Laser interference device and laser interference equipment

Abstract

The invention provides a laser interference device and laser interference equipment, which are used for solving the problem of abbe error during detection of a measuring tool. The laser interference device comprises a light source, a light path assembly and a detector. The light source is used for emitting a detection light beam. The measuring light and the reference light enter from one light-transmitting surface of the light path assembly, and the measuring light and the reference light advance in the light path assembly until the measuring light and the reference light exit from the same light-transmitting surface of the light path assembly; the detector is used for receiving the measuring light and the reference light emitted by the light path assembly; the light path assembly is configured to guide the measuring light to advance on at least two effective measuring light paths, and the two effective measuring light paths are parallel in the measuring length direction of the measured object and are arranged on the two sides of the measured object at equal intervals. According to the invention, the effective measurement light paths are arranged on the two sides of the measured object, so that opposite Abbe errors can be generated and offset mutually.

Description

Technical Field

[0001] The present application relates to the field of optical metrology technology, and in particular to a laser interferometer device and a laser interferometer equipment. Background Art

[0002] Laser interferometry utilizes the coherence principle of lasers to accurately measure optical path differences through changes in interference fringes. Furthermore, because laser interferometry can achieve sub-nanometer resolution, it also enables non-contact, non-destructive, and long-distance detection. Consequently, laser interferometry is widely used in modern ultra-precision manufacturing, such as microelectronics, micromechanics, and micro-optics, as well as in photolithography and aerospace, to improve the processing quality of high-tech products.

[0003] Laser interferometry technology is currently used to detect the measured length of measuring tools. During testing, a measuring mirror is placed on one side of the measuring tool, and the movement of the measuring mirror reflects the change in the measured length of the measuring tool. However, in actual testing, the measuring optical path formed during measurement is often not aligned with the length direction of the measuring tool, which can easily cause Abbe error. This results in a slope error between the measured length result and the actual length change of the measuring tool, thus affecting the accuracy of the measuring tool test results. Summary of the Invention

[0004] The present application provides a laser interferometer and a laser interferometer device, which aim to solve the technical problem of inaccurate detection results caused by Abbe error during detection.

[0005] In some embodiments of the present application, a laser interferometer device is provided for detecting a measured length of an object to be measured. The laser interferometer device includes:

[0006] a light source for emitting a detection light beam having a measurement light and a reference light with different polarization directions;

[0007] an optical path component, wherein the measuring light and the reference light enter from a light-transmitting surface of the optical path component, and the measuring light and the reference light respectively travel along respective optical paths within the optical path component until the measuring light and the reference light are emitted from the same light-transmitting surface of the optical path component; and

[0008] a detector, configured to receive the measuring light and the reference light emitted by the optical path component to detect the measuring length of the object to be measured;

[0009] The optical path component is configured to guide the measuring light to travel on at least two effective measuring optical paths, and the two effective measuring optical paths are parallel along a measuring length direction of the object to be measured and are equidistantly arranged on both sides of the object to be measured.

[0010] In some embodiments, the optical path assembly includes a beam splitting mechanism, a redirector, and three reflectors;

[0011] The beam splitting mechanism has a first light-transmitting surface and three second light-transmitting surfaces. The light source and the detector face the first light-transmitting surface. The three reflectors are respectively used to reflect light that passes through the three second light-transmitting surfaces of the beam splitting mechanism. Any two of the three reflectors are measuring devices. The two measuring devices are respectively arranged on both sides of the object to be measured and can move synchronously along the measuring length direction of the object to be measured. The incident surfaces of the two measuring devices are located on the same plane. The deflector is used to fold the optical path to guide the measuring light to travel between the measuring device and the beam splitting mechanism. The effective measuring optical path is formed between the measuring device and the beam splitting mechanism, or the effective measuring optical path is formed between the measuring device and the deflector.

[0012] In some embodiments, the two measuring devices are configured to reflect light transmitted through the second light-transmitting surfaces at adjacent or opposite positions of the beam splitting mechanism.

[0013] In some embodiments, the beam splitting mechanism includes a beam splitter and two quarter-wave plates, and the optical path component includes one of the diverters;

[0014] The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at adjacent positions of the beam splitter. The deflector is arranged on the optical path between the beam splitter and one of the measuring devices. The two 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the two measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The first light-transmitting surface is used to transmit the light emitted by the light source and the light received by the detector.

[0015] In some embodiments, the beam splitting mechanism includes a beam splitter and two quarter-wave plates, and the optical path component includes two of the redirectors;

[0016] The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at relative positions of the beam splitter. The two redirectors are respectively arranged on the optical path between the beam splitter and the two measuring devices. The two 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the two measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The first light-transmitting surface is used to transmit the light emitted by the light source and the light received by the detector.

[0017] In some embodiments, the optical path component further includes a polarizing mechanism;

[0018] The polarizing mechanism is arranged between the beam splitting mechanism, the light source and the detector, and is used to separate the detection light beam into the measuring light and the reference light.

[0019] In some embodiments, the beam splitting mechanism includes a beam splitter and three quarter-wave plates, and the optical path component includes one of the diverters;

[0020] The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at adjacent positions of the beam splitter. The deflector is arranged on the optical path between the beam splitter and one of the measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The three 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the three reflectors. The first light-transmitting surface is used to transmit the measurement light after being separated by the polarizing mechanism.

[0021] In some embodiments, the beam splitting mechanism includes a beam splitter and three quarter-wave plates, and the optical path component includes two of the redirectors;

[0022] The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at opposite positions of the beam splitter. The two deflectors are respectively arranged on the optical path between the beam splitter and the two measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The three 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the three reflectors. The first light-transmitting surface is used to transmit the measurement light after being separated by the polarizing mechanism.

[0023] In some embodiments, the laser interferometer device further includes a housing;

[0024] The light source and the detector are integrated in the housing.

[0025] Some embodiments of the present application further provide a laser interferometer device, including:

[0026] The laser interferometer device described in any of the above embodiments;

[0027] a base, used for supporting the object to be measured; and

[0028] The moving platform is movably arranged on the base. The laser interference device includes a measuring device, and the measuring device is installed on the moving platform.

[0029] According to the laser interferometer device of the above-described embodiment, after the detection beam is emitted by the light source, the reference light travels along the optical path designed by the optical path assembly and is received by the detector, while the measurement light travels along the effective measurement optical paths on both sides of the object being measured and is received by the detector. Because the two effective measurement optical paths are parallel to the object being measured and are arranged at equal intervals, the two effective measurement optical paths can generate opposite Abbe errors with the object being measured. By utilizing the opposite nature of the Abbe errors on the effective measurement optical paths on both sides of the object being measured, the Abbe errors can be at least partially offset, thereby reducing or even eliminating the impact of the Abbe errors on the object being measured. By counting the interference fringes resynthesized by the detector, the result is closer to the actual measured length of the object being measured, thereby facilitating improved accuracy in laser interferometer detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural diagram of a laser interferometer used to detect an object in the related art;

[0031] Figure 2 This is a schematic structural diagram of a laser interferometer device in one embodiment of the present application;

[0032] Figure 3 This is a schematic diagram of the principle of using the laser interferometer device of the present application to detect the object being measured;

[0033] Figure 4 This is a schematic structural diagram of a first embodiment of the laser interferometer device of the present application;

[0034] Figure 5 This is a structural diagram of the second embodiment of the laser interferometer device of the present application;

[0035] Figure 6 for Figure 2 A schematic structural diagram of another embodiment of a polarizing mechanism in a laser interferometer device;

[0036] Figure 7 This is a schematic structural diagram of the third embodiment of the laser interferometer device of the present application;

[0037] Figure 8 This is a schematic structural diagram of a fourth embodiment of the laser interferometer device of the present application;

[0038] Figure 9 for Figure 7 A schematic structural diagram of another embodiment of the laser interferometer device.

[0039] in:

[0040] 11-light source; 12-optical path component; 121-beam splitting mechanism; 121a-first light-transmitting surface; 121b-second light-transmitting surface; 1211-beam splitter; 1212-1 / 4 wave plate; 1213-second 1 / 2 wave plate; 122-reflector; 1220-measuring device; 123-steering device; 13-detector; 14-polarizing mechanism; 141-interferometer; 142-reflector; 143-first 1 / 2 wave plate; 15-housing; 2-base; 3-moving platform; 4-guide mechanism; 5-measured object; 6-effective measuring optical path. Specific embodiments

[0041] The present application is further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. Similar elements in different embodiments are numbered with associated similar elements. In the following embodiments, many detailed descriptions are provided to enable the present application to be better understood. However, those skilled in the art will readily appreciate that some of the features may be omitted in different circumstances, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification. This is to avoid the core portion of the present application being overwhelmed by excessive descriptions, and for those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0042] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments, and the operational steps involved in each embodiment may be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the specification and drawings are only for the purpose of clearly describing a particular embodiment and do not imply a required composition and / or sequence.

[0043] The serial numbers assigned to components herein, such as "first," "second," etc., are used solely to distinguish the objects being described and do not convey any sequential or technical meaning. References to "connection" and "coupling" herein, unless otherwise specified, include both direct and indirect connections (couplings).

[0044] After long-term use, the measuring tool needs to be tested for its measurement accuracy to ensure the accuracy of the measuring tool. Figure 1 As shown, in the prior art, a laser interferometer is used to test the measurement accuracy of a ruler. During measurement, the laser interferometer and ruler remain relatively fixed. The measuring mirror moves to replace the change in the ruler's measured length. The laser interferometer transmits and receives light signals along the aa direction toward the measuring mirror to detect the distance between the laser interferometer and the measuring mirror. The ruler's measurement accuracy can then be determined by comparing the actual measured length of the ruler with the detected distance between the laser interferometer and the measuring mirror.

[0045] During this process, the optical path difference between the laser interferometer and the measuring mirror changes to △L`=2L1`, where L1` is the distance between the laser interferometer and the measuring mirror. Theoretically, L`=L1`, where L` is the actual measured length of the ruler. However, because the measuring optical path between the laser interferometer and the measuring mirror is not aligned with the length of the ruler, an Abbe error exists. This results in a slope error between L1` measured by the laser interferometer and the actual measured length L` of the ruler: L1`=L`±δ, where δ is the Abbe error. When the laser interferometer measurement results are subsequently compared with the nominal measured length on the ruler, the presence of the Abbe error will result in an inaccurate comparison, making it difficult to accurately determine the accuracy of the ruler.

[0046] It is understandable that the above embodiment is illustrated by taking a ruler as an example. In the present application, the object to be detected (hereinafter referred to as the object to be measured 5) is not limited to the ruler. For example, the object to be measured 5 can also be a measuring tool such as a gauge block, a vernier caliper, a step gauge, a micrometer, a wire guide, etc. These measuring tools will inevitably produce Abbe errors during the process of being detected by the laser interferometer. In addition, the object to be measured 5 is not limited to a measuring tool. The object to be measured 5 can also be a movable component in an automation device such as a machine tool, a gantry, and a cutting machine. These components also need to be detected after long-term use to ensure the stability of the operation of the automation device. Therefore, the present application does not impose any special restrictions on the specific type of the object to be measured 5.

[0047] In order to better detect the object 5, the present application provides a laser interferometer device, such as Figure 2 As shown, the laser interferometer device may include a laser interferometer device, a base 2 and a moving platform 3. The base 2 is used to support the object to be measured 5. The moving platform 3 is movably set on the base 2. The laser interferometer device may include a measurer 1220, which is installed on the moving platform 3.

[0048] Among them, a guide rail mechanism 4 can be set between the moving table 3 and the base 2, and the guide rail mechanism 4 is used to drive the moving table 3 to move along the straight line aa on the base 2. For example, the guide rail mechanism 4 may include a linear rail and a motor that drives the linear rail to move, and the moving table 3 is installed on the linear rail and moves along the straight line aa through the linear rail. In addition, a mechanism such as a slide groove or a slider can also be set on the base 2 to make the moving table 3 move along the straight line aa on the base 2. The present application does not impose any special restrictions on the driving structure for the movement of the moving table 3. In other embodiments, the measuring device 1220 can also be directly set on the object to be measured 5 for measurement. For example, when testing a vernier caliper, the measuring device 1220 can be set on the vernier caliper, so that the laser interferometer device does not need to separately set up the moving table 3 and the guide rail mechanism 4. The present application does not impose any special restrictions on whether the laser interferometer device is provided with a moving table 3.

[0049] In order to reduce the Abbe error generated during the detection of the object 5, the present application also provides a laser interferometer device, such as Figure 2 and Figure 3 As shown, the laser interferometer device is used to detect the measured length of the object 5 to be measured. The laser interferometer device may include a light source 11, an optical path component 12 and a detector 13. The light source 11 is used to emit a detection light beam of measuring light and reference light with different polarization directions; the measuring light and the reference light are incident from a light-transmitting surface of the optical path component 12, and the measuring light and the reference light respectively travel along their respective optical paths in the optical path component 12 until the measuring light and the reference light are emitted from the same light-transmitting surface of the optical path component 12; the detector 13 is used to receive the measuring light and the reference light emitted by the optical path component 12 to detect the measured length of the object 5 to be measured; wherein the optical path component 12 is configured to guide the measuring light to travel on at least two effective measuring optical paths 6, and the two effective measuring optical paths 6 are parallel along the measuring length direction of the object 5 to be measured and are equidistantly arranged on both sides of the object 5 to be measured.

[0050] During the detection process, after light source 11 emits a detection beam, measuring light and reference light are incident from the same position on the same light-transmitting surface of optical path component 12. The reference light travels along the optical path designed by optical path component 12 and is received by detector 13. The measuring light is guided along at least two effective measurement optical paths 6 and received by detector 13. When the same end of the two effective measurement optical paths 6 moves synchronously along the measured length of the object 5 (for example, the two measuring devices 1220 move synchronously), the change in the optical path length of the two effective measurement optical paths 6 can represent the change in the measured length of the object 5, thereby enabling the laser interferometer device to detect the measured length of the object 5. Ultimately, the measuring light and reference light are emitted from the same position on the same light-transmitting surface of optical path component 12, but different from the position at which they entered, so that detector 13 can receive the measuring light and reference light at the same position. Detector 13 then recombines the measuring light and reference light to form interference fringes. By counting the movement of the interference fringes, the actual measured length of the object 5 can be accurately detected, thereby ensuring the accuracy of the detection results of the object 5.

[0051] Specifically, if Figure 2 and Figure 3As shown, since effective measurement optical paths 6 are arranged parallel and equidistantly on both sides of the object 5, when the motion stage 3 moves, the optical path length of the effective measurement optical path 6 changes by ΔL = 2(L1 + L2), where L1 is the unidirectional optical path length of the effective measurement optical path 6 on the left side of the object 5, and L2 is the unidirectional optical path length of the effective measurement optical path 6 on the right side of the object 5. Theoretically, L = L1 = L2, where L is the actual measured length of the object 5. However, due to the Abbe error, there is a slope error between the measured L1 and L2 and L. Since L1 and L2 are parallel to the two sides of the object 5 and are equidistant from L, the Abbe error between L1 and L is exactly opposite to the Abbe error between L2 and L, i.e., L1 = L + δ and L2 = L - δ, where δ is the Abbe error. Therefore, the actual measured length of the object 5 after eliminating the Abbe error is: L = 1 / 2(L1 + L2) = 1 / 4ΔL, where ΔL is the optical path difference between the reference light and the measurement light, i.e., the optical path length change along the effective measurement optical path 6. This shows that the Abbe errors on both sides of the object 5 cancel each other out, thereby reducing the impact of the Abbe errors on the detection process of the object 5.

[0052] Therefore, after the light source 11 emits the detection beam in the present application, the reference light travels along the optical path designed by the optical path component 12 and is received by the detector 13, and the measurement light travels on the effective measurement optical paths 6 on both sides of the object 5 and is received by the detector 13. Since the two effective measurement optical paths 6 are respectively parallel to the object 5 and are arranged at equal intervals, opposite Abbe errors can be generated between the two effective measurement optical paths 6 and the object 5. By utilizing the opposite nature of the Abbe errors on the effective measurement optical paths 6 on both sides of the object 5, the Abbe errors can be at least partially offset, thereby reducing or even eliminating the impact of the Abbe errors in the detection of the object 5. By counting the interference fringes re-synthesized by the detector 13, the result is also closer to the actual measured length of the object 5, which is beneficial to improving the accuracy of laser interferometry detection.

[0053] In some embodiments, as Figure 2As shown, the optical path assembly 12 may include a beam splitting mechanism 121, a deflector 123, and three reflectors 122. The beam splitting mechanism 121 has a first light-transmitting surface 121a and three second light-transmitting surfaces 121b. The light source 11 and the detector 13 face the first light-transmitting surface 121a. The three reflectors 122 are respectively used to reflect light that has passed through the three second light-transmitting surfaces 121b of the beam splitting mechanism 121. Any two of the three reflectors 122 are measuring devices 1220. The two measuring devices 1220 are respectively arranged on either side of the object to be measured 5 and can move synchronously along the measuring length direction of the object to be measured 5. The incident surfaces of the two measuring devices 1220 are located on the same plane. The deflector 123 is used to fold the optical path to guide the measuring light to travel between the measuring device 1220 and the beam splitting mechanism 121. The effective measurement optical path 6 is formed between the measuring device 1220 and the beam splitting mechanism 121 , or the effective measurement optical path 6 is formed between the measuring device 1220 and the redirector 123 .

[0054] By placing any two of the three reflectors 122 as measuring devices 1220 on either side of the object 5 under test, an effective measuring optical path 6 can be established between the beam splitting mechanism 121 and the diverter 123 on either side of the object 5 under test, thereby accurately detecting the measured length of the object 5 under test. The remaining reflector 122 is placed on the remaining second light-transmitting surface 121b of the three second light-transmitting surfaces 121b of the beam splitting mechanism 121, allowing this reflector 122 to circulate the detection light beam within the beam splitting mechanism 121. In addition, the light source 11 and the detector 13 are arranged on the same side of the beam splitting mechanism 121, for example, facing the same light-transmitting surface (i.e., the first light-transmitting surface 121a), and the three reflectors 122 are respectively arranged on the remaining three light-transmitting surfaces of the beam splitting mechanism 121 (i.e., the second light-transmitting surface 121b). The four light-transmitting surfaces of the beam splitting mechanism 121 are fully utilized for light transmission, making the structural design of the beam splitting mechanism 121 compact, thereby facilitating the reduction of the volume of the beam splitting mechanism 121 and miniaturization of the laser interferometer device. In this application, the meaning of a component being arranged on a light-transmitting surface is that the component is in the optical path of light passing through the light-transmitting surface, and whether the component is fixed to or in close contact with the light-transmitting surface is not specifically limited.

[0055] It should be understood that the reflector 122 is used to reflect the light from the light-transmitting surface of the beam-splitting mechanism 121, which includes both the reflector 122 being arranged at a position close to or far away from the light-transmitting surface of the beam-splitting mechanism 121, so that the reflector 122 can directly reflect the light transmitted by the light-transmitting surface; and the deflector 123 being arranged between the beam-splitting mechanism 121 and the reflector 122, so that the reflector 122 can reflect the light transmitted by the light-transmitting surface through the deflector 123. Among them, the beam-splitting mechanism 121 can adopt structures such as a polarization beam splitter prism, a wire grid polarizer or an electro-optical modulator, the reflector 122 can adopt structures such as a corner cube prism, a microprism array or a plane mirror combination, and the deflector 123 can adopt optical devices such as a plane mirror or a right-angle prism. This application does not impose any special restrictions on the specific devices of the beam-splitting mechanism 121, the reflector 122 and the deflector 123.

[0056] In some embodiments, as Figure 4 and Figure 5 As shown, the two measuring devices 1220 can be configured to reflect light that passes through the second light-transmitting surfaces 121b at adjacent or opposite positions of the beam splitting mechanism 121. When the two measuring devices 1220 are used to reflect light that passes through the second light-transmitting surfaces 121b at adjacent positions of the beam splitting mechanism 121, the detection beam can be drawn out from the second light-transmitting surfaces 121b at adjacent positions of the beam splitting mechanism 121; when the two measuring devices 1220 are used to reflect light that passes through the second light-transmitting surfaces 121b at opposite positions of the beam splitting mechanism 121, the detection beam can be drawn out from the second light-transmitting surfaces 121b at opposite positions of the beam splitting mechanism 121. During detection, based on factors such as the position of the object to be detected 5, the size of the detection space, and the orientation of the detection, a beam splitting mechanism 121 with different detection beam drawing directions can be reasonably selected for detection. This application does not impose any special restrictions on the specific direction in which the detection beam is drawn out by the beam splitting mechanism 121.

[0057] The above embodiment is a detailed introduction to the overall structure of the laser interferometer device. In order to realize the function that the detection light beam can cancel out the Abbe errors on both sides of the object 5 to be measured, the following embodiment will provide a detailed introduction to the optical path design of the measuring light and the reference light. Among them, the plane where the incident light and the reflected light are located is defined as the incident plane, S light (Senkrecht) is linearly polarized light with a polarization direction perpendicular to the incident plane, and P light (Parallel) is linearly polarized light with a polarization direction parallel to the incident plane. The S light will be reflected by the splitting surface of the beam splitting mechanism 121, and the P light will pass through the splitting surface of the beam splitting mechanism 121. The hollow arrow represents the S light, and the solid arrow represents the P light.

[0058] In some embodiments, as Figure 4As shown, the beam splitting mechanism 121 may include a beam splitter 1211 and two quarter-wave plates 1212, and the optical path assembly 12 may include a deflector 123. The two measuring devices 1220 are used to reflect light that has passed through the second light-transmitting surfaces 121b located adjacent to the beam splitter 1211. The deflector 123 is disposed in the optical path between the beam splitter 1211 and one of the measuring devices 1220. The two quarter-wave plates 1212 are respectively disposed in the optical path between the beam splitter 1211 and the two measuring devices 1220. The remaining reflectors 122 are disposed in the optical path of light that has passed through the remaining second light-transmitting surfaces 121b and reflect the light back to the second light-transmitting surfaces 121b. The first light-transmitting surface 121a is used to transmit light emitted by the light source 11 and light received by the detector 13.

[0059] Specifically, P light serves as the measuring light, and S light serves as the reference light. The reference light (S light) emitted by the light source 11 is reflected by the beam splitter surface of the beam splitter 1211 and enters the reflector 122 on the right side. After being reflected by the reflector 122 on the right side, it enters the beam splitter 1211 again and is reflected back to the detector 13 by the beam splitter surface. The measuring light (P light) emitted by the light source 11 transmits the beam splitter surface of the beam splitter 1211 and the 1 / 4 wave plate 1212 above the beam splitter 1211. It is then transmitted from the upper 1 / 4 wave plate 1212 to the measuring device 1220 on the right side of the object under test 5 on the motion stage 3, and then reflected by the measuring device 1220 on the right side of the object under test 5 to the upper 1 / 4 wave plate 1212. At this time, an effective measuring optical path 6 is formed between the measuring device 1220 on the right side of the object under test 5 and the beam splitting mechanism 121. The measuring light (P light) continues to transmit through the upper quarter-wave plate 1212, where its polarization state is adjusted to that of the measuring light (S light). The measuring light (S light) is then reflected by the beam splitter surface of beam splitter 1211 and transmits through the left quarter-wave plate 1212. It is then reflected by diverter 123 to the measuring device 1220 on the left side of the object 5 on the motion stage 3. After being reflected by measuring device 1220 on the left side of the object 5, it returns to diverter 123. At this point, another effective measuring optical path 6 is formed between measuring device 1220 on the left side of the object 5 and diverter 123. After being reflected by diverter 123, the measuring light (S light) transmits through the left quarter-wave plate 1212, where its polarization state is adjusted to that of the measuring light (P light). The measuring light (P light) then transmits through the beam splitter surface of beam splitter 1211, is reflected by reflector 122 on the right side, and transmits through beam splitter 1211 again. The measuring light (P light) continues to pass through the left quarter-wave plate 1212 before being reflected by the diverter 123 and arriving at the measuring device 1220 on the left side of the object 5 on the motion stage 3. After being reflected by the measuring device 1220 on the left side of the object 5, it returns to the diverter 123. The measuring light (P light) continues to pass through the diverter 123 and is reflected by the left quarter-wave plate 1212. After that, its polarization state is adjusted to the measuring light (S light). The measuring light (S light) is reflected by the beam splitter surface of the beam splitter 1211 and passes through the upper quarter-wave plate 1212 to the measuring device 1220 on the right side of the object 5. After being reflected by the measuring device 1220 on the right side of the object 5, it passes through the upper quarter-wave plate 1212 again and its polarization state is adjusted to the measuring light (P light). The measuring light (P light) passes through the beam splitter surface of the beam splitter 1211 and returns to the detector 13.

[0060] When the motion stage 3 moves, only the distances of segments L1 and L2 in the reference and measurement light paths are unknown. The remaining optical paths can be accurately determined based on the pre-set modules. That is, except for L1 and L2, which are variables, the remaining optical paths are quantitative. Simultaneously, the measurement light reaches the measuring devices 1220 on both sides of the object 5 twice and returns, meaning that the measurement light travels eight times (four L1s and four L2s) along the path of the measured length change of the object 5. Therefore, by removing the quantitative portions of the remaining optical paths, the change in optical path length ΔL along the effective measurement optical path 6 can be obtained as 4(L1+L2), where L1 is the unidirectional optical path length along the effective measurement optical path 6 on the left side of the object 5, and L2 is the unidirectional optical path length along the effective measurement optical path 6 on the right side of the object 5. Based on the optical path difference ΔL, the actual measured length change of the object 5 can be obtained as L = 1 / 2(L1+L2) = 1 / 8ΔL, where ΔL is the optical path difference between the reference and measurement light, i.e., the change in optical path length along the effective measurement optical path 6. Since L1 and L2 are located on both sides of the object 5 and are equidistant from L, the Abbe errors δ of L1 and L2 cancel each other out, thereby reducing the impact of the Abbe error on the detection of the object 5.

[0061] In this embodiment, the beam splitting mechanism 121 can be positioned opposite the measuring device 1220 on the right side of the object 5, and the diverter 123 can be positioned opposite the measuring device 1220 on the left side of the object 5. Since the two effective measurement optical paths 6 are symmetrically arranged about the object 5, in other embodiments, the beam splitting mechanism 121 can also be positioned opposite the measuring device 1220 on the left side of the object 5, and the diverter 123 can also be positioned opposite the measuring device 1220 on the right side of the object 5. Furthermore, the incoming and outgoing measurement light of the beam splitter 1211 is both P light, and the incoming and outgoing reference light is both S light. This allows the beam splitting mechanism 121 to be configured to inherently separate the detection beam into measurement light and reference light. Furthermore, because the measurement light travels eight times (four L1s and four L2s) along the measurement length change path of the object 5, i.e., an eight-pass optical path, the accuracy of the detection of the object 5 can be improved. Therefore, this embodiment only needs to set up two 1 / 4 wave plates 1212 and one deflector 123. Under the condition of using fewer optical components, it can not only reduce the cost of the laser interferometer device, but also achieve a longer-range optical path.

[0062] In some implementations, such as Figure 5As shown, the beam splitting mechanism 121 may include a beam splitter 1211 and two quarter-wave plates 1212, and the optical path assembly 12 may include two redirectors 123. The two measuring devices 1220 are used to reflect light that passes through the second light-transmitting surface 121b at a position opposite to the beam splitter 1211. The two redirectors 123 are respectively disposed in the optical path between the beam splitter 1211 and the two measuring devices 1220. The two quarter-wave plates 1212 are respectively disposed in the optical path between the beam splitter 1211 and the two measuring devices 1220. The remaining reflectors 122 are disposed in the optical path of light that passes through the remaining second light-transmitting surfaces 121b and reflect the light back to the second light-transmitting surfaces 121b. The first light-transmitting surface 121a is used to transmit light emitted by the light source 11 and light received by the detector 13.

[0063] Specifically, S light serves as the measuring light, and P light serves as the reference light. The reference light (P light) emitted by the light source 11 transmits the beam splitter 1211 through the beam splitter surface and enters the reflector 122 above. After being reflected by the reflector 122 above, it transmits the beam splitter 1211 through the beam splitter surface again and returns to the detector 13. The measuring light (S light) emitted by the light source 11 is reflected by the beam splitter 1211 through the beam splitter surface to the 1 / 4 wave plate 1212 on the right, and then transmitted through the deflector 123 on the right to the measuring device 1220 on the right side of the object under test 5 on the moving stage 3. It is then reflected back to the deflector 123 on the right side by the measuring device 1220 on the right side of the object under test 5. At this time, an effective measuring optical path 6 is formed between the measuring device 1220 on the right side of the object under test 5 and the deflector 123 on the right side. The measurement light (S light) is reflected by the right-hand deflector 123 onto the right-hand quarter-wave plate 1212. The polarization state of the measurement light (S light) is adjusted to that of the measurement light (P light). The measurement light (P light) then passes through the beam splitter surface of the beam splitter 1211 and the left-hand quarter-wave plate 1212. It then passes through the left-hand deflector 123 and is transmitted to the measuring device 1220 on the left side of the object 5 on the motion stage 3. The measuring device 1220 on the left side of the object 5 is then reflected back to the left-hand deflector 123. At this point, another effective measurement optical path 6 is formed between the measuring device 1220 on the left side of the object 5 and the left-hand deflector 123. The measuring light (P light) is reflected by the deflector 123 on the left to the 1 / 4 wave plate 1212 on the left, and the polarization state of the measuring light (P light) is adjusted to the measuring light (S light). The measuring light (S light) is reflected by the splitting surface of the beam splitter 1211 to the reflector 122 above the beam splitter 1211, and then reflected back to the beam splitter 1211 through the reflector 122 above the beam splitter 1211 and reflected by the splitting surface to the 1 / 4 wave plate 1212 on the left, and then transmitted to the measuring device 1220 on the left side of the object to be measured 5 on the moving platform 3 through the deflector 123 on the left, and then reflected back to the deflector 123 on the left side through the measuring device 1220 on the left side of the object to be measured 5. The measuring light (S light) continues to pass through the left-side deflector 123 and is reflected onto the left-side quarter-wave plate 1212, where its polarization state is adjusted to that of the measuring light (P light). The measuring light (P light) then passes through the beam splitter 1211's beam splitting surface and the right-side quarter-wave plate 1212. It then passes through the right-side deflector 123 and is transmitted to the measuring device 1220 on the right side of the object under test 5 on the motion stage 3. It then passes through the measuring device 1220 on the right side of the object under test 5 and is reflected back to the right-side deflector 123. The measuring light (P light) is then reflected by the right-side deflector 123 onto the right-side quarter-wave plate 1212, where its polarization state is adjusted to that of the measuring light (S light). The measuring light (S light) then passes through the beam splitter 1211's beam splitter surface and is reflected back to the detector 13.

[0064] and Figure 4The same is true for the embodiment described above. When the motion stage 3 moves, only the distances of segments L1 and L2 in the optical paths of the reference and measurement beams are unknown. The remaining optical paths can be accurately determined based on the pre-set modules. That is, except for L1 and L2, which are variables, the remaining optical paths are all quantitative. Simultaneously, the measurement light reaches the measuring devices 1220 on both sides of the object 5 twice and returns, meaning that the measurement light travels eight times (four L1s and four L2s) along the path of the measured length change of the object 5. Therefore, by removing the quantitative portions of the remaining optical paths, the change in optical path length ΔL along the effective measurement optical path 6 can be obtained as 4(L1+L2), where L1 is the unidirectional optical path length along the effective measurement optical path 6 on the left side of the object 5, and L2 is the unidirectional optical path length along the effective measurement optical path 6 on the right side of the object 5. Based on the optical path difference ΔL, the actual measured length change of the object 5 can be obtained as L = 1 / 2(L1+L2) = 1 / 8ΔL, where ΔL is the optical path difference between the reference and measurement beams, i.e., the change in optical path length along the effective measurement optical path 6. Since L1 and L2 are located on both sides of the object 5 and are equidistant from L, the Abbe errors δ of L1 and L2 cancel each other out, thereby reducing the impact of the Abbe error on the detection of the object 5.

[0065] Different from Figure 4 In this embodiment, two deflectors 123 can be positioned opposite measuring devices 1220 on either side of the object 5, while the beam splitting mechanism 121 can be positioned anywhere between the two measuring devices 1220. This reduces the requirements for the placement of the beam splitting mechanism 121 and the difficulty of manufacturing the laser interferometer device. Furthermore, compared to the first embodiment, this embodiment can also achieve an eight-pass optical path while providing an additional deflector 123.

[0066] In the above embodiment, the beam splitting mechanism 121 has the function of separating the detection beam into the measurement light and the reference light. In other embodiments, the laser interferometer device can also be provided with a polarizing mechanism 14 separately, such as Figure 2 As shown, the laser interferometer device may further include a polarizing mechanism 14; the polarizing mechanism 14 is disposed between the beam splitting mechanism 121 and the light source 11 and the detector 13, and the polarizing mechanism 14 is used to separate the detection beam into a measurement light and a reference light with different polarization directions. Figure 4 and Figure 5 The optical path component 12 may also be provided with a matching polarizing mechanism 14 .

[0067] For example, see Figure 2The polarizing mechanism 14 may include an interferometer 141, a reflector 142, and a first half-wave plate 143. After the detection beam emitted by the light source 11 enters the interferometer 141, the reference light (S light) is reflected by the beam splitting surface of the interferometer 141 and enters the reflector 142 above. After being reflected by the reflector 142, it enters the interferometer 141 again and is reflected back to the detector 13 by the beam splitting surface. The measurement light (P light) is directly transmitted through the interferometer 141 to the beam splitting mechanism 121. When the measurement light (P light) travels in the beam splitting mechanism 121, its polarization state may be adjusted from P light to S light. By providing the first half-wave plate 143 on the light-transmitting surface of the interferometer 141, the measurement light (S light) can be adjusted back to the measurement light (P light) by the first half-wave plate 143, so that the measurement light (P light) can be recombined with the reference light (S light) in the detector 13 to form interference fringes to detect the object under test 5.

[0068] Thus, the polarizing mechanism 14 can separate the detection light beam emitted by the light source 11 into a measurement light and a reference light with different polarization directions. Figure 2 The polarizing structure shown in the figure can adaptively adjust the position of the beam splitter of the interferometer 141, the position or number of the reflector 142 relative to the interferometer 141, whether to set the first 1 / 2 wave plate 143, whether to set the 1 / 4 wave plate, and the position of the wave plate according to the different polarization states of the measurement light and the reference light. As long as the polarizing mechanism 14 can separate the detection light beam into the measurement light and the reference light with different polarization directions. For example, Figure 6 As shown, when the detection light beam emitted by the light source 11 enters the interferometer 141, the reference light (P light) transmits the interferometer 141 and is reflected by the reflector 142 on the right side and then transmitted through the interferometer 141 again to be recovered to the detector 13. The measuring light (S light) is reflected by the spectroscopic surface of the interferometer 141 and transmitted upward to the optical path component 12 to travel. Finally, the measuring light (S light) emitted by the optical path component 12 enters the interferometer 141 again and is reflected back to the detector 13 by the spectroscopic surface of the interferometer 141. Therefore, without setting the first 1 / 2 wave plate 143, the polarizing mechanism 14 can also divide the detection light beam into measuring light and reference light. In addition, the P light can be used as both measuring light and reference light. Similarly, the S light can be used as both measuring light and reference light. This application does not impose any special restrictions on the specific structure of the polarizing mechanism 14.

[0069] In some embodiments, as Figure 7As shown, the beam splitting mechanism 121 may include a beam splitter 1211 and three quarter-wave plates 1212, and the optical path assembly 12 may include a deflector 123. Two measuring devices 1220 are used to reflect light that passes through the second light-transmitting surfaces 121b at adjacent positions of the beam splitter 1211. The deflector 123 is arranged in the optical path between the beam splitter 1211 and one of the measuring devices 1220. The remaining reflectors 122 are arranged in the optical path of light that passes through the remaining second light-transmitting surfaces 121b and reflect the light back to the second light-transmitting surfaces 121b. The three quarter-wave plates 1212 are respectively arranged in the optical path between the beam splitter 1211 and the three reflectors 122. The first light-transmitting surface 121a is used to transmit the measurement light separated by the polarizing mechanism 14.

[0070] Specifically, P light is used as the measurement light, S light is used as the reference light, and the optical path of the reference light can be as follows: Figure 2 The optical path of the polarizing mechanism 14 is shown. The measuring light (P light) emitted by the light source 11 transmits the beam splitting surface of the beam splitter 1211 and the quarter-wave plate 1212 on the right side of the beam splitter 1211. It is then reflected by the diverter 123 to the measuring device 1220 on the right side of the object 5 on the moving stage 3. After being reflected by the measuring device 1220 on the right side of the object 5, it returns to the diverter 123. At this point, an effective measuring optical path 6 is formed between the measuring device 1220 on the right side of the object 5 and the diverter 123. After being reflected by the diverter 123, the measuring light (P light) transmits the quarter-wave plate 1212 on the right side of the beam splitter 1211. At this time, the measuring light (P light) transmits twice through the quarter-wave plate 1212, and the polarization state of the measuring light (P light) is adjusted to the measuring light (S light). The measurement light (S light) is reflected by the beam splitter surface of beam splitter 1211 and enters the quarter-wave plate 1212 and reflector 122 below beam splitter 1211. Reflected by reflector 122 below beam splitter 1211, the measurement light (S light) then passes through the quarter-wave plate 1212 below beam splitter 1211, adjusting the polarization state of the measurement light (S light) to that of the measurement light (P light). The measurement light (P light) then passes through the beam splitter surface of beam splitter 1211 and the quarter-wave plate 1212 above it. It then travels from the quarter-wave plate 1212 above to the measuring device 1220 on the left side of the object 5 on the motion stage 3. The measurement light is then reflected by the measuring device 1220 on the left side of the object 5 and returns to the quarter-wave plate 1212 above it. At this point, another effective measurement optical path 6 is formed between the measuring device 1220 on the left side of the object 5 and the beam splitting mechanism 121. The measuring light (P light) again passes through the 1 / 4 wave plate 1212 above the beam splitter 1211. At this time, the polarization state of the measuring light (P light) is adjusted to the measuring light (S light). After reaching the splitting surface of the beam splitter 1211, the measuring light (S light) is reflected into the detector 13. Since the measuring light incident on the beam splitter 1211 is P light and the measuring light emitted is S light, it can be detected by Figure 2The first 1 / 2 wave plate 143 shown adjusts the polarization state of the measuring light (S light) to the measuring light (P light), and finally recombines the measuring light (P light) and the reference light (S light) in the detector 13 to form interference fringes for interferometric measurement.

[0071] When the motion stage 3 moves, only the distances of segments L1 and L2 in the reference and measurement light paths are unknown. The remaining optical paths can be accurately determined based on the pre-set modules. That is, except for L1 and L2, which are variables, the remaining optical paths are quantitative. Simultaneously, the measurement light reaches the measuring devices 1220 on both sides of the object 5 once and returns, meaning that the measurement light travels four times (two L1s and two L2s) along the path of the measured length change of the object 5. Therefore, by removing the quantitative portions of the remaining optical paths, the change in optical path length ΔL along the effective measurement optical path 6 can be obtained as 2(L1+L2), where L1 is the unidirectional optical path length along the effective measurement optical path 6 on the left side of the object 5, and L2 is the unidirectional optical path length along the effective measurement optical path 6 on the right side of the object 5. Based on the optical path difference ΔL, the actual change in length of the object 5 can be obtained as L = 1 / 2(L1+L2) = 1 / 4ΔL, where ΔL is the optical path difference between the reference and measurement light, i.e., the change in optical path length along the effective measurement optical path 6. Since L1 and L2 are located on both sides of the object 5 and are equidistant from L, the Abbe errors δ of L1 and L2 cancel each other out, thereby reducing the impact of the Abbe error on the detection of the object 5.

[0072] In this embodiment, the measurement light incident on the beam splitter 1211 is P light. In other embodiments, the measurement light incident on the beam splitter 1211 can also be S light, and P light serves as reference light. The specific path can be determined by the polarizing mechanism 14. For example, the optical path of the reference light can be as follows: Figure 6 Regarding the optical path of the polarizing mechanism 14 shown, when the measurement light incident on the beam splitter 1211 is S light, the measurement light will first travel to the measuring device 1220 on the left side of the object 5 to establish an effective measurement optical path 6, and then travel to the measuring device 1220 on the right side of the object 5 to establish another effective measurement optical path 6. This application will not further describe this. However, regardless of whether the measurement light incident on the beam splitter 1211 is P light or S light, the measurement light can travel four times (two L1s and two L2s) along the length-varying path of the object 5, i.e., a four-pass optical path.

[0073] In addition, this embodiment and Figure 4The embodiment described above is similar in that the beam splitting mechanism 121 can be disposed opposite the measuring device 1220 on the left side of the object 5, and the diverter 123 can be disposed opposite the measuring device 1220 on the right side of the object 5. Since the two effective measurement optical paths 6 are symmetrically arranged about the object 5, in other embodiments, the beam splitting mechanism 121 can also be disposed opposite the measuring device 1220 on the right side of the object 5, and the diverter 123 can also be disposed opposite the measuring device 1220 on the left side of the object 5.

[0074] In some embodiments, as Figure 8 As shown, the beam splitting mechanism 121 may include a beam splitter 1211 and three quarter-wave plates 1212, and the optical path assembly 12 may include two redirectors 123. The two measuring devices 1220 are used to reflect light that has passed through the second light-transmitting surface 121b at a position opposite to the beam splitter 1211. The two redirectors 123 are respectively arranged in the optical path between the beam splitter 1211 and the two measuring devices 1220. The remaining reflectors 122 are arranged in the optical path of light that has passed through the remaining second light-transmitting surfaces 121b and reflect the light back to the second light-transmitting surfaces 121b. The three quarter-wave plates 1212 are respectively arranged in the optical path between the beam splitter 1211 and the three reflectors 122. The first light-transmitting surface 121a is used to transmit the measurement light separated by the polarizing mechanism 14.

[0075] Specifically, Figure 8 In the optical path between the light source 11 and the beam splitter 1211, the polarizing mechanism 14 is omitted. The P light is used as the measuring light, and the S light is used as the reference light. The optical path of the reference light can be as follows: Figure 2The optical path of the polarizing mechanism 14 is shown. The detection beam emitted by the light source 11 includes the measuring light (P light), which is transmitted from the polarizing mechanism 14 to the beam splitter 1211. It can pass through the beam splitter surface of the beam splitter 1211 and the quarter-wave plate 1212 above the beam splitter 1211 to be transmitted to the reflector 122 above the beam splitter 1211. After being reflected by the reflector 122 above the beam splitter 1211, it is again transmitted through the quarter-wave plate 1212 above the beam splitter 1211. The polarization state of the measuring light (P light) is adjusted to the measuring light (S light). The measuring light (S light) is reflected by the beam splitter surface of the beam splitter 1211 and then passes through the quarter-wave plate 1212 on the left side of the beam splitter 1211. It is then transmitted through the deflector 123 on the left side to the measuring device 1220 on the left side of the object 5 under test on the motion stage 3. It is then reflected by the measuring device 1220 on the left side of the object 5 under test back to the deflector 123 on the left side. At this point, an effective measurement optical path 6 is formed between the measuring device 1220 on the left side of the object 5 and the left-side deflector 123. The measurement light (S light) is reflected by the left-side deflector 123 onto the 1 / 4 wave plate 1212 on the left side of the beam splitter 1211. The polarization state of the measurement light (S light) is adjusted to that of the measurement light (P light). The measurement light (P light) then passes through the beam splitting surface of the beam splitter 1211 and the 1 / 4 wave plate 1212 on the right side of the beam splitter 1211. It then passes through the right-side deflector 123 and is transmitted to the measuring device 1220 on the right side of the object 5 on the motion stage 3. It is then reflected by the measuring device 1220 on the right side of the object 5 back to the right-side deflector 123. At this point, another effective measurement optical path 6 is formed between the measuring device 1220 on the right side of the object 5 and the right-side deflector 123. The measuring light (P light) is reflected by the deflector 123 on the right side to the 1 / 4 wave plate 1212 on the right side of the beam splitter 1211, and the polarization state of the measuring light (P light) is adjusted to the measuring light (S light). The measuring light (S light) is reflected back to the detector 13 through the splitting surface of the beam splitter 1211.

[0076] and Figure 7The same is true for the embodiments described above. When the motion stage 3 moves, only the distances of two segments, L1 and L2, in the optical paths of the reference light and the measurement light are unknown. The remaining optical paths can be accurately determined based on the pre-set modules. That is, except for L1 and L2, which are variables, the remaining optical paths are all quantitative. Simultaneously, the measurement light reaches the measuring devices 1220 on both sides of the object 5 once and returns, meaning that the measurement light travels four times (two L1s and two L2s) along the path of the measured length change of the object 5. Therefore, by removing the quantitative portions of the remaining optical paths, the change in optical path length ΔL along the effective measurement optical path 6 can be obtained: 2(L1+L2), where L1 is the unidirectional optical path length along the effective measurement optical path 6 on the left side of the object 5, and L2 is the unidirectional optical path length along the effective measurement optical path 6 on the right side of the object 5. Based on the optical path difference ΔL, the actual change in length of the object 5 can be obtained: L = 1 / 2(L1+L2) = 1 / 4ΔL, where ΔL is the optical path difference between the reference light and the measurement light, i.e., the change in optical path length along the effective measurement optical path 6. Since L1 and L2 are located on both sides of the object 5 and are equidistant from L, the Abbe errors δ of L1 and L2 cancel each other out, thereby reducing the impact of the Abbe error on the detection of the object 5.

[0077] and Figure 5 The same as the embodiment is that the two deflectors 123 can be respectively arranged opposite to the measuring devices 1220 on both sides of the object to be measured 5, and the beam splitting mechanism 121 can be set at any position between the two measuring devices 1220, thereby reducing the requirements for the setting position of the beam splitting mechanism 121, thereby reducing the difficulty of manufacturing the laser interferometer device.

[0078] In addition, this embodiment is described by taking the measurement light incident on the beam splitter 1211 as P light as an example. In other embodiments, the measurement light incident on the beam splitter 1211 may also be S light, and the P light serves as the reference light. For example, the optical path of the reference light may be as follows: Figure 6 The optical path of the polarizing mechanism 14 is shown. When the measurement light incident on the beam splitter 1211 is S light, the measurement light will first travel to the measuring device 1220 on the right side of the object 5 to establish an effective measurement optical path 6, and then travel to the measuring device 1220 on the left side of the object 5 to establish another effective measurement optical path 6. This application will not further describe this. However, regardless of whether the measurement light incident on the beam splitter 1211 is P light or S light, the measurement light can still travel four times (two L1s and two L2s) along the measurement length change path of the object 5, i.e., a four-pass optical path.

[0079] The above embodiment is a detailed description of the specific structure of the optical path component 12. Among them, the wave plate adopts the structural design of the 1 / 4 wave plate 1212. In other embodiments, the wave plate can also adopt the structural design of the second 1 / 2 wave plate 1213. Figure 9 As shown, Figure 7Taking the optical path component 12 of the embodiment as an example, the 1 / 4 wave plate 1212 is replaced by a 1 / 2 wave plate 1213, but compared with the 1 / 4 wave plate 1212, it only covers a single-side optical path, and the other structures remain unchanged. Figure 9 The polarizing element 14 between the light source 11 and the beam splitter 1211 is omitted. Specifically, a second 1 / 2 wave plate 1213 can be set on each of the three light-transmitting surfaces of the beam splitter 1211 for transmitting light to the reflector 122, and the three second 1 / 2 wave plates 1213 are all set in the area where the light path returns on the light-transmitting surface. During detection, P light is used as the measurement light and S light is used as the reference light, and the optical path of the reference light can be adopted as follows: Figure 7 The optical path of the polarizing mechanism 14 is shown. The measuring light (P light) emitted by the light source 11 passes through the beam splitter surface of the beam splitter 1211 and is directly transmitted to the diverter 123. The diverter 123 reflects the measuring light to the measuring device 1220 on the right side of the object 5 on the moving stage 3. After being reflected by the measuring device 1220 on the right side of the object 5, it returns to the diverter 123. At this point, an effective measuring optical path 6 is formed between the measuring device 1220 on the right side of the object 5 and the diverter 123. After being reflected by the diverter 123, the measuring light (P light) passes through the second half-wave plate 1213 on the right side of the beam splitter 1211. At this point, the polarization state of the measuring light (P light) is adjusted to that of the measuring light (S light). The measurement light (S light) is reflected by the beam splitter surface of beam splitter 1211 and transmitted directly to reflector 122 below beam splitter 1211. Reflected by reflector 122 below beam splitter 1211, the measurement light (S light) then passes through second half-wave plate 1213 below beam splitter 1211, adjusting the polarization state of the measurement light (S light) to measurement light (P light). The measurement light (P light) passes through the beam splitter surface of beam splitter 1211 and is transmitted directly to measuring device 1220 on the left side of object 5 on motion stage 3. The measurement light (P light) is then reflected by measuring device 1220 on the left side of object 5 and then to second half-wave plate 1213 above. At this point, another effective measurement optical path 6 is formed between measuring device 1220 on the left side of object 5 and beam splitting mechanism 121. The measuring light (P light) passes through the second half-wave plate 1213 above the beam splitter 1211 and its polarization state is adjusted to the measuring light (S light). The measuring light (S light) reaches the splitting surface of the beam splitter 1211 and is reflected into the detector 13 .

[0080] Of course, the above Figure 4 、 Figure 5 and Figure 8 In the embodiment, the second 1 / 2 wave plate 1213 can also be used to replace or partially replace the 1 / 4 wave plate 1212, so that the two effective measurement optical paths 6 are respectively set on both sides of the object 5 to reduce the influence of the Abbe error of the object 5 during the detection process. Figure 4 、 Figure 5 and Figure 8 The modified embodiments of the middle optical path component 12 are not described in detail.

[0081] In addition, if Figure 2 As shown, the laser interferometer device may further include a housing 15 (shown in the dotted box in the figure); the light source 11 and the detector 13 may be integrated into the housing 15. Since the light source 11 and the detector 13 are both arranged on the first light-transmitting surface 121a of the beam splitting mechanism 121, the light source 11 and the detector 13 can be conditionally integrated into the housing 15 to form a laser interferometer, thereby making the laser interferometer device easy to carry, so as to better perform measurement operations, and the photoelectric signals in the laser interferometer device can also be better centrally controlled. However, the present application is not limited to integrating only the light source 11 and the detector 13 into the housing 15. For example, in the first and second embodiments, since the beam splitting mechanism 121 has the function of separating the detection light beams, there is no need to set the polarizing mechanism 14. Therefore, the beam splitting mechanism 121 may also be integrated into the housing 15. Alternatively, in the third and fourth embodiments, since the polarizing mechanism 14 is set separately, the polarizing mechanism 14 may also be integrated into the housing 15. The present application does not impose any special restrictions on the optical devices integrated into the housing 15.

[0082] Therefore, the present application only requires a single laser interferometer to achieve the function of canceling out Abbe errors, which not only reduces the impact of Abbe errors on detection, but also simplifies the overall system and reduces costs. Furthermore, the beam splitting mechanism 121 and / or the polarizing mechanism 14 are integrated into the housing 15, which can also reduce the size of the laser interferometer.

[0083] The above specific examples are used to illustrate the present application, which is only used to help understand the present application and is not intended to limit the present application. For those skilled in the art of the present application, they can make some simple deductions, modifications or substitutions based on the ideas of the present application.

Claims

1. A laser interferometer device, characterized in that: For detecting the measured length of an object to be measured, the laser interferometer device comprises: a light source for emitting a detection light beam having a measurement light and a reference light with different polarization directions; an optical path component, wherein the measuring light and the reference light enter from a light-transmitting surface of the optical path component, and the measuring light and the reference light respectively travel along respective optical paths within the optical path component until the measuring light and the reference light are emitted from the same light-transmitting surface of the optical path component; and a detector, configured to receive the measuring light and the reference light emitted by the optical path component to detect the measuring length of the object to be measured; The optical path component is configured to guide the measuring light to travel on at least two effective measuring optical paths, and the two effective measuring optical paths are parallel along a measuring length direction of the object to be measured and are equidistantly arranged on both sides of the object to be measured.

2. The laser interferometer device according to claim 1, wherein The optical path assembly includes a beam splitting mechanism, a diverter and three reflectors; The beam splitting mechanism has a first light-transmitting surface and three second light-transmitting surfaces. The light source and the detector face the first light-transmitting surface. The three reflectors are respectively used to reflect light that passes through the three second light-transmitting surfaces of the beam splitting mechanism. Any two of the three reflectors are measuring devices. The two measuring devices are respectively arranged on both sides of the object to be measured and can move synchronously along the measuring length direction of the object to be measured. The incident surfaces of the two measuring devices are located on the same plane. The deflector is used to fold the optical path to guide the measuring light to travel between the measuring device and the beam splitting mechanism. The effective measuring optical path is formed between the measuring device and the beam splitting mechanism, or the effective measuring optical path is formed between the measuring device and the deflector.

3. The laser interferometer device according to claim 2, wherein: The two measuring devices are configured to reflect light that has passed through the second light-transmitting surfaces at adjacent or opposite positions of the beam splitting mechanism.

4. The laser interferometer device according to claim 3, wherein: The beam splitting mechanism includes a beam splitter and two quarter wave plates, and the optical path component includes a diverter; The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at adjacent positions of the beam splitter. The deflector is arranged on the optical path between the beam splitter and one of the measuring devices. The two 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the two measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The first light-transmitting surface is used to transmit the light emitted by the light source and the light received by the detector.

5. The laser interferometer device according to claim 3, wherein: The beam splitting mechanism includes a beam splitter and two quarter wave plates, and the optical path component includes two of the diverters; The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at relative positions of the beam splitter. The two redirectors are respectively arranged on the optical path between the beam splitter and the two measuring devices. The two 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the two measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The first light-transmitting surface is used to transmit the light emitted by the light source and the light received by the detector.

6. The laser interferometer device according to claim 3, wherein: The optical path component further includes a polarizing mechanism; The polarizing mechanism is arranged between the beam splitting mechanism, the light source and the detector, and is used to separate the detection light beam into the measuring light and the reference light.

7. The laser interferometer device according to claim 6, wherein: The beam splitting mechanism includes a beam splitter and three quarter wave plates, and the optical path component includes a diverter; The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at adjacent positions of the beam splitter. The deflector is arranged on the optical path between the beam splitter and one of the measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The three 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the three reflectors. The first light-transmitting surface is used to transmit the measurement light after being separated by the polarizing mechanism.

8. The laser interferometer device according to claim 6, wherein: The beam splitting mechanism includes a beam splitter and three quarter wave plates, and the optical path component includes two of the diverters; The two measuring devices are used to reflect light that passes through the second light-transmitting surfaces at opposite positions of the beam splitter. The two deflectors are respectively arranged on the optical path between the beam splitter and the two measuring devices. The remaining reflectors are arranged on the optical path of light that passes through the remaining second light-transmitting surfaces and reflect the light back to the second light-transmitting surfaces. The three 1 / 4 wave plates are respectively arranged on the optical path between the beam splitter and the three reflectors. The first light-transmitting surface is used to transmit the measurement light after being separated by the polarizing mechanism.

9. The laser interferometer device according to any one of claims 1 to 8, wherein: The laser interference device further includes a housing; The light source and the detector are integrated in the housing.

10. A laser interferometer device, characterized in that: include: The laser interferometer device according to any one of claims 1 to 9; A base, used for supporting the object to be measured; as well as, The moving platform is movably arranged on the base. The laser interference device includes a measuring device, and the measuring device is installed on the moving platform.

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