Linear displacement measurement and space positioning device for high-precision virtual synthesis wavelength

Abstract

The invention discloses a linear displacement measurement and spatial positioning device for high-precision virtual synthesis wavelength. The linear displacement measurement and spatial positioning device comprises a double-frequency laser polarization separation module, a first laser measurement module, a second laser measurement module, a measurement reference mirror, a workbench and a signal processing module, in the double-frequency laser polarization separation module, the reflected light serves as a reference local oscillator signal, and the transmission light is split into first transmission light and first reflected light which are perpendicular to each other; the first laser measurement module forms optical subdivision of a first preset multiple to obtain a first measurement local oscillator signal; the second laser measurement module forms optical subdivision of a second preset multiple to obtain a second measurement local oscillator signal; and the signal processing module performs virtual synthesis wavelength test according to the reference local oscillation signal, the first measurement local oscillation signal, the second measurement local oscillation signal and the obtained laser local oscillation signal to obtain a displacement measurement value. According to the invention, the measurement precision and the spatial positioning accuracy of the device can be effectively improved, and the problem of laser wavelength flutter fluctuation is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of displacement measurement devices and displacement measurement methods, and particularly relates to a linear displacement measurement and spatial positioning device with high-precision virtual synthetic wavelength. Background Art

[0002] With the continuous development of science and technology, the research on high-end equipment integration devices represented by lithography machines has become increasingly important, and the demand for high-precision displacement measurement and high-precision spatial positioning of displacement stages is also becoming stronger. Among them, the displacement measurement sensor is a key component for accurately measuring and positioning the spatial position of a large-size workpiece stage. Currently, the commonly used ASML six-dimensional precision measurement workpiece stage has a repeat measurement error of less than 5 nm and an angle detection of less than 10" in the overall integrated state. Using the laser wavelength as the measurement reference for high-precision displacement measurement is one of the mainstream measurement methods for non-contact, high-stability, and high-accuracy measurements. It mainly realizes precise linear measurement by the laser optical path difference caused by the laser beam inside the measurement mirror group and the change of the measurement reference phase.

[0003] Currently, the research on the laser interference displacement measurement model includes the following two schemes: Among them, the first scheme is the multi-pass measurement model of Pisani.M of the Italian National Institute of Metrology in 2009, which mainly uses the angular relationship of two plane mirrors in space to realize multiple round trips of the homodyne measurement beam in the two plane mirrors. Its measurement resolution can reach 0.4 nm, but due to the lateral offset of multiple reflections, this scheme cannot perform long-distance measurement; the second scheme is the laser synthetic wavelength displacement measurement model carried out by the team of Professor Chen Benyong of Zhejiang Sci-Tech University, which mainly uses laser polarization locking to form double-wavelength incidence, and then constructs an interference measurement system using the different polarization characteristics of different wavelengths. However, this scheme still has the problem of insufficient synthetic wavelength stability.

[0004] Therefore, the existing laser displacement measurement devices have problems such as insufficient measurement accuracy, insufficient spatial positioning accuracy, and wavelength flutter and fluctuation. Summary of the Invention

[0005] The present invention provides a linear displacement measurement and spatial positioning device with high-precision virtual synthetic wavelength, which solves the technical problems existing in the prior art that the laser displacement measurement device has insufficient measurement accuracy, insufficient spatial positioning accuracy, and wavelength flutter and fluctuation.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention provides a linear displacement measurement and spatial positioning device with high-precision virtual synthetic wavelength, which device comprises: a dual-frequency laser polarization separation module, a first laser measurement module, a second laser measurement module, a measurement reference mirror, a workbench, and a signal processing module;

[0008] The dual-frequency laser polarization separation module is configured to emit orthogonally linearly polarized light, polarization split the orthogonally linearly polarized light into a transmitted light and a reflected light, use the reflected light as a reference local oscillator signal, and split the transmitted light into a first transmitted light and a first reflected light that are perpendicular to each other;

[0009] The first laser measurement module and the second laser measurement module are parallel to each other. The measurement reference mirror is disposed between the first laser measurement module and the workbench, and between the second laser measurement module and the workbench, and the measurement reference mirror moves along with the workbench;

[0010] The first laser measurement module is disposed on the optical path of the first transmitted light, and is configured to cooperate with the measurement reference mirror to form an optical subdivision with a first preset multiple, so as to obtain a first measurement local oscillator signal;

[0011] The second laser measurement module is disposed on the optical path of the first reflected light, and is configured to cooperate with the measurement reference mirror to form an optical subdivision with a second preset multiple, so as to obtain a second measurement local oscillator signal; the second preset multiple is greater than the first preset multiple;

[0012] The signal processing module is configured to perform a virtual synthetic wavelength test according to the reference local oscillator signal, the first measurement local oscillator signal, the second measurement local oscillator signal, and the obtained laser local oscillator signal, so as to obtain a displacement measurement value.

[0013] In a possible implementation manner, the signal processing module includes a first photodetector, a second photodetector, a third photodetector, a signal information acquisition card, and a host computer; the signal information acquisition card is electrically connected to the first photodetector, the second photodetector, the third photodetector, and the host computer respectively;

[0014] The first photodetector, the second photodetector, and the third photodetector are respectively configured to receive the optical signals corresponding to the reference local oscillator signal, the first measurement local oscillator signal, and the second measurement local oscillator signal, and convert the optical signals into corresponding electrical signals;

[0015] The signal information acquisition card is configured to determine the laser local oscillator signal according to the converted reference local oscillator signal and the local oscillator signal generated by the host computer and injected into the dual-frequency laser polarization separation module;

[0016] The signal information acquisition card is also used to perform a virtual synthesized wavelength test based on the converted reference local oscillator signal, the laser local oscillator signal, the converted first measurement local oscillator signal, and the converted second measurement local oscillator signal to obtain a displacement measurement value;

[0017] The host computer is also used to receive and display the displacement measurement value.

[0018] In a possible implementation manner, the dual-frequency laser polarization separation module includes a dual-frequency laser, a first polarization beam splitter prism, and a first beam splitter prism;

[0019] The dual-frequency laser is used to emit two orthogonal linearly polarized lights with a frequency difference within a first preset range and a wavelength of a first preset value;

[0020] The first polarization beam splitter prism is used to polarization beam split the orthogonal linearly polarized lights into the transmitted light and the reflected light;

[0021] The first beam splitter prism is arranged on the optical path of the transmitted light and is used to energy beam split the transmitted light into the mutually perpendicular first transmitted light and first reflected light.

[0022] In a possible implementation manner, the first laser measurement module includes a second polarization beam splitter prism, a first quarter-wave plate, a first right-angle reflecting prism, and a second right-angle reflecting prism;

[0023] The second polarization beam splitter prism is located between the dual-frequency laser polarization separation module and the measurement reference mirror and is used to transmit and reflect the first transmitted light; the cross-section of the second polarization beam splitter prism is rectangular and includes a first side surface, a second side surface, and a third side surface. The first side surface and the second side surface are both parallel to the measurement reference mirror. The first transmitted light perpendicularly enters the second polarization beam splitter prism from the first side surface, and the light after transmission of the first transmitted light perpendicularly exits from the second side surface, and the light after reflection of the first transmitted light perpendicularly exits from the third side surface;

[0024] The first quarter-wave plate is arranged between the second side surface and the measurement reference mirror and is parallel to the second side surface, and is used to perpendicularly transmit the light perpendicularly exiting from the second side surface and the light perpendicularly emitted from the measurement reference mirror; the light incident on the first quarter-wave plate forms a 45° angle with the optical axis of the first quarter-wave plate;

[0025] The inclined surface of the first right-angle reflecting prism is parallel to the third side surface and is used to reflect the light perpendicularly exiting from the third side surface and then shoot it back to the second polarization beam splitter prism;

[0026] The inclined surface of the second right-angled reflecting prism is parallel to the first side surface, and is used to reflect the light transmitted through the first side surface back to the second polarization beam splitter prism. The reflected light is transmitted through the second polarization beam splitter prism and exits from the first side surface to form a first measurement local oscillator signal.

[0027] In a possible implementation manner, the device further includes a first reflecting mirror and a second beam splitter prism;

[0028] The first reflecting mirror is arranged on the optical path of the first reflected light and is used to reflect the first reflected light to be parallel to the first transmitted light;

[0029] The second beam splitter prism is arranged on the optical path between the first reflecting mirror and the second laser measurement module and is used to perform energy splitting on the first transmitted light to obtain a second transmitted light.

[0030] In a possible implementation manner, the second laser measurement module includes a third polarization beam splitter prism, a second quarter-wave plate, a third right-angled reflecting prism, a second reflecting mirror, and a fourth right-angled reflecting prism;

[0031] The third polarization beam splitter prism is located between the dual-frequency laser polarization separation module and the measurement reference mirror and is used to transmit and reflect the second transmitted light; the cross section of the third polarization beam splitter prism is rectangular and includes a fourth side surface, a fifth side surface, and a sixth side surface. The fourth side surface and the fifth side surface are both parallel to the measurement reference mirror. The second transmitted light vertically enters the third polarization beam splitter prism from the fourth side surface, and the light after transmission of the second transmitted light vertically exits from the fifth side surface, and the light after reflection of the second transmitted light vertically exits from the sixth side surface;

[0032] The second quarter-wave plate is parallel to the fifth side surface and is arranged between the fifth side surface and the measurement reference mirror and is used to vertically transmit the light vertically exiting from the fifth side surface and the light vertically emitted from the measurement reference mirror; the light incident on the second quarter-wave plate forms an angle of 45° with the optical axis of the second quarter-wave plate;

[0033] The inclined surface of the third right-angled reflecting prism is parallel to the sixth side surface and is used to reflect the light vertically exiting from the sixth side surface back to the third polarization beam splitter prism;

[0034] The second reflecting mirror is parallel to the inclined surface of the third right-angled reflecting prism and is located on the side of the third right-angled reflecting prism away from the second quarter-wave plate and is used to reflect the light reflected from the side of the sixth side surface away from the second quarter-wave plate back to the third right-angled reflecting prism;

[0035] The inclined surface of the fourth right-angle reflecting prism is parallel to the fourth side surface, and is used to reflect the light transmitted through the fourth side surface back into the third right-angle reflecting prism. The reflected light is transmitted through the third right-angle reflecting prism and exits from the fourth side surface to form a second measurement local oscillator signal.

[0036] In a possible implementation manner, the outgoing optical path of the second measurement local oscillator signal coincides with the incoming optical path of the second transmitted light entering the third polarization beam splitter prism;

[0037] The second beam splitter prism is arranged on the optical path between the first mirror and the fourth side surface, and is used for energy splitting to obtain the second measurement local oscillator signal.

[0038] In a possible implementation manner, the dual-frequency laser polarization separation module further includes a Michelson stable structure composed of a fourth polarization beam splitter prism, a third quarter-wave plate, a first partially transmissive cavity mirror, a first highly reflective cavity mirror, a fourth quarter-wave plate, a second partially transmissive cavity mirror, and a second highly reflective cavity mirror;

[0039] The fourth polarization beam splitter prism is arranged on the outgoing optical path of the dual-frequency laser, and is used for splitting the orthogonally linearly polarized light into mutually perpendicular transmitted light beams and reflected light beams;

[0040] The third quarter-wave plate, the first partially transmissive cavity mirror, and the first highly reflective cavity mirror are sequentially arranged in parallel on the optical path of the transmitted light beam;

[0041] The fourth quarter-wave plate, the second partially transmissive cavity mirror, and the second highly reflective cavity mirror are sequentially arranged in parallel on the optical path of the reflected light beam;

[0042] The first polarization beam splitter prism and the third quarter-wave plate are oppositely arranged on both sides of the fourth polarization beam splitter prism.

[0043] In a possible implementation manner, the signal information acquisition card specifically includes a first acquisition unit, a second acquisition unit, a third acquisition unit, a fourth acquisition unit, a subtraction operation unit, an addition operation unit, a mixing and combining processing unit, and a measurement processing and calculation unit;

[0044] The first acquisition unit, the third acquisition unit, and the fourth acquisition unit are respectively used to acquire the reference local oscillator signal, the first measurement local oscillator signal, and the second measurement local oscillator signal after signal conversion, and the second acquisition unit is used to acquire the laser local oscillator signal;

[0045] The subtraction operation unit is used to perform a subtraction operation on the local oscillator signal of the laser and the reference local oscillator signal to obtain a first signal; the addition operation unit is used to perform an addition operation on the first measurement local oscillator signal and the second measurement local oscillator signal to obtain a second signal;

[0046] The mixing and combining processing unit is used to perform a mixing and combining process on the first signal and the second signal to obtain a comprehensive measurement signal;

[0047] The mixing and combining processing unit is further used to perform a mixing and combining process on the first signal and the first measurement local oscillator signal to obtain a first measurement signal corresponding to the first laser measurement module; and perform a mixing and combining process on the first signal and the second measurement local oscillator signal to obtain a second measurement signal corresponding to the second laser measurement module;

[0048] The measurement processing and calculation unit is used to calculate a displacement measurement value based on the Doppler frequency shift calculation formula according to the obtained ideal motion displacement amount of the workbench, the first measurement signal, the second measurement signal, and the comprehensive measurement signal.

[0049] In a possible implementation manner, the signal information acquisition card further includes a data processing unit, which is used to perform amplification, shaping, filtering, direction discrimination, and normalization processing on the displacement measurement value processed by the measurement processing and calculation unit, and transmit the processing result to the host computer.

[0050] The high-precision virtual composite wavelength linear displacement measurement and spatial positioning device provided by the embodiment of the present invention constructs a high-precision virtual composite wavelength measurement structure by using the special effect of multiple laser reflections and the special effect of virtual composite wavelength, uses the multi-point characteristics to perform absolute positioning of the spatial position of the measurement reference mirror, then adopts wavelength virtual combination to achieve the purpose of wavelength frequency stabilization, and finally uses the phase shift amount of the measurement reference mirror under different characteristics to measure the linear length information of the measurement reference mirror, thereby effectively improving the measurement accuracy and spatial positioning accuracy of the device, and at the same time solving the problem of laser wavelength flutter and fluctuation. Description of the Drawings

[0051] Figure 1 It is a schematic diagram of the overall structure of a high-precision virtual composite wavelength linear displacement measurement and spatial positioning device provided by the embodiment of the present invention;

[0052] Figure 2 It is a schematic diagram of the overall structure of the dual-frequency laser polarization separation module after adding the Michelson stabilization structure in a high-precision virtual composite wavelength linear displacement measurement and spatial positioning device provided by the embodiment of the present invention;

[0053] Figure 3Schematic structural diagram of the processing flow of the signal information acquisition card of the signal processing module in a linear displacement measurement and spatial positioning device with high-precision virtual synthetic wavelength provided by an embodiment of the present invention.

[0054] Reference numerals and descriptions:

[0055] 1. Dual-frequency laser polarization separation module; 101. Dual-frequency laser; 102. First polarization beam splitter prism; 103. First beam splitter prism; 104. Fourth polarization beam splitter prism; 105. Third quarter-wave plate; 106. First partial transmission cavity mirror; 107. First high-reflection cavity mirror; 108. Fourth quarter-wave plate; 109. Second partial transmission cavity mirror; 110. Second high-reflection cavity mirror; 2. First laser measurement module; 201. Second polarization beam splitter prism; 202. First quarter-wave plate; 203. First right-angle reflecting prism; 204. Second right-angle reflecting prism; 3. First reflector; 4. Second beam splitter prism; 5. Second laser measurement module; 501. Third polarization beam splitter prism; 502. Second quarter-wave plate; 503. Third right-angle reflecting prism; 504. Fourth right-angle reflecting prism; 505. Second reflector; 601. First photodetector; 602. Second photodetector; 603. Third photodetector; 7. Measurement reference mirror; 8. Signal information acquisition card; 9. Host computer; 10. Workbench. Specific embodiments

[0056] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0057] Hereinafter, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "a plurality" is two or more. Additionally, the use of "based on" or "in accordance with" means open and inclusive, as a process, step, calculation, or other action based on one or more of the stated conditions or values may in practice be based on additional conditions or values beyond those stated.

[0058] High-precision displacement measurement with the laser wavelength as the measurement reference is one of the mainstream measurement methods for non-contact, high-stability, and high-accuracy measurements. Since the Michelson interferometry was proposed by Michelson in the United States in 1881, laser interferometers have entered a stage of rapid development. Currently, common products on the market include the high-precision laser interferometer positioning system of Keysight Technologies in the United States, the nano-displacement sensor module structure of Zygo Corporation in the United States, the spatial separation linear displacement measurement system of Harbin Institute of Technology, and the plane interference measurement system of Tsinghua University and China Laser Measurement Technology Co., Ltd. Among them, the laser vacuum wavelength stability of the high-precision laser interferometer positioning system of Keysight Technologies is better than 2 ppb, with four-fold optical subdivision, and the interference displacement measurement resolution is better than 0.15 nm; the laser vacuum wavelength stability of the nano-displacement sensor module structure of Zygo Corporation is better than 2 ppb, with four-fold optical subdivision, and the interference displacement measurement resolution is better than 0.31 nm; the non-linear error of the spatial separation linear displacement measurement system of Harbin Institute of Technology is better than ±1 nm, and the 1024-fold phase subdivision measurement resolution is better than 0.15 nm; the laser wavelength stability of the plane interference measurement system of Tsinghua University and China Laser Measurement Technology Co., Ltd. is better than ±20 ppb, the non-linear error is better than 0.5 nm, and the 1024-fold phase subdivision measurement resolution is better than 1 nm.

[0059] In the prior art, the research on the laser interference displacement measurement model also includes the multi-range measurement model of Pisani.M from the Italian National Institute of Metrology in 2009, and the laser synthetic wavelength displacement measurement model by the research team of Professor Chen Benyong from Zhejiang Sci-Tech University. Among them, the multi-range measurement model mainly uses the angular relationship of two plane mirrors in spatial positions to achieve multiple round trips of the homodyne measurement beam in the two plane mirrors. Its measurement resolution can reach 0.4 nm, but due to the lateral offset of multiple reflections, this scheme cannot perform long-distance measurements; the laser synthetic wavelength displacement measurement model mainly uses laser polarization locking to form a dual-wavelength incident, and then constructs an interference measurement system using the different polarization characteristics of different wavelengths, but this scheme still has the problem of insufficient synthetic wavelength stability.

[0060] Through the research on the prior art, the researchers found that the prior art mainly has the following three problems: First, the optical subdivision accuracy is insufficient, and the measurement accuracy of the optical structure cannot be improved; second, the measurement stability of the laser wavelength is insufficient, and high-precision laser frequency stabilization accuracy cannot be obtained in real-time measurements; third, the measurement reference positioning is inaccurate, and the measurement reference often synchronously carries horizontal and vertical errors in large-scale measurements, and the horizontal and vertical measurement errors cannot be synchronously reduced.

[0061] To solve the problems of insufficient measurement accuracy, insufficient spatial positioning accuracy, and wavelength flutter and fluctuation existing in the prior art in laser displacement measurement devices, an embodiment of the present invention provides a high-precision linear displacement measurement and spatial positioning device with virtual synthesized wavelength.

[0062] As Figure 1 shown, the high-precision linear displacement measurement and spatial positioning device with virtual synthesized wavelength provided by the embodiment of the present invention includes a dual-frequency laser polarization separation module 1, a first laser measurement module 2, a second laser measurement module 5, a measurement reference mirror 7, a workbench 10, and a signal processing module.

[0063] The dual-frequency laser polarization separation module 1 is used to emit orthogonally linearly polarized light, polarization split the orthogonally linearly polarized light into a transmitted light and a reflected light, use the reflected light as a reference local oscillator signal, and split the transmitted light into a first transmitted light and a first reflected light that are perpendicular to each other.

[0064] Among them, the orthogonally linearly polarized light refers to two linearly polarized lights with vibration directions perpendicular to each other, and a polarization beam splitter can be used to separate the transmitted light and the reflected light in the orthogonally linearly polarized light. Among them, the transmitted light refers to the linearly polarized light with a polarization direction parallel to the incident plane, and the reflected light refers to the linearly polarized light with a polarization direction perpendicular to the incident plane.

[0065] Collect the reflected light obtained after polarization splitting as a reference local oscillator signal, perform secondary splitting on the transmitted light obtained after polarization splitting, split the transmitted light into a first transmitted light and a first reflected light that are perpendicular to each other, use the first transmitted light as the incident laser of the first laser measurement module 2, and use the first reflected light as the incident beam of the second laser measurement module 5.

[0066] The first laser measurement module 2 and the second laser measurement module 5 are parallel to each other. The measurement reference mirror 7 is arranged between the first laser measurement module 2 and the workbench 10, and between the second laser measurement module 5 and the workbench 10, and the measurement reference mirror 7 moves along with the workbench 10.

[0067] The first laser measurement module 2 is arranged on the optical path of the first transmitted light, and is used to cooperate with the measurement reference mirror 7 to form an optical subdivision with a first preset multiple to obtain a first measurement local oscillator signal.

[0068] The second laser measurement module 5 is arranged on the optical path of the first reflected light, and is used to cooperate with the measurement reference mirror 7 to form an optical subdivision with a second preset multiple to obtain a second measurement local oscillator signal. The second preset multiple is greater than the first preset multiple.

[0069] Specifically, the measurement reference mirror 7 is the same measurement base plane for the first laser measurement module 2 and the second laser measurement module 5. The measurement reference mirror 7 and the workbench 10 move synchronously, and the movement of the worktable is mainly divided into two parts, namely, linear movement along the X direction and linear movement along the Y direction.

[0070] The linear movement of the workbench 10 along the X direction refers to the vertical linear displacement measurement direction, which is the linear measurement of the actual length; the linear movement along the Y direction refers to the horizontal linear displacement measurement direction, which is to realize the horizontal linear deviation of the measurement reference mirror 7 during movement.

[0071] That is to say, when the worktable moves along the X direction, the measurement reference mirror 7 will move along the X direction with the worktable, and the same is true for the Y direction movement.

[0072] Among them, the optical subdivision of the first preset multiple means that the wavelength or phase change of the first transmitted light is amplified by the first preset multiple through an optical method to improve the measurement accuracy. The optical subdivision of the second preset multiple means that the wavelength or phase change of the first reflected light is amplified by the second preset multiple through an optical method to improve the measurement accuracy.

[0073] The optical method refers to using an optical system such as an interferometer or a grating to amplify the first transmitted light by the first preset multiple and simultaneously amplify the first reflected light by the second preset multiple, thereby achieving higher-precision measurement.

[0074] Both the first preset multiple and the second preset multiple are powers of 2, and the second preset multiple is greater than the first preset multiple, that is, the measurement accuracy of the second laser measurement module 5 is greater than that of the first laser measurement module 2.

[0075] The signal processing module is used to perform virtual synthesized wavelength testing based on the reference local oscillator signal, the first measurement local oscillator signal, the second measurement local oscillator signal, and the obtained laser local oscillator signal to obtain a displacement measurement value.

[0076] Among them, the virtual synthesized wavelength testing is a high-precision measurement method based on optical interference and signal processing technologies, mainly used to solve the phase ambiguity problem in single laser wavelength measurement. Its core idea is to generate a "virtual synthesized wavelength" longer than the original wavelength by combining multiple laser signals with different wavelengths, thereby expanding the unambiguous measurement range while maintaining high precision.

[0077] The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device provided by the embodiment of the present invention uses the special effects of multiple laser reflections and virtual synthetic wavelengths to construct a high-precision virtual synthetic wavelength measurement structure, uses the multi-point characteristics to perform absolute positioning of the spatial position of the measurement reference mirror, then adopts wavelength virtual synthesis to achieve the purpose of wavelength frequency stabilization, and finally uses the phase shift amount of the measurement reference mirror under different characteristics to measure the linear length information of the measurement reference mirror, thereby effectively improving the measurement accuracy and spatial positioning accuracy of the device, and at the same time solving the problem of laser wavelength flutter and fluctuation.

[0078] In the embodiment of the present invention, the first preset multiple is 8 times, the second preset multiple is 36 times, the number of first transmitted light beams incident on the first laser measurement module 2 is 4, and the number of first reflected light beams incident on the second laser measurement module 5 is 18. In the first laser measurement module 2, the number of times the laser reflects back and forth is 4, carrying 8 times the optical linear distance information; in the second laser measurement module 5, the number of times the laser reflects back and forth is 18, carrying 36 times the optical linear distance information.

[0079] The present invention uses a dual-frequency laser to make multiple round trips on the measurement reference mirror to obtain high-precision overlapping length measurement information and achieve high-precision laser displacement measurement.

[0080] The present invention utilizes the principle of optical path reversibility to realize a high-precision measurement device with 36-fold optical subdivision, forming a high-precision laser measuring ruler with multiple Doppler frequency shifts.

[0081] The present invention uses a second laser measurement module with 36-fold optical subdivision and a first laser measurement module with 8-fold optical subdivision to obtain the first measurement local oscillator signal and the second measurement local oscillator signal through a signal information acquisition card, and then forms a virtual synthetic laser wavelength measurement signal to achieve the frequency stabilization accuracy of the laser wavelength.

[0082] The first laser measurement module and the second laser measurement module of the present invention use the same measurement reference mirror as the measurement reference surface, and can be accurately positioned in space to achieve the absolute position accuracy of the measurement reference mirror.

[0083] Furthermore, the signal processing module includes a first photodetector 601, a second photodetector 602, a third photodetector 603, a signal information acquisition card 8, and a host computer 9, and the signal information acquisition card 8 is electrically connected to the first photodetector 601, the second photodetector 602, the third photodetector 603, and the host computer 9 respectively.

[0084] The first photodetector 601, the second photodetector 602, and the third photodetector 603 are respectively used to receive the optical signals corresponding to the reference local oscillator signal, the first measurement local oscillator signal, and the second measurement local oscillator signal, and convert the optical signals into corresponding electrical signals.

[0085] The signal information acquisition card 8 is used to determine the local oscillator signal of the laser according to the converted reference local oscillator signal and the local oscillator signal generated by the host computer 9 and injected into the dual-frequency laser polarization splitting module 1.

[0086] The signal information acquisition card 8 is also used to perform a virtual synthesized wavelength test according to the converted reference local oscillator signal, the local oscillator signal of the laser, the converted first measurement local oscillator signal, and the converted second measurement local oscillator signal to obtain a displacement measurement value.

[0087] The host computer 9 is also used to receive and display the displacement measurement value.

[0088] That is to say, the first photodetector 601, the second photodetector 602, and the third photodetector 603 are all used to convert the received optical signal into an electrical signal. After transmitting the converted electrical signal displacement amount to the signal information acquisition card 8, the signal information acquisition card 8 performs virtual synthesized wavelength test processing on the converted reference local oscillator signal, the local oscillator signal of the laser, the converted first measurement local oscillator signal, and the converted second measurement local oscillator signal, and transmits the obtained displacement measurement value to the host computer 9 for display measurement.

[0089] Further, as Figure 1 , Figure 2 shown, the dual-frequency laser polarization splitting module 1 includes a dual-frequency laser 101, a first polarization beam splitter prism 102, and a first beam splitter prism 103.

[0090] The dual-frequency laser 101 is used to emit two orthogonal linearly polarized lights with a frequency difference within a first preset range and a wavelength of a first preset value.

[0091] Among them, the first preset range is ±1 to 5 MHz, and the first preset value is 632.8 nm.

[0092] The first polarization beam splitter prism 102 is used to polarization split the orthogonal linearly polarized light into a transmitted light and a reflected light.

[0093] The first beam splitter prism 103 is arranged on the optical path of the transmitted light and is used to split the transmitted light into mutually perpendicular first transmitted light and first reflected light according to energy.

[0094] Specifically, two orthogonal linearly polarized light beams with a frequency difference of ±1 to 5 MHz and a laser wavelength of 632.8 nm are emitted by a dual-frequency laser 101. The linearly polarized light is polarization-split by a first polarization beam splitter prism 102. The transmitted light is projected onto a first beam splitter prism 103, and the reflected light is reflected to a first photodetector 601 as a reference local oscillator signal. The transmitted light is energy-split by the first beam splitter prism 103 into a first transmitted light and a first reflected light that are perpendicular to each other. The first transmitted light is directly incident on a first laser measurement module 2, and the first reflected light is converted to be parallel to the first transmitted light and then incident on a second laser measurement module 5.

[0095] Further, the high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device of the present invention further includes a first reflecting mirror 3 and a second beam splitter prism 4.

[0096] Among them, the first reflecting mirror 3 is arranged on the optical path of the first reflected light and is used to reflect the first reflected light to be parallel to the first transmitted light.

[0097] The second beam splitter prism 4 is arranged on the optical path between the first reflecting mirror 3 and the second laser measurement module 5 and is used to perform energy splitting on the first transmitted light to obtain a second transmitted light.

[0098] That is to say, the first reflected light is reflected by the first reflecting mirror 3 to be parallel to the first transmitted light, and then energy splitting is performed by the second beam splitter prism 4, and the obtained second transmitted light is incident on the second laser measurement module 5.

[0099] Further, the first laser measurement module 2 includes a second polarization beam splitter prism 201, a first quarter-wave plate 202, a first right-angled reflecting prism 203, and a second right-angled reflecting prism 204.

[0100] The second polarization beam splitter prism 201 is located between the dual-frequency laser polarization separation module 1 and the measurement reference mirror 7 and is used to transmit and reflect the first transmitted light.

[0101] Among them, the cross-section of the second polarization beam splitter prism 201 is rectangular and includes a first side surface, a second side surface, and a third side surface. The first side surface and the second side surface are both parallel to the measurement reference mirror 7. The first transmitted light vertically enters the second polarization beam splitter prism 201 from the first side surface. The light after the first transmitted light is transmitted vertically exits from the second side surface, and the light after the first transmitted light is reflected vertically exits from the third side surface.

[0102] The first quarter-wave plate 202 is arranged between the second side surface and the measurement reference mirror 7 and is parallel to the second side surface, and is used to vertically transmit the light vertically exiting from the second side surface and the light vertically exiting from the measurement reference mirror 7.

[0103] Among them, the light incident on the first quarter-wave plate 202 forms an angle of 45° with the optical axis of the first quarter-wave plate 202.

[0104] The inclined surface of the first right-angled reflecting prism 203 is parallel to the third side surface, and is used for reflecting the light vertically emitted from the third side surface and then shooting it back to the second polarization beam splitter prism 201.

[0105] The inclined surface of the second right-angled reflecting prism 204 is parallel to the first side surface, and is used for reflecting the light transmitted through the first side surface back to the second polarization beam splitter prism 201, and the reflected light is transmitted through the second polarization beam splitter prism 201 and exits from the first side surface to form the first measurement local oscillator signal.

[0106] Specifically, the first transmitted light is transmitted through the second polarization beam splitter prism 201, transmitted through the first quarter-wave plate 202, and the polarization state is changed from horizontal linearly polarized light to circularly polarized light, and is vertically incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the first quarter-wave plate 202, the polarization state is changed from circularly polarized light to vertical linearly polarized light, is reflected by the second polarization beam splitter prism 201, is internally reflected twice in the first right-angled reflecting prism 203, and is reflected in the second polarization beam splitter prism 201, is transmitted through the first quarter-wave plate 202, the polarization state is changed from vertical linearly polarized light to circularly polarized light, and is vertically incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the first quarter-wave plate 202, is internally reflected twice in the second right-angled reflecting prism 204, is transmitted through the second polarization beam splitter prism 201, is transmitted through the first quarter-wave plate 202, the polarization state is changed from horizontal linearly polarized light to circularly polarized light, and is vertically incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the first quarter-wave plate 202, the polarization state is changed from circularly polarized light to vertical linearly polarized light, is reflected by the second polarization beam splitter prism 201, is internally reflected twice in the first right-angled reflecting prism 203, and is reflected in the second polarization beam splitter prism 201, is transmitted through the first quarter-wave plate 202, the polarization state is changed from vertical linearly polarized light to circularly polarized light, and is vertically incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the first quarter-wave plate 202, the polarization state is changed from circularly polarized light to horizontal linearly polarized light, is transmitted through the second polarization beam splitter prism 201, and is incident on the second photodetector 602, thereby realizing the acquisition of the first measurement local oscillator signal.

[0107] Further, the second laser measurement module 5 includes a third polarization beam splitter prism 501, a second quarter-wave plate 502, a third right-angled reflecting prism 503, a second mirror 505, and a fourth right-angled reflecting prism 504.

[0108] The third polarization beam splitter prism 501 is located between the dual-frequency laser polarization separation module 1 and the measurement reference mirror 7, and is used for transmitting and reflecting the second transmitted light.

[0109] Among them, the cross-section of the third polarization beam splitter prism 501 is rectangular, including a fourth side surface, a fifth side surface, and a sixth side surface. The fourth side surface and the fifth side surface are both parallel to the measurement reference mirror 7. The second transmitted light is perpendicularly incident into the third polarization beam splitter prism 501 from the fourth side surface. The light after the second transmitted light is transmitted perpendicularly exits from the fifth side surface, and the light after the second transmitted light is reflected perpendicularly exits from the sixth side surface.

[0110] The second quarter-wave plate 502 is parallel to the fifth side surface and is arranged between the fifth side surface and the measurement reference mirror 7, and is used for perpendicularly transmitting the light perpendicularly exiting from the fifth side surface and the light perpendicularly exiting from the measurement reference mirror 7.

[0111] Among them, the light incident on the second quarter-wave plate 502 forms an angle of 45° with the optical axis of the second quarter-wave plate 502.

[0112] The inclined surface of the third right-angle reflecting prism 503 is parallel to the sixth side surface, and is used for reflecting the light perpendicularly exiting from the sixth side surface back to the third polarization beam splitter prism 501.

[0113] The second reflecting mirror 505 is parallel to the inclined surface of the third right-angle reflecting prism 503 and is located on the side of the third right-angle reflecting prism 503 away from the second quarter-wave plate 502, and is used for reflecting the light reflected from the side of the sixth side surface away from the second quarter-wave plate 502 back to the third right-angle reflecting prism 503.

[0114] The inclined surface of the fourth right-angle reflecting prism 504 is parallel to the fourth side surface, and is used for reflecting the light transmitted through the fourth side surface back into the third right-angle reflecting prism 503. The reflected light is transmitted through the third right-angle reflecting prism 503 and exits from the fourth side surface to form a second measurement local oscillator signal.

[0115] Furthermore, the outgoing optical path of the second measurement local oscillator signal coincides with the incoming optical path of the second transmitted light entering the third polarization beam splitter prism 501.

[0116] The second beam splitter prism 4 is arranged on the optical path between the first reflecting mirror 3 and the fourth side surface, and is used for performing energy splitting to obtain a second measurement local oscillator signal.

[0117] Specifically, the second transmitted light is transmitted through the third polarization beam splitter prism 501 and then through the second quarter-wave plate 502, and its polarization state changes from horizontal linearly polarized light to circularly polarized light, and it vertically enters the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502, and its polarization state changes from circularly polarized light to vertical linearly polarized light, is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflecting prism 503, is reflected by the third polarization beam splitter prism 501, passes through the second quarter-wave plate 502, and its polarization state changes from vertical linearly polarized light to circularly polarized light, and it vertically enters the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502, and its polarization state changes from circularly polarized light to horizontal linearly polarized light, is transmitted through the third polarization beam splitter prism 501, undergoes two internal reflections in the fourth right-angle reflecting prism 504, is transmitted through the third polarization beam splitter prism 501, passes through the second quarter-wave plate 502, and its polarization state changes from horizontal linearly polarized light to circularly polarized light, and it vertically enters the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502, and its polarization state changes from circularly polarized light to vertical linearly polarized light, is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflecting prism 503, is reflected by the third polarization beam splitter prism 501, passes through the second quarter-wave plate 502, and its polarization state changes from vertical linearly polarized light to circularly polarized light, and it vertically enters the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502, and its polarization state changes from circularly polarized light to horizontal linearly polarized light, is transmitted through the third polarization beam splitter prism 501, undergoes two internal reflections in the fourth right-angle reflecting prism 504, is transmitted through the third polarization beam splitter prism 501, passes through the second quarter-wave plate 502, and its polarization state changes from horizontal linearly polarized light to circularly polarized light, and it vertically enters the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502, and its polarization state changes from circularly polarized light to vertical linearly polarized light, is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflecting prism 503 and is reflected by the third polarization beam splitter prism 501, passes through the second quarter-wave plate 502, and its polarization state changes from vertical linearly polarized light to circularly polarized light, and it vertically enters the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502, and its polarization state changes from circularly polarized light to horizontal linearly polarized light, is transmitted through the third polarization beam splitter prism 501, undergoes two internal reflections in the fourth right-angle reflecting prism 504, is transmitted through the third polarization beam splitter prism 501, passes through the second quarter-wave plate 502, and its polarization state changes from horizontal linearly polarized light to circularly polarized light, and it vertically enters the measurement reference mirror 7;Then it returns along the original path, is transmitted through the second quarter-wave plate 502, and the polarization state changes from circularly polarized light to vertically linearly polarized light. It is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflecting prism 503, is reflected by the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state changes from vertically linearly polarized light to circularly polarized light, and is perpendicularly incident on the measurement reference mirror 7; then, it returns along the original path, is transmitted through the second quarter-wave plate 502, and the polarization state changes from circularly polarized light to horizontally linearly polarized light. It is transmitted through the third polarization beam splitter prism 501, undergoes two internal reflections in the fourth right-angle reflecting prism 504, is transmitted through the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state changes from horizontally linearly polarized light to circularly polarized light, and is perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the second quarter-wave plate 502, and the polarization state changes from circularly polarized light to vertically linearly polarized light. It is reflected by the third polarization beam splitter prism 501, is reflected by the second mirror 505, and then returns along the original path.

[0118] The reflected light of the second reflector 505 is reflected by the third polarization beam splitter prism 501, transmitted through the second quarter-wave plate 502, and the polarization state is changed from vertically polarized light to circularly polarized light, and perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the second quarter-wave plate 502, the polarization state is changed from circularly polarized light to horizontally polarized light, is transmitted through the third polarization beam splitter prism 501, undergoes two internal reflections in the fourth right-angle reflector prism 504, is transmitted through the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state is changed from horizontally polarized light to circularly polarized light, and perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the second quarter-wave plate 502, the polarization state is changed from circularly polarized light to vertically polarized light, is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflector prism 503 and is reflected by the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state is changed from vertically polarized light to circularly polarized light, and perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the second quarter-wave plate 502, the polarization state is changed from circularly polarized light to horizontally polarized light, is transmitted through the third polarization beam splitter prism 501, undergoes two internal reflections in the fourth right-angle reflector prism 504, is transmitted through the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state is changed from horizontally polarized light to circularly polarized light, and perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the second quarter-wave plate 502, the polarization state is changed from circularly polarized light to vertically polarized light, is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflector prism 503, is reflected by the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state is changed from vertically polarized light to circularly polarized light, and perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the second quarter-wave plate 502, the polarization state is changed from circularly polarized light to horizontally polarized light, is transmitted through the third polarization beam splitter prism 501, undergoes two internal reflections in the fourth right-angle reflector prism 504, is transmitted through the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state is changed from horizontally polarized light to circularly polarized light, and perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, is transmitted through the second quarter-wave plate 502, the polarization state is changed from circularly polarized light to vertically polarized light, is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflector prism 503, is reflected by the third polarization beam splitter prism 501, is transmitted through the second quarter-wave plate 502, and the polarization state is changed from vertically polarized light to circularly polarized light, and perpendicularly incident on the measurement reference mirror 7;Then it returns along the original path, passes through the second quarter-wave plate 502 by transmission, and the polarization state changes from circularly polarized light to horizontally linearly polarized light. It passes through the third polarization beam splitter prism 501 by transmission, undergoes two internal reflections in the fourth right-angle reflecting prism 504, passes through the third polarization beam splitter prism 501 by transmission, passes through the second quarter-wave plate 502 by transmission, and the polarization state changes from horizontally linearly polarized light to circularly polarized light, and is perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502 by transmission, and the polarization state changes from circularly polarized light to vertically linearly polarized light. It is reflected by the third polarization beam splitter prism 501, undergoes two internal reflections in the third right-angle reflecting prism 503 and is reflected by the third polarization beam splitter prism 501, passes through the second quarter-wave plate 502 by transmission, and the polarization state changes from vertically linearly polarized light to circularly polarized light, and is perpendicularly incident on the measurement reference mirror 7; then it returns along the original path, passes through the second quarter-wave plate 502 by transmission, and the polarization state changes from circularly polarized light to horizontally linearly polarized light. It passes through the third polarization beam splitter prism 501 by transmission, is split according to energy in the second beam splitter 4, and the reflected light is incident on the third photodetector 603, thereby realizing the acquisition of the second measurement local oscillator signal.;

[0119] Further, as Figure 2 shown, the dual-frequency laser polarization separation module 1 further includes a Michelson stabilization structure composed of a fourth polarization beam splitter prism 104, a third quarter-wave plate 105, a first partial transmission cavity mirror 106, a first high-reflection cavity mirror 107, a fourth quarter-wave plate 108, a second partial transmission cavity mirror 109, and a second high-reflection cavity mirror 110.

[0120] The fourth polarization beam splitter prism 104 is arranged on the outgoing light path of the dual-frequency laser 101 and is used to split the orthogonally linearly polarized light into a transmitted light beam and a reflected light beam that are perpendicular to each other.

[0121] The third quarter-wave plate 105, the first partial transmission cavity mirror 106, and the first high-reflection cavity mirror 107 are sequentially arranged in parallel on the light path of the transmitted light beam.

[0122] The fourth quarter-wave plate 108, the second partial transmission cavity mirror 109, and the second high-reflection cavity mirror 110 are sequentially arranged in parallel on the light path of the reflected light beam.

[0123] The first polarization beam splitter prism 102 and the third quarter-wave plate 105 are oppositely arranged on both sides of the fourth polarization beam splitter prism 104.

[0124] Specifically, the orthogonally linearly polarized light emitted by the dual-frequency laser 101 is split into a transmitted light P and a reflected light S according to the polarization state by the fourth polarization beam splitter prism 104.

[0125] Among them, the reflected light S is transmitted through the third quarter-wave plate 105, and its polarization state changes from linearly polarized light to circularly polarized light. It enters the cavity mirror measurement structure and is split by the first partial transmission cavity mirror 106. One part of the reflected light is transmitted through the third quarter-wave plate 105, and its polarization state changes from circularly polarized light to horizontally polarized light. It is transmitted through the fourth polarization beam splitter prism 104 and incident on the first polarization beam splitter prism 102. One part of the transmitted light is perpendicularly incident on the first high-reflection cavity mirror 107 and returns along the original path. It is split by the first partial transmission cavity mirror 106. The transmitted light is transmitted through the third quarter-wave plate 105, and its polarization state changes from circularly polarized light to horizontally polarized light. It is transmitted through the fourth polarization beam splitter prism 104 and incident on the first polarization beam splitter prism 102. The reflected light is perpendicularly incident on the first high-reflection cavity mirror 107 and returns along the original path. It is split by the first partial transmission cavity mirror 106. The transmitted light is transmitted through the third quarter-wave plate 105, and its polarization state changes from circularly polarized light to horizontally polarized light. It is transmitted through the fourth polarization beam splitter prism 104 and incident on the first polarization beam splitter prism 102, and so on in sequence.

[0126] The transmitted light P is transmitted through the fourth quarter-wave plate 108, and its polarization state changes from horizontally polarized light to circularly polarized light. It enters the cavity mirror measurement structure and is split by the second partial transmission cavity mirror 109. One part of the reflected light is transmitted through the fourth quarter-wave plate 108, and its polarization state changes from circularly polarized light to vertically polarized light. It is reflected by the fourth polarization beam splitter prism 104 and incident on the first polarization beam splitter prism 102. One part of the transmitted light is perpendicularly incident on the second high-reflection cavity mirror 110 and returns along the original path. It is split by the second partial transmission cavity mirror 109. The transmitted light is transmitted through the fourth quarter-wave plate 108, and its polarization state changes from circularly polarized light to vertically polarized light. It is reflected by the fourth polarization beam splitter prism 104 and incident on the first polarization beam splitter prism 102. The reflected light is perpendicularly incident on the second high-reflection cavity mirror 110 and returns along the original path. It is split by the second partial transmission cavity mirror 109. The transmitted light is transmitted through the fourth quarter-wave plate 108, and its polarization state changes from circularly polarized light to vertically polarized light. It is reflected by the fourth polarization beam splitter prism 104 and incident on the first polarization beam splitter prism 102, and so on in sequence.

[0127] A laser frequency stabilization measurement device based on multiple reflections and continuous signal reset using a double cavity mirror is realized by adding a Michelson stabilization structure in the dual-frequency laser polarization separation module 1. The added Michelson stabilization structure stabilizes the measurement system by introducing a feedback control mechanism and using the interference signal, mainly for improving the stability, accuracy, and anti-interference ability of the optical system.

[0128] Furthermore, the signal information acquisition card 8 specifically includes a first acquisition unit, a second acquisition unit, a third acquisition unit, a fourth acquisition unit, a subtraction operation unit, an addition operation unit, a mixing and frequency combining processing unit, and a measurement processing and calculation unit.

[0129] The first acquisition unit, the third acquisition unit, and the fourth acquisition unit are respectively used to acquire the reference local oscillator signal, the first measurement local oscillator signal, and the second measurement local oscillator signal after signal conversion, and the second acquisition unit is used to acquire the laser local oscillator signal.

[0130] The subtraction operation unit is used to perform a subtraction operation on the laser local oscillator signal and the reference local oscillator signal to obtain a first signal.

[0131] The addition operation unit is used to perform an addition operation on the first measurement local oscillator signal and the second measurement local oscillator signal to obtain a second signal.

[0132] The mixing and combining processing unit is used to perform mixing and combining processing on the first signal and the second signal to obtain a comprehensive measurement signal.

[0133] The mixing and combining processing unit is also used to perform mixing and combining processing on the first signal and the first measurement local oscillator signal to obtain a first measurement signal corresponding to the first laser measurement module 2. And perform mixing and combining processing on the first signal and the second measurement local oscillator signal to obtain a second measurement signal corresponding to the second laser measurement module 5.

[0134] The measurement processing and calculation unit is used to calculate the displacement measurement value based on the Doppler frequency shift calculation formula according to the obtained ideal motion displacement amount of the workbench 10, the first measurement signal, the second measurement signal, and the comprehensive measurement signal.

[0135] Furthermore, the signal information acquisition card 8 further includes a data processing unit, which is used to perform amplification, shaping, filtering, direction discrimination, and normalization processing on the displacement measurement value processed by the measurement processing and calculation unit, and transmit the processing result to the host computer 9.

[0136] As Figure 3 shown, taking the first laser measurement module 2 to achieve 8-fold optical subdivision and the second laser measurement module 5 to achieve 36-fold optical subdivision as an example, the dual-frequency laser polarization separation module emits orthogonally polarized light, polarization splits the orthogonally polarized light into a reflected light with a frequency of f1 and a transmitted light with a frequency of f2, and uses the reflected light with a frequency of f1 as the reference local oscillator signal, and splits the transmitted light with a frequency of f2 into a first transmitted light and a first reflected light that are perpendicular to each other.

[0137] That is to say, the signal frequency of the reference local oscillator signal obtained by the first acquisition unit from the first photodetector 601 is f1; the signal frequency of the laser local oscillator signal is f1 - f2; the signal frequency of the first measurement local oscillator signal obtained by the third acquisition unit from the second photodetector 602 is f2 - 4Δf; the signal frequency of the second measurement local oscillator signal obtained by the fourth acquisition unit from the third photodetector 603 is f2 - 18Δf. Wherein, Δf represents the frequency offset.

[0138] The subtraction operation unit performs a subtraction operation on the local oscillator signal of the laser and the reference local oscillator signal, and the signal frequency of the obtained first signal is -f2.

[0139] The addition operation unit performs an addition operation on the first measurement local oscillator signal and the second measurement local oscillator signal, and the signal frequency of the obtained second signal is 2f2 - 22Δf.

[0140] The mixing and combining processing unit performs a mixing and combining process on the first signal and the second signal, that is, multiplies the second signal by 2, and then performs a subtraction operation on the two signals. The signal frequency of the obtained comprehensive measurement signal is 22Δf.

[0141] The mixing and combining processing unit also performs a mixing and combining process on the first signal and the first measurement local oscillator signal, and the signal frequency of the obtained first measurement signal corresponding to the first laser measurement module 2 is 4Δf; the mixing and combining processing unit also performs a mixing and combining process on the second signal and the second measurement local oscillator signal, and the signal frequency of the obtained second measurement signal corresponding to the second laser measurement module 5 is 18Δf.

[0142] When performing a high-precision virtual synthesized wavelength test in the measurement processing and calculation unit, the actual displacement measurement value is calculated according to the following formula:

[0143]

[0144] Where, ΔL1 represents the actual displacement measurement value, λ represents the incident wavelength of the orthogonally linearly polarized light emitted by the dual-frequency laser 101; 44 is determined based on the signal frequency of the comprehensive measurement signal, indicating that the laser reflects back and forth 22 times, carrying 44 times the optical linear distance information.

[0145] Δλ = λ1 - λ2, where λ1 represents the real-time quantity of the wavelength of the first measurement signal, and λ2 represents the real-time quantity of the wavelength of the second measurement signal.

[0146] In actual measurement, and is the mean value obtained by adding and then dividing by 2, where, represents the change amount of the phase difference between the first measurement signal and the reference local oscillator signal, represents the change amount of the phase difference between the second measurement signal and the reference local oscillator signal, and:

[0147]

[0148] Among them, 8 represents that the laser reflects 4 times back and forth in the first laser measurement module 2, carrying 8 times the optical linear distance information; 36 represents that the laser reflects 18 times back and forth in the second laser measurement module 5, carrying 36 times the optical linear distance information; ΔL represents the ideal movement displacement of the worktable.

[0149] Finally, after the virtual synthetic wavelength test, the output sensor data is respectively subjected to signal amplification, shaping, filtering, direction discrimination, and normalization processing, and the processing results are transmitted to the host computer 9 for display, so as to convert the calculated displacement measurement value into high-precision and anti-interference displacement data.

[0150] The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device of the present invention utilizes the first laser measurement module with 8-fold optical subdivision and the second laser measurement module with 36-fold optical subdivision, obtains a 44-fold optical subdivision measurement reference through phase coupling, and then uses the method of single-signal frequency spatial separation to obtain the accurate Δf change amount. Under the action of frequency mixing processing, the linear displacement measurement accuracy of the laser in real-time transmission is improved.

[0151] In the high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device of the present invention, the incident light points of the first laser measurement module are 4 linearly arranged light points, and the incident light points of the second laser measurement module are 18 linearly and reversibly overlapping arranged light points. The present invention uses multiple light sources of the same measurement reference mirror for precise alignment of spatial positions, reduces the horizontal movement error of the measurement reference mirror, and improves the spatial positioning accuracy of the laser displacement measurement system.

[0152] The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device of the present invention uses different laser measurement modules of the same reference measurement mirror, forms a virtual synthetic measurement reference wavelength based on the original laser wavelength through mathematical operations and the synthesis of theoretical models, and uses this to feedback and control the original measurement laser wavelength in real-time, reducing the wavelength fluctuation of the laser in space transmission. At the same time, a temperature sensor, a vibration sensor, etc. can also be introduced to achieve the purpose of high-precision laser frequency stabilization measurement.

[0153] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device, characterized in that: It includes a dual-frequency laser polarization separation module, a first laser measurement module, a second laser measurement module, a measurement reference mirror, a workbench and a signal processing module; The dual-frequency laser polarization separation module is used to emit orthogonal linear polarized light, polarize and split the orthogonal linear polarized light into transmitted light and reflected light, and use the reflected light as a reference local oscillator signal to split the transmitted light into a first transmitted light and a first reflected light that are perpendicular to each other; The first laser measurement module and the second laser measurement module are parallel to each other, the measurement reference mirror is arranged between the first laser measurement module and the workbench, and between the second laser measurement module and the workbench, and the measurement reference mirror moves with the workbench; The first laser measurement module is arranged on the optical path of the first transmitted light, and is used to cooperate with the measurement reference mirror to form an optical subdivision of a first preset multiple to obtain a first measurement local oscillator signal; The second laser measurement module is arranged on the optical path of the first reflected light, and is used to cooperate with the measurement reference mirror to form an optical subdivision of a second preset multiple to obtain a second measurement local oscillator signal; the second preset multiple is greater than the first preset multiple; The signal processing module is used to perform a virtual synthetic wavelength test according to the reference local oscillator signal, the first measurement local oscillator signal, the second measurement local oscillator signal, and the acquired laser local oscillator signal to obtain a displacement measurement value.

2. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 1, characterized in that: The signal processing module includes a first photodetector, a second photodetector, a third photodetector, a signal information acquisition card and a host computer; the signal information acquisition card is electrically connected to the first photodetector, the second photodetector, the third photodetector and the host computer respectively; The first photodetector, the second photodetector and the third photodetector are used to receive optical signals corresponding to the reference local oscillator signal, the first measurement local oscillator signal and the second measurement local oscillator signal, respectively, and convert the optical signals into corresponding electrical signals; The signal information acquisition card is used to determine the laser local oscillator signal according to the converted reference local oscillator signal and the local oscillator signal generated by the host computer and injected into the dual-frequency laser polarization separation module; The signal information acquisition card is also used to perform a virtual synthetic wavelength test according to the converted reference local oscillator signal, the laser local oscillator signal, the converted first measurement local oscillator signal and the converted second measurement local oscillator signal to obtain a displacement measurement value; The host computer is also used to receive and display the displacement measurement value.

3. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 1, characterized in that: The dual-frequency laser polarization separation module includes a dual-frequency laser, a first polarization beam splitter prism and a first beam splitter prism; The dual-frequency laser is used to emit two beams of orthogonal linear polarized light with a frequency difference of a first preset range and a wavelength of a first preset value; The first polarization beam splitter prism is used to polarization-split the orthogonal linear polarized light into the transmitted light and the reflected light; The first beam splitter prism is disposed on the optical path of the transmitted light, and is used to split the transmitted light into the first transmitted light and the first reflected light which are perpendicular to each other according to energy.

4. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 1, characterized in that: The first laser measurement module includes a second polarization beam splitter prism, a first quarter wave plate, a first right-angle reflection prism and a second right-angle reflection prism; The second polarization beam splitter prism is located between the dual-frequency laser polarization separation module and the measurement reference mirror, and is used to transmit and reflect the first transmitted light; the cross-section of the second polarization beam splitter prism is rectangular, and includes a first side surface, a second side surface, and a third side surface, the first side surface and the second side surface are parallel to the measurement reference mirror, the first transmitted light is vertically incident into the second polarization beam splitter prism from the first side surface, the light after the first transmitted light is transmitted is vertically emitted through the second side surface, and the light after the first transmitted light is reflected is vertically emitted through the third side surface; The first quarter wave plate is arranged between the second side surface and the measurement reference mirror and is parallel to the second side surface, and is used for vertically transmitting the light vertically emitted from the second side surface and the light vertically emitted from the measurement reference mirror; the light incident on the first quarter wave plate forms an angle of 45° with the optical axis of the first quarter wave plate; The inclined surface of the first right-angle reflecting prism is parallel to the third side surface, and is used to reflect the light vertically emitted from the third side surface and then emit it back to the second polarization beam splitting prism; The inclined surface of the second right-angle reflection prism is parallel to the first side surface, and is used to reflect the light transmitted through the first side surface back to the second polarization beam splitter prism. The reflected light is transmitted through the second polarization beam splitter prism and emitted from the first side surface to form a first measurement local oscillator signal.

5. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 4, characterized in that: The device also includes a first reflector and a second beam splitter prism; The first reflector is disposed on the optical path of the first reflected light, and is used to reflect the first reflected light to be parallel to the first transmitted light; The second beam splitter prism is disposed on the optical path between the first reflector and the second laser measurement module, and is used to perform energy splitting on the first transmitted light to obtain second transmitted light.

6. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 5, characterized in that: The second laser measurement module includes a third polarization beam splitter prism, a second quarter wave plate, a third right-angle reflection prism, a second reflection mirror and a fourth right-angle reflection prism; The third polarization beam splitter prism is located between the dual-frequency laser polarization separation module and the measurement reference mirror, and is used to transmit and reflect the second transmitted light; the cross section of the third polarization beam splitter prism is rectangular, and includes a fourth side surface, a fifth side surface and a sixth side surface, and the fourth side surface and the fifth side surface are parallel to the measurement reference mirror, and the second transmitted light is vertically incident from the fourth side surface into the third polarization beam splitter prism, and the light after the second transmitted light is transmitted is vertically emitted through the fifth side surface, and the light after the second transmitted light is reflected is vertically emitted through the sixth side surface; The second quarter wave plate is parallel to the fifth side surface and is disposed between the fifth side surface and the measurement reference mirror, and is used to vertically transmit the light vertically emitted from the fifth side surface and the light vertically emitted from the measurement reference mirror; the light incident on the second quarter wave plate forms an angle of 45° with the optical axis of the second quarter wave plate; The inclined surface of the third right-angle reflecting prism is parallel to the sixth side surface, and is used to reflect the light vertically emitted from the sixth side surface back to the third polarization beam splitting prism; The second reflector is parallel to the inclined surface of the third right-angle reflective prism and is located on a side of the third right-angle reflective prism away from the second quarter-wave plate, and is used to reflect the light reflected from the side of the sixth side away from the second quarter-wave plate back to the third right-angle reflective prism; The inclined surface of the fourth right-angle reflection prism is parallel to the fourth side surface, and is used to reflect the light transmitted through the fourth side surface back into the third right-angle reflection prism. The reflected light is transmitted through the third right-angle reflection prism and emitted from the fourth side surface to form a second measurement local oscillator signal.

7. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 6, characterized in that: The outgoing optical path of the second measurement local oscillator signal coincides with the incident optical path of the second transmitted light entering the third polarization beam splitter prism; The second beam splitter prism is disposed on the optical path between the first reflector and the fourth side surface, and is used for performing energy splitting to obtain the second measurement local oscillator signal.

8. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 3, characterized in that: The dual-frequency laser polarization separation module also includes a Michelson stable structure consisting of a fourth polarization beam splitter prism, a third quarter wave plate, a first partially transmissive cavity mirror, a first highly reflective cavity mirror, a fourth quarter wave plate, a second partially transmissive cavity mirror, and a second highly reflective cavity mirror; The fourth polarization beam splitter prism is arranged on the outgoing light path of the dual-frequency laser, and is used to split the orthogonal linear polarized light into a transmission light beam and a reflection light beam that are perpendicular to each other; The third quarter wave plate, the first partially transmitting cavity mirror and the first highly reflecting cavity mirror are sequentially and parallelly arranged on the optical path of the transmitted light beam; The fourth quarter wave plate, the second partially transmitting cavity mirror and the second highly reflecting cavity mirror are sequentially and parallelly arranged on the optical path of the reflected light beam; The first polarization beam splitter prism and the third quarter wave plate are arranged opposite to each other on both sides of the fourth polarization beam splitter prism.

9. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 2, characterized in that: The signal information acquisition card specifically includes a first acquisition unit, a second acquisition unit, a third acquisition unit, a fourth acquisition unit, a subtraction operation unit, an addition operation unit, a frequency mixing and combining processing unit, and a measurement processing and calculation unit; The first acquisition unit, the third acquisition unit and the fourth acquisition unit are respectively used to acquire the reference local oscillator signal, the first measurement local oscillator signal and the second measurement local oscillator signal after signal conversion, and the second acquisition unit is used to acquire the laser local oscillator signal; The subtraction operation unit is used to perform a subtraction operation on the laser local oscillator signal and the reference local oscillator signal to obtain a first signal; the addition operation unit is used to perform an addition operation on the first measurement local oscillator signal and the second measurement local oscillator signal to obtain a second signal; The frequency mixing and combining processing unit is used to perform frequency mixing and combining processing on the first signal and the second signal to obtain a comprehensive measurement signal; The frequency mixing and combining processing unit is further used to perform frequency mixing and combining processing on the first signal and the first measurement local oscillator signal to obtain a first measurement signal corresponding to the first laser measurement module; and perform frequency mixing and combining processing on the first signal and the second measurement local oscillator signal to obtain a second measurement signal corresponding to the second laser measurement module; The measurement processing calculation unit is used to calculate the displacement measurement value based on the Doppler frequency shift calculation formula according to the acquired ideal motion displacement of the workbench, the first measurement signal, the second measurement signal and the comprehensive measurement signal.

10. The high-precision virtual synthetic wavelength linear displacement measurement and spatial positioning device according to claim 9, characterized in that: The signal information acquisition card also includes a data processing unit for amplifying, shaping, filtering, direction identification and normalization of the displacement measurement value processed by the measurement processing and calculation unit, and transmitting the processing result to the host computer.

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