Position measuring device, measuring method and photoetching equipment

Abstract

The invention provides a position measuring device, a measuring method and photoetching equipment. The measuring device comprises a reading head, a grating, a light source, a light detection module and a light signal processing module, the light source is used for providing first light beams with first frequency and second light beams with second frequency; the reading head and the grating are oppositely arranged, the reading head comprises a first light splitting element, and the first light splitting element is used for splitting the first light beam and the second light beam so as to output multiple paths of double-frequency measuring light beams which are simultaneously provided with a first light splitting light beam with a first frequency and a second light splitting light beam with a second frequency, two paths of double-frequency measuring light beams are symmetrically emitted relative to a plane vertical to the horizontal direction; for each path of double-frequency measurement light beam, the double-frequency measurement light beam is diffracted for multiple times by the grating to form a measurement interference light beam carrying measurement phase information; the optical detection module is used for collecting multiple groups of measurement interference beams; and the optical signal processing module is used for obtaining horizontal displacement information and vertical displacement information of the grating based on the multiple groups of measurement interference light beams. Two-dimensional, three-dimensional or higher-dimensional high-precision grating ruler measurement is realized by adopting a double-frequency technology, an optical detection structure is simple, stable phase acquisition is easy to realize, and the quality of a measurement signal is improved.

Description

Technical Field

[0001] The present invention relates to the field of photolithography technology, and in particular to a position measurement device, a measurement method and photolithography equipment. Background Art

[0002] Nano-measurement technology is the foundation of nano-machining, nano-manipulation, nano-materials, and other fields. The IC industry, precision machinery, and micro-electromechanical systems (MEMS) all require high-resolution, high-precision displacement sensors to achieve nanometer-precision positioning.

[0003] As integrated circuits develop rapidly towards large scale and high integration, the overlay accuracy requirements of lithography machines are becoming increasingly higher. Correspondingly, the accuracy of obtaining the six-degree-of-freedom position information of the workpiece stage and mask stage is also increasing.

[0004] The optical path length of a grating ruler measurement system can be very small, typically a few millimeters. Its optical path length is independent of the measurement range, making its measurement accuracy insensitive to environmental influences. Its high measurement stability, simple structure, and ease of miniaturization have given it a significant position in the field of nano-measurement. In the next generation of lithography systems, it is now responsible for high-precision, high-stability picometer-precision measurements.

[0005] Existing technology proposes a two-dimensional, high-precision grating scale position measurement system that can measure horizontal (X / Y) and vertical (Z) displacements using phase-shifted signals. This technology utilizes single-frequency technology, resulting in a stable light output structure and minimal environmental interference. However, the optical detection scheme is complex, and signal acquisition quality is significantly affected by fluctuations in optical power.

[0006] The existing technology also offers a solution for two-dimensional grating measurement using dual-frequency technology, combining dual-core optical fibers and polarization beam splitters to control the interference of the measurement beam. However, in this solution, the environments in which the measurement and reference optical paths exist differ significantly, and the phase signal is significantly affected by environmental interference.

[0007] The prior art also provides a technical solution that uses dual-frequency technology to achieve horizontal and vertical displacement measurement. However, in this technical solution, the environments in which the measurement optical path and the reference optical path are located are quite different, and the phase signal is greatly affected by environmental interference.

[0008] Existing technology also offers a three-dimensional grating ruler measurement solution. This solution uses single-frequency technology, resulting in a stable light output structure and minimal environmental interference. However, the optical detection scheme is complex, and signal acquisition quality is significantly affected by fluctuations in optical power.

[0009] It should be noted that the information disclosed in the background technology section of the invention is only intended to deepen the understanding of the general background technology of the invention, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art. Summary of the Invention

[0010] The purpose of the present invention is to provide a position measurement device, a measurement method and a photolithography device, which adopt dual-frequency technology to realize two-dimensional, three-dimensional or higher-dimensional high-precision grating scale measurement, have a simple light detection structure, are easy to achieve stable phase acquisition, and improve the quality of the measurement signal.

[0011] To achieve the above object, the present invention provides a position measurement device, comprising a read head, a grating, a light source, a light detection module and an optical signal processing module;

[0012] The light source is configured to provide a first light beam of a first frequency and a second light beam of a second frequency;

[0013] The read head is arranged opposite to the grating, and the read head includes a first beam splitter element, which is used to split the first light beam and the second light beam to output multiple dual-frequency measurement beams having a first split light beam of a first frequency and a second split light beam of a second frequency;

[0014] For each of the dual-frequency measurement beams, the dual-frequency measurement beam is diffracted multiple times by the grating to form a measurement interference beam carrying measurement phase information;

[0015] The light detection module is used to collect multiple groups of measurement interference light beams;

[0016] The optical signal processing module is used to obtain the horizontal displacement information and the vertical displacement information of the grating based on the multiple groups of measurement interference light beams.

[0017] Optionally, the reader also includes a polarization screening and control unit, which is used to control the polarization direction of a first first-order diffraction beam in the +m-order diffraction direction formed by the first diffraction of the first split beam by the grating and a second first-order diffraction beam in the -m-order diffraction direction formed by the first diffraction of the second split beam by the grating.

[0018] Optionally, the reader also includes a first refractive unit, which is used to realize the deflection of a first first-order diffraction beam in the +m-order diffraction direction formed by the first diffraction of the first split light beam by the grating, and to realize the deflection of a second first-order diffraction beam in the -m-order diffraction direction formed by the first diffraction of the second split light beam by the grating.

[0019] Optionally, the reader also includes a reverse reflection unit, which is used to reversely reflect a first first diffraction beam in the +m-order diffraction direction formed by the first diffraction of the first split light beam by the grating, and to reversely reflect a second first diffraction beam in the -m-order diffraction direction formed by the first diffraction of the second split light beam by the grating.

[0020] Optionally, the reading head further includes a second refraction unit, and the second refraction unit is used to realize the deflection of the first first-order diffraction light beam and the second first-order diffraction light beam reflected back through the reverse reflection unit.

[0021] Optionally, the reading head further includes a beam translation unit, which is used to change the relative spacing between the first first-order diffraction beam and / or the second first-order diffraction beam reflected back through the back-reflection unit.

[0022] Optionally, the reader also includes a beam translation and polarization control unit, which is used to change the relative spacing between the first first diffraction beam and the second first diffraction beam reflected back through the reverse reflection unit, and control the polarization direction of the first first diffraction beam and the second first diffraction beam reflected back through the reverse reflection unit.

[0023] Optionally, the read head also includes a first polarization control unit, which is used to control the first secondary diffraction beam formed by the secondary diffraction of the first split beam by the grating and the second secondary diffraction beam formed by the secondary diffraction of the second split beam by the grating to achieve coherence to form a measurement interference beam carrying measurement phase information.

[0024] Optionally, the first polarization control unit includes a light output refraction element, a pair of birefringent wedge plates and a polarizer, the light output refraction element is used to fold the first secondary diffraction beam and the second secondary diffraction beam so that the measurement interference beam formed by the first secondary diffraction beam and the second secondary diffraction beam is perpendicular to the light output receiving end face as a whole, the birefringent wedge plate pair is used to make the folded first secondary diffraction beam and the folded second secondary diffraction beam parallel, and the polarizer is used to control the polarization direction of the parallel first secondary diffraction beam and the second secondary diffraction beam.

[0025] Optionally, the reader also includes a first coupling lens and a plurality of first light-emitting optical fibers arranged in one-to-one correspondence with the multiple groups of measurement interference beams, the first coupling lens is used to focus and couple the measurement interference beams into the correspondingly arranged first light-emitting optical fibers, and the first light-emitting optical fibers are used to transmit the measurement interference beams to the optical detection module.

[0026] Optionally, the reader further includes a dual-frequency fiber-optic light input structure and a collimating lens, wherein the dual-frequency fiber-optic light input structure is used to output the first light beam and the second light beam, and the collimating lens is used to collimate the first light beam and the second light beam output by the dual-frequency fiber-optic light input structure.

[0027] Optionally, the reader also includes a second spectroscopic element and a second polarization control unit, the second spectroscopic element is arranged between the collimating lens and the first spectroscopic element, the second spectroscopic element is used to branch the first light beam and the second light beam to output a dual-frequency reference beam having a first reference beam of a first frequency and a second reference beam of a second frequency, the second polarization control unit is used to control the first reference beam and the second reference beam to achieve coherence to form a reference interference beam carrying reference phase information, the grating detection module is also used to collect the reference interference beam, and the optical signal processing module is also used to correct the measurement phase information carried by the measurement interference beam according to the reference phase information carried by the reference interference beam.

[0028] Optionally, the first split beam and the second split beam in the dual-frequency measurement beam are irradiated onto the grating at an angle or in parallel.

[0029] Optionally, the first beam splitter is used to output a first dual-frequency measurement beam and a second dual-frequency measurement beam that are symmetrically emitted relative to the XZ plane, and the optical signal processing module is used to calculate the horizontal displacement of the grating along the Y direction and the vertical displacement along the Z direction according to the following formula:

[0030]

[0031]

[0032] Wherein, ΔY is the horizontal displacement of the grating along the Y direction, ΔZ is the vertical displacement of the grating along the Z direction, P is the grating pitch of the grating, λ is the wavelength of the light source, δ1 is the incident angle of the first dual-frequency measurement beam incident on the grating, δ2 is the incident angle of the second dual-frequency measurement beam incident on the grating, is the phase change of the first measurement interference beam corresponding to the first dual-frequency measurement beam, is the phase change of the second measuring interference beam corresponding to the second dual-frequency measuring beam, α1 is the diffraction angle of the first split beam in the first dual-frequency measuring beam in the +m-order diffraction direction after the first diffraction along the Y direction of the grating, β1 is the diffraction angle of the second split beam in the first dual-frequency measuring beam in the -m-order diffraction direction after the first diffraction along the Y direction of the grating, α2 is the diffraction angle of the first split beam in the second dual-frequency measuring beam in the +m-order diffraction direction after the first diffraction along the Y direction of the grating, β2 is the diffraction angle of the second split beam in the second dual-frequency measuring beam in the -m-order diffraction direction after the first diffraction along the Y direction of the grating.

[0033] Optionally, the first beam splitter is further configured to output a third dual-frequency measurement beam emitted along the XZ plane, and the optical signal processing module is configured to calculate the horizontal displacement of the grating along the X-axis according to the following formula:

[0034]

[0035] Where ΔX is the horizontal displacement of the grating along the X-axis, is the phase change of the third measurement interference beam corresponding to the third dual-frequency measurement beam.

[0036] To achieve the above object, the present invention further provides a position measurement method, which includes:

[0037] providing a first light beam at a first frequency and a second light beam at a second frequency;

[0038] Splitting the first light beam and the second light beam to output multiple dual-frequency measurement beams each having a first split light beam of a first frequency and a second split light beam of a second frequency, wherein two of the dual-frequency measurement beams are emitted symmetrically with respect to a plane perpendicular to a horizontal direction;

[0039] For each of the dual-frequency measurement beams, the dual-frequency measurement beam is irradiated onto a grating and formed into a measurement interference beam carrying measurement phase information after multiple diffraction by the grating;

[0040] collecting a plurality of groups of the measurement interference beams;

[0041] The horizontal displacement information and the vertical displacement information of the grating are obtained based on the multiple groups of the measurement interference light beams.

[0042] Optionally, the splitting of the first light beam and the second light beam to output multiple dual-frequency measurement beams having a first split light beam of a first frequency and a second split light beam of a second frequency includes:

[0043] performing a first splitting of the first light beam and the second light beam to output a dual-frequency reference beam having both a first reference beam of a first frequency and a second reference beam of a second frequency, and a measuring beam having both a first measuring beam of the first frequency and a second measuring beam of the second frequency;

[0044] Splitting the first measuring beam and the second measuring beam to output multiple dual-frequency measuring beams having a first split beam of a first frequency and a second split beam of a second frequency;

[0045] The position measurement method further includes:

[0046] Controlling the first reference beam and the second reference beam to be coherent to form a reference interference beam carrying reference phase information;

[0047] collecting the reference interference beam; and

[0048] Correcting the measurement phase information carried by the measurement interference beam according to the reference phase information carried by the reference interference beam;

[0049] The obtaining of the horizontal displacement information and the vertical displacement information of the grating based on the multiple groups of the measurement interference beams includes:

[0050] The horizontal displacement information and the vertical displacement information of the grating are obtained based on the multiple groups of corrected measurement interference beams.

[0051] To achieve the above object, the present invention further provides a lithography device, which includes the position measurement device described in any one of the above items.

[0052] Compared with the prior art, the position measurement device, measurement method and lithography equipment provided by the present invention have the following beneficial effects:

[0053] The present invention includes a reader, a grating, a light source, a light detection module, and an optical signal processing module; the light source is used to provide a first light beam of a first frequency and a second light beam of a second frequency; the reader is arranged opposite to the grating, and the reader includes a first spectroscopic element, which is used to split the first light beam and the second light beam to output multiple dual-frequency measurement beams having a first spectroscopic beam of a first frequency and a second spectroscopic beam of a second frequency; for each dual-frequency measurement beam, the dual-frequency measurement beam is diffracted multiple times by the grating to form a measurement interference beam carrying measurement phase information; the light detection module is used to collect multiple groups of the measurement interference beams; and the optical signal processing module is used to obtain horizontal and vertical displacement information of the grating based on the multiple groups of the measurement interference beams. Therefore, the position measurement device provided by the present invention adopts dual-frequency detection, and the light detection structure is simple, so that the effective signal is less affected by changes in optical power, and it is easy to obtain a stable phase, thereby improving the quality of the measurement signal. Furthermore, the position measurement device provided by the present invention employs a first beam splitter element within the readhead to split the first and second beams of different frequencies to output multiple dual-frequency measurement beams. This allows for the multi-axis measurement light source to be generated by the internal beam splitting within the readhead, and for the multi-axis optical paths to be staggered, thereby ensuring good relative structural stability between the multi-axis optical paths and effectively reducing the impact of changes in the measurement environment, such as temperature and pressure, on measurement performance. Furthermore, the position measurement device provided by the present invention allows for the reuse of dual-frequency boards in situations where single-frequency board detection technology is immature, accelerating the engineering research and development of two-dimensional and three-dimensional high-precision grating scale systems.

[0054] Since the position measurement method and photolithography equipment provided by the present invention belong to the same inventive concept as the present invention, the position measurement method and photolithography equipment provided by the present invention have at least all the beneficial effects of the present invention. For details, please refer to the relevant description of the beneficial effects of the present invention in the above text. Therefore, the beneficial effects of the position measurement method and photolithography equipment provided by the present invention will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A front view of the ZY plane of the position measuring device provided by the first embodiment of the present invention;

[0056] Figure 2 A left side view of the ZX plane of the position measuring device provided by the first embodiment of the present invention;

[0057] Figure 3 A rear view of the ZY plane of the position measuring device provided by the first embodiment of the present invention;

[0058] Figure 4 A schematic diagram of a reverse retroreflective unit provided in a first embodiment of the present invention;

[0059] Figure 5 A schematic diagram of a reverse retroreflective unit provided in a second embodiment of the present invention;

[0060] Figure 6 A front view of the ZY plane of the position measuring device provided by the second embodiment of the present invention;

[0061] Figure 7 A left side view of the ZX plane of the position measuring device provided by the second embodiment of the present invention;

[0062] Figure 8 A rear view of the ZY plane of the position measuring device provided by the second embodiment of the present invention;

[0063] Figure 9 A schematic diagram of the light emission mode of the reader provided in the first embodiment of the present invention;

[0064] Figure 10 A schematic diagram of the light emission mode of the reader provided in the second embodiment of the present invention;

[0065] Figure 11 A schematic diagram of a light emitting method of a reader provided in a third embodiment of the present invention;

[0066] Figure 12 A front view of the ZY plane of the position measuring device provided by the third embodiment of the present invention;

[0067] Figure 13A left side view of the ZX plane of the position measuring device provided by the third embodiment of the present invention;

[0068] Figure 14 A rear view of the ZY plane of the position measuring device provided by the third embodiment of the present invention;

[0069] Figure 15 A front view of the ZY plane of the position measuring device provided by the fourth embodiment of the present invention;

[0070] Figure 16 A left side view of the ZX plane of the position measuring device provided by the fourth embodiment of the present invention;

[0071] Figure 17 A rear view of the ZY plane of the position measuring device provided by the fourth embodiment of the present invention;

[0072] Figure 18 A schematic diagram of light incident on a reading head of a measuring device provided by one embodiment of the present invention;

[0073] Figure 19 A schematic flow chart of a position measurement method provided by an embodiment of the present invention.

[0074] The accompanying drawings are numerals as follows:

[0075] Reader 100; first beam splitter 111; second beam splitter 112; polarization screening and control unit 120; polarization screening and control elements 121a, 121b, 121c, 121d; first refraction unit 130; first refraction elements 131a, 131b, 131c, 131d, 131e, 131f; retroreflective unit 140; first retroreflective elements 141a, 141b; second retroreflective elements 142a, 142b, 142c, 142d; third retroreflective elements 143a, 143b; second refraction unit 150; second refraction elements 151a, 151b, 151c, 151d; beam shifting unit 160; first beam shifting element Components 161a, 161b, 161c, 161d; second beam shifting elements 162a, 162b, 162c, 162d; first polarization control unit 171; light output deflection element 1711; first birefringent wedge pair 1712; first polarizer 1713; second polarization control unit 172; second birefringent wedge pair 1721; second polarizer 1722; first coupling lens 181; first light output fiber 182a, 182b, 182c; dual-frequency fiber input structure 183; collimating lens 184; second coupling lens 185; second light output fiber 186; beam shifting and polarization control unit 190; beam shifting and polarization control elements 191a, 191b;

[0076] Raster-200;

[0077] First light beam 311; second light beam 312; first split light beam 3111a, 3111b, 3111c; second split light beam 3121a, 3121b, 3121c; first dual-frequency measurement beam 321; second dual-frequency measurement beam 322; third dual-frequency measurement beam 323; first measurement interference beam 341; second measurement interference beam 342; third measurement interference beam 343; first first-order diffraction beam 351a, 351b, 351c; second first-order diffraction beam 352a, 352b, 352c; first second-order diffraction beam 331a, 331b, 331c; second second-order diffraction beam 332a, 332b, 332c; first reference beam 361; second reference beam 362; reference interference beam 360; first measurement beam 371; second measurement beam 372. DETAILED DESCRIPTION

[0078] The position measurement device, measurement method, and lithography apparatus proposed in the present invention are described in further detail below, in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the purpose of the embodiments of the present invention. To make the purposes, features, and advantages of the present invention more readily apparent, please refer to the drawings. It should be noted that the structures, proportions, and sizes illustrated in the drawings of this specification are intended solely to facilitate understanding and reading by those skilled in the art, and are not intended to limit the implementation of the present invention. Any structural modifications, changes in proportions, or adjustments in size, provided they produce the same or similar effects and achieve the same objectives, are still within the scope of the technical content disclosed herein. The specific design features of the present invention disclosed herein, including, for example, specific dimensions, directions, positions, and shapes, will be determined in part by the specific application and environment in which they are intended. Furthermore, in the embodiments described below, the same reference numerals may be used across different drawings to denote the same parts or parts having the same functions, and their repeated descriptions may be omitted. In this specification, similar reference numerals and letters are used to refer to similar items, so once an item is defined in one figure, it need not be further discussed in subsequent figures. In addition, if the method described herein includes a series of steps, the order in which the steps are presented herein is not necessarily the only order in which the steps can be performed, and some of the steps described may be omitted and / or some other steps not described herein may be added to the method.

[0079] It should be noted that, in this document, relational terms such as first and second, etc., are merely used to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations, nor should they be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Moreover, the terms "comprises," "includes," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, article, or device that includes the element. The singular forms "a", "an" and "the" include plural referents, the term "or" is generally used in a sense including "and / or", the term "several" is generally used in a sense including "at least one", the term "at least two" is generally used in a sense including "two or more", and the term "multiple" is generally used in a sense including "at least two".

[0080] The core idea of ​​the present invention is to provide a position measurement device, a measurement method and a lithography device, which adopt dual-frequency technology to realize two-dimensional, three-dimensional or higher-dimensional high-precision grating scale measurement. The light detection structure is simple, and stable phase acquisition is easy to achieve, thereby improving the quality of the measurement signal. It should be noted that, as can be understood by those skilled in the art, the position measurement device and position measurement method provided by the present invention can be used in the motion control feedback system of the workpiece stage, mask stage and other moving stages in the stepper lithography machine or the scanning lithography machine to realize ultra-high precision multi-degree-of-freedom posture control of the moving stage, and can also be used in other high-precision measurements, such as the measurement and feedback control of moving devices in laser, X-ray, ion beam and other equipment.

[0081] To realize the above idea, the present invention provides a position measuring device, please refer to Figures 1 to 3 ,in, Figure 1 A front view of the ZY plane of the position measuring device provided by the first embodiment of the present invention; Figure 2 A left side view of the ZX plane of the position measuring device provided by the first embodiment of the present invention; Figure 3 This is a rear view of the ZY plane of the position measuring device provided by the first embodiment of the present invention. Figures 1 to 3As shown, the position measurement device provided by the present invention includes a reader 100, a grating 200, a light source (not shown in the figure), a light detection module (not shown in the figure) and an optical signal processing module (not shown in the figure); the light source is used to provide a first light beam 311 of a first frequency and a second light beam 312 of a second frequency; the reader 100 is arranged opposite to the grating 200, and the reader 100 includes a first spectroscopic element 111, which is used to split the first light beam 311 and the second light beam 312 to output multiple (including two) dual-frequency measurement beams having a first spectroscopic beam of a first frequency and a second spectroscopic beam of a second frequency; for each of the dual-frequency measurement beams, the dual-frequency measurement beam is diffracted multiple times (including twice) by the grating 200 to form a measurement interference beam carrying measurement phase information; the light detection module is used to collect multiple groups (including two groups) of the measurement interference beams; and the optical signal processing module is used to obtain horizontal displacement information and vertical displacement information of the grating 200 based on the multiple (including two) groups of the measurement interference beams.

[0082] Therefore, the position measurement device provided by the present invention adopts dual-frequency detection, and the optical detection structure is simple, so that the effective signal is less affected by the change of optical power, and it is easy to obtain a stable phase, thereby improving the quality of the measurement signal. In addition, the position measurement device provided by the present invention sets a first spectroscopic element 111 in the reader 100 to split the first light beam 311 and the second light beam 312 of different frequencies to output multiple dual-frequency measurement light beams, thereby realizing that the multi-axis measurement light source is realized by the internal light splitting of the reader 100, and the multi-axis light path is staggered, so that the relative structural stability between the multi-axis light paths is good, and the influence of changes in the measurement environment temperature, pressure, etc. on the measurement performance is effectively reduced. In addition, by adopting the position measurement device provided by the present invention, when the single-frequency board detection technology is not mature, the dual-frequency board can be reused, thereby accelerating the engineering research and development process of the two-dimensional and three-dimensional high-precision grating 200-foot system.

[0083] It should be noted that, as those skilled in the art will understand, the first beam splitter element 111 may be, but is not limited to, a beam splitter, a polarization beam splitter, a beam splitter grating 200 , and the like.

[0084] Preferably, the polarization directions of the first light beam 311 and the second light beam 312 are orthogonal (for example, Figure 3 As shown, the first light beam 311 is P-polarized light, and the second light beam 312 is S-polarized light. Thus, by selecting the first light beam 311 and the second light beam 312 with mutually orthogonal polarization directions, interference can be effectively reduced and the detection signal quality can be improved.

[0085] Preferably, there are two dual-frequency measurement beams emitted symmetrically with respect to a plane perpendicular to the horizontal direction. Therefore, this arrangement not only facilitates subsequent displacement calculation, but also further reduces the impact of changes in measurement environment temperature, pressure, etc. on measurement performance.

[0086] Please continue to refer to Figures 1 to 3 ,like Figures 1 to 3 As shown, in this embodiment, the first spectroscopic element 111 is used to split the first light beam 311 into two first spectroscopic beams, and split the second light beam 312 into two second spectroscopic beams, so as to output two dual-frequency measurement beams having both a first spectroscopic beam of a first frequency and a second spectroscopic beam of a second frequency, which are respectively a first dual-frequency measurement beam 321 and a second dual-frequency measurement beam 322, and the first dual-frequency measurement beam 321 and the second dual-frequency measurement beam 322 are emitted symmetrically with respect to the XZ plane.

[0087] Please continue to refer to Figure 3 ,like Figure 3 As shown, in this embodiment, the first light beam 311 and the second light beam 312 are incident on the first spectroscopic element 111 in parallel with each other. After being split by the first spectroscopic element 111, they are divided into a first dual-frequency measurement beam 321 and a second dual-frequency measurement beam 322. The first split light beam 3111a and the second split light beam 3121a in the first dual-frequency measurement beam 321 are irradiated to the grating 200 in parallel, and the first split light beam 3111b and the second split light beam 3121b in the second dual-frequency measurement beam 322 are irradiated to the grating 200 in parallel. After being diffracted by the grating 200, corresponding diffracted light beams are output along the Y-direction +m-level (e.g., positive first-level) and -m-level (e.g., negative first-level) diffraction directions of the grating 200, respectively, where m is a positive integer.

[0088] Please continue to refer to Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the read head 100 further includes a polarization screening and control unit 120, which is configured to control the polarization directions of a first first-order diffraction beam in the +m-order diffraction direction formed by the first diffraction of the first split beam by the grating 200, and a second first-order diffraction beam in the -m-order diffraction direction formed by the first diffraction of the second split beam by the grating 200. Thus, by controlling the polarization directions of the first first-order diffraction beam in the +m-order diffraction direction and the second first-order diffraction beam in the -m-order diffraction direction by the polarization screening and control unit 120, the first first-order diffraction beam and the second first-order diffraction beam in the appropriate polarization state (e.g., the first first-order diffraction beam in the P polarization state and the second first-order diffraction beam in the S polarization state) can be screened to enter the grating 200, thereby forming a measurement interference beam carrying measurement phase information.

[0089] Please continue to refer to Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the polarization screening and control unit 120 includes independently provided polarization screening and control elements 121a, polarization screening and control elements 121b, polarization screening and control elements 121c, and polarization screening and control elements 121d. The polarization screening and control element 121a can screen the polarization direction of the first first-order diffraction beam 351a in the +m-order diffraction direction formed by the first diffraction of the first split beam 3111a in the first dual-frequency measurement beam 321 by the grating 200, so as to screen out the first first-order diffraction beam 351a in the P-polarization state; the polarization screening and control element 121b can screen the polarization direction of the second first-order diffraction beam 352a in the -m-order diffraction direction formed by the first diffraction of the second split beam 3121a in the first dual-frequency measurement beam 321 by the grating 200, so as to screen out the second first-order diffraction beam 352a in the S-polarization state. a; the polarization screening and control element 121c can screen the polarization direction of the first first-order diffraction beam 351b in the +m-order diffraction direction formed by the first diffraction of the first split beam 3111b in the second dual-frequency measurement beam 322 by the grating 200, so as to screen out the first first-order diffraction beam 351b in the P-polarization state; the polarization screening and control element 121d can screen the polarization direction of the second first-order diffraction beam 352b in the -m-order diffraction direction formed by the first diffraction of the second split beam 3121b in the second dual-frequency measurement beam 322 by the grating 200, so as to screen out the second first-order diffraction beam 352b in the S-polarization state. It should be noted that, as can be understood by those skilled in the art, the polarization screening and control element 121a, the polarization screening and control element 121b, the polarization screening and control element 121c, and the polarization screening and control element 121d can be, but are not limited to, polarization devices.

[0090] Please continue to refer to Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the reader 100 further includes a first refraction unit 130, which is used to deflect the first first-order diffracted light beam and the second first-order diffracted light beam. Thus, the first refraction unit 130 can achieve a beam deflection effect.

[0091] Please continue to refer to Figure 3 ,like Figure 3As shown, in some exemplary embodiments, the first refraction unit 130 includes independently provided first refraction elements 131a, 131b, 131c, and 131d. The first refraction element 131a is provided corresponding to the polarization screening and control element 121a, the first refraction element 131b is provided corresponding to the polarization screening and control element 121b, the first refraction element 131c is provided corresponding to the polarization screening and control element 121c, and the first refraction element 131d is provided corresponding to the polarization screening and control element 121d. The first refraction element 131a can be used to deflect the first first-order diffracted light beam 351a, the first refraction element 131b can be used to deflect the second first-order diffracted light beam 352a, the first refraction element 131c can be used to deflect the first first-order diffracted light beam 351b, and the first refraction element 131d can be used to deflect the second first-order diffracted light beam 352b. It should be noted that, as will be understood by those skilled in the art, the first refractive element 131a, the first refractive element 131b, the first refractive element 131c, and the first refractive element 131d may be, but are not limited to, a wedge prism, a refractive grating, a refractive lens, etc. Preferably, to improve the integration of the read head 100 and reduce the overall structural size of the read head 100, the first refractive element 131a, the first refractive element 131b, the first refractive element 131c, and the first refractive element 131d are preferably refractive gratings or refractive lenses. Since refractive gratings or refractive lenses have a flat-plate structure, they are easier to manufacture and integrate, thereby improving the structural stability of the read head 100.

[0092] Please continue to refer to Figure 3 ,like Figure 3 As shown, in some exemplary embodiments, the read head 100 further includes a reverse retroreflection unit 140, which is configured to reversely reflect a first first-order diffracted beam in a +m-order diffraction direction formed by the first diffraction of the first split beam by the grating 200, and to reversely reflect a second first-order diffracted beam in a -m-order diffraction direction formed by the first diffraction of the second split beam by the grating 200. Thus, the reverse retroreflection unit 140 can offset the beam by a certain distance and reversely reflect the beam.

[0093] Please continue to refer to Figure 3 ,like Figure 3As shown, in some exemplary embodiments, the retroreflective unit 140 includes a first retroreflective element 141a and a first retroreflective element 141b that are independently provided. The first first-order diffraction beam 351a deflected by the first refractive element 131a and the first first-order diffraction beam 351b deflected by the first refractive element 131c are retroreflected by the first retroreflective element 141a, and the second first-order diffraction beam 352a deflected by the first refractive element 131b and the second first-order diffraction beam 352b deflected by the first refractive element 131d are retroreflected by the first retroreflective element 141b.

[0094] Please continue to refer to Figure 4 , which is a schematic diagram of the reverse reflection unit 140 provided by the first embodiment of the present invention. Figure 4 As shown, in some exemplary embodiments, the first retroreflective element 141a and the first retroreflective element 141b may be mirrors.

[0095] Please continue to refer to Figure 5 , which is a schematic diagram of the reverse reflection unit 140 provided by the second embodiment of the present invention. Figure 5 As shown, in some other exemplary embodiments, the first retroreflective element 141a and the first retroreflective element 141b may be right-angle prisms.

[0096] It should be noted that, as those skilled in the art can understand, the first retroreflective element 141a and the first retroreflective element 141b can also be a reflector combination structure, a corner cube prism, a retroreflective prism assembly, a cat's eye reflector, a dove prism, etc.

[0097] Please continue to refer to Figure 1 ,like Figure 1 As shown, in some exemplary embodiments, the reader 100 further includes a second refraction unit 150, which is configured to deflect the first first-order diffracted light beam and the second first-order diffracted light beam reflected back through the back-reflection unit 140. Thus, the second refraction unit 150 can further achieve a beam deflection effect.

[0098] Please continue to refer to Figure 1 ,like Figure 1As shown, in some exemplary embodiments, the second refractive element 150 includes independently arranged second refractive elements 151a, second refractive elements 151b, second refractive elements 151c, and second refractive elements 151d, wherein the second refractive element 151a is arranged opposite to the first refractive element 131a, the second refractive element 151b is arranged opposite to the first refractive element 131b, the second refractive element 151c is arranged opposite to the first refractive element 131c, and the second refractive element 151d is arranged opposite to the first refractive element 131d. Thus, the first first-order diffracted light beam 351a reflected back can be deflected by the second refractive element 151a, the second first-order diffracted light beam 352a reflected back can be deflected by the second refractive element 151b, the first first-order diffracted light beam 351b reflected back can be deflected by the second refractive element 151c, and the second first-order diffracted light beam 352b reflected back can be deflected by the second refractive element 151d. It should be noted that, as will be understood by those skilled in the art, the second refractive elements 151a, 151b, 151c, and 151d may be, but are not limited to, wedge prisms, refractive gratings, refractive lenses, etc. Preferably, to further improve the integration of the read head 100 and reduce the overall structural size of the read head 100, the second refractive elements 151a, 151b, 151c, and 151d are preferably refractive gratings or refractive lenses. Since refractive gratings or refractive lenses have a flat-plate structure, they are easier to manufacture and integrate, thereby improving the structural stability of the read head 100.

[0099] Please continue to refer to Figure 1 ,like Figure 1 As shown, in some exemplary embodiments, the read head 100 further includes a beam shifting unit 160, which is configured to change the relative spacing between the first first-order diffraction beam and / or the second first-order diffraction beam retroreflected by the retroreflecting unit 140. Thus, the relative spacing of the beams can be changed by the beam shifting unit 160.

[0100] Please continue to refer to Figure 1 ,like Figure 1As shown, in some exemplary embodiments, the beam translation unit 160 includes independently arranged first beam translation element 161a, first beam translation element 161b, first beam translation element 161c and first beam translation element 161d, the first beam translation element 161a is arranged corresponding to the second refractive element 151a, the first beam translation element 161b is arranged corresponding to the second refractive element 151b, the first beam translation element 161c is arranged corresponding to the second refractive element 151c, and the first beam translation element 161d is arranged corresponding to the second refractive element 151d. Thus, the first beam shifting element 161a and the first beam shifting element 161c can change the relative distance between the first first-order diffraction beam 351a and the first first-order diffraction beam 351b retroreflected by the first retroreflective element 141a, the first beam shifting element 161c and the first beam shifting element 161b can change the relative distance between the first first-order diffraction beam 351b retroreflected by the first retroreflective element 141a and the second first-order diffraction beam 352a retroreflected by the second retroreflective element 142b, and the first beam shifting element 161b and the first beam shifting element 161d can change the relative distance between the second first-order diffraction beam 352a and the second first-order diffraction beam 352b retroreflected by the second retroreflective element 142b. It should be noted that, as understood by those skilled in the art, the first beam shifting element 161a, the first beam shifting element 161b, the first beam shifting element 161c, and the first beam shifting element 161d can be, but are not limited to, glass plates. It should also be noted that, as those skilled in the art can understand, in some other embodiments, the beam translation unit 160 can also be an integrated structure, that is, the first beam translation element 161a, the first beam translation element 161b, the first beam translation element 161c and the first beam translation element 161d are combined into one element.

[0101] Please continue to refer to Figure 1 ,like Figure 1As shown, in some exemplary embodiments, the read head 100 further includes a first polarization control unit 171, which is configured to control a first secondary diffracted beam formed by the secondary diffraction of the first split beam by the grating 200 and a second secondary diffracted beam formed by the secondary diffraction of the second split beam by the grating 200 to achieve coherence, thereby forming a measurement interference beam carrying measurement phase information. Thus, the first polarization control unit 171 can control the polarization directions of a first secondary diffracted beam 331a in the -m-order diffraction direction formed by the secondary diffraction of the first split beam 3111a in the first dual-frequency measurement beam 321 by the grating 200 and a second secondary diffracted beam 332a in the +m-order diffraction direction formed by the secondary diffraction of the second split beam 3121a in the first dual-frequency measurement beam 321 by the grating 200, so that the polarization directions of the first secondary diffracted beam 331a and the second secondary diffracted beam 332a are no longer orthogonal, thereby forming a first measurement interference beam 341 carrying measurement phase information. At the same time, the first polarization control unit 171 can also control the polarization directions of the first secondary diffracted beam 331b in the -m-order diffraction direction formed by the secondary diffraction of the first split beam 3111b in the second dual-frequency measurement beam 322 by the grating 200, and the second secondary diffracted beam 332b in the +m-order diffraction direction formed by the secondary diffraction of the second split beam 3121b in the second dual-frequency measurement beam 322 by the grating 200, so that the polarization directions of the first secondary diffracted beam 331b and the second secondary diffracted beam 332b are no longer orthogonal, thereby forming a second measurement interference beam 342 carrying measurement phase information. It should be noted that, as will be understood by those skilled in the art, the first polarization control unit 171 in this embodiment can be, but is not limited to, a polarization device.

[0102] Please continue to refer to Figure 1 ,like Figure 1As shown, in some exemplary embodiments, the reader 100 further includes a first coupling lens 181 and a plurality of (including a plurality of) first light-emitting optical fibers 182 arranged in a one-to-one correspondence with the plurality of groups of measurement interference light beams, the first coupling lens 181 being used to focus and couple the measurement interference light beam into the correspondingly arranged first light-emitting optical fiber 182, and the first light-emitting optical fiber 182 being used to transmit the measurement interference light beam to the light detection module. Thus, by adopting the first coupling lens 181 to focus and couple the plurality of groups of measurement interference light beams into the correspondingly arranged first light-emitting optical fiber 182 and transmitting them to the light detection module through the first light-emitting optical fiber 182, the anti-interference capability can be improved, thereby improving the measurement accuracy. In addition, by integrating the first light-emitting optical fiber 182 on the reader 100, the structural size of the position measurement device can be reduced, the measurement convenience of the position measurement device provided by the present invention can be improved, and the scope of application can be expanded.

[0103] Specifically, if Figure 1 As shown, the first measuring interference beam 341 can be focused and coupled into the first light-emitting optical fiber 182a through the first coupling lens 181, and the second measuring interference beam 342 can be focused and coupled into the first light-emitting optical fiber 182b.

[0104] The specific working principle of the position measurement device provided in this embodiment is:

[0105] The first light beam 311 and the second light beam 312 output by the light source are divided into two light paths, a first dual-frequency measurement beam 321 and a second dual-frequency measurement beam 322, after passing through the first light splitting element 111. The first split light beam 3111a and the second split light beam 3121a in the first dual-frequency measurement beam 321 are parallel to the grating 200. After being diffracted by the grating 200, they are diffracted along the Y direction of the grating 200 along the +m level (for example, the positive first level), the -m level (for example, the negative first level), and the -m level (for example, the negative first level). The first first-order diffraction beam 351a and the second first-order diffraction beam 352a are formed in the diffraction direction of the +m-order (for example, the positive first order) and the -m-order (for example, the negative first order) diffraction directions of the Y direction of the grating 200, respectively. The first split beam 3111b and the second split beam 3121b in the second dual-frequency measurement beam 322 are irradiated onto the grating 200 in parallel. After being diffracted by the grating 200, the first first-order diffraction beam 351b and the second first-order diffraction beam 352b are formed. The first first-order diffracted light beam 351a is acted upon by the polarization screening and control element 121a, the first refractive element 131a, the first retroreflective element 141a, the second refractive element 151a, and the first beam shifting element 161a, and then strikes the grating 200. After being diffracted by the grating 200, a first second-order diffracted light beam 331a is formed. The second first-order diffracted light beam 352a is acted upon by the polarization screening and control element 121b, the first refractive element 131b, the first retroreflective element 141b, the second refractive element 151b, and the first beam shifting element 161b, and then strikes the grating 200. After being diffracted by the grating 200, a second second-order diffracted light beam 332a is formed. The first first-order diffraction beam 351b is acted upon by the polarization screening and control element 121c, the first refractive element 131c, the first retroreflective element 141a, the second refractive element 151c and the first beam translation element 161c, and then irradiates the grating 200. After being diffracted by the grating 200, a first second-order diffraction beam 331b is formed. The second first-order diffraction beam 352b is acted upon by the polarization screening and control element 121d, the first refractive element 131d, the first retroreflective element 141b, the second refractive element 151d and the first beam translation element 161d, and then irradiates the grating 200. After being diffracted by the grating 200, a second second-order diffraction beam 332b is formed. After the first polarization control unit 171 acts on the first secondary diffraction beam 331a and the second secondary diffraction beam 332a, a first measurement interference beam 341 carrying measurement phase information is formed. After the first polarization control unit 171 acts on the first secondary diffraction beam 331b and the second secondary diffraction beam 332b, a second measurement interference beam 342 carrying measurement phase information is formed.After being converged by the first coupling lens 181, the light is transmitted to the optical detection module by the first light-emitting optical fiber 182a and the first light-emitting optical fiber 182b. The optical detection module collects the first measurement interference beam 341 and the second measurement interference beam 342 and transmits them to the optical signal processing module. The optical signal processing module can obtain the horizontal displacement of the grating 200 along the Y direction and the vertical displacement along the Z direction by performing displacement calculation on the first measurement interference beam 341 and the second measurement interference beam 342.

[0106] In some exemplary embodiments, the optical signal processing module is configured to calculate the horizontal displacement of the grating 200 along the Y direction and the vertical displacement along the Z direction according to the following formula:

[0107]

[0108]

[0109] Wherein, ΔY is the horizontal displacement of the grating 200 along the Y direction, ΔZ is the vertical displacement of the grating 200 along the Z direction, P is the grating pitch of the grating 200, λ is the wavelength of the light source, δ1 is the incident angle of the first dual-frequency measurement beam 321 incident on the grating 200, δ2 is the incident angle of the second dual-frequency measurement beam 322 incident on the grating 200, is the phase change of the first measurement interference beam 341 corresponding to the first dual-frequency measurement beam 321, is the phase change of the second measuring interference beam 342 corresponding to the second dual-frequency measurement beam 322, α1 is the diffraction angle of the first split beam in the first dual-frequency measurement beam 321 in the +m-order diffraction direction after the first diffraction along the Y direction of the grating 200, β1 is the diffraction angle of the second split beam in the first dual-frequency measurement beam 321 in the -m-order diffraction direction after the first diffraction along the Y direction of the grating 200, α2 is the diffraction angle of the first split beam in the second dual-frequency measurement beam 322 in the +m-order diffraction direction after the first diffraction along the Y direction of the grating 200, and β2 is the diffraction angle of the second split beam in the second dual-frequency measurement beam 322 in the -m-order diffraction direction after the first diffraction along the Y direction of the grating 200.

[0110] Please continue to refer to Figures 6 to 8 ,in, Figure 6 A front view of the ZY plane of the position measuring device provided by the second embodiment of the present invention; Figure 7 A left side view of the ZX plane of the position measuring device provided by the second embodiment of the present invention;

[0111] Figure 8 This is a rear view of the ZY plane of the position measuring device provided by the second embodiment of the present invention. Figures 6 to 8 As shown, the main difference between the position measurement device provided by this embodiment and the position measurement device provided by the first embodiment is that the reader 100 in the position measurement device provided by this embodiment further includes a dual-frequency fiber-optic light input structure 183 and a collimating lens 184. The dual-frequency fiber-optic light input structure 183 is used to output the first light beam 311 and the second light beam 312, and the collimating lens 184 is used to collimate the first light beam 311 and the second light beam 312 output by the dual-frequency fiber-optic light input structure 183. Thus, by using the dual-frequency fiber-optic light input structure 183 for light input, the light input stability can be improved, and by using the collimating lens 184, the first light beam 311 and the second light beam 312 can be collimated, thereby achieving the collimated output of the first dual-frequency measurement beam 321 and the second dual-frequency measurement beam 322. In addition, by integrating the dual-frequency fiber-optic light input structure 183 with the reader 100, the structural size of the position measurement device can be further reduced, the measurement convenience of the position measurement device provided by the present invention can be improved, and the scope of application can be expanded. It should be noted that, as those skilled in the art will appreciate, the dual-frequency optical fiber light input structure 183 may be, but is not limited to, a dual-core optical fiber structure.

[0112] Please continue to refer to Figure 6 ,like Figure 6 As shown, the position measurement device provided in this embodiment differs from the position measurement device provided in the first embodiment in that the beam translation unit 160 in the position measurement device provided in this embodiment is an independent optical element, which can be an integral glass plate. It should be noted that, as will be understood by those skilled in the art, in other implementations, the beam translation unit 160 in this embodiment can also employ a structure of multiple independently disposed first beam translation elements 161, as in the first embodiment.

[0113] Please continue to refer to Figure 8 ,like Figure 8As shown, the position measurement device provided in this embodiment differs from the position measurement device provided in the first embodiment in that, in this embodiment, the first light beam 311 and the second light beam 312 are incident on the first beam splitting element 111 at a certain angle. After being split by the first beam splitting element 111, they are divided into a first dual-frequency measurement beam 321 and a second dual-frequency measurement beam 322. The first split beam 3111a and the second split beam 3121a in the first dual-frequency measurement beam 321 are irradiated onto the grating 200 at an angle, and the first split beam 3111b and the second split beam 3121b in the second dual-frequency measurement beam 322 are irradiated onto the grating 200 at an angle. Thus, by irradiating the grating 200 at an angle between the first split beam 3111a and the second split beam 3111b, and between the first split beam 3121b and the second split beam 3121b, the influence of interfering light signals on the measurement can be effectively filtered out, eliminating nonlinear errors in the measurement, and thereby effectively improving measurement accuracy.

[0114] The specific working principle of the position measurement device provided in this embodiment is:

[0115] The first light beam 311 and the second light beam 312 output by the light source are output through the dual-frequency fiber-optic light input structure 183, and after passing through the collimating lens 184 and the first spectroscopic element 111, they are split into a first dual-frequency measurement beam 321 and a second dual-frequency measurement beam 322 for collimated output. The first split light beam 3111a and the second split light beam 3121a in the first dual-frequency measurement beam 321 are irradiated onto the grating 200 at a certain small angle. After being diffracted by the grating 200, they form a first first-order diffracted light beam 351a and a second first-order diffracted light beam 352a along the +m-order (e.g., positive first-order) and -m-order (e.g., negative first-order) diffraction directions of the Y-direction of the grating 200, respectively. The first split beam 3111b and the second split beam 3121b in the second dual-frequency measurement beam 322 are irradiated onto the grating 200 at a certain small angle. After being diffracted by the grating 200, the first first-order diffraction beam 351b and the second first-order diffraction beam 352b are formed along the +m-order (for example, positive first order) and -m-order (for example, negative first order) diffraction directions of the Y direction of the grating 200 respectively. The first first-order diffracted light beam 351a is acted upon by the polarization screening and control element 121a, the first refractive element 131a, the first retroreflective element 141a, the second refractive element 151a, and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a first second-order diffracted light beam 331a is formed. The second first-order diffracted light beam 352a is acted upon by the polarization screening and control element 121b, the first refractive element 131b, the first retroreflective element 141b, the second refractive element 151b, and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a second second-order diffracted light beam 332a is formed. The first first-order diffraction beam 351b is acted upon by the polarization screening and control element 121c, the first refractive element 131c, the first retroreflective element 141a, the second refractive element 151c and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a first second-order diffraction beam 331b is formed. The second first-order diffraction beam 352b is acted upon by the polarization screening and control element 121d, the first refractive element 131d, the first retroreflective element 141b, the second refractive element 151d and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a second second-order diffraction beam 332b is formed. After the first polarization control unit 171 acts on the first secondary diffraction beam 331a and the second secondary diffraction beam 332a, a first measurement interference beam 341 carrying measurement phase information is formed. After the first polarization control unit 171 acts on the first secondary diffraction beam 331b and the second secondary diffraction beam 332b, a second measurement interference beam 342 carrying measurement phase information is formed.After being converged by the first coupling lens 181, the light is transmitted to the optical detection module via the first output optical fiber 182a and the first output optical fiber 182b. The optical detection module collects the first measuring interference beam 341 and the second measuring interference beam 342 and transmits them to the optical signal processing module. The optical signal processing module calculates the displacement of the first measuring interference beam 341 and the second measuring interference beam 342 to obtain the horizontal displacement of the grating 200 along the Y direction and the vertical displacement along the Z direction. Specifically, for details on how to calculate the horizontal displacement of the grating 200 along the Y direction and the vertical displacement along the Z direction, please refer to the relevant description above and will not be repeated here.

[0116] In some exemplary embodiments, the first polarization control unit 171 includes a light-emitting refraction element 1711, a first birefringent wedge pair 1712, and a first polarizer 1713. The light-emitting refraction element 1711 is used to fold the first second-order diffraction beam and the second second-order diffraction beam so that the measurement interference beam formed by the first second-order diffraction beam and the second second-order diffraction beam is perpendicular to the light-emitting receiving end face as a whole. The first birefringent wedge pair 1712 is used to make the folded first second-order diffraction beam and the folded second second-order diffraction beam parallel. The first polarizer 1713 is used to control the polarization directions of the parallel first second-order diffraction beam and the second second-order diffraction beam. Thus, the light-emitting deflection element 1711 can make the first measurement interference beam 341 formed by the first secondary diffracted beam 331a and the second secondary diffracted beam 332a perpendicular to the light-emitting receiving end face of the first light-emitting optical fiber 182a, and the second measurement interference beam 342 formed by the first secondary diffracted beam 331b and the second secondary diffracted beam 332b perpendicular to the light-emitting receiving end face of the first light-emitting optical fiber 182b. The birefringent wedge pair can compensate for the angle between the first split beam and the second split beam in the dual-frequency measurement beam caused by the dual-frequency optical fiber input structure 183 and the collimating lens 184, so that the directions of the two beams after secondary diffraction are parallel, thereby improving the quality of the light-emitting signal. The polarizing plate can control the polarization directions of the first and second secondary diffracted beams after being adjusted by the birefringent wedge plate, thereby ensuring the polarization directions of the first and second secondary diffracted beams 331a, 332a in the first measurement interference beam 341, and the polarization directions of the first and second secondary diffracted beams 331b, 332b in the second measurement interference beam 342. It should be noted that, as will be understood by those skilled in the art, the birefringent wedge plate pair may be, but is not limited to, a Wollaston prism.

[0117] Please continue to refer to Figure 9 , which is a schematic diagram of the light emitting mode of the reader 100 provided by the first embodiment of the present invention. Figure 9 As shown, in some embodiments, the light-exiting deflection element 1711 is a dual-lens assembly similar to an image-side telecentric assembly. Since the dual-lens assembly also has the effect of coupling the converging light beam into the first light-exiting optical fiber 182, when the light-exiting deflection element 1711 is a dual-lens assembly, the position measurement device does not need to be provided with the first coupling lens 181.

[0118] Please continue to refer to Figure 10 , which is a schematic diagram of the light emitting mode of the reader 100 provided in the second embodiment of the present invention. Figure 10 As shown, in other embodiments, the light output deflection element 1711 is a deflection grating 200 .

[0119] Please continue to refer to Figure 11 , which is a schematic diagram of the light emitting mode of the reader 100 provided in the third embodiment of the present invention. Figure 11 As shown, in some other embodiments, the light-emitting deflection element 1711 is a trapezoidal deflection prism.

[0120] It should be noted that, as those skilled in the art can understand, more details about the position measurement device provided in this embodiment can be adaptively understood by referring to the relevant details about the position measurement device provided in the first embodiment, and will not be elaborated here.

[0121] Please continue to refer to Figures 12 to 14 ,in, Figure 12 A front view of the ZY plane of the position measuring device provided by the third embodiment of the present invention; Figure 13 A left side view of the ZX plane of the position measuring device provided by the third embodiment of the present invention; Figure 14 This is a rear view of the ZY plane of the position measuring device provided by the third embodiment of the present invention. Figures 12 to 14As shown, the main difference between the position measuring device provided by this embodiment and the position measuring device provided by the second embodiment is that the reader 100 in the position measuring device provided by this embodiment does not include the polarization screening and control unit 120 and the second refractive unit 150, and in this embodiment, the reverse retroreflective unit 140 includes four independently set second reverse retroreflective elements 142, namely, the second reverse retroreflective element 142a, the second reverse retroreflective element 142b, the second reverse retroreflective element 142c and the second reverse retroreflective element 142d, and the beam translation unit 160 includes four independently set second beam translation elements 162, namely, the second beam translation element 162a, the second beam translation element 162b, the second beam translation element 162c and the second retroreflective element 142d. The translation element 162b, the second beam translation element 162c and the second beam translation element 162d, the first refractive element 131a, the second retroreflective element 142a and the second beam translation element 162a are correspondingly arranged, the first refractive element 131b, the second retroreflective element 142b and the second beam translation element 162b are correspondingly arranged, the first refractive element 131c, the second retroreflective element 142c and the second beam translation element 162c are correspondingly arranged, the first refractive element 131d, the second retroreflective element 142d and the second beam translation element 162d are correspondingly arranged.

[0122] Please continue to refer to Figure 12 and Figure 14 ,like Figure 12 and Figure 14 As shown, in this embodiment, the first refractive element 131a, the first refractive element 131b, the first refractive element 131c, and the first refractive element 131d are preferably wedge-shaped prisms. Compared to refractive gratings, wedge-shaped prisms have higher transmittance, thereby improving system power utilization. It should be noted that, as will be understood by those skilled in the art, when the first polarization control unit 171 is used to fully compensate for the angular deviation of the angled measurement beam in the measurement signal, the first refractive element 130 can be omitted in this embodiment.

[0123] The specific working principle of the position measurement device provided in this embodiment is as follows: the first light beam 311 and the second light beam 312 output by the light source are output through the dual-frequency fiber input structure 183, and after passing through the collimating lens 184 and the first light splitting element 111, they are divided into a first dual-frequency measurement beam 321 and a second dual-frequency measurement beam 322, and the two light paths are collimated and output. The first split light beam 3111a and the second split light beam 3121a in the first dual-frequency measurement beam 321 are irradiated onto the grating 200 at a certain small angle, and after being diffracted by the grating 200, they are respectively diffracted along the light path. The first first-order diffraction beam 351a and the second first-order diffraction beam 352a are formed in the +m-order (for example, positive first order) and -m-order (for example, negative first order) diffraction directions of the grating 200 in the Y direction. The first split beam 3111b and the second split beam 3121b in the second dual-frequency measurement beam 322 are irradiated onto the grating 200 at a certain small angle. After being diffracted by the grating 200, the first first-order diffraction beam 351b and the second first-order diffraction beam 352b are formed along the +m-order (for example, positive first order) and -m-order (for example, negative first order) diffraction directions of the grating 200 in the Y direction. The first first-order diffracted light beam 351a is acted upon by the first refractive element 131a, the second retroreflective element 142a, and the second beam shifting element 162a, and then irradiates the grating 200. After being diffracted by the grating 200, a first second-order diffracted light beam 331a is formed. The second first-order diffracted light beam 352a is acted upon by the first refractive element 131b, the second retroreflective element 142b, and the second beam shifting element 162b, and then irradiates the grating 200. After being diffracted by the grating 200, a second second-order diffracted light beam 331a is formed. 32a; the first first-order diffraction light beam 351b is acted upon by the first refractive element 131c, the second retroreflective element 142c and the second beam shifting element 162c, and then irradiates the grating 200, and is diffracted by the grating 200 to form a first second-order diffraction light beam 331b; the second first-order diffraction light beam 352b is acted upon by the first refractive element 131d, the second retroreflective element 142d and the second beam shifting element 162d, and then irradiates the grating 200, and is diffracted by the grating 200 to form a second second-order diffraction light beam 332b.After being acted upon by the first polarization control unit 171, the first and second secondary diffracted beams 331a and 332a form a first measuring interference beam 341 carrying measurement phase information. After being acted upon by the first polarization control unit 171, the first and second secondary diffracted beams 331b and 332b form a second measuring interference beam 342 carrying measurement phase information. After being converged by the first coupling lens 181, the beams are transmitted to the optical detection module via the first and second output optical fibers 182a and 182b. The optical detection module collects the first and second measuring interference beams 341 and 342 and transmits them to the optical signal processing module. The optical signal processing module calculates the displacement of the first and second measuring interference beams 341 and 342 to obtain the horizontal displacement of the grating 200 along the Y direction and the vertical displacement along the Z direction. Specifically, for information on how to calculate the horizontal displacement of the grating 200 along the Y direction and the vertical displacement along the Z direction, reference can be made to the relevant description above and will not be repeated here.

[0124] It should be noted that, as will be understood by those skilled in the art, the second retroreflective elements 142a, 142b, 142c, and 142d may be, but are not limited to, reflectors, reflector combinations, right-angle prisms, corner cube prisms, retroreflective prism assemblies, cat's-eye reflectors, dove prisms, etc. The second beam shifting elements 162a, 162b, 162c, and 162d may be, but are not limited to, glass plates.

[0125] Furthermore, it should be noted that, as those skilled in the art will appreciate, the specific structure of the first polarization control unit 171 in the position measurement device provided in this embodiment is the same as the structure of the first polarization control unit 171 in the position measurement device provided in the second embodiment. For details, reference may be made to the relevant description above and will not be repeated here. Furthermore, it should be noted that, as those skilled in the art will appreciate, further details regarding the position measurement device provided in this embodiment can be adaptively understood by referring to the relevant details regarding the position measurement device provided in the first embodiment and will not be repeated here.

[0126] Please continue to refer to Figures 15 to 17 ,in, Figure 15 A front view of the ZY plane of the position measuring device provided by the fourth embodiment of the present invention; Figure 16 A left side view of the ZX plane of the position measuring device provided by the fourth embodiment of the present invention; Figure 17 This is a rear view of the ZY plane of the position measuring device provided by the fourth embodiment of the present invention. Figures 15 to 17 As shown, the main difference between the position measurement device provided by this embodiment and the position measurement device provided by the second embodiment is that in the position measurement device provided by this embodiment, the first light beam 311 and the second light beam 312 are split by the first beam splitter 111 into three light paths: a first dual-frequency measurement beam 321, a second dual-frequency measurement beam 322, and a third dual-frequency measurement beam 323. The first dual-frequency measurement beam 321 and the second dual-frequency measurement beam 322 are emitted symmetrically with respect to the XZ plane, and the third dual-frequency measurement beam 323 is emitted along the XZ plane. The retroreflective unit 140 in the read head 100 includes, in addition to the first retroreflective element 141a and the first retroreflective element 141b, third retroreflective elements 143a and 143b. The first refractive element 130 includes, in addition to the first refractive element 131a, the first refractive element 131b, the first refractive element 131c, and the first refractive element 131d, first refractive element 131e and first refractive element 131f. In addition, the reader 100 further includes a beam translation and polarization control unit 190, which is used to change the first first diffraction beam (specifically, the first split beam 3111c in the third dual-frequency measurement beam 323 is diffracted by the grating 200 to form a first diffraction beam 351c) and the second first diffraction beam (specifically, the second split beam 3121c in the third dual-frequency measurement beam 323 is diffracted by the grating 200 to form a first diffraction beam 351c) reflected by the reverse reflection unit 140. The relative spacing between the first first diffraction beam 351c and the second first diffraction beam 352c formed by the first diffraction of the first split beam 3111c in the third dual-frequency measurement beam 323 through the grating 200) and the polarization direction of the first first diffraction beam 351c (specifically, the first first diffraction beam 351c formed by the first diffraction of the first split beam 3111c in the third dual-frequency measurement beam 323 through the grating 200) reflected back through the reverse reflection unit 140 is changed.

[0127] Please continue to refer to Figure 16 ,like Figure 16 As shown, the beam translation and polarization control unit 190 includes a beam translation and polarization control element 191a and a beam translation and polarization control element 191b.

[0128] The specific working principle of the position measurement device provided in this embodiment is as follows: the first light beam 311 and the second light beam 312 output by the light source are output through the dual-frequency fiber-optic light input structure 183, and after passing through the collimating lens 184 and the first spectrometer 111, they are divided into three collimated light paths: a first dual-frequency measurement beam 321, a second dual-frequency measurement beam 322, and a third dual-frequency measurement beam 323. The first split light beam 3111a and the second split light beam 3121a in the first dual-frequency measurement beam 321 are irradiated onto the grating 200 at a certain small angle. After being diffracted by the grating 200, they form a first first-order diffracted light beam 351a and a second first-order diffracted light beam 352a along the +m-order (e.g., positive first-order) and -m-order (e.g., negative first-order) diffraction directions of the Y direction of the grating 200, respectively. The first split beam 3111b and the second split beam 3121b in the second dual-frequency measurement beam 322 are irradiated onto the grating 200 at a certain small angle. After being diffracted by the grating 200, they form a first first-order diffraction beam 351b and a second first-order diffraction beam 352b along the +m-order (for example, positive first order) and -m-order (for example, negative first order) diffraction directions of the grating 200 in the Y direction, respectively. The first split beam 3111c and the second split beam 3121c in the third dual-frequency measurement beam 323 are irradiated onto the grating 200 at a certain small angle. After being diffracted by the grating 200, they form a first first-order diffraction beam 351c and a second first-order diffraction beam 352c along the +m-order (for example, positive first order) and -m-order (for example, negative first order) diffraction directions of the grating 200 in the X direction, respectively.The first first-order diffracted light beam 351a is acted upon by the polarization screening and control element 121a, the first refractive element 131a, the first retroreflective element 141a, the second refractive element 151a, and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a first second-order diffracted light beam 331a is formed. The second first-order diffracted light beam 352a is acted upon by the polarization screening and control element 121b, the first refractive element 131b, the first retroreflective element 141b, the second refractive element 151b, and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a second second-order diffracted light beam 332a is formed. The first first-order diffraction beam 351b is acted upon by the polarization screening and control element 121c, the first refractive element 131c, the first retroreflective element 141a, the second refractive element 151c and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a first second-order diffraction beam 331b is formed. The second first-order diffraction beam 352b is acted upon by the polarization screening and control element 121d, the first refractive element 131d, the first retroreflective element 141b, the second refractive element 151d and the beam translation unit 160, and then irradiates the grating 200. After being diffracted by the grating 200, a second second-order diffraction beam 332b is formed. The first first-order diffraction beam 351c is acted upon by the third retroreflective element 143a, the first refractive element 131e and the beam translation and polarization control element 191a, and is then irradiated onto the grating 200. After being diffracted by the grating 200, a first second-order diffraction beam 331c is formed. The second first-order diffraction beam 352c is acted upon by the beam translation and polarization control element 191b, the second refractive element 151e and the third retroreflective element 143b, and is then irradiated onto the grating 200. After being diffracted by the grating 200, a second second-order diffraction beam 332c is formed. After the first polarization control unit 171 acts on the first secondary diffraction beam 331a and the second secondary diffraction beam 332a, a first measurement interference beam 341 carrying measurement phase information is formed; after the first polarization control unit 171 acts on the first secondary diffraction beam 331b and the second secondary diffraction beam 332b, a second measurement interference beam 342 carrying measurement phase information is formed; after the first polarization control unit 171 acts on the first secondary diffraction beam 331c and the second secondary diffraction beam 332c, a third measurement interference beam 343 carrying measurement phase information is formed.After being converged by the first coupling lens 181, the light is transmitted to the optical detection module via the first output optical fiber 182a, the first output optical fiber 182b, and the first output optical fiber 182c. The optical detection module collects the first measurement interference beam 341, the second measurement interference beam 342, and the third measurement interference beam 343, and transmits them to the optical signal processing module. The optical signal processing module calculates the displacement of the first measurement interference beam 341, the second measurement interference beam 342, and the third measurement interference beam 343 to obtain the horizontal displacement of the grating 200 along the Y direction, the horizontal displacement along the X direction, and the vertical displacement along the Z direction. Specifically, for the relevant content on how to calculate the horizontal displacement of the grating 200 along the Y direction and the vertical displacement along the Z direction, please refer to the relevant description above and will not be repeated here.

[0129] In some exemplary embodiments, the optical signal processing module is configured to calculate the horizontal displacement of the grating 200 along the X-axis according to the following formula:

[0130]

[0131] Wherein, ΔX is the horizontal displacement of the grating 200 along the X-axis, is the phase change of the third measurement interference beam 343 corresponding to the third dual-frequency measurement beam 323.

[0132] It should be noted that, as those skilled in the art will appreciate, further details regarding the position measurement device provided in this embodiment can be adaptively understood by referring to the relevant details regarding the position measurement device provided in the first embodiment, and will not be elaborated upon here. It should also be noted that, as those skilled in the art will appreciate, in other implementations, the beam shifting unit 160 in this embodiment may also employ a structure of multiple independently disposed first beam shifting elements 161, as in the first embodiment.

[0133] Please continue to refer to Figure 18 , which is a schematic diagram of light incident on the reading head 100 of the measuring device provided by one embodiment of the present invention. Figure 18As shown, in some exemplary embodiments, the reader 100 also includes a second spectroscopic element 112 and a second polarization control unit 172, and the second spectroscopic element 112 is arranged between the collimating lens 184 and the first spectroscopic element 111, and the second spectroscopic element 112 is used to branch the first light beam 311 and the second light beam 312 to output a dual-frequency reference beam having a first reference beam 361 of a first frequency and a second reference beam 362 of a second frequency. The second polarization control unit 172 is used to control the first reference beam 361 and the second reference beam 362 to achieve coherence to form a reference interference beam 360 carrying reference phase information. The grating 200 detection module is also used to collect the reference interference beam 360, and the optical signal processing module is also used to correct the measurement phase information carried by the measurement interference beam (including the first measurement interference beam 341, the second measurement interference beam 342 and the third measurement interference beam 343) based on the reference phase information carried by the reference interference beam 360. Since the phases of the first light beam 311 and the second light beam 312 are affected by the optical fiber transmission when the dual-frequency optical fiber light input structure 183 is used for light input, by separating a dual-frequency reference beam and correcting the measurement phase information carried by the measurement interference beam using the reference phase information carried by the reference interference beam 360 formed by the dual-frequency reference beam, the phase difference crosstalk caused by the two incident light beams being transmitted through different optical fibers can be effectively eliminated, thereby further improving the measurement accuracy of the position measurement device provided by the present invention. It should be noted that, as can be understood by those skilled in the art, the second spectroscopic element 112 also outputs a measurement beam having both a first measurement beam 371 of the first frequency and a second measurement beam 372 of the second frequency. After the measurement beam enters the first spectroscopic element 111, it is further divided into multiple dual-frequency measurement beams by the first spectroscopic element 111.

[0134] Specifically, the measured interference signal can be corrected according to the following formula:

[0135]

[0136]

[0137]

[0138] Where, is the measured phase variation carried by the first measuring interference beam 341, is the measured phase change carried by the second measuring interference beam 342, is the measured phase variation carried by the third measuring interference beam 343, is the reference phase change carried by the reference interference beam 360.

[0139] Please continue to refer to Figure 18 ,like Figure 18 As shown, in some exemplary embodiments, the second polarization control unit 172 includes a second birefringent wedge pair 1721 and a second polarizer 1722, the second birefringent wedge pair 1721 is used to make the first reference beam 361 and the second reference beam 362 set at an angle to be emitted in parallel, and the second polarizer 1722 is used to make the parallel emitted first reference beam 361 and the second reference beam 362 coherent to form a reference interference beam 360.

[0140] Please continue to refer to Figure 18 ,like Figure 18 As shown, in some exemplary embodiments, the reader 100 also includes a second coupling lens 185 and a second light-emitting fiber 186, wherein the second coupling lens 185 is used to focus and couple the reference interference beam 360 into the second light-emitting fiber 186, and the second light-emitting fiber 186 is used to transmit the reference interference beam 360 to the optical detection module.

[0141] Based on the same inventive concept, the present invention further provides a lithographic apparatus, comprising the position measurement device described in any of the above embodiments. Because the lithographic apparatus provided by the present invention includes the position measurement device provided by the present invention, the lithographic apparatus provided by the present invention possesses at least all the beneficial effects of the position measurement device provided by the present invention. For details, reference may be made to the above description of the beneficial effects of the position measurement device provided by the present invention. Therefore, a detailed description of the beneficial effects of the lithographic apparatus provided by the present invention will not be repeated here.

[0142] Based on the same inventive concept, the present invention also provides a position measurement method, which is applied to the position measurement device described in any of the above embodiments. Figure 19 , which is a flow chart of a position measurement method provided by an embodiment of the present invention. Figure 19 As shown, the position measurement method provided by the present invention includes the following steps:

[0143] Step S100 : providing a first light beam 311 of a first frequency and a second light beam 312 of a second frequency.

[0144] Step S200 : splitting the first light beam 311 and the second light beam 312 to output multiple dual-frequency measurement beams having a first split light beam of a first frequency and a second split light beam of a second frequency.

[0145] Step S300 : for each of the dual-frequency measurement beams, irradiate the dual-frequency measurement beam onto the grating 200 and form a measurement interference beam carrying measurement phase information after multiple diffraction by the grating 200 .

[0146] Step S400: collecting multiple groups of the measurement interference beams.

[0147] Step S500: Obtain horizontal displacement information and vertical displacement information of the grating 200 based on the multiple groups of measurement interference beams.

[0148] Therefore, the position measurement method provided by the present invention adopts dual-frequency detection, and the optical detection structure is simple, so that the effective signal is less affected by the change of optical power, and it is easy to obtain a stable phase, thereby improving the quality of the measurement signal. In addition, the position measurement method provided by the present invention splits the first light beam 311 and the second light beam 312 of different frequencies to output multiple dual-frequency measurement light beams, thereby realizing that the multi-axis measurement light source is realized by the internal light splitting of the reader 100, thereby achieving good relative structural stability between the multi-axis optical paths, and effectively reducing the impact of changes in the measurement environment temperature, pressure, etc. on the measurement performance. In addition, by adopting the position measurement method provided by the present invention, dual-frequency boards can be reused when the single-frequency board detection technology is not mature, thereby accelerating the engineering research and development process of two-dimensional and three-dimensional high-precision grating 200-foot systems.

[0149] In some exemplary embodiments, the splitting of the first light beam 311 and the second light beam 312 to output multiple dual-frequency measurement beams having a first split light beam of a first frequency and a second split light beam of a second frequency includes:

[0150] The first light beam 311 and the second light beam 312 are split for the first time to output a dual-frequency reference beam having both a first reference beam 361 of the first frequency and a second reference beam 362 of the second frequency, and a second reference beam ≦;

[0151] The first measuring beam 371 and the second measuring beam 372 are split to output multiple dual-frequency measuring beams having a first split beam of a first frequency and a second split beam of a second frequency.

[0152] The position measurement method provided by the present invention further includes:

[0153] Controlling the first reference beam 361 and the second reference beam 362 to be coherent to form a reference interference beam 360 carrying reference phase information;

[0154] collecting the reference interference beam 360; and

[0155] The measurement phase information carried by the measurement interference beam is corrected according to the reference phase information carried by the reference interference beam 360 .

[0156] Correspondingly, obtaining the horizontal displacement information and the vertical displacement information of the grating 200 based on the multiple groups of the measurement interference beams includes:

[0157] The horizontal displacement information and the vertical displacement information of the grating 200 are obtained based on the multiple sets of corrected measurement interference beams.

[0158] In some exemplary embodiments, splitting the first measuring beam 371 and the second measuring beam 372 to output multiple dual-frequency measuring beams having a first split beam of a first frequency and a second split beam of a second frequency includes:

[0159] The first measuring beam 371 and the second measuring beam 372 are split to output a first dual-frequency measuring beam 321 and a second dual-frequency measuring beam 322 that are symmetrically emitted relative to the XZ plane.

[0160] In some other exemplary embodiments, the splitting of the first measuring beam 371 and the second measuring beam 372 to output multiple dual-frequency measuring beams having a first split beam of a first frequency and a second split beam of a second frequency includes:

[0161] The first measuring beam 371 and the second measuring beam 372 are split to output a first dual-frequency measuring beam 321 and a second dual-frequency measuring beam 322 symmetrically emitted relative to the XZ plane, and a third dual-frequency measuring beam 323 emitted along the XZ plane.

[0162] Specifically, for the specific content on how to form multiple groups of measurement interference beams carrying measurement phase information and how to calculate the horizontal displacement of the grating 200 along the Y direction, the horizontal displacement along the X direction, and the vertical displacement along the Z direction, please refer to the relevant description above and will not be repeated here.

[0163] In summary, compared with the prior art, the position measurement device, measurement method, and lithography apparatus provided by the present invention have the following beneficial effects:

[0164] The present invention adopts dual-frequency detection, and the optical detection structure is simple, so that the effective signal is less affected by the change of optical power, and it is easy to obtain a stable phase, thereby improving the quality of the measurement signal. In addition, the present invention sets a first spectroscopic element 111 in the reader 100 to split the first light beam 311 and the second light beam 312 of different frequencies to output multiple dual-frequency measurement light beams. This can realize the multi-axis measurement light source by the internal light splitting of the reader 100, and realize the staggered distribution of the multi-axis light paths, so that the relative structural stability between the multi-axis light paths is good, and effectively reduce the impact of changes in the measurement environment temperature, pressure, etc. on the measurement performance. In addition, by adopting the present invention, when the single-frequency board detection technology is not mature, the dual-frequency board can be reused, accelerating the engineering research and development process of the two-dimensional and three-dimensional high-precision grating 200-foot system.

[0165] It should be noted that, in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0166] It should also be noted that the above description is merely a description of preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes or modifications made by a person skilled in the art based on the above disclosure are within the scope of protection of the present invention. Obviously, various changes and modifications may be made by a person skilled in the art without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the present invention and its equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A position measuring device, characterized in that: It includes a reader, a grating, a light source, a light detection module and an optical signal processing module; The light source is configured to provide a first light beam of a first frequency and a second light beam of a second frequency; The read head is arranged opposite to the grating, and the read head includes a first beam splitter element, which is used to split the first light beam and the second light beam to output multiple dual-frequency measurement beams having a first split light beam of a first frequency and a second split light beam of a second frequency; For each of the dual-frequency measurement beams, the dual-frequency measurement beam is diffracted multiple times by the grating to form a measurement interference beam carrying measurement phase information; The light detection module is used to collect multiple groups of measurement interference light beams; The optical signal processing module is used to obtain the horizontal displacement information and the vertical displacement information of the grating based on the multiple groups of measurement interference light beams.

2. The position measuring device according to claim 1, characterized in that The reader also includes a polarization screening and control unit, which is used to control the polarization direction of a first first-order diffraction beam in the +m-order diffraction direction formed by the first diffraction of the first split beam by the grating and a second first-order diffraction beam in the -m-order diffraction direction formed by the first diffraction of the second split beam by the grating.

3. The position measuring device according to claim 1, characterized in that The reader also includes a first refractive unit, which is used to realize the deflection of a first first-order diffraction beam in the +m-order diffraction direction formed by the first diffraction of the first split light beam by the grating, and to realize the deflection of a second first-order diffraction beam in the -m-order diffraction direction formed by the first diffraction of the second split light beam by the grating.

4. The position measuring device according to claim 1, wherein: The reader also includes a reverse reflection unit, which is used to reversely reflect a first first diffraction beam in the +m-order diffraction direction formed by the first diffraction of the first split light beam by the grating, and to reversely reflect a second first diffraction beam in the -m-order diffraction direction formed by the first diffraction of the second split light beam by the grating.

5. The position measuring device according to claim 4, characterized in that The reading head further includes a second refraction unit, which is used to realize the deflection of the first first-order diffraction light beam and the second first-order diffraction light beam reflected back through the reverse reflection unit.

6. The position measuring device according to claim 4, characterized in that The reading head further includes a beam translation unit, which is used to change the relative spacing between the first first-order diffraction beam and / or the second first-order diffraction beam reflected back through the back-reflection unit.

7. The position measuring device according to claim 4, characterized in that The reading head also includes a beam translation and polarization control unit, which is used to change the relative spacing between the first first diffraction beam and the second first diffraction beam reflected back through the reverse reflection unit, and to control the polarization direction of the first first diffraction beam and the second first diffraction beam reflected back through the reverse reflection unit.

8. The position measuring device according to claim 1, wherein: The read head also includes a first polarization control unit, which is used to control the first secondary diffraction beam formed by the secondary diffraction of the first split beam by the grating and the second secondary diffraction beam formed by the secondary diffraction of the second split beam by the grating to achieve coherence, so as to form a measurement interference beam carrying measurement phase information.

9. The position measuring device according to claim 8, characterized in that The first polarization control unit includes a light-emitting deflection element, a pair of birefringent wedge plates and a polarizer. The light-emitting deflection element is used to deflect the first secondary diffraction beam and the second secondary diffraction beam so that the measurement interference beam formed by the first secondary diffraction beam and the second secondary diffraction beam is perpendicular to the light-emitting receiving end face as a whole. The birefringent wedge plate pair is used to make the deflected first secondary diffraction beam and the deflected second secondary diffraction beam parallel. The polarizer is used to control the polarization direction of the parallel first secondary diffraction beam and the second secondary diffraction beam.

10. The position measuring device according to claim 1, characterized in that The read head also includes a first coupling lens and a plurality of first light-emitting optical fibers arranged in one-to-one correspondence with the multiple groups of measurement interference light beams. The first coupling lens is used to focus and couple the measurement interference light beams into the corresponding first light-emitting optical fibers. The first light-emitting optical fibers are used to transmit the measurement interference light beams to the optical detection module.

11. The position measuring device according to claim 1, characterized in that The reader also includes a dual-frequency fiber-optic light input structure and a collimating lens. The dual-frequency fiber-optic light input structure is used to output the first light beam and the second light beam. The collimating lens is used to collimate the first light beam and the second light beam output by the dual-frequency fiber-optic light input structure.

12. The position measuring device according to claim 11, characterized in that The reader also includes a second spectroscopic element and a second polarization control unit, the second spectroscopic element is arranged between the collimating lens and the first spectroscopic element, the second spectroscopic element is used to branch the first light beam and the second light beam to output a dual-frequency reference beam having a first reference beam of a first frequency and a second reference beam of a second frequency, the second polarization control unit is used to control the first reference beam and the second reference beam to achieve coherence to form a reference interference beam carrying reference phase information, the grating detection module is also used to collect the reference interference beam, and the optical signal processing module is also used to correct the measurement phase information carried by the measurement interference beam according to the reference phase information carried by the reference interference beam.

13. The position measuring device according to claim 1, characterized in that The first split beam and the second split beam in the dual-frequency measurement beam are irradiated onto the grating at an angle or in parallel.

14. The position measuring device according to claim 1, characterized in that The first beam splitter is used to output a first dual-frequency measurement beam and a second dual-frequency measurement beam that are symmetrically emitted relative to the XZ plane. The optical signal processing module is used to calculate the horizontal displacement of the grating along the Y direction and the vertical displacement along the Z direction according to the following formula: Wherein, ΔY is the horizontal displacement of the grating along the Y direction, ΔZ is the vertical displacement of the grating along the Z direction, P is the grating pitch of the grating, λ is the wavelength of the light source, δ1 is the incident angle of the first dual-frequency measurement beam incident on the grating, δ2 is the incident angle of the second dual-frequency measurement beam incident on the grating, is the phase change of the first measurement interference beam corresponding to the first dual-frequency measurement beam, is the phase change of the second measuring interference beam corresponding to the second dual-frequency measuring beam, α1 is the diffraction angle of the first split beam in the first dual-frequency measuring beam in the +m-order diffraction direction after the first diffraction along the Y direction of the grating, β1 is the diffraction angle of the second split beam in the first dual-frequency measuring beam in the -m-order diffraction direction after the first diffraction along the Y direction of the grating, α2 is the diffraction angle of the first split beam in the second dual-frequency measuring beam in the +m-order diffraction direction after the first diffraction along the Y direction of the grating, β2 is the diffraction angle of the second split beam in the second dual-frequency measuring beam in the -m-order diffraction direction after the first diffraction along the Y direction of the grating.

15. The position measuring device according to claim 14, characterized in that The first beam splitter is further configured to output a third dual-frequency measurement beam emitted along the XZ plane, and the optical signal processing module is configured to calculate the horizontal displacement of the grating along the X-axis according to the following formula: Where ΔX is the horizontal displacement of the grating along the X-axis, is the phase change of the third measurement interference beam corresponding to the third dual-frequency measurement beam.

16. A position measurement method, characterized in that: include: providing a first light beam at a first frequency and a second light beam at a second frequency; Splitting the first light beam and the second light beam to output multiple dual-frequency measurement beams having a first split light beam of a first frequency and a second split light beam of a second frequency; For each of the dual-frequency measurement beams, the dual-frequency measurement beam is irradiated onto a grating and formed into a measurement interference beam carrying measurement phase information after multiple diffraction by the grating; collecting a plurality of groups of the measurement interference beams; The horizontal displacement information and the vertical displacement information of the grating are obtained based on the multiple groups of the measurement interference light beams.

17. The position measurement method according to claim 16, characterized in that: The splitting of the first light beam and the second light beam to output multiple dual-frequency measurement light beams having a first split light beam of a first frequency and a second split light beam of a second frequency comprises: performing a first splitting of the first light beam and the second light beam to output a dual-frequency reference beam having both a first reference beam of a first frequency and a second reference beam of a second frequency, and a measuring beam having both a first measuring beam of the first frequency and a second measuring beam of the second frequency; Splitting the first measuring beam and the second measuring beam to output multiple dual-frequency measuring beams having a first split beam of a first frequency and a second split beam of a second frequency; The position measurement method further includes: Controlling the first reference beam and the second reference beam to be coherent to form a reference interference beam carrying reference phase information; collecting the reference interference beam; and Correcting the measurement phase information carried by the measurement interference beam according to the reference phase information carried by the reference interference beam; The obtaining of the horizontal displacement information and the vertical displacement information of the grating based on the multiple groups of the measurement interference beams includes: The horizontal displacement information and the vertical displacement information of the grating are obtained based on the multiple groups of corrected measurement interference beams.

18. A lithographic apparatus, characterized in that: A position measuring device comprising the position measuring device according to any one of claims 1 to 15.

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