inc. | Differential interferometer with improved cyclic nonlinearity |
| US7705994B2 (en) * | 2005-11-23 | 2010-04-27 | Agilent Technologies, Inc. | Monolithic displacement measuring interferometer with spatially separated but substantially equivalent optical pathways and optional dual beam outputs |
| CN101216286B (en) * | 2007-12-26 | 2010-09-15 | 上海微电子装备有限公司 | Heterodyne interferometer measuring system for measuring displacement and its measurement method |
| CN101586941B (en) * | 2009-05-12 | 2012-12-12 | 上海微电子装备有限公司 | Low non-linear error and low temperature drift two-frequency laser interference device |
| CN101566459B (en) * | 2009-05-27 | 2010-12-29 | 上海微电子装备有限公司 | Dual-frequency laser interferometer |
| CN102519358B (en) * | 2011-12-26 | 2013-12-25 | 哈尔滨工业大学 | Phase-shift diffraction/interference measuring instrument and method for detecting three-dimensional shape of microsphere |
| CN103376055A (en) * | 2012-04-20 | 2013-10-30 | 上海微电子装备有限公司 | High-resolution linear interferometer |
| CN202853565U (en) * | 2012-06-29 | 2013-04-03 | 上海理工大学 | Acousto-optic heterodyne ineterferometer light path device |
| CN102853771B (en) * | 2012-09-19 | 2015-07-29 | 哈尔滨工业大学 | Miniaturized high-speed ultra-precise laser difference interference measuring method and device |
| CN205014944U (en) * | 2015-04-27 | 2016-02-03 | 中国计量学院 | Dual -frenquency heterodyne laser interferometer of quadruple journey |
| RU2601530C1 (en) * | 2015-09-14 | 2016-11-10 | Открытое акционерное общество "Корпорация космических систем специального назначения "Комета" | Device for measuring angular movements of object |
| CN107806821B (en) * | 2017-10-31 | 2019-09-24 | 浙江理工大学 | With the difference single-frequency interference signal processing unit and method of integrated four photodetectors |
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