Displacement measurement system and method

Abstract

The invention discloses a displacement measurement system and method. The displacement measurement system comprises a laser, a beam splitting module, a resolution multiplication module, a detection module and an analysis module, a laser beam emitted by a laser enters a beam splitting module, and the beam splitting module splits the laser beam into signal light and local oscillation light; the signal light enters the detection module after passing through the resolution multiplication module, and the local oscillation light directly enters the detection module; the detection module generates an electrical signal according to interference signals of the signal light and the local oscillation light and transmits the electrical signal to the analysis module; the analysis module determines the displacement of the to-be-measured target based on the electrical signal; wherein the target to be measured is located in the resolution multiplication module, the signal light is reflected for m times in the resolution multiplication module and passes through the moving distance of the object to be measured for n times, the resolution is improved by n times, n is an even number larger than 2, and m is an integer larger than n. The displacement measurement system provided by the invention not only can improve the resolution during measurement, but also can reduce the influence of phase noise on displacement measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of laser measurement, and in particular, to a displacement measurement system and method. Background Art

[0002] Due to factors such as temperature and the frequency selection bandwidth of the resonant cavity, semiconductor lasers have relatively large phase noise, which is manifested as the broadening of the laser linewidth in the laser spectrum. Generally, the laser linewidth of semiconductor lasers is in the range of 50 kHz to 3 MHz. Without external cavity frequency selection or phase locking, etc., it is very difficult to further compress the linewidth of semiconductor lasers, and the method of compressing the linewidth by external auxiliary means will increase the cost and volume of the laser.

[0003] The phase noise of semiconductor lasers has a significant impact on the measurement accuracy and resolution in the laser interferometric homodyne displacement measurement system. Because the laser interferometric homodyne ranging is to calculate the relative displacement by detecting the beat frequency phase difference of lasers in different optical paths, the phase noise of the laser will bring measurement system errors to the ranging accuracy of the laser, and this phase noise is very difficult to eliminate through system optimization. Summary of the Invention

[0004] The present invention provides a displacement measurement system and method. By setting a resolution doubling module, the signal light emitted by the laser can be reflected multiple times in the resolution doubling module, increasing the number of times the signal light passes through the moving distance of the target to be measured, thereby reducing the displacement phase coefficient and improving the resolution of displacement measurement, making it possible to achieve low-cost and high-precision homodyne interferometric displacement measurement.

[0005] According to a first aspect of the present invention, there is provided a displacement measurement system, comprising: a laser, a beam splitting module, a resolution doubling module, a detection module, and an analysis module;

[0006] The laser beam emitted by the laser is incident on the beam splitting module, and the beam splitting module splits the laser beam into signal light and local oscillator light;

[0007] The signal light is incident on the detection module after passing through the resolution doubling module, and the local oscillator light is directly incident on the detection module;

[0008] The detection module generates an electrical signal according to the interference signal of the signal light and the local oscillator light, and transmits it to the analysis module;

[0009] The analysis module determines the displacement of the target to be measured based on the electrical signal;

[0010] Among them, the target to be measured is located within the resolution multiplication module. The signal light is reflected m times within the resolution multiplication module and passes through the moving distance of the object to be measured n times, and the resolution is increased by n times. n is an even number greater than 2, and m is an integer greater than n.

[0011] Optionally, the resolution multiplication module includes an optical transceiver unit, a first collimation unit, at least one prism, a second collimation unit, and a first reflection unit; the prism includes a first side and a second side; the prism is fixedly connected to the target to be measured;

[0012] The signal light emitted by the beam splitting module is incident on the optical transceiver unit. The signal light emitted by the optical transceiver unit passes through the first collimation unit and is incident on the prism. After the signal light is reflected by the first side and the second side of the prism, it passes through the second collimation unit and is incident on the first reflection unit;

[0013] The signal light is reflected by the first reflection unit and is received by the optical transceiver unit along the reverse optical path and is emitted to the detection module.

[0014] Optionally, at least one of the prisms includes a first prism and a second prism; both the first prism and the first reflection unit are fixedly connected to the target to be measured;

[0015] The signal light emitted by the beam splitting module is incident on the optical transceiver unit. The signal light emitted by the optical transceiver unit passes through the first collimation unit and is incident on the first prism. After the signal light is reflected by the first side and the second side of the first prism, it is incident on the second prism. After the signal light is reflected by the first side and the second side of the second prism, it passes through the second collimation unit and is incident on the first reflection unit;

[0016] The signal light is reflected by the first reflection unit and is received by the optical transceiver unit along the reverse optical path and is emitted to the detection module.

[0017] Optionally, the resolution multiplication module further includes a polarization beam splitter, a polarizer, a quarter-wave plate, and a second reflection unit; the prism is fixedly connected to the target to be measured;

[0018] The signal light emitted by the beam splitting module is incident on the optical transceiver unit. The signal light emitted by the optical transceiver unit passes through the first collimating unit and is incident on the polarizer. The polarizer converts the signal light into first polarized light. The first polarized light is transmitted through the polarization beam splitter to the prism. After being reflected by the first side and the second side of the prism, it is incident on the quarter-wave plate. The first polarized light is converted into circularly polarized light after passing through the quarter-wave plate. The circularly polarized light is reflected by the second reflection unit and then incident on the quarter-wave plate again. The circularly polarized light is converted into second polarized light after passing through the quarter-wave plate. The second polarized light is incident on the polarization beam splitter along the reverse optical path;

[0019] The second polarized light is reflected by the polarization beam splitter to the second collimating unit. The second polarized light passes through the second collimating unit and is transmitted to the first reflection unit. The first reflection unit reflects the second polarized light to the polarization beam splitter. The second polarized light is reflected by the polarization beam splitter to the prism. After being reflected by the first side and the second side of the prism, it is incident on the quarter-wave plate. The second polarized light is converted into circularly polarized light after passing through the quarter-wave plate. The circularly polarized light is reflected by the second reflection unit and then incident on the quarter-wave plate again. The circularly polarized light is converted into first polarized light after passing through the quarter-wave plate. The first polarized light is received by the optical transceiver unit along the reverse optical path and is emitted to the detection module.

[0020] Optionally, at least one of the prisms includes a third prism and a fourth prism; both the third prism and the second reflection unit are fixedly connected to the target to be measured;

[0021] The signal light emitted by the beam splitting module is incident on the optical transceiver unit. The signal light emitted by the optical transceiver unit passes through the first collimating unit and is incident on the polarizer. The polarizer converts the signal light into first polarized light. The first polarized light is transmitted through the polarization beam splitter to the third prism. After being reflected by the third prism and the fourth prism, it is incident on the quarter-wave plate. The first polarized light is converted into circularly polarized light after passing through the quarter-wave plate. The circularly polarized light is reflected by the second reflection unit and then incident on the quarter-wave plate again. The circularly polarized light is converted into second polarized light after passing through the quarter-wave plate. The second polarized light is incident on the polarization beam splitter along the reverse optical path;

[0022] The second polarized light is reflected by the polarization beam splitter to the second collimating unit, and the second polarized light is incident on the first reflecting unit through the second collimating unit. The first reflecting unit reflects the second polarized light to the polarization beam splitter, and the second polarized light is reflected by the polarization beam splitter to the third prism. After being reflected by the third prism and the fourth prism, the second polarized light is incident on the quarter-wave plate. The second polarized light is converted into circularly polarized light after passing through the quarter-wave plate. After being reflected by the second reflecting unit, the circularly polarized light is incident on the quarter-wave plate again. The circularly polarized light is converted into first polarized light after passing through the quarter-wave plate. The first polarized light is incident on the polarization beam splitter along the reverse optical path; the first polarized light passes through the polarization beam splitter and is transmitted to the optical transceiver unit, and is emitted by the optical transceiver unit to the detection module.

[0023] Optionally, the prism further includes an antireflection film.

[0024] The signal light is incident on the prism through the antireflection film, and / or the prism reflects the signal light and exits through the antireflection film.

[0025] Optionally, the included angle between the third side surface of the prism and the first direction is greater than 0° and less than 90°;

[0026] Wherein, the first direction is perpendicular to the displacement direction of the target to be measured.

[0027] Optionally, the prism includes a right-angle prism, a reflecting triangular pyramid or a diffractive optical waveguide.

[0028] Optionally, the second reflecting unit includes a specular reflector or a reflecting triangular pyramid.

[0029] According to the second aspect of the present invention, there is provided a displacement measurement method, which uses any one of the displacement measurement systems in the first aspect of the present invention. The displacement measurement method includes:

[0030] The laser beam emitted by the laser is incident on the beam splitting module, and the beam splitting module splits the laser beam into a signal light and a local oscillator light;

[0031] The signal light is incident on the detection module after passing through the resolution doubling module, and the local oscillator light is directly incident on the detection module;

[0032] The detection module generates an electrical signal according to the interference signal of the signal light and the local oscillator light, and transmits it to the analysis module;

[0033] The analysis module determines the displacement amount of the target to be measured based on the electrical signal;

[0034] Among them, the target to be measured is located within the resolution multiplication module. The signal light is reflected m times within the resolution multiplication module and passes through the moving distance of the object to be measured n times, with the resolution increased by n times. n is an even number greater than 2, and m is an integer greater than n.

[0035] The present invention discloses a displacement measurement system and method, including: a laser, a beam splitting module, a resolution multiplication module, a detection module, and an analysis module; the laser beam emitted by the laser is incident on the beam splitting module, and the beam splitting module splits the laser beam into a signal light and a local oscillator light; the signal light is incident on the detection module after passing through the resolution multiplication module, and the local oscillator light is directly incident on the detection module; the detection module generates an electrical signal according to the interference signal of the signal light and the local oscillator light and transmits it to the analysis module; the analysis module determines the displacement amount of the target to be measured by using the homodyne method based on the electrical signal; among them, the target to be measured is located within the resolution multiplication module, the signal light is reflected m times within the resolution multiplication module and passes through the moving distance of the object to be measured n times, with the resolution increased by n times. n is an even number greater than 2, and m is an integer greater than n. The displacement measurement system provided by the present invention can make the signal light emitted by the laser be reflected multiple times in the resolution multiplication module by setting the resolution multiplication module, increasing the number of times the signal light passes through the moving distance of the target to be measured, thereby reducing the displacement phase coefficient and improving the resolution of displacement measurement, making it possible for low-cost and high-precision homodyne method interference displacement measurement.

[0036] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 is a schematic diagram of the principle of a laser homodyne method interference displacement measurement system;

[0039] Figure 2 is a schematic structural diagram of a displacement measurement system provided by an embodiment of the present invention;

[0040] Figure 3 is a schematic structural diagram of a resolution multiplication module in a displacement measurement system provided by an embodiment of the present invention;

[0041] Figure 4It is a schematic structural diagram of a resolution doubling module in a displacement measurement system provided by an embodiment of the present invention;

[0042] Figure 5 It is a schematic structural diagram of a resolution doubling module in a displacement measurement system provided by an embodiment of the present invention;

[0043] Figure 6 It is a schematic structural diagram of a resolution doubling module in a displacement measurement system provided by an embodiment of the present invention;

[0044] Figure 7 It is a schematic structural diagram of a resolution doubling module in a displacement measurement system provided by an embodiment of the present invention;

[0045] Figure 8 It is a schematic structural diagram of a resolution doubling module in a displacement measurement system provided by an embodiment of the present invention;

[0046] Figure 9 It is a flowchart of a displacement measurement method provided by an embodiment of the present invention. Detailed implementation manners

[0047] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below 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 of 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.

[0048] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0049] It should be understood that the various forms of the processes shown above can be used, steps can be reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. There is no limitation herein.

[0050] Figure 1 is a schematic diagram of the principle of a laser homodyne interferometric displacement measurement system. Refer to Figure 1 , the laser beam emitted by the laser 1 is incident on the beam splitting module 2. The beam splitting module 2 splits the laser beam into a signal light A and a local oscillator light L. The signal light A passes through the lens 6 and is incident on the target to be measured 31, and then is reflected back to the lens 6 by the target to be measured 31 and received by the detection module 4. The local oscillator light L is directly incident on the detection module 4. The signal light A is incident on the target to be measured 31, and the signal light A returned by the target to be measured 31 is incident on the detection module 4. The signal light A and the local oscillator light L achieve homodyne interference in the detection module 4. The detection module 4 obtains the I component and Q component of the interference signal, thereby obtaining the complete phase and amplitude information, and further calculating the displacement of the target to be measured 31. Refer to Figure 1 , the target to be measured 31 displaces along the displacement direction X. The signal light A hits the surface of the target to be measured 31 and returns, which means that the displacement of the signal light relative to the target to be measured 31 has traveled twice the displacement amount. That is, if the target to be measured 31 moves a displacement amount d of half a wavelength, the signal light A will travel a displacement of one whole wavelength. At this time, the change amount of the optical path difference is one wavelength λ, and the change amount of the phase is 2π. The displacement phase coefficient is defined as the ratio of the displacement amount of the target to be measured 31 to the change amount of the optical path difference of the signal light A, that is, the displacement phase coefficient This value represents the displacement amount of the target to be measured corresponding to each unit change in the optical phase. At a certain temperature, the phase noise of the semiconductor laser randomly changes within a certain range, and this change range is τ. Then the displacement resolution of the target to be measured 31 is σ×τ.

[0051] Refer to Figure 1 As shown, the signal light A travels back and forth through the displacement distance of the target to be measured 31 twice in total. Therefore, its displacement phase coefficient

[0052] Under the conditions of a certain laser and temperature, τ is a constant. Therefore, to improve the displacement measurement resolution, it is necessary to reduce σ, or increase

[0053] Increase The method is to increase the number of times the signal light passes through the displacement distance of the target to be measured during displacement measurement. The more the number of times increased, the larger the value of , and this value is proportional to the number of times the signal light passes through the displacement distance of the target to be measured.

[0054] Based on the above inventive concept, an embodiment of the present invention provides a displacement measurement system. Figure 2 is a schematic diagram of the structure of a displacement measurement system provided by an embodiment of the present invention. Refer to Figure 2, comprising: a laser 1, a beam splitting module 2, a resolution multiplication module 3, a detection module 4, and an analysis module 5; the laser beam emitted by the laser 1 is incident on the beam splitting module 2, and the beam splitting module 2 splits the laser beam into a signal light A and a local oscillator light L; the signal light A is incident on the detection module 4 after passing through the resolution multiplication module 3, and the local oscillator light L is directly incident on the detection module 4; the detection module 4 generates an electrical signal based on the interference signal of the signal light A and the local oscillator light L, and transmits it to the analysis module 5; the analysis module 5 determines the displacement of the target to be measured based on the electrical signal; wherein, the target to be measured 31 is located in the resolution multiplication module 3, and the signal light A is reflected m times in the resolution multiplication module 3 and passes through the moving distance of the object to be measured 31 n times ( Figure 2 not shown in the figure), the resolution is increased by n times, n is an even number greater than 2, and m is an integer greater than n.

[0055] Specifically, the displacement measurement system provided by the embodiment of the present invention includes a laser 1, a beam splitting module 2, a resolution multiplication module 3, a detection module 4, and an analysis module 5. The laser 1 emits a laser beam into the beam splitting module 2, and the beam splitting module 2 splits the laser beam into a signal light A and a local oscillator light L. Among them, the signal light A is incident on the target to be measured 31 in the resolution multiplication module 3. In the embodiment of the present invention, in addition to the target to be measured 31, the resolution multiplication module 3 also includes a plurality of optical elements such as prisms ( Figure 2 not shown in the figure), which can make the signal light A reflect m times in the resolution multiplication module 3 and pass through the displacement distance of the target to be measured 31 n times, so as to increase the optical path of the signal light A, thereby increasing the resolution by n times. Among them, n is an even number greater than 2, and m is an integer greater than n. The signal light A passing through the resolution multiplication module 3 and the local oscillator light L not passing through the resolution multiplication module 3 are combined to generate a beat frequency and are incident on the detection module 4. The detection module 4 receives the beat frequency signal of the signal light A to generate an electrical signal IQ and transmits it to the analysis module 5. The analysis module 5 can calculate the phase difference between the signal light A and the local oscillator light L by solving the IQ signal, thereby determining the displacement of the target to be measured 31.

[0056] The displacement measurement system provided by the embodiment of the present invention increases the resolution multiplication module in the system, so that the signal light can be reflected multiple times in the resolution multiplication module, thereby increasing the number of times the signal light passes through the moving distance of the target to be measured in the system, thereby reducing the displacement phase coefficient and improving the resolution of displacement measurement, making it possible to perform homodyne interference displacement measurement with low cost and high precision.

[0057] Figure 3 is a schematic structural diagram of the resolution multiplication module in a displacement measurement system provided by an embodiment of the present invention. Refer to Figure 2 and Figure 3, Optionally, the resolution doubling module includes an optical transceiver unit 32, a first collimating unit 33, at least one prism 34, a second collimating unit 35, and a first reflecting unit 36; the prism 34 includes a first side surface ( Figure 3 the left side surface in Figure 3 and a second side surface ( Figure 3 the right side surface in Figure 3 not shown); the prism 34 is fixedly connected to the target to be measured ( Figure 3 not shown); the signal light A emitted by the beam splitting module (

[0058] not shown) is incident on the optical transceiver unit 32, the signal light emitted by the optical transceiver unit 32 is incident on the prism 34 through the first collimating unit 33, after the signal light is reflected by the first side surface and the second side surface of the prism 34, it is incident on the first reflecting unit 36 through the second collimating unit 35; the signal light is reflected by the first reflecting unit 36 and then received by the optical transceiver unit 32 along the reverse optical path and is emitted to the detection module (

[0059] not shown). Figure 3 Specifically, the resolution doubling module includes an optical transceiver unit 32, a first collimating unit 33, at least one prism 34, a second collimating unit 35, and a first reflecting unit 36. The prism 34 includes a first side surface and a second side surface. The prism 34 is fixedly connected to the target to be measured and moves together along the displacement direction X. The signal light A split by the beam splitting module is incident on the optical transceiver unit 32. The signal light A emitted by the optical transceiver unit 32 is collimated by the first collimating unit 33 and then incident on the first side surface of the prism 34. After being reflected by the first side surface of the prism 34, the signal light A is incident on the second side surface of the prism 34. After being reflected by the second side surface of the prism 34, the signal light A is incident on the first reflecting unit 36 through the second collimating unit 35. After the signal light A is incident on the first reflecting unit 36, it is reflected by the first reflecting unit 36, and then passes through the second collimating unit 35 again and is incident on the second side surface of the prism 34. After being reflected by the second side surface of the prism 34, the signal light A is incident on the first side surface of the prism 34. After being reflected by the first side surface of the prism 34, the signal light A passes through the first collimating unit 33 and is received by the optical transceiver unit 32. The optical transceiver unit 32 receives the signal light A and emits it to the detection module. For example, as shown in Figure 3 , in the embodiment of the present invention, the prism 34 is fixedly connected to the target to be measured, and the prism 34 moves with the movement of the target to be measured (exemplarily, the prism 34 and the target to be measured can be fixedly installed on the displacement table together), and moves with the movement of the target to be measured. Therefore, with the movement of the target to be measured, the signal light A passes through the moving distance of the target to be measured 4 times, so its displacement phase coefficient wherein, the optical transceiver unit 32 can be an optical fiber or a planar lightwave circuit waveguide (PLC).

[0060] In the displacement measurement system provided by the embodiment of the present invention, by arranging a prism and a first reflection unit, the signal light can be reflected 5 times in the resolution multiplication module, so as to pass through the moving distance of the object to be measured 4 times, thereby improving the resolution and increasing the accuracy of the measured displacement.

[0061] Optionally, the prism 34 further includes an antireflection film 3401, and the signal light A is incident on the prism 34 through the antireflection film 3401, and / or the signal light A reflected by the prism 34 exits through the antireflection film 3401.

[0062] Specifically, in order to avoid stray light generated by reflection on the inclined surface of the prism 34, an antireflection film 3401 can be additionally coated on the third side surface of the prism 34. After the additional coating, the antireflection film 3401 can make the signal light A pass through the antireflection film 3401 before entering the prism 34 and then enter the prism 34, and / or the signal light A reflected by the prism 34 exits after passing through the antireflection film 3401.

[0063] The embodiment of the present invention can avoid the technical effect of generating stray light on the inclined surface of the prism by additionally coating an antireflection film on the prism.

[0064] Figure 4 It is a schematic structural diagram of a resolution multiplication module in a displacement measurement system provided by an embodiment of the present invention. Refer to Figure 4 , optionally, the included angle between the third side surface of the prism 34 and the first direction Y is greater than 0° and less than 90°; wherein, the first direction Y is perpendicular to the displacement direction X of the object to be measured.

[0065] Specifically, in order to avoid generating more stray light when the signal light A is reflected in the prism 34, the embodiment of the present invention can rotate the prism 34 by a certain angle so that the third side surface (i.e., the horizontal surface) of the prism 34 is not perpendicular to the signal light A, that is, the included angle a between the third side surface of the prism 34 and the first direction Y is greater than 0° and less than 90° (such as Figure 4 is 8° in), wherein, the first direction Y is perpendicular to the displacement direction X of the object to be measured.

[0066] By rotating the prism by a small angle in the embodiment of the present invention, the third side surface of the prism is not perpendicular to the signal light, so as to achieve the technical effect of avoiding generating stray light on the inclined surface of the prism.

[0067] Figure 5 It is a schematic structural diagram of a resolution multiplication module in a displacement measurement system provided by an embodiment of the present invention. Refer to Figure 5, Optionally, at least one prism includes a first prism 3402 and a second prism 3403; the first prism 3402 and the first reflection unit 36 are both fixedly connected to the target to be measured; the signal light A emitted by the beam splitting module is incident on the optical transceiver unit 32, and the signal light A emitted by the optical transceiver unit 32 passes through the first collimation unit 33 and is incident on the first prism 3402. After the signal light A is reflected by the first side and the second side of the first prism 3402, it is incident on the second prism 3403. After the signal light A is reflected by the first side and the second side of the second prism 3403, it passes through the second collimation unit 35 and is incident on the first reflection unit 36; the signal light A is reflected by the first reflection unit 36 and is received by the optical transceiver unit 33 along the reverse optical path, and then is emitted to the detection module.

[0068] Specifically, at least one prism includes a first prism 3402 and a second prism 3403. Among them, the first prism 3402 and the first reflection unit 36 are both fixedly connected to the target to be measured. The signal light A split by the beam splitting module is incident on the optical transceiver unit 32, and the signal light A emitted by the optical transceiver unit 32 is incident on the first side of the first prism 3402 (i.e., Figure 5 the left side of the first prism 3402 in Figure 5 ) through the first collimation unit 33. After the signal light A is reflected by the first side of the first prism 3402, it is incident on the second side of the first prism 3402 (i.e., Figure 5 the right side of the first prism 3402 in Figure 5 ). After the signal light A is reflected by the second side of the first prism 3402, it is incident on the first side of the second prism 3403 (i.e.,

[0069] the left side of the second prism 3403 in

[0070] ). After the signal light A is reflected by the first side of the second prism 3403, it is incident on the second side of the second prism 3403 (i.e., Figure 5 the right side of the second prism 3403 in

[0071] ). After the signal light A is reflected by the second side of the second prism 3403, it passes through the second collimation unit 35 and is incident on the first reflection unit 36;

[0069] The signal light A after being reflected by the first reflection unit 36 returns along the reverse optical path and is finally received by the optical transceiver unit 32. After the optical transceiver unit 32 receives the signal light A, it is emitted to the detection module.

[0070] As Figure 5 shown, the displacement measurement system provided by the embodiment of the present invention includes a first prism 3402 and a second prism 3403. The first prism 3402 and the first reflection unit are both fixedly connected to the target to be measured. In this system, the signal light A has passed through the displacement distance of the measured object a total of 6 times. Then the displacement phase coefficient

[0071] Similarly, if the number of prisms is continuously increased, that is, if the number of times the signal light passes through the displacement distance of the target to be measured is continuously increased by cascading expansion, the displacement phase coefficient will continuously decrease. If the number of times the signal light passes through the displacement distance of the target to be measured is n, the displacement phase coefficient

[0072] Figure 6 is a schematic structural diagram of a resolution doubling module in a displacement measurement system provided by an embodiment of the present invention. Refer to Figure 6 :

[0073] Optionally, the resolution doubling module further includes a polarization beam splitter 37, a polarizer 38, a quarter-wave plate 39, and a second reflection unit 341; the prism 34 is fixedly connected to the target to be measured;

[0074] The signal light A emitted by the beam splitting module is incident on the optical transceiver unit 32. The signal light A emitted by the optical transceiver unit 32 passes through the first collimation unit 33 and is incident on the polarizer 38. The polarizer 38 converts the signal light A into first polarized light. The first polarized light is transmitted through the polarization beam splitter 37 to the prism 34. After being reflected by the first side and the second side of the prism 34, it is incident on the quarter-wave plate 39. The first polarized light is converted into circularly polarized light after passing through the quarter-wave plate 39. The circularly polarized light is reflected by the second reflection unit 341 and then incident on the quarter-wave plate 39 again. The circularly polarized light is converted into second polarized light after passing through the quarter-wave plate 39. The second polarized light is incident on the polarization beam splitter 37 along the reverse optical path;

[0075] The second polarized light is reflected by the polarization beam splitter 37 to the second collimation unit 35. The second polarized light passes through the second collimation unit 35 and is transmitted to the first reflection unit 36. The first reflection unit 36 reflects the second polarized light to the polarization beam splitter 37. The second polarized light is reflected by the polarization beam splitter 37 to the prism 34. After being reflected by the first side and the second side of the prism 34, it is incident on the quarter-wave plate 39. The second polarized light is converted into circularly polarized light after passing through the quarter-wave plate 39. The circularly polarized light is reflected by the second reflection unit 341 and then incident on the quarter-wave plate 39 again. The circularly polarized light is converted into first polarized light after passing through the quarter-wave plate 39. The first polarized light is received by the optical transceiver unit 32 along the reverse optical path and emitted to the detection module.

[0076] Specifically, the signal light A emitted from the beam splitting module is incident on the optical transceiver unit 32. The optical transceiver unit 32 emits the signal light A. After the signal light A passes through the first collimating unit 33, it is incident on the polarizer 38. The polarizer 38 converts the signal light A into the first polarized light (for example, S polarized light). After passing through the transmission of the polarization beam splitter 37, the first polarized light is incident on the first side surface of the prism 34. After being reflected by the first side surface of the prism 34, the first polarized light is incident on the second side surface of the prism 34. After being reflected by the second side surface of the prism 34, the first polarized light is incident on the quarter-wave plate 39. The quarter-wave plate 39 converts the first polarized light into circularly polarized light and then is incident on the second reflection unit 341. After being reflected by the second reflection unit 341, the circularly polarized light is incident on the quarter-wave plate 39 again. The quarter-wave plate 39 converts the circularly polarized light into the second polarized light (for example, P polarized light). After being reflected by the second side surface of the prism 34, the second polarized light is incident on the first side surface of the prism 34. After being reflected by the first side surface, the second polarized light is incident on the polarization beam splitter 37. Due to the characteristic that the polarization beam splitter 37 can transmit S polarized light and reflect P polarized light, after being reflected by the polarization beam splitter 37, the second polarized light passes through the second collimating unit 35 and is incident on the first reflection unit 36. After being reflected by the first reflection unit 36, the second polarized light passes through the second collimating unit 35 again and is incident on the polarization beam splitter 37. After being reflected by the polarization beam splitter 37, the second polarized light is incident on the prism 34 again. After being reflected by the first side surface and the second side surface of the prism 34, the second polarized light is incident on the quarter-wave plate 39. The quarter-wave plate 39 converts the second polarized light into circularly polarized light. The circularly polarized light is incident on the second reflection unit 341. After being reflected by the second reflection unit 341, the circularly polarized light is incident on the quarter-wave plate 39 again and is converted into the first polarized light. After being reflected by the second side surface and the first side surface of the prism, the first polarized light is incident on the polarization beam splitter 37. After passing through the transmission of the polarization beam splitter 37, the first polarized light is received by the optical transceiver unit 32 and emitted to the detection module.

[0077] As Figure 6 shown, the prism 34 is fixedly connected to the target to be measured. The signal light A has passed through the displacement distance of the target to be measured a total of 8 times. Therefore, its displacement phase coefficient

[0078] Optionally, the prism can also be rotated by a certain angle to prevent unnecessary stray light from being generated in this system.

[0079] Figure 7 is a schematic structural diagram of the resolution doubling module in a displacement measurement system provided by an embodiment of the present invention. Refer to Figure 7 ,

[0080] Optionally, at least one prism includes a third prism 3404 and a fourth prism 3405; both the third prism 3404 and the second reflection unit 341 are fixedly connected to the target to be measured;

[0081] The signal light A emitted by the beam splitting module is incident on the optical transceiver unit 32. The signal light A emitted by the optical transceiver unit 32 passes through the first collimation unit 33 and is incident on the polarizer 38. The polarizer 38 converts the signal light A into the first polarized light. The first polarized light is transmitted through the polarization beam splitter 37 to the third prism 3404. After being reflected by the third prism 3404 and the fourth prism 3405, the first polarized light is incident on the quarter-wave plate 39. After passing through the quarter-wave plate 39, the first polarized light is converted into circularly polarized light. The circularly polarized light is reflected by the second reflection unit 341 and then incident on the quarter-wave plate 39 again. After passing through the quarter-wave plate 39, the circularly polarized light is converted into the second polarized light. The second polarized light is incident on the polarization beam splitter 37 along the reverse optical path;

[0082] The second polarized light is reflected by the polarization beam splitter 37 to the second collimation unit 35. The second polarized light passes through the second collimation unit 35 and is incident on the first reflection unit 36. The first reflection unit 36 reflects the second polarized light to the polarization beam splitter 37. The second polarized light is reflected by the polarization beam splitter 37 to the third prism 3404. After being reflected by the third prism 3404 and the fourth prism 3405, the second polarized light is incident on the quarter-wave plate 39. After passing through the quarter-wave plate 39, the second polarized light is converted into circularly polarized light. The circularly polarized light is reflected by the second reflection unit 341 and then incident on the quarter-wave plate 39 again. After passing through the quarter-wave plate 39, the circularly polarized light is converted into the first polarized light. The first polarized light is incident on the polarization beam splitter 37 along the reverse optical path; the first polarized light is transmitted through the polarization beam splitter 37 to the optical transceiver unit 32 and is emitted by the optical transceiver unit 32 to the detection module.

[0083] Specifically, the signal light A emitted from the beam splitting module is incident on the optical transceiver unit 32. The optical transceiver unit 32 emits the signal light A and is incident on the polarizer 38. The polarizer 38 converts the signal light A into the first polarized light (for example, S polarized light). After the first polarized light passes through the transmission of the polarization beam splitter 37, it is incident on the first side surface of the third prism 3404. After the first polarized light is reflected by the first side surface of the third prism 3404, it is incident on the second side surface of the third prism 3404. After the first polarized light is reflected by the second side surface of the third prism 3404, it is incident on the first side surface of the fourth prism 3405. After the first polarized light is reflected by the first side surface of the fourth prism 3405, it is incident on the second side surface of the fourth prism 3405. After the first polarized light is reflected by the second side surface of the fourth prism 3405, it is incident on the quarter-wave plate 39. The quarter-wave plate 39 converts the first polarized light into circularly polarized light and is incident on the second reflection unit 341. After the circularly polarized light is reflected by the second reflection unit 341, it is incident on the quarter-wave plate 39 again. The quarter-wave plate converts the circularly polarized light into the second polarized light (for example, P polarized light). The second polarized light is incident on the polarization beam splitter 37 along the reverse optical path. Due to the characteristic that the polarization beam splitter 37 transmits S polarized light and reflects P polarized light, after the second polarized light is reflected by the polarization beam splitter 37, it passes through the second collimation unit 35 and is incident on the first reflection unit 36. After the first reflection unit 36 reflects the second polarized light, it passes through the second collimation unit 35 again and is incident on the polarization beam splitter 37. After the second polarized light is reflected by the polarization beam splitter 37, it is incident on the third prism 3404. After the second polarized light is reflected by the first side surface and the second side surface of the third prism 3404, it is incident on the fourth prism 3405. After the second polarized light is reflected by the first side surface and the second side surface of the fourth prism 3405, it is incident on the quarter-wave plate 39. The quarter-wave plate 39 converts the second polarized light into circularly polarized light. The circularly polarized light is incident on the second reflection unit 341. After the circularly polarized light is reflected by the second reflection unit 341, it is incident on the quarter-wave plate 39. After the quarter-wave plate 39 converts the circularly polarized light into the first polarized light, the first polarized light is incident on the polarization beam splitter 37 along the reverse optical path. After the first polarized light passes through the transmission of the polarization beam splitter 37, it is received by the optical transceiver unit 32 and emitted to the detection module.

[0084] As Figure 7 shown, the principle is the same as that of Figure 6 . The signal light is reflected by the prism 4 times and passes through the displacement distance of the target to be measured 12 times in total. Therefore, its displacement phase coefficient

[0085] Optionally, the second reflection unit 341 includes a specular reflector or a reflecting triangular pyramid.

[0086] Optionally, the prism 34 includes a right-angle prism, a reflecting triangular pyramid, or a diffractive optical waveguide.

[0087] Specifically, when the prism is a right-angle prism or a reflective triangular pyramid, the optical path is as Figure 3 shown;

[0088] Figure 8 is a schematic structural diagram of a resolution doubling module in a displacement measurement system provided by an embodiment of the present invention. Refer to Figure 8 ,

[0089] When the prism is a diffractive optical waveguide 3406, the optical path is as Figure 8 shown. The reflection principle of the signal light A is similar to that of the above-mentioned embodiment of the invention, and will not be elaborated here.

[0090] According to the same inventive concept, an embodiment of the present invention provides a displacement measurement method, which uses the displacement measurement system in any of the above-mentioned embodiments of the invention. Figure 9 is a flowchart of a displacement measurement method provided by an embodiment of the present invention. Refer to Figure 9 , the method includes:

[0091] S1. The laser beam emitted by the laser is incident on the beam splitting module, and the beam splitting module splits the laser beam into a signal light and a local oscillator light.

[0092] Specifically, the laser beam emitted by the laser is incident on the beam splitting module. The laser can be a semiconductor laser, and the beam splitting module splits the laser beam into a signal light and a local oscillator light.

[0093] S2. The signal light is incident on the detection module after passing through the resolution doubling module, and the local oscillator light is directly incident on the detection module.

[0094] Specifically, the signal light split in the previous step S1 travels along the optical path and is incident on the resolution doubling module. After passing through the resolution doubling module, the signal light is then incident on the detection module. The local oscillator light split in the previous step S1 is directly incident on the detection module.

[0095] S3. The detection module generates an electrical signal based on the interference signal of the signal light and the local oscillator light and transmits it to the analysis module.

[0096] Specifically, after both the signal light and the local oscillator light are incident on the detection module, the detection module performs interference beat frequency based on the signal light and the local oscillator light and generates an electrical IQ signal. The detection module transmits the generated electrical IQ signal to the analysis module.

[0097] S4. The analysis module determines the displacement of the target to be measured based on the electrical signal.

[0098] Specifically, the analysis module performs calculations on the electrical IQ signals obtained according to the above step S3, and finally determines the displacement of the target to be measured. Among them, the target to be measured is located within the resolution multiplication module. The signal light is reflected m times within the resolution multiplication module and passes through the moving distance of the object to be measured n times, and the resolution is increased by n times. n is an even number greater than 2, and m is an integer greater than n.

[0099] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A displacement measurement system, characterized in that: include: Laser, beam splitting module, resolution multiplication module, detection module and analysis module; The laser beam emitted by the laser is incident on the beam splitting module, and the beam splitting module splits the laser beam into signal light and local oscillator light; The signal light is incident on the detection module after passing through the resolution multiplication module, and the local oscillator light is directly incident on the detection module; The detection module generates an electrical signal according to the interference signal between the signal light and the local oscillation light, and transmits the electrical signal to the analysis module; The analysis module determines the displacement of the target to be measured based on the electrical signal; The target to be measured is located in the resolution multiplication module, the signal light is reflected m times in the resolution multiplication module, and passes through the moving distance of the target to be measured n times, and the resolution is improved n times, where n is an even number greater than 2, and m is an integer greater than n.

2. The displacement measurement system according to claim 1, characterized in that: The resolution multiplication module includes an optical transceiver unit, a first collimation unit, at least one prism, a second collimation unit and a first reflection unit; the prism includes a first side surface and a second side surface; the prism is fixedly connected to the target to be measured; The signal light emitted by the beam splitting module is incident on the optical transceiver unit, the signal light emitted by the optical transceiver unit is incident on the prism through the first collimating unit, and the signal light is reflected by the first side surface and the second side surface of the prism, and then is incident on the first reflecting unit through the second collimating unit; After being reflected by the first reflecting unit, the signal light is received by the optical transceiver unit along the reverse light path and emitted to the detection module.

3. The displacement measurement system according to claim 2, characterized in that: At least one of the prisms includes a first prism and a second prism; the first prism and the first reflection unit are both fixedly connected to the target to be measured; The signal light emitted by the beam splitting module is incident on the optical transceiver unit, the signal light emitted by the optical transceiver unit is incident on the first prism through the first collimating unit, the signal light is incident on the second prism after being reflected by the first side surface and the second side surface of the first prism, and the signal light is incident on the first reflecting unit after being reflected by the first side surface and the second side surface of the second prism through the second collimating unit; After being reflected by the first reflecting unit, the signal light is received by the optical transceiver unit along the reverse light path and emitted to the detection module.

4. The displacement measurement system according to claim 2, characterized in that: The resolution multiplication module further includes a polarization beam splitter, a polarizer, a quarter wave plate and a second reflection unit; the prism is fixedly connected to the target to be measured; The signal light emitted by the beam splitter module is incident on the optical transceiver unit, and the signal light emitted by the optical transceiver unit is incident on the polarizer through the first collimation unit, and the polarizer converts the signal light into a first polarized light, and the first polarized light is transmitted to the prism through the polarization beam splitter, and after being reflected by the first side surface and the second side surface of the prism, it is incident on the 1 / 4 wave plate, and the first polarized light is converted into circular polarized light after passing through the 1 / 4 wave plate, and the circular polarized light is reflected by the second reflection unit and is incident on the 1 / 4 wave plate again, and the circular polarized light is converted into a second polarized light after passing through the 1 / 4 wave plate, and the second polarized light is incident on the polarization beam splitter along the reverse light path; The second polarized light is reflected by the polarization beam splitter to the second collimation unit, the second polarized light is transmitted by the second collimation unit to the first reflection unit, the first reflection unit reflects the second polarized light to the polarization beam splitter, the second polarized light is reflected by the polarization beam splitter to the prism, after being reflected by the first side surface and the second side surface of the prism, it is incident on the 1 / 4 wave plate, the second polarized light is converted into circular polarized light after passing through the 1 / 4 wave plate, the circular polarized light is reflected by the second reflection unit and is incident on the 1 / 4 wave plate again, the circular polarized light is converted into the first polarized light after passing through the 1 / 4 wave plate, the first polarized light is received by the optical transceiver unit along the reverse light path, and is emitted to the detection module.

5. The displacement measurement system according to claim 4, characterized in that: At least one of the prisms includes a third prism and a fourth prism; the third prism and the second reflection unit are both fixedly connected to the target to be measured; The signal light emitted by the beam splitter module is incident on the optical transceiver unit, the signal light emitted by the optical transceiver unit is incident on the polarizer through the first collimator unit, the polarizer converts the signal light into a first polarized light, the first polarized light is transmitted to the third prism through the polarization beam splitter, the first polarized light is reflected by the third prism and the fourth prism, and then is incident on the 1 / 4 wave plate, the first polarized light is converted into circular polarized light after passing through the 1 / 4 wave plate, the circular polarized light is reflected by the second reflector unit, and then is incident on the 1 / 4 wave plate again, the circular polarized light is converted into a second polarized light after passing through the 1 / 4 wave plate, and the second polarized light is incident on the polarization beam splitter along the reverse light path; The second polarized light is reflected by the polarization beam splitter to the second collimation unit, the second polarized light is incident on the first reflection unit through the second collimation unit, the first reflection unit reflects the second polarized light to the polarization beam splitter, the second polarized light is reflected by the polarization beam splitter to the third prism, the second polarized light is reflected by the third prism and the fourth prism, and is incident on the 1 / 4 wave plate, the second polarized light is converted into circular polarized light after passing through the 1 / 4 wave plate, the circular polarized light is reflected by the second reflection unit, and is incident on the 1 / 4 wave plate again, the circular polarized light is converted into first polarized light after passing through the 1 / 4 wave plate, and the first polarized light is incident on the polarization beam splitter along the reverse light path; the first polarized light is transmitted to the optical transceiver unit through the polarization beam splitter, and is emitted by the optical transceiver unit to the detection module.

6. The displacement measurement system according to claim 2, characterized in that: The prism also includes an anti-reflection film, The signal light passes through the anti-reflection film and is incident on the prism, and / or the prism reflects the signal light and the signal light is emitted through the anti-reflection film.

7. The displacement measurement system according to claim 2, characterized in that: The angle between the third side surface of the prism and the first direction is greater than 0° and less than 90°; Wherein, the first direction is perpendicular to the displacement direction of the target to be measured.

8. The optical system for improving displacement measurement resolution according to claim 5, characterized in that: The prism includes a right-angle prism, a reflective triangular pyramid or a diffractive optical waveguide.

9. The optical system for improving displacement measurement resolution according to claim 3, characterized in that: The second reflection unit includes a mirror reflection plate or a reflection triangular pyramid.

10. A displacement measurement method, characterized in that: Using the displacement measurement system according to any one of claims 1 to 9, the displacement measurement method comprises: The laser beam emitted by the laser is incident on the beam splitting module, and the beam splitting module splits the laser beam into signal light and local oscillator light; The signal light is incident on the detection module after passing through the resolution multiplication module, and the local oscillator light is directly incident on the detection module; The detection module generates an electrical signal according to the interference signal between the signal light and the local oscillation light, and transmits the electrical signal to the analysis module; The analysis module determines the displacement of the target to be measured based on the electrical signal; The target to be measured is located in the resolution multiplication module, the signal light is reflected m times in the resolution multiplication module, and passes through the moving distance of the target to be measured n times, and the resolution is improved n times, where n is an even number greater than 2, and m is an integer greater than n.

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