Optical path system and sound pressure detection method for improving acousto-optic coupling effect

Abstract

The application is suitable for the field of laser technology, and provides an optical path system for improving acousto-optic coupling effect and a sound pressure detection method.The optical path system comprises a laser for emitting laser light; a first light splitter is arranged in the light emitting direction of the laser; a first mirror is arranged on the reflected light path of the first light splitter; a second mirror is arranged on the transmitted light path of the first light splitter; a 1 / 4 wave plate is arranged between the second mirror and the first light splitter; an acousto-optic coupling area is further arranged between the 1 / 4 wave plate and the second mirror; and a detection device is arranged between the laser and the first light splitter.Through the cooperation of the first light splitter, the 1 / 4 wave plate, the first mirror and the second mirror, the laser reciprocally passes through the acousto-optic coupling area four times, so that the acousto-optic coupling effect and the deflection angle of the laser can be improved.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to an optical path system and a sound pressure detection method for improving the acoustic-optical coupling effect. Background Technology

[0002] A laser hydrophone is a high-tech device that uses laser technology to detect underwater sound fields. It indirectly obtains sound field information by measuring the changes after the laser couples with underwater sound waves. The working principle of the laser hydrophone is based on the acousto-optic effect: when sound waves pass through water, they cause minute changes in the water's density and refractive index. These changes affect the propagation path of the laser beam passing through the water, causing the laser to deflect. By detecting the deflection angle of the laser, the sound pressure of the sound field is indirectly measured.

[0003] However, in the optical path system of traditional laser acoustic field hydrophones, the laser usually passes through the sound field only once, resulting in poor coupling between the laser and the sound waves in the sound field, and the small deflection angle of the laser is not convenient for measurement. Summary of the Invention

[0004] The purpose of this application is to provide an optical path system that improves the acoustic-optical coupling effect, aiming to solve the problems in the optical path system of traditional laser acoustic field hydrophones, such as poor coupling effect between laser and sound waves in the sound field, and small laser deflection angle that is inconvenient to measure.

[0005] This application embodiment is implemented as follows: an optical path system for improving acoustic-optical coupling effect includes:

[0006] A laser, used to emit laser light;

[0007] A first beam splitter is located in the light output direction of the laser, and the beam splitting mirror of the first beam splitter is configured to transmit P-polarized light and reflect S-polarized light.

[0008] The first reflector is located on the reflected light path of the first beam splitter, and the mirror surface of the first reflector forms a 45° angle with the beam splitter mirror surface of the first beam splitter.

[0009] The second reflector is located on the transmission light path of the first beam splitter, and the mirror surface of the second reflector forms a 45° angle with the beam splitting mirror surface of the first beam splitter.

[0010] A quarter-wave plate is disposed between the second reflector and the first beam splitter. An acousto-optic coupling region is also provided between the quarter-wave plate and the second reflector. The laser undergoes an acousto-optic effect in the acousto-optic coupling region, causing the propagation path of the laser to deflect and generate a deflection angle.

[0011] A detection device is arranged between the laser and the first beam splitter, and is configured to detect the deflection angle of the laser returned from the first beam splitter.

[0012] In some preferred embodiments of the present application, the detection device comprises a second beam splitter arranged between the laser and the first beam splitter, and a detector arranged on the reflected light path of the second beam splitter, wherein the second beam splitter is configured to reflect the laser returned from the first beam splitter to the detector.

[0013] In some preferred embodiments of the present application, the detector is a position sensitive detector.

[0014] In some preferred embodiments of the present application, a convex lens is arranged between the second beam splitter and the detector, and the detector is located on the focal plane of the convex lens, and the deflection angle of the laser after single acousto-optic coupling is:

[0015] wherein d is the offset of the laser spot formed on the detector relative to the origin, and f is the focal length of the convex lens.

[0016] In some preferred embodiments of the present application, a half-wave plate is arranged between the laser and the second beam splitter, and is configured to change the polarization direction of the laser so that the light intensity of the P-polarized light transmitted by the first beam splitter is maximum.

[0017] In some preferred embodiments of the present application, the second beam splitter is a common beam splitter prism, which is configured to transmit light with a light intensity greater than that of reflected light.

[0018] In some preferred embodiments of the present application, the first beam splitter is a polarization beam splitter prism.

[0019] The embodiments of the present application also provide an acoustic pressure detection method for improving acousto-optic coupling effect, based on the optical system described above, the method comprising:

[0020] Polarization splitting the laser based on the first beam splitter to obtain P-polarized light;

[0021] Making the P-polarized light pass through the 1 / 4 wave plate and the acousto-optic coupling area, so that the P-polarized light is converted into first circularly polarized light and undergoes first acousto-optic coupling;

[0022] Reflecting the first circularly polarized light based on the second mirror, so that the first circularly polarized light passes through the acousto-optic coupling area and the 1 / 4 wave plate again, undergoes second acousto-optic coupling and is converted into S-polarized light;

[0023] S-polarized light is reflected by the first beam splitter into the first mirror. The first mirror reflects the S-polarized light back to the first beam splitter. The first beam splitter reflects the S-polarized light again, causing the S-polarized light to pass through the quarter-wave plate and the acousto-optic coupling region, transforming the S-polarized light into second circularly polarized light and performing a third acousto-optic coupling.

[0024] The second circularly polarized light is reflected by the second mirror, so that the second circularly polarized light passes through the acousto-optic coupling region and the quarter-wave plate again, undergoes a fourth acousto-optic coupling, and converts the second circularly polarized light back into P-polarized light.

[0025] After the second circularly polarized light is converted back to P-polarized light, it is transmitted through the first beam splitter to obtain deflected laser light. The deflection angle of the deflected laser light is detected by a detection device to obtain the sound pressure information in the acousto-optic coupling region.

[0026] In some preferred embodiments of this application, the detection device includes: a second beam splitter, a convex lens, and a position-sensitive detector. The second beam splitter is disposed between the laser and the first beam splitter. The detector is disposed on the reflected light path of the second beam splitter. The convex lens is disposed between the second beam splitter and the position-sensitive detector, and the position-sensitive detector is located on the focal plane of the convex lens. The method for detecting the deflection angle of the deflected laser using the detection device includes:

[0027] The deflected laser is reflected to the convex lens by the second beam splitter, and the deflected laser forms a spot on the position-sensitive detector after passing through the convex lens;

[0028] Based on the position-sensitive detector, the offset of the spot formed by the deflected laser on the position-sensitive detector relative to the origin is obtained;

[0029] To obtain the focal length of a convex lens, use the formula... Calculate the deflection angle of the deflecting laser, where θ is the deflection angle of the laser, d is the offset of the laser spot formed on the position-sensitive detector relative to the origin, and f is the focal length of the convex lens.

[0030] The embodiments of this application provide an optical path system for improving the acoustic-optical coupling effect. Through the combined action of a first beam splitter, a quarter-wave plate, a first reflector, and a second reflector, the laser passes through the acoustic-optical coupling zone four times. The deflection angles of the laser are linearly superimposed, thereby improving the acoustic-optical coupling effect and increasing the laser deflection angle for easier detection. Attached Figure Description

[0031] Figure 1 A schematic diagram of an optical path system for improving acoustic-optical coupling is provided in an embodiment of this application;

[0032] Figure 2 A schematic diagram of the laser propagation path in an optical system for improving acoustic-optical coupling, provided as an embodiment of this application;

[0033] Figure 3 This is a schematic diagram of laser deflection angle measurement in an optical path system for improving acoustic-optical coupling, provided as an embodiment of this application.

[0034] in:

[0035] 100, Laser; 200, Half-wave plate; 300, Second beam splitter; 400, First beam splitter; 500, Quarter-wave plate; 600, First reflector; 700, Convex lens; 800, Position-sensitive detector; 900, Second reflector;

[0036] 10. Acousto-optic coupling region; 20. First optical path; 30. Auxiliary line; 40. Laser to be tested; 50. Focal plane. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] The specific implementation of this application will be described in detail below with reference to specific embodiments.

[0039] The inventors discovered that in the optical path system of traditional laser acoustic hydrophones, the laser typically passes through the sound field only once, resulting in poor coupling between the laser and the sound waves in the sound field. This leads to a small laser deflection angle, requiring a high-precision detector for measurement of this minute deflection angle, increasing system complexity and cost. The optical path system provided in this application, however, allows the laser to pass through the acoustic-optical coupling region four times, improving the acoustic-optical coupling effect and increasing the laser deflection angle. This reduces the reliance on high-precision detectors and lowers costs. The following description, in conjunction with the accompanying drawings, further illustrates this.

[0040] like Figure 1 The diagram shown is a schematic diagram of an optical path system for improving acoustic-optical coupling provided in an embodiment of this application, including: a laser 100, a first beam splitter 400, a first reflector 600, a second reflector 900, and a quarter-wave plate 500.

[0041] Laser 100 is used to emit laser light. Its specific structure and principle are existing mature technologies and will not be described in detail here.

[0042] The first beam splitter 400 is located in the light-emitting direction of the laser 100. The first beam splitter 400 is configured to transmit P-polarized light and reflect S-polarized light. P-polarized light refers to linearly polarized light whose polarization direction is parallel to the incident plane. "P" stands for "parallel," meaning that the vibration direction of the light is parallel to the incident plane. In contrast to P-polarized light is S-polarized light, whose polarization direction is perpendicular to the incident plane. "S" stands for "senkrecht," which means "perpendicular" in German.

[0043] The first reflector 600 is located on the reflected light path of the first beam splitter 400. The mirror surface of the first reflector 600 forms a 45° angle with the beam splitting mirror surface of the first beam splitter 400. The first reflector 600 is used to reflect the reflected light from the first beam splitter 400 back to the first beam splitter 400.

[0044] The second reflector 900 is located on the transmitted light path of the first beam splitter 400. The mirror surface of the second reflector 900 forms a 45° angle with the beam splitting mirror surface of the first beam splitter 400. The second reflector 900 is used to reflect the transmitted light of the first beam splitter 400 back to the first beam splitter 400.

[0045] A quarter-wave plate 500 is disposed between the second reflector 900 and the first beam splitter 400. The quarter-wave plate 500 is mainly used to change the polarization state of light. It can cause a phase delay of 1 / 4 wavelength between the two mutually perpendicular polarization directions of the laser, making linearly polarized light circularly polarized light, and circularly polarized light linearly polarized light. Specifically, in this embodiment, P-polarized light becomes first circularly polarized light after passing through the quarter-wave plate 500. The first circularly polarized light becomes S-polarized light after passing through the quarter-wave plate 500 again. The S-polarized light becomes second circularly polarized light after passing through the quarter-wave plate 500 again. The second circularly polarized light becomes P-polarized light again after passing through the quarter-wave plate 500 again. Simply put, after passing through the quarter-wave plate 500 twice, the polarization direction of P-polarized light rotates by 90° to become S-polarized light, and after passing through the quarter-wave plate 500 twice, the polarization direction of S-polarized light rotates by 90° to become P-polarized light.

[0046] An acousto-optic coupling region 10 is also provided between the quarter-wave plate 500 and the second reflector 900. The laser undergoes an acousto-optic effect in this region, causing a deflection angle in the laser's propagation path. When sound waves pass through water, they cause minute changes in the water's density and refractive index. These changes affect the propagation path of the laser passing through the water, causing it to deflect. By detecting the angle of laser deflection, the sound pressure information of the sound wave can be measured.

[0047] In this embodiment, as Figure 1 and Figure 2As shown, laser 100 emits laser light, which is split into P-polarized light and S-polarized light by the first beam splitter 400. The S-polarized light is reflected upwards by the first beam splitter 400 and is no longer used, while the P-polarized light passes through the first beam splitter 400 and through the quarter-wave plate 500 and the acousto-optic coupling region 10, converting the P-polarized light into first circularly polarized light and undergoing the first acousto-optic coupling. Then, the second reflector 900 reflects the first circularly polarized light, causing it to propagate back and pass through the acousto-optic coupling region 10 and the quarter-wave plate 500, undergoing the second acousto-optic coupling and converting the first circularly polarized light into S-polarized light. The S-polarized light cannot pass through the first beam splitter 400 and can only be reflected by the first beam splitter 400 to the first reflector 600. S-polarized light is reflected back to the first beam splitter 400 by the first reflector 600. The first beam splitter 400 reflects the S-polarized light again into the quarter-wave plate 500 and the acousto-optic coupling region 10, converting the S-polarized light into second circularly polarized light and performing a third acousto-optic coupling. Then, the second reflector 900 reflects the second circularly polarized light, causing it to pass through the acousto-optic coupling region 10 and the quarter-wave plate 500, converting it back into P-polarized light and performing a fourth acousto-optic coupling. The P-polarized light passes through the first beam splitter 400 and enters the detection device for deflection angle detection. In this way, the laser travels back and forth to the acousto-optic fusion region four times, with the deflection angles linearly superimposed, improving the acousto-optic coupling effect and the laser deflection angle, and also increasing the sensitivity to sound pressure detection by four times.

[0048] Figure 2 This is a schematic diagram of the laser propagation path in an optical system for improving acoustic-optical coupling, provided as an embodiment of this application. Figure 2 As shown, when the laser beam is incident horizontally from left to right onto the first beam splitter 400, it deflects upwards by θ after the first pass through the acousto-optic coupling region 10. After being reflected by the second mirror 900 and entering the acousto-optic coupling region 10 for a second acousto-optic coupling, the laser deflection angle is 2θ. This deflection angle remains 2θ after reflections by the first beam splitter 400 and the first mirror 600. After the third acousto-optic coupling, the laser deflects by 3θ, and this angle remains 3θ after a second reflection by the second mirror. After the fourth acousto-optic coupling, the laser deflects again, reaching a deflection angle of 4θ. Therefore, in traditional optical systems, only one acousto-optic coupling occurs, resulting in a deflection angle of only θ. In contrast, the acousto-optic coupling optical system of this application can achieve four acousto-optic couplings, resulting in a laser deflection angle of 4θ.

[0049] It should be noted that the laser deflection caused by acousto-optic coupling is typically on the order of a few tenths of a degree. The laser's path back and forth within the acousto-optic coupling region is essentially the same; therefore, the deflection angles occurring during multiple passes through the acousto-optic coupling region can be considered equal. Furthermore, a deflection angle that is too small to be easily demonstrated... Figure 2The laser deflection angle shown in the image has been magnified. Figure 2 The deflection angle in degrees is not intended to limit this application.

[0050] like Figure 1 As shown, in a preferred embodiment of this application, the detection device includes a second beam splitter 300 and a detector. The second beam splitter 300 is disposed between the laser 100 and the first beam splitter 400, and the detector is disposed on the reflected light path of the second beam splitter 300. The second beam splitter 300 is used to reflect the laser returning from the first beam splitter 400 to the detector.

[0051] In this embodiment, as Figure 1 As shown, the laser emitted by laser 100 is incident on the second beam splitter 300. Part of the light is reflected upwards and is no longer used, while the other part passes through the second beam splitter 300 and enters the first beam splitter 400. When the laser undergoes four acousto-optic couplings and returns to the second beam splitter 300 after passing through the first beam splitter 400, part of the laser is reflected downwards by the second beam splitter 300 and enters the detector. The detector detects the deflection angle of the laser, thereby obtaining the sound pressure information.

[0052] In some embodiments of this application, the second beam splitter 300 is a beam-splitting prism configured such that the intensity of the transmitted light is greater than the intensity of the reflected light. This reduces the intensity of light reflected into the detection device by the second beam splitter 300, preventing damage to the detection device. In some embodiments, the second beam splitter 300 is a conventional beam-splitting prism, distinguished from a polarizing beam-splitting prism. Conventional beam-splitting prisms are insensitive to polarization and are used to split incident light into transmitted and reflected light according to a specific intensity ratio.

[0053] like Figure 1 As shown in the preferred embodiment of this application, the detector is a position-sensitive detector 800. In this embodiment, when the laser does not deflect, the laser illuminates the origin of the detector 800 to form an initial light spot. When the laser has a deflection angle, the position of the light spot shifts. By measuring the shift of the light spot through the detector 800, the deflection angle of the laser can be obtained. In this way, the deflection angle of the laser can be easily obtained.

[0054] like Figure 1 and Figure 3 As shown, in a preferred embodiment of this application, a convex lens 700 is disposed between the second beam splitter 300 and the position-sensitive detector 800, and the position-sensitive detector 800 is located on the focal plane 50 of the convex lens 700. The deflection angle of the laser single-shot acousto-optic coupling... Where d is the offset of the laser spot formed by the position-sensitive detector 800 relative to the origin, and f is the focal length of the convex lens 700.

[0055] like Figure 2 and Figure 3 As shown, according to the characteristics of a convex lens, parallel light rays will converge at the same point on the focal plane 50 after passing through the lens. Therefore, if the auxiliary line 30, parallel to the laser light 40 to be tested, passes through the optical center (point c) of the convex lens and intersects the focal plane 50 at point a, then the laser light 40 to be tested will illuminate point a after passing through the convex lens 700. Based on geometric relationships, we can obtain... Wherein, the distance l between point a and point b a Equal to the spot offset d measured by the position-sensitive detector 800, and the distance l between points b and c. b The focal length f of a convex lens equal to 700° can be rearranged to obtain... By using the convex lens 700, parallel light rays can be directed to the same point on the focal plane 50. This allows for the measurement of only the laser deflection angle, reducing interference from reflections of the laser from different positions on the second beam splitter 300. Since lasers with the same deflection angle remain parallel even after reflection from different positions on the second beam splitter 300, they will still strike the same point on the focal plane 50. Therefore, the measured spot offset is the same, enabling accurate measurement of the laser deflection angle.

[0056] like Figure 1 As shown, in a preferred embodiment of this application, a half-wave plate 200 is disposed between the laser 100 and the second beam splitter 300. The half-wave plate 200 is used to change the polarization direction of the laser so that the intensity of the P-polarized light transmitted by the first beam splitter 400 is maximized. In this way, the light utilization rate can be improved.

[0057] like Figure 1 As shown, in a preferred embodiment of this application, the first beam splitter 400 is a polarizing beam splitter prism. Compared with other polarizing beam splitters, the polarizing beam splitter prism has better polarization separation effect, less light energy loss, and higher mechanical stability.

[0058] This application also provides a sound pressure detection method to improve the acoustic-optical coupling effect. The method is based on the above-described optical path system and includes:

[0059] The laser light is polarized and split by the first beam splitter 400 to obtain P-polarized light. In this embodiment, the laser 100 emits laser light, which hits the first beam splitter 400. The first beam splitter 400 splits the laser light into S-polarized light and P-polarized light, and reflects the S-polarized light and transmits the P-polarized light, thus obtaining P-polarized light.

[0060] P-polarized light is passed through a quarter-wave plate 500 and an acousto-optic coupling region 10, transforming it into first circularly polarized light and initiating the first acousto-optic coupling. In this embodiment, the quarter-wave plate 500 is primarily used to change the polarization state of the light. It can cause a phase delay of 1 / 4 wavelength between the two mutually perpendicular polarization directions of the laser, converting linearly polarized light into circularly polarized light and vice versa. When the laser passes through the acousto-optic coupling region 10, an acousto-optic effect occurs, causing the laser to deviate from its original path and propagate at a deflection angle.

[0061] The first circularly polarized light is reflected by the second reflector 900, causing it to pass through the acousto-optic coupling region 10 and the quarter-wave plate 500 again for a second acousto-optic coupling, converting it into S-polarized light. In this embodiment, after passing through the quarter-wave plate 500 again, the first circularly polarized light becomes S-polarized light. This S-polarized light cannot penetrate the first beam splitter 400 to enter the detection device; it is reflected by the beam splitter 400 to continue subsequent acousto-optic coupling. When the laser passes through the acousto-optic coupling region a second time, it undergoes a second acousto-optic coupling and is deflected again; the deflection angles are superimposed.

[0062] S-polarized light is reflected by the first beam splitter 400 into the first reflector 600. The first reflector 600 reflects the S-polarized light back to the first beam splitter 400. The first beam splitter 400 reflects the S-polarized light again, causing the S-polarized light to pass through the quarter-wave plate 500 and the acousto-optic coupling region 10, thus converting the S-polarized light into second circularly polarized light and performing a third acousto-optic coupling.

[0063] The second circularly polarized light is reflected by the second reflector 900, so that the second circularly polarized light passes through the acousto-optic coupling region 10 and the quarter-wave plate 500 again, and undergoes a fourth acousto-optic coupling, converting the second circularly polarized light back into P-polarized light.

[0064] After the second circularly polarized light is converted back to P-polarized light, it passes through the first beam splitter 400 to obtain deflected laser light. The deflection angle of the deflected laser light is detected by a detection device to obtain the sound pressure information of the acousto-optic coupling region 10. In this embodiment, the laser light passes through the quarter-wave plate 500 four times and then becomes P-polarized light again, which can pass through the first beam splitter 400 and enter the detection device. The detection device detects the deflection angle of the laser light, and based on the correspondence between the laser deflection angle and the sound pressure in the acousto-optic coupling region 10, the sound pressure information in the acousto-optic coupling region 10 can be obtained.

[0065] In this embodiment, the laser travels back and forth to the acoustic-optical fusion zone four times to improve the acoustic-optical coupling effect. Furthermore, the laser deflection angles are linearly superimposed, which increases the laser deflection angle and facilitates the measurement of the laser deflection angle by the detection device.

[0066] In some embodiments of this application, the detection device includes: a second beam splitter 300, a convex lens 700, and a position-sensitive detector 800. The second beam splitter 300 is disposed between the laser 100 and the first beam splitter 400. The position-sensitive detector 800 is disposed on the reflected light path of the second beam splitter 300. The convex lens 700 is disposed between the second beam splitter 300 and the position-sensitive detector 800. The position-sensitive detector 800 is located on the focal plane of the convex lens 300. The method for detecting the deflection angle of the deflected laser using the detection device includes:

[0067] The deflected laser is reflected by the second beam splitter 300 to the convex lens 700, and the deflected laser forms a light spot on the position-sensitive detector 800 after passing through the convex lens 700.

[0068] Based on the position-sensitive detector 800, the offset of the light spot formed by the deflected laser on the position-sensitive detector 800 relative to the origin is obtained. In this embodiment, the laser hitting the position-sensitive detector 800 generates an electrical signal. The electrical signal will differ depending on the location of the laser hitting the detector, thus allowing the detection of the light spot offset. The specific structure and working principle of the position-sensitive detector 800 are existing mature technologies and will not be described in detail here.

[0069] To obtain the focal length of a convex lens 70°, use the formula... Calculate the deflection angle of the deflecting laser, where θ is the deflection angle of the deflecting laser, d is the offset of the spot formed by the deflecting laser in the position-sensitive detector 800 relative to the origin, and f is the focal length of the convex lens 700.

[0070] In this embodiment, the deflection angle of the deflected laser can be obtained by acquiring the offset of the light spot formed by the deflected laser on the position-sensitive detector 800 relative to the origin. In addition, the deflected laser is focused onto the position-sensitive detector 800 located at the focal plane of the convex lens 700 by the convex lens 700, ensuring that the deflected laser can stably hit the position-sensitive detector 800 to form a light spot.

[0071] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An optical path system for improving acoustic-optical coupling, characterized in that, include: A laser, used to emit laser light; A first beam splitter is located in the light output direction of the laser, and the beam splitting mirror of the first beam splitter is configured to transmit P-polarized light and reflect S-polarized light. The first reflector is located on the reflected light path of the first beam splitter, and the mirror surface of the first reflector forms a 45° angle with the beam splitter mirror surface of the first beam splitter. The second reflector is located on the transmission light path of the first beam splitter, and the mirror surface of the second reflector forms a 45° angle with the beam splitting mirror surface of the first beam splitter. A quarter-wave plate is disposed between the second reflector and the first beam splitter. An acousto-optic coupling region is also provided between the quarter-wave plate and the second reflector. The laser undergoes an acousto-optic effect in the acousto-optic coupling region, causing the propagation path of the laser to deflect to produce a deflection angle. A detection device is disposed between the laser and the first beam splitter, and the detection device is used to detect the deflection angle of the laser returning from the first beam splitter.

2. The optical path system for improving acoustic-optical coupling effect according to claim 1, characterized in that, The detection device includes a second beam splitter and a detector. The second beam splitter is located between the laser and the first beam splitter, and the detector is located on the reflected light path of the second beam splitter. The second beam splitter is used to reflect the laser light returning from the first beam splitter to the detector.

3. The optical path system for improving acoustic-optical coupling effect according to claim 2, characterized in that, The detector is a position-sensitive detector.

4. The optical path system for improving acoustic-optical coupling effect according to claim 3, characterized in that, A convex lens is disposed between the second beam splitter and the position-sensitive detector, with the position-sensitive detector located on the focal plane of the convex lens. The deflection angle of the laser after a single acousto-optic coupling is: Where d is the offset of the laser spot formed by the laser on the position-sensitive detector relative to the origin, and f is the focal length of the convex lens.

5. The optical path system for improving acoustic-optical coupling effect according to claim 2, characterized in that, A half-wave plate is disposed between the laser and the second beam splitter. The half-wave plate is used to change the polarization direction of the laser so that the intensity of the P-polarized light transmitted by the first beam splitter is maximized.

6. The optical path system for improving acoustic-optical coupling effect according to claim 2, characterized in that, The second beam splitter is a beam splitting prism, which is configured such that the intensity of the transmitted light is greater than the intensity of the reflected light.

7. The optical path system for improving acoustic-optical coupling effect according to claim 2, characterized in that, The first beam splitter is a polarizing beam splitter prism.

8. A method for sound pressure detection to improve acoustic-optical coupling, based on the optical path system of claim 1, characterized in that, The method includes: The laser is polarized and split using the first beam splitter to obtain P-polarized light. The P-polarized light is passed through the quarter-wave plate and the acousto-optic coupling region, causing the P-polarized light to be converted into the first circularly polarized light and undergoing the first acousto-optic coupling. The first circularly polarized light is reflected by the second mirror, allowing it to pass through the acousto-optic coupling region and the quarter-wave plate again for a second acousto-optic coupling, thus converting the first circularly polarized light into S-polarized light. S-polarized light is reflected by the first beam splitter into the first mirror. The first mirror reflects the S-polarized light back to the first beam splitter. The first beam splitter reflects the S-polarized light again, causing the S-polarized light to pass through the quarter-wave plate and the acousto-optic coupling region. The S-polarized light is then converted into second circularly polarized light and undergoes a third acousto-optic coupling. The second circularly polarized light is reflected by the second mirror, so that the second circularly polarized light passes through the acousto-optic coupling region and the quarter-wave plate again, undergoes a fourth acousto-optic coupling, and converts the second circularly polarized light back into P-polarized light. After the second circularly polarized light is converted back to P-polarized light, it is transmitted through the first beam splitter to obtain deflected laser light. The deflection angle of the deflected laser light is detected by a detection device to obtain the sound pressure information of the acousto-optic coupling region.

9. The sound pressure detection method for improving acoustic-optical coupling effect according to claim 8, characterized in that, The detection device includes: a second beam splitter, a convex lens, and a position-sensitive detector. The second beam splitter is disposed between the laser and the first beam splitter. The detector is disposed on the reflected light path of the second beam splitter. The convex lens is disposed between the second beam splitter and the position-sensitive detector, and the position-sensitive detector is located on the focal plane of the convex lens. The method for detecting the deflection angle of the deflected laser using the detection device includes: The deflected laser is reflected to the convex lens by the second beam splitter, and the deflected laser forms a spot on the position-sensitive detector after passing through the convex lens; Based on the position-sensitive detector, the offset of the spot formed by the deflected laser on the position-sensitive detector relative to the origin is obtained; To obtain the focal length of a convex lens, use the formula... Calculate the deflection angle of the deflecting laser, where θ is the deflection angle of the laser, d is the offset of the laser spot formed on the position-sensitive detector relative to the origin, and f is the focal length of the convex lens.

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