Interference fringe fast modulation device and modulation method based on light path reversibility principle

Abstract

The application discloses an interference fringe fast modulation device and modulation method based on an optical path reversible principle, belongs to the field of interference pattern modulation, and comprises a test table and a modulation device. The modulation device comprises optical emission modules, an optical path regulation module, a grating test piece, a light spot capturing and interference generation module and a signal acquisition module which are sequentially arranged along an optical path. The optical path regulation module is a double-beam interference source directional regulation unit. The double-beam interference source directional regulation unit comprises a main body and at least two groups of reflection angle adjusting components and light transmission components which are arranged on the main body and correspond to the reflection angle adjusting components one by one. The interference fringe fast modulation device and modulation method based on the optical path reversible principle are used. According to the optical path reversible principle, the incident light and the reflected light are overlapped by calibrating the grating test piece to determine the direction of the diffracted light, the interference fringe fast modulation is realized, the modulated fringe is clear and has high contrast, and the detection efficiency and precision are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of interferogram modulation technology, and in particular to a fast modulation device and method for interference fringes based on the principle of optical path reversibility. Background Technology

[0002] As one of the core technologies in the field of optical detection, laser moiré interference fringe modulation technology is widely used in scenarios such as material micro-deformation measurement, structural stress analysis, and material mechanical property characterization under high temperature environment (such as thermal expansion coefficient testing of aerospace materials). Its core principle is to construct a controllable optical interference system to convert the physical changes (such as displacement and deformation) of the object under test into observable interference fringe signals, thereby achieving high-precision quantitative analysis.

[0003] The traditional implementation path of this technology typically uses a "dual-beam incident - grating diffraction - spatial interference" chain as its core: First, two independent collimated beams are output from a conventional laser as incident sources. The two beams are guided to the surface of a grating specimen (which is often an etched metal grating or a holographic grating, serving as the core diffraction element for generating interference fringes) through an optical path adjustment mechanism. According to grating diffraction theory, when the two incident beams diffract on the grating surface, they simultaneously generate multiple orders of diffraction, such as 0th order, ±1st order, and ±2nd order. Among these, the ±1st order diffraction beams, due to their relatively concentrated energy and stable propagation direction, become the key order for constructing spatial interference fringes. Finally, the ±1st order diffraction beams corresponding to the two incident beams are projected into a specific area in space through optical path guidance. When the two diffraction beams meet the interference conditions of "same frequency, stable phase difference, and consistent vibration direction," observable laser moiré interference fringes can be formed in space.

[0004] However, this traditional technical approach suffers from significant drawbacks in practical operation, particularly the extreme difficulty in identifying and locating diffracted light. On one hand, limited by the performance of conventional optical systems, the intensity distribution of the two incident beams is poorly uniform (typically exhibiting a Gaussian distribution with strong intensity at the center and weak intensity at the edges). Furthermore, the energy conversion efficiency of the grating for ±1st-order diffracted light is low (the ±1st-order diffraction efficiency of conventional metal gratings is generally below 10%, and while holographic gratings are slightly higher, they are still less than 20%). This results in weak ±1st-order diffracted light, which is easily masked by ambient stray light (such as indoor lighting and equipment heat dissipation sources) in a typical laboratory environment (not a strictly dark room), making it difficult to directly identify with the naked eye or ordinary optical detectors. On the other hand, existing technologies lack the ability to accurately detect and locate diffracted light. The precise constraint mechanism for the propagation path of diffracted light is based on the theory of grating diffraction. The propagation direction of diffracted light is directly related to the incident angle of the incident light. However, the incident angle calibration accuracy in conventional schemes can only reach the 1° level. This results in a deviation between the actual propagation direction of ±1 order diffracted light and the theoretically calculated direction. Operators need to move photodetectors (such as CCD cameras) in three-dimensional space to check for possible propagation paths one by one. The entire search process depends on the operator's experience and judgment. A single positioning usually takes more than 30 minutes, and the positioning accuracy is difficult to guarantee (the deviation is likely to exceed 0.5 mm, which directly affects the clarity of subsequent interference fringes).

[0005] Furthermore, even if the two ±1st order diffracted beams are successfully located, the modulation process of the interference fringes remains cumbersome and inefficient. Because current technology lacks a precise matching mechanism between the incident light and the grating's relative positions, the ±1st order diffracted beams corresponding to the two incident beams often fail to directly meet the interference conditions in space. This necessitates continuously changing the incident angles of the two beams manually or semi-automatically (adjustment accuracy must be within 0.1° to ensure stable interference phase difference). Each angle adjustment requires re-detecting the propagation direction of the diffracted light to prevent the loss of located diffracted light due to angle shifts. Simultaneously, to ensure the contrast of the interference fringes (typically requiring a contrast ≥80% to meet detection requirements), the incident angle must be repeatedly fine-tuned and the fringes' clarity observed. This process requires 5-8 iterations, with each adjustment taking approximately 10 minutes. Consequently, the complete interference fringe modulation cycle (including incident light calibration, diffracted light search, incident angle fine-tuning, and fringe verification) generally exceeds one hour, far from meeting the needs of high-efficiency detection scenarios (such as real-time quality monitoring of industrial production lines and dynamic mechanical property testing of materials).

[0006] These shortcomings have become the core bottleneck restricting the in-depth promotion and application expansion of laser moiré interferometric fringe modulation technology. In high-precision detection fields (such as micro-deformation measurement of aerospace materials), low modulation efficiency leads to excessively long detection times for a single sample, making it difficult to achieve rapid screening of batch samples. In dynamic detection scenarios (such as thermal expansion testing of materials in a high-temperature moiré experimental furnace), during long-term modulation, environmental temperature fluctuations (±5℃) and equipment vibrations (amplitude ≥0.1mm) can easily cause the calibrated optical path to deviate, requiring re-modulation and further reducing detection accuracy and stability. In addition, the complex operation process requires extremely high professional skills from operators (who need to master professional knowledge such as grating diffraction theory and optical system calibration), significantly raising the threshold for technology promotion and making it difficult for this technology to be popularized in small and medium-sized enterprises or grassroots research institutions, thus limiting its application scope in industrial testing and people's livelihood fields (such as stress testing of building materials). Summary of the Invention

[0007] The purpose of this invention is to provide a fast modulation device and method for interference fringes based on the principle of optical path reversibility, thereby solving the above-mentioned technical problems.

[0008] To achieve the above objectives, this invention provides a rapid modulation device for interference fringes based on the principle of optical path reversibility. The device includes a test bench and a modulation device mounted on the test bench. The modulation device comprises an optical emission module, an optical path control module, a grating specimen, a spot capture and interference generation module, and a signal acquisition module arranged sequentially along the optical path. The optical path control module is a dual-beam interference source orientation control unit. This unit includes a main body and at least two sets of reflection angle adjustment components mounted on the main body, as well as selectively openable and closed light-transmitting components corresponding one-to-one with the reflection angle adjustment components. A tuning hole is provided at the center of the main body. The incident light emitted by the optical emission module, the tuning hole, and the center of the grating specimen are located on the same optical axis. The spot capture and interference generation module is placed between the grating specimen and the tuning hole, and arranged coaxially, thus forming a forward incident light path between the dual-beam interference source orientation control unit and the grating specimen. This forward incident light path coincides with and is opposite in direction to the reverse propagation light path between the ±1st order diffracted light generated by the grating specimen and the dual-beam interference source orientation control unit. At this time, the spot capture and interference generation module captures the diffracted light, generating interference fringes.

[0009] Preferably, the optical emission module includes a laser, a beam expander, and an aspherical lens arranged sequentially in the optical path. The beam expander and the aspherical lens are arranged coaxially, and the beam expander is fixed at the focal length of the aspherical lens.

[0010] The laser is used to output spherical collimated light, the beam expander is used to convert the spherical collimated light output by the laser into divergent light, and the aspherical lens is used to convert the divergent light back into parallel light and correct the spherical wavefront to a plane wavefront to obtain plane collimated light with uniform intensity.

[0011] Preferably, the laser, beam expander, and aspherical lens are located on the same optical axis;

[0012] Alternatively, the collimated spherical wave light emitted by the laser is reflected by the first and second mirrors arranged vertically and then projected onto the center of the beam expander. In this case, the line connecting the center of the laser and the center of the first mirror is parallel to the line connecting the center of the second mirror, the beam expander, and the aspherical lens.

[0013] Preferably, the light-transmitting components have two light-transmitting holes symmetrically distributed about the central axis of the main body; the light-transmitting holes of multiple sets of light-transmitting components are evenly arranged in a ring array about the center of the main body and aligned with the planar collimated light emitted by the optical emission module; during modulation, only one set of light-transmitting components is opened, and the remaining light-transmitting components are blocked;

[0014] The reflection angle adjustment assembly includes two sets of reflection angle adjustment components that are respectively aligned with the two light-transmitting holes of the corresponding light-transmitting components. The reflection angle adjustment components include a fixed inner reflector and an adjustable outer reflector disposed at the light-transmitting hole. The fixed inner reflector is arranged at a 45° angle with the collimated plane light incident from the light-transmitting hole, and the center of the effective reflection area of ​​the fixed inner reflector and the center of the corresponding light-transmitting hole are located on the same optical axis.

[0015] The adjustable outer reflector is mounted on the main body via an adjustment bracket, and the adjustable outer reflector is arranged opposite to and parallel to the fixed inner reflector.

[0016] Preferably, the dual-beam interference source orientation control unit includes two sets of light-transmitting components and two sets of reflection angle adjustment components corresponding to the two sets of light-transmitting components respectively; the line connecting the centers of the two light-transmitting holes of one set of light-transmitting components is a horizontal line, and the line connecting the centers of the two light-transmitting holes of the other set of light-transmitting components is a vertical line.

[0017] Preferably, the adjustment bracket includes a suspension rod fixed to the end face of the main body, radial adjustment holes arranged in a linear array, and a rotating shaft. One end of the rotating shaft is positioned in the radial adjustment hole by a positioning set screw, and the other end passes through the radial adjustment hole and the L-shaped positioning plate in sequence and is rotatably connected to one side of the adjustable outer reflector. The L-shaped positioning plate fits against the adjustable outer reflector. The adjustment bolt passes through the L-shaped positioning plate and is movably connected to the side of the adjustable outer reflector away from the fixed inner reflector. The adjustment bolt is also threadedly connected to the L-shaped positioning plate.

[0018] The L-shaped positioning plate is positioned so that the side facing away from the adjustable outer reflector is in contact with the suspension rod.

[0019] Preferably, the grating specimen is fixed on a high-temperature mottled experimental furnace to provide a high-temperature experimental environment for the grating specimen.

[0020] Preferably, the spot capture and interference generation module includes a screen or total reflection mirror disposed between the dual-beam interference source orientation control unit and the grating specimen;

[0021] The signal acquisition module includes a camera and a computer connected to the camera, used to receive and store the generated interference fringes.

[0022] The modulation method of the fast modulation device for interference fringes based on the principle of optical path reversibility includes the following steps:

[0023] S1. Determine the front and rear positions of the dual-beam interference source orientation control unit: First, arrange the laser and the grating specimen coaxially on the test bench, so that the spherical wave collimated light emitted by the laser is projected to the center of the grating specimen, generating horizontal ±1st order diffraction light and vertical ±1st order diffraction light on the surface of the grating specimen. Then, arrange the dual-beam interference source orientation control unit between the laser and the grating specimen, and make the adjustment hole on the dual-beam interference source orientation control unit located on the optical axis of the spherical wave collimated light. Adjust the position of the dual-beam interference source orientation control unit back and forth along the optical axis until the horizontal ±1st order diffraction light is projected to the center of the horizontally arranged adjustable outer mirror of the dual-beam interference source orientation control unit, and the vertical ±1st order diffraction light is projected to the center of the vertically arranged adjustable outer mirror of the dual-beam interference source orientation control unit. Fix the position of the dual-beam interference source orientation control unit at this time.

[0024] S2. First, a beam expander and an aspherical lens are arranged sequentially between the laser and the dual-beam interference source orientation control unit, so that the laser, beam expander, and aspherical lens are on the same optical axis. Then, the two vertically arranged light-transmitting holes on the dual-beam interference source orientation control unit are blocked, and the two horizontally arranged light-transmitting holes are opened. At this time, the spherical collimated light emitted by the laser is successively modulated by the beam expander and the aspherical lens and transformed into a plane collimated light with uniform intensity. This plane collimated light with uniform intensity is used as the initial incident light. After passing through the two horizontally arranged light-transmitting holes of the dual-beam interference source orientation control unit, it is projected to the central area of ​​the two horizontally arranged fixed inner mirrors. Then, it is projected to the center of the grating specimen as the new incident light through the two horizontally arranged adjustable outer mirrors. According to the principle of optical path reversibility, the horizontal ±1 order diffracted light generated by the grating specimen at this time is coaxial with the initial incident light and opposite in direction.

[0025] S3. Modulate interference fringes: First, arrange the screen on the optical axis of the horizontal ±1st order diffraction light between the dual-beam interference source orientation control unit and the grating specimen. Then, tighten the adjusting bolt. With the cooperation of the thread, the adjusting bolt extends and retracts in the L-shaped positioning plate, thereby driving the adjusting outer mirror to rotate around the rotating axis, changing the angle of the adjusting outer mirror, until the horizontal ±1st order diffraction light overlaps on the screen to form horizontal interference fringes.

[0026] S4. Remove the screen and place the total reflection mirror in the same position. The camera will capture the horizontal interference fringes formed and store them in the computer.

[0027] S5. Block the two horizontally arranged light-transmitting holes, open the two vertically arranged light-transmitting holes, and repeat steps S3 and S4 to obtain vertical interference fringes.

[0028] Therefore, the present invention employs the above-mentioned fast modulation device and modulation method for interference fringes based on the principle of optical path reversibility, and has the following beneficial effects:

[0029] 1. Solve the core pain point of difficulty in finding diffracted light in existing technologies: By using the principle of optical path reversibility, the incident light and reflected light are completely superimposed by calibrating the grating specimen, ensuring that the ±1st order diffracted light generated by the grating accurately returns to the orientation control unit area of ​​the dual-beam interference source along the reverse path of the incident light, eliminating the need to search for the propagation direction of diffracted light in space, and greatly reducing the difficulty of diffracted light identification and positioning.

[0030] 2. Significantly improves interference fringe modulation efficiency: There is no need to repeatedly change the incident light angle to adjust the ±1st order diffraction light. Only the reflection angle of the dual-beam interference source orientation control unit needs to be fixed (adjusting the angle of the adjustable outer mirror so that the reflection angle is 45° with the normal plane of the test stage). By selecting the single-dimensional incident light and adjusting the overlap of the diffraction spots, interference fringes can be quickly generated. Compared with existing technologies, this significantly shortens the modulation time, meeting the requirements of high-efficiency detection (this invention can modulate clear interference fringes in about 1 hour, while traditional methods require more than 10 days).

[0031] 3. Optimize interference fringe quality: By using a combination of a beam expander and an aspherical lens (with the beam expander positioned at the focal length of the aspherical lens), the spherical collimated light output from the laser is corrected into a large-area planar collimated light with uniform intensity. At the same time, stray light is filtered by opening and closing a single set of light-transmitting holes in the dual-beam interference source orientation control unit. The resulting interference fringe image is clear and has high contrast, providing a high-quality signal foundation for subsequent detection.

[0032] 4. Simplified modulation operation process: The step-by-step debugging logic of first adjusting the left and right (horizontal dimension) and then adjusting the up and down (vertical dimension) is adopted. Based on the horizontal reference of the test bench, a stable horizontal optical path reference is first established, and then extended to the vertical dimension. This avoids mutual interference between optical paths in different dimensions, reduces the complexity of operation, and can complete the debugging without relying on the operator's high experience.

[0033] 5. Ensure detection accuracy and stability: By precisely adjusting the angle of the adjustable outer reflector, it is ensured that the two ±1 order diffracted beams meet the interference conditions of the same frequency, stable phase difference, and consistent vibration direction, reducing the interference of optical path offset and ambient stray light on the fringes, and improving the accuracy and reliability of results in subsequent applications such as material deformation detection and stress analysis.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0035] Figure 1 This is an optical path arrangement diagram of the fast modulation device for interference fringes based on the principle of optical path reversibility of the present invention;

[0036] Figure 2 This is a schematic diagram of the dual-beam interference source directional control unit of the fast modulation device for interference fringes based on the principle of optical path reversibility of the present invention.

[0037] Figure 3 These are comparative diagrams of embodiments of the present invention, wherein (a) is the modulation result using the method described in the present invention, and (b) is the modulation result using the conventional method.

[0038] Figure Labels

[0039] 1. Main body; 2. Light-transmitting hole; 3. Suspension rod; 4. Adjustable outer reflector; 5. L-shaped positioning plate; 6. Adjusting bolt; 7. Fixed inner reflector. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0041] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0042] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0043] like Figure 1 and Figure 2As shown, the interference fringe rapid modulation device based on the principle of optical path reversibility includes a test bench and a modulation device set on the test bench. The modulation device includes an optical emission module, an optical path control module, a grating specimen, a spot capture and interference generation module, and a signal acquisition module arranged sequentially along the optical path. The optical path control module is a dual-beam interference source orientation control unit. The dual-beam interference source orientation control unit includes a main body 1 and at least two sets of reflection angle adjustment components and light-transmitting components that can be selectively opened and closed and correspond one-to-one with the reflection angle adjustment components. A debugging hole is opened in the center of the main body 1. The incident light emitted by the optical emission module, the debugging hole, and the center of the grating specimen are located on the same optical axis. The spot capture and interference generation module is placed between the grating specimen and the debugging hole and is arranged coaxially, thereby forming a forward incident light path between the dual-beam interference source orientation control unit and the grating specimen, which coincides with and is opposite in direction to the reverse propagation light path between the ±1st order diffraction light generated by the grating specimen and the dual-beam interference source orientation control unit. At this time, the diffraction light is captured by the spot capture and interference generation module to generate interference fringes.

[0044] The optical emission module includes a laser, a beam expander, and an aspherical lens arranged sequentially in the optical path. The beam expander and the aspherical lens are arranged coaxially, and the beam expander is fixed at the focal length of the aspherical lens. In this embodiment, the laser is a helium-neon laser. The laser is used to output spherical collimated light, the beam expander is used to convert the spherical collimated light output by the laser into divergent light, and the aspherical lens is used to convert the divergent light back into parallel light and correct the spherical wavefront to a plane wavefront to obtain plane collimated light with uniform intensity.

[0045] The laser, beam expander, and aspherical lens are located on the same optical axis. This arrangement can be chosen if the test site is large. Alternatively, the collimated spherical wave light emitted by the laser is reflected by the first and second mirrors arranged vertically and then projected onto the center of the beam expander. In this case, the line connecting the center of the laser and the center of the first mirror is parallel to the line connecting the center of the second mirror, the beam expander, and the aspherical lens. This arrangement can be chosen if the test site is limited.

[0046] Two light-transmitting holes 2 are symmetrically distributed about the central axis of the main body 1. The light-transmitting holes 2 of multiple sets of light-transmitting components are evenly arranged in a ring array about the center of the main body 1 and aligned with the plane collimated light emitted by the optical emission module. During modulation, only one set of light-transmitting components is opened, and the remaining light-transmitting components are blocked. The reflection angle adjustment component includes two sets of reflection angle adjustment parts that are respectively aligned with the two light-transmitting holes 2 of the corresponding light-transmitting components. The reflection angle adjustment parts include a fixed inner reflector 7 and an adjustable outer reflector 4 set at the light-transmitting hole 2. The fixed inner reflector 7 is arranged at a 45° angle with the plane collimated light incident from the light-transmitting hole 2, and the center of the effective reflection area of ​​the fixed inner reflector 7 is located on the same optical axis as the center of the corresponding light-transmitting hole 2. The adjustable outer reflector 4 is set on the main body 1 via an adjustment bracket, and the adjustable outer reflector 4 is arranged opposite to and parallel to the fixed inner reflector 7.

[0047] The dual-beam interference source orientation control unit includes two sets of light-transmitting components and two sets of reflection angle adjustment components corresponding to the two sets of light-transmitting components respectively; the line connecting the centers of the two light-transmitting holes 2 of one set of light-transmitting components is a horizontal line, and the line connecting the centers of the two light-transmitting holes 2 of the other set of light-transmitting components is a vertical line.

[0048] The adjustment bracket includes a suspension rod 3 fixed to the end face of the main body 1, radial adjustment holes arranged in a linear array, and a rotating shaft. One end of the rotating shaft is positioned in the radial adjustment hole by a positioning set screw, and the other end passes through the radial adjustment hole and the L-shaped positioning plate 5 in sequence and is rotatably connected to one side of the adjustable outer reflector 4. The L-shaped positioning plate 5 is in contact with the adjustable outer reflector 4. The adjustment bolt 6 passes through the L-shaped positioning plate 5 and is movably connected to the side of the adjustable outer reflector 4 away from the fixed inner reflector 7. The adjustment bolt 6 is also threadedly connected to the L-shaped positioning plate. The side of the L-shaped positioning plate 5 away from the adjustable outer reflector 4 is in contact with the suspension rod 3.

[0049] The grating specimen is fixed on a high-temperature moiré experimental furnace to provide a high-temperature experimental environment for the grating specimen. Since the structure and operation of the high-temperature moiré experimental furnace are common knowledge in this field, they will not be described in detail here.

[0050] The light spot capture and interference generation module includes a screen or total reflection mirror positioned between the dual-beam interference source orientation control unit and the grating specimen; the signal acquisition module includes a camera and a computer connected to the camera, used to receive and store the generated interference fringes.

[0051] The modulation method of the fast modulation device for interference fringes based on the principle of optical path reversibility includes the following steps:

[0052] S1. Determine the front and rear positions of the dual-beam interference source orientation control unit: First, arrange the laser and the grating specimen coaxially on the test bench, so that the spherical wave collimated light emitted by the laser is projected to the center of the grating specimen, generating horizontal ±1st order diffraction light and vertical ±1st order diffraction light on the surface of the grating specimen. Then, arrange the dual-beam interference source orientation control unit between the laser and the grating specimen, and make the adjustment hole on the dual-beam interference source orientation control unit located on the optical axis of the spherical wave collimated light. Adjust the position of the dual-beam interference source orientation control unit back and forth along the optical axis until the horizontal ±1st order diffraction light is projected to the center of the horizontally arranged adjustable outer mirror 4 of the dual-beam interference source orientation control unit, and the vertical ±1st order diffraction light is projected to the center of the vertically arranged adjustable outer mirror 4 of the dual-beam interference source orientation control unit. Fix the position of the dual-beam interference source orientation control unit at this time.

[0053] S2. First, a beam expander and an aspherical lens are arranged sequentially between the laser and the dual-beam interference source orientation control unit, so that the laser, beam expander and aspherical lens are located on the same optical axis. Then, the two vertically arranged light-transmitting holes 2 on the dual-beam interference source orientation control unit are blocked, and the two horizontally arranged light-transmitting holes 2 are opened. At this time, the spherical collimated light emitted by the laser is successively modulated by the beam expander and the aspherical lens and transformed into a plane collimated light with uniform light intensity. This plane collimated light with uniform light intensity is used as the initial incident light and passes through the two horizontally arranged light-transmitting holes 2 of the dual-beam interference source orientation control unit. It is then projected to the central area of ​​the two horizontally arranged fixed inner mirrors 7. Then, it is projected to the center of the grating specimen as the new incident light through the two horizontally arranged adjustable outer mirrors 4. According to the principle of optical path reversibility, the horizontal ±1st order diffracted light generated by the grating specimen is coaxial with the initial incident light and opposite in direction, thus obtaining the direction of the horizontal ±1st order diffracted light.

[0054] S3. Modulating Interference Fringes: First, a screen is arranged on the optical axis of the horizontal ±1st order diffraction light between the dual-beam interference source orientation control unit and the grating specimen. Then, the adjusting bolt 6 is turned. With the thread engagement, the adjusting bolt 6 extends and retracts within the L-shaped positioning plate 5, thereby driving the adjustable outer reflector 4 to rotate around the axis, changing the angle of the adjustable outer reflector 4 until the horizontal ±1st order diffraction light overlaps on the screen to form the following pattern: Figure 3 The horizontal interference fringes shown in Figure (a), combined with Figure 3 As shown in Figure (b), the horizontal interference fringes generated by the conventional method are clearer than those generated by the present invention, thus proving the effectiveness of the present invention.

[0055] S4. Remove the screen and place the total reflection mirror in the same position. The camera will capture the horizontal interference fringes formed and store them in the computer.

[0056] S5. Block the two horizontally arranged light-transmitting holes 2, open the two vertically arranged light-transmitting holes 2, and repeat steps S3 and S4 to obtain vertical interference fringes.

[0057] It should be noted that in this embodiment, internal and external reflectors at other angles can also be set to obtain interference fringes at multiple angles. Those skilled in the art should be able to obtain modulation methods for interference fringes at other angles according to the technical solution described in this invention, so they will not be described in detail here.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A rapid modulation device for interference fringes based on the principle of optical path reversibility, comprising a test bench and a modulation device mounted on the test bench, the modulation device comprising an optical emission module, an optical path control module, a grating specimen, a light spot capture and interference generation module, and a signal acquisition module arranged sequentially along the optical path, characterized in that: The optical path control module is a dual-beam interference source orientation control unit. The dual-beam interference source orientation control unit includes a main body and at least two sets of reflection angle adjustment components and light-transmitting components that can be selectively opened and closed and correspond one-to-one with the reflection angle adjustment components. An adjustment hole is opened in the center of the main body. The incident light emitted by the optical emission module, the adjustment hole, and the center of the grating specimen are located on the same optical axis. The spot capture and interference generation module is placed between the grating specimen and the adjustment hole and is arranged coaxially, thereby forming a forward incident light path between the dual-beam interference source orientation control unit and the grating specimen, which coincides with and is opposite in direction to the reverse propagation light path between the ±1st order diffraction light generated by the grating specimen and the dual-beam interference source orientation control unit. At this time, the diffraction light is captured by the spot capture and interference generation module to generate interference fringes. The optical emission module includes a laser, a beam expander, and an aspherical lens arranged sequentially in the optical path. The beam expander and the aspherical lens are arranged coaxially, and the beam expander is fixed at the focal length of the aspherical lens. The laser is used to output spherical collimated light, the beam expander is used to convert the spherical collimated light output by the laser into divergent light, and the aspherical lens is used to convert the divergent light back into parallel light and correct the spherical wavefront to a plane wavefront to obtain plane collimated light with uniform intensity. The laser, beam expander, and aspherical lens are located on the same optical axis; Alternatively, the collimated spherical wave light emitted by the laser is reflected by the first and second mirrors arranged vertically and then projected onto the center of the beam expander. In this case, the line connecting the center of the laser and the center of the first mirror is parallel to the line connecting the center of the second mirror, the beam expander, and the aspherical lens. Two light-transmitting holes are symmetrically distributed about the central axis of the main body in the light-transmitting component; the light-transmitting holes of multiple sets of light-transmitting components are evenly arranged in a ring array about the center of the main body and aligned with the planar collimated light emitted by the optical emission module; during modulation, only one set of light-transmitting components is opened, and the remaining light-transmitting components are blocked; The reflection angle adjustment assembly includes two sets of reflection angle adjustment components that are respectively aligned with the two light-transmitting holes of the corresponding light-transmitting components. The reflection angle adjustment components include a fixed inner reflector and an adjustable outer reflector disposed at the light-transmitting hole. The fixed inner reflector is arranged at a 45° angle with the collimated plane light incident from the light-transmitting hole, and the center of the effective reflection area of ​​the fixed inner reflector and the center of the corresponding light-transmitting hole are located on the same optical axis. The adjustable outer reflector is mounted on the main body via an adjustment bracket, and the adjustable outer reflector is arranged opposite to and parallel to the fixed inner reflector.

2. The fast modulation device for interference fringes based on the principle of optical path reversibility according to claim 1, characterized in that: The dual-beam interference source orientation control unit includes two sets of light-transmitting components and two sets of reflection angle adjustment components corresponding to the two sets of light-transmitting components respectively; the line connecting the centers of the two light-transmitting holes of one set of light-transmitting components is a horizontal line, and the line connecting the centers of the two light-transmitting holes of the other set of light-transmitting components is a vertical line.

3. The interference fringe fast modulation device based on the principle of optical path reversibility according to claim 2, characterized in that: The adjustment bracket includes a suspension rod fixed to the end face of the main body, radial adjustment holes arranged in a linear array, and a rotating shaft. One end of the rotating shaft is positioned in the radial adjustment hole by a positioning set screw, and the other end passes through the radial adjustment hole and the L-shaped positioning plate in sequence and is rotatably connected to one side of the adjustable outer reflector. The L-shaped positioning plate fits against the adjustable outer reflector. The adjustment bolt passes through the L-shaped positioning plate and is movably connected to the side of the adjustable outer reflector away from the fixed inner reflector. The adjustment bolt is also threadedly connected to the L-shaped positioning plate. The L-shaped positioning plate is positioned so that the side facing away from the adjustable outer reflector is in contact with the suspension rod.

4. The interference fringe fast modulation device based on the principle of optical path reversibility according to claim 3, characterized in that: The grating specimen is fixed on a high-temperature mottled experimental furnace to provide a high-temperature experimental environment for the grating specimen.

5. The interference fringe fast modulation device based on the principle of optical path reversibility according to claim 4, characterized in that: The beam spot capture and interference generation module includes a screen or total reflection mirror positioned between the dual-beam interference source orientation control unit and the grating specimen; The signal acquisition module includes a camera and a computer connected to the camera, used to receive and store the generated interference fringes.

6. The modulation method of the fast modulation device for interference fringes based on the principle of optical path reversibility as described in claim 5, characterized in that: Includes the following steps: S1. Determine the front and rear positions of the dual-beam interference source orientation control unit: First, arrange the laser and the grating specimen coaxially on the test bench, so that the spherical wave collimated light emitted by the laser is projected to the center of the grating specimen, generating horizontal ±1st order diffraction light and vertical ±1st order diffraction light on the surface of the grating specimen. Then, arrange the dual-beam interference source orientation control unit between the laser and the grating specimen, and make the adjustment hole on the dual-beam interference source orientation control unit located on the optical axis of the spherical wave collimated light. Adjust the position of the dual-beam interference source orientation control unit back and forth along the optical axis until the horizontal ±1st order diffraction light is projected to the center of the horizontally arranged adjustable outer mirror of the dual-beam interference source orientation control unit, and the vertical ±1st order diffraction light is projected to the center of the vertically arranged adjustable outer mirror of the dual-beam interference source orientation control unit. Fix the position of the dual-beam interference source orientation control unit at this time. S2. First, a beam expander and an aspherical lens are arranged sequentially between the laser and the dual-beam interference source orientation control unit, so that the laser, beam expander, and aspherical lens are on the same optical axis. Then, the two vertically arranged light-transmitting holes on the dual-beam interference source orientation control unit are blocked, and the two horizontally arranged light-transmitting holes are opened. At this time, the spherical collimated light emitted by the laser is successively modulated by the beam expander and the aspherical lens and transformed into a plane collimated light with uniform intensity. This plane collimated light with uniform intensity is used as the initial incident light. After passing through the two horizontally arranged light-transmitting holes of the dual-beam interference source orientation control unit, it is projected to the central area of ​​the two horizontally arranged fixed inner mirrors. Then, it is projected to the center of the grating specimen as the new incident light through the two horizontally arranged adjustable outer mirrors. According to the principle of optical path reversibility, the horizontal ±1 order diffracted light generated by the grating specimen at this time is coaxial with the initial incident light and opposite in direction. S3. Modulate interference fringes: First, arrange the screen on the optical axis of the horizontal ±1st order diffraction light between the dual-beam interference source orientation control unit and the grating specimen. Then, tighten the adjusting bolt. With the cooperation of the thread, the adjusting bolt extends and retracts in the L-shaped positioning plate, thereby driving the adjusting outer mirror to rotate around the rotating axis, changing the angle of the adjusting outer mirror, until the horizontal ±1st order diffraction light overlaps on the screen to form horizontal interference fringes. S4. Remove the screen and place the total reflection mirror in the same position. The camera will capture the horizontal interference fringes formed and store them in the computer. S5. Block the two horizontally arranged light-transmitting holes, open the two vertically arranged light-transmitting holes, and repeat steps S3 and S4 to obtain vertical interference fringes.

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