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

Abstract

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

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and particularly to an optical path system for improving acousto-optic coupling effect and a sound pressure detection method. Background Art

[0002] A laser acoustic field hydrophone is a high-tech device that uses laser technology to detect underwater acoustic fields. It indirectly obtains acoustic field information by measuring the changes after the coupling of laser and underwater acoustic waves. The working principle of the laser hydrophone is based on the acousto-optic effect. That is, when an acoustic wave passes through a water body, it will cause slight changes in the density and refractive index of the water body. These changes will affect the propagation path of the laser beam passing through the water body, causing the laser to deflect. The sound pressure of the acoustic field is indirectly measured by detecting the deflection angle of the laser.

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

[0004] The purpose of the embodiments of the present application is to provide an optical path system for improving acousto-optic coupling effect, aiming to solve the problems that in the optical path system of traditional laser acoustic field hydrophones, the coupling effect between the laser and the acoustic waves in the acoustic field is poor, and the deflection angle of the laser is small and not easy to measure.

[0005] The embodiments of the present application are implemented as follows. An optical path system for improving acousto-optic coupling effect includes:

[0006] A laser for emitting laser light;

[0007] A first beam splitter disposed in the light-emitting direction of the laser, and the splitting mirror surface of the first beam splitter is configured to transmit P-polarized light and reflect S-polarized light;

[0008] A first reflecting mirror located on the reflected light path of the first beam splitter, and the mirror surface of the first reflecting mirror forms a 45° angle with the splitting mirror surface of the first beam splitter;

[0009] A second reflecting mirror located on the transmitted light path of the first beam splitter, and the mirror surface of the second reflecting mirror forms a 45° angle with the splitting mirror surface of the first beam splitter;

[0010] A 1 / 4 wave plate is disposed between the second reflecting mirror and the first beam splitter. An acousto-optic coupling region is also provided between the 1 / 4 wave plate and the second reflecting mirror. Acousto-optic effect occurs to the laser in the acousto-optic coupling region, causing the propagation path of the laser to deviate and generating a deflection angle;

[0011] The detection device is arranged between the laser and the first beam splitter, and is used 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 includes a second beam splitter and a detector. The second beam splitter is arranged between the laser and the first beam splitter, and the detector is arranged on the reflection light path of the second beam splitter. The second beam splitter is used 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. The deflection angle after single acousto-optic coupling of the laser is:

[0015] where d is the offset of the light spot formed by the laser 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 the half-wave plate is used 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 the maximum.

[0017] In some preferred embodiments of the present application, the second beam splitter is an ordinary beam splitting prism, and the ordinary beam splitting prism is configured such that the light intensity of the transmitted light is greater than the light intensity of the reflected light.

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

[0019] The embodiment of the present application also provides an acoustic pressure detection method for improving the acousto-optic coupling effect. Based on the above optical path system, the method includes:

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

[0021] Making the P-polarized light pass through a quarter-wave plate and an acousto-optic coupling region to convert the P-polarized light into a first circularly polarized light and perform the first acousto-optic coupling;

[0022] Reflecting the first circularly polarized light based on the second reflector so that the first circularly polarized light passes through the acousto-optic coupling region and the quarter-wave plate again, perform the second acousto-optic coupling and convert the first circularly polarized light into S-polarized light;

[0023] The S-polarized light is reflected by the first beam splitter and enters the first reflector. The first reflector 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 a quarter-wave plate and an acousto-optic coupling region, converting the S-polarized light into a second circularly polarized light and performing the third acousto-optic coupling;

[0024] Based on the reflection of the second circularly polarized light by the second reflector, the second circularly polarized light passes through the acousto-optic coupling region and the quarter-wave plate again, performing the fourth acousto-optic coupling and converting the second circularly polarized light back into P-polarized light;

[0025] After the second circularly polarized light is converted back into P-polarized light, it transmits 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 acoustic pressure information in the acousto-optic coupling region.

[0026] In some preferred embodiments of the present 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 reflection light path of the second beam splitter. The convex lens is disposed between the second beam splitter and the position-sensitive detector. 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 light by the detection device includes:

[0027] Based on the second beam splitter reflecting the deflected laser light to the convex lens, the deflected laser light forms a light spot on the position-sensitive detector after passing through the convex lens;

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

[0029] Obtain the focal length of the convex lens, and based on the formula Calculate the deflection angle of the deflected laser light, where θ is the deflection angle of the laser, d is the offset of the light spot formed by the laser on the position-sensitive detector relative to the origin, and f is the focal length of the convex lens.

[0030] An optical path system for improving acousto-optic coupling effect provided by the embodiments of the present application, through the combined action of the first beam splitter, the quarter-wave plate, the first reflector, and the second reflector, enables the laser to pass through the acousto-optic coupling region four times reciprocally, and the deflection angles of the laser are linearly superimposed. In this way, the acousto-optic coupling effect can be improved, and the deflection angle of the laser can be increased for easy detection. Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of an optical path system for improving acousto-optic coupling effect provided by the embodiments of the present application;

[0032] Figure 2 Schematic diagram of the propagation path of laser in an optical path system for improving acousto-optic coupling effect provided by an embodiment of the present application;

[0033] Figure 3 Schematic diagram of measuring the deflection angle of laser in an optical path system for improving acousto-optic coupling effect provided by an embodiment of the present application.

[0034] Wherein:

[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 measured; 50. Focal plane. Detailed implementation manners

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present 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 only used to explain the present invention, but not to limit the present invention.

[0038] The following describes the specific implementation of the present application in detail with reference to specific embodiments.

[0039] The inventor's research found that in the optical path system of traditional laser-acoustic field hydrophones, the laser usually only passes through the acoustic field once, resulting in poor coupling effect between the laser and the sound wave in the acoustic field, and a small deflection angle of the laser. The measurement of small deflection angles requires a high-precision detector, which increases the complexity and cost of the system. However, the optical path system provided by the present application enables the laser to pass through the acousto-optic coupling region four times reciprocally, improving the acousto-optic coupling effect and increasing the deflection angle of the laser. In this way, the dependence on high-precision detectors is reduced and the cost is lowered. The following is an explanation with reference to the accompanying drawings.

[0040] As Figure 1 shown, it is a schematic structural diagram of an optical path system for improving acousto-optic coupling effect provided by an embodiment of the present application, including: laser 100, first beam splitter 400, first reflector 600, second reflector 900 and quarter-wave plate 500.

[0041] The laser 100 is used to emit laser, and its specific structure and principle are existing mature technologies, which will not be elaborated here.

[0042] The first beam splitter 400 is arranged 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 with a polarization direction parallel to the incident plane. "P" represents "parallel", that is, the vibration direction of the light is parallel to the incident plane. Opposite to the P-polarized light is the S-polarized light, whose polarization direction is perpendicular to the incident plane, and "S" represents "senkrecht", which means "perpendicular" in German.

[0043] The first reflector 600 is located on the reflection 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 of the first beam splitter 400 back to the first beam splitter 400.

[0044] The second reflector 900 is located on the transmission 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] The 1 / 4 wave plate 500 is arranged between the second reflector 900 and the first beam splitter 400. The 1 / 4 wave plate 500 is mainly used to change the polarization state of light. It can cause a phase delay of 1 / 4 wavelength between two mutually perpendicular polarization directions of the laser, making the linearly polarized light become circularly polarized light and the circularly polarized light become linearly polarized light. Specifically, in this embodiment, the P-polarized light becomes the first circularly polarized light after passing through the 1 / 4 wave plate 500, and the first circularly polarized light becomes the S-polarized light after passing through the 1 / 4 wave plate 500 again. The S-polarized light becomes the second circularly polarized light after passing through the 1 / 4 wave plate 500, and the second circularly polarized light becomes the P-polarized light again after passing through the 1 / 4 wave plate 500. It can be simply understood that after the P-polarized light passes through the 1 / 4 wave plate 500 twice, the polarization direction rotates 90° to become the S-polarized light, and after the S-polarized light passes through the 1 / 4 wave plate 500 twice, the polarization direction rotates 90° to become the P-polarized light.

[0046] An acousto-optic coupling region 10 is also provided between the 1 / 4 wave plate 500 and the second reflector 900. Acousto-optic effect occurs to the laser in the acousto-optic coupling region, causing the propagation path of the laser to deviate and generating a deflection angle. When sound waves pass through the water body, it will cause slight changes in the density and refractive index of the water body, and these changes will affect the propagation path of the laser passing through the water body, causing the laser to deflect. By detecting the deflection angle of the laser, the sound pressure information of the sound wave can be measured.

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

[0048] Figure 2 This is a schematic diagram of the propagation path of laser light in an optical path system for improving the acousto-optic coupling effect provided by an embodiment of the present application. As Figure 2 shown, when the laser is horizontally incident on the first beam splitter 400 from left to right, the laser will deflect upward by θ after passing through the acousto-optic coupling region 10 for the first time. After being reflected by the second mirror 900 and entering the acousto-optic coupling region 10 for the second acousto-optic coupling, the deflection angle of the laser is 2θ, and after being reflected by the first beam splitter 400 and the first mirror 600, the deflection angle remains 2θ. After the laser passes through the acousto-optic coupling for the third time, the deflection angle is 3θ, and after the second reflection by the second mirror, it remains 3θ. After the fourth acousto-optic coupling, the laser deflects again, and the deflection angle reaches 4θ. Therefore, in the traditional optical path system, only one acousto-optic coupling is performed, and the deflection angle is only θ, while in the acousto-optic coupling optical path system of the present application, four acousto-optic couplings can be achieved, and the deflection angle of the laser can reach 4θ.

[0049] It should be noted that the laser deflection caused by acousto-optic coupling is usually on the order of a few tenths of a degree, and the paths of the laser traveling back and forth in the acousto-optic coupling region are basically the same. Therefore, the deflection angles of the laser traveling back and forth in the acousto-optic coupling region multiple times can be considered equal. In addition, the deflection angle of the laser is too small to be conveniently shown. Figure 2The laser deflection angle shown in Figure 2 The degree of the deflection angle in

[0050] As shown in Figure 1 As a preferred embodiment of the present 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 reflection light path of the second beam splitter 300. The second beam splitter 300 is configured to reflect the laser returned from the first beam splitter 400 to the detector.

[0051] In this embodiment, as shown in Figure 1 The laser emitted by the laser 100 is incident on the second beam splitter 300. A part of the light is reflected upward and no longer used, and another part of the light passes through the second beam splitter 300 and enters the first beam splitter 400. When the laser passes through four acousto-optic couplings and passes through the first beam splitter 400 and returns to the second beam splitter 300 again, a part of the laser is reflected downward by the second beam splitter 300 and enters the detector. The deflection angle of the laser is detected by the detector, and then the sound pressure information is obtained.

[0052] In some embodiments of the present application, the second beam splitter 300 is a beam splitting prism, and the beam splitting prism is configured such that the light intensity of the transmitted light is greater than the light intensity of the reflected light. Thus, the light intensity of the light reflected by the second beam splitter 300 into the detection device can be reduced, preventing damage to the detection device. In some embodiments, the second beam splitter 300 is an ordinary beam splitting prism. The term "ordinary" herein is used to distinguish from a polarization beam splitting prism. An ordinary beam splitting prism is insensitive to polarization and is configured to split an incident light into transmitted light and reflected light according to a specific light intensity ratio.

[0053] As shown in Figure 1 As a preferred embodiment of the present application, the detector is a position sensitive detector 800. In this embodiment, when the laser does not deflect, the laser irradiates 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 amount of the light spot by the detector 800, the deflection angle of the laser can be obtained. Thus, the deflection angle of the laser can be conveniently obtained.

[0054] As shown in Figure 1 and Figure 3 As a preferred embodiment of the present application, a 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 50 of the convex lens 700. The deflection angle of the laser for a single acousto-optic coupling Wherein, d is the offset of the light spot formed by the laser on the position sensitive detector 800 relative to the origin, and f is the focal length of the convex lens 700.

[0055] As Figure 2 and Figure 3 shown, according to the characteristics of the convex lens, parallel light rays will converge at the same point on the focal plane 50 after passing through the lens. Therefore, draw an auxiliary line 30 parallel to the laser 40 to be measured passing through the optical center (point c) of the convex lens. The auxiliary line 30 intersects the focal plane 50 at point a. Then, the laser 40 to be measured will irradiate at point a after passing through the convex lens 700. According to the geometric relationship, it can be obtained that wherein, the distance l between point a and point b a is equal to the light spot offset d measured by the position sensitive detector 800, and the distance l between point b and point c b is equal to the focal length f of the convex lens 700. After arrangement, it can be obtained that The convex lens 700 can make parallel light hit the same point on the focal plane 50. In this way, it is possible to measure only the deflection angle of the laser and reduce the interference caused by the reflection of the laser from different positions of the second beam splitter 300. Since lasers with the same deflection angle, even if they are reflected from different positions of the second beam splitter 300, they are still parallel light after reflection, and the parallel light will hit the same point on the focal plane 50, that is, the measured light spot offset is the same. In this way, the deflection angle of the laser can be accurately measured.

[0056] As Figure 1 shown, as a preferred embodiment of the present application, a half-wave plate 200 is provided 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 light intensity of the P-polarized light transmitted by the first beam splitter 400 is the maximum. In this way, the light utilization rate can be improved.

[0057] As Figure 1 shown, as a preferred embodiment of the present application, the first beam splitter 400 is a polarization beam splitting prism. Compared with other polarization beam splitters, the polarization beam splitting prism has good polarization separation effect, small light energy loss, and high mechanical stability.

[0058] The embodiment of the present application also provides a sound pressure detection method for improving the acousto-optic coupling effect. The method is based on the above optical path system, and the method includes:

[0059] Polarization beam splitting of the laser is performed based on the first beam splitter 400 to obtain P-polarized light. In this embodiment, the laser 100 emits laser light, and the laser light hits the first beam splitter 400. The first beam splitter 400 divides the laser light into S-polarized light and P-polarized light, reflects the S-polarized light, and transmits the P-polarized light. In this way, P-polarized light can be obtained.

[0060] The P polarized light is made to pass through the 1 / 4 wave plate 500 and the acousto-optic coupling region 10, so that the P polarized light is converted into the first circularly polarized light and the first acousto-optic coupling is performed. In this embodiment, the 1 / 4 wave plate 500 is mainly used to change the polarization state of light. It can make the two mutually perpendicular polarization directions of the laser produce a phase delay of 1 / 4 wavelength, so that the linear polarized light is converted into circularly polarized light, and the circularly polarized light is converted into linearly polarized light. When the laser passes through the acousto-optic coupling region 10, an acousto-optic effect occurs, and the laser deviates from the original path to propagate, generating a deflection angle.

[0061] Based on the reflection of the first circularly polarized light by the second reflector 900, the first circularly polarized light passes through the acousto-optic coupling zone 10 and the 1 / 4 wave plate 500 again, performs a second acousto-optic coupling and converts the first circularly polarized light into S polarized light. In this embodiment, the first circularly polarized light becomes S polarized light after passing through the 1 / 4 wave plate 500 again. The S polarized light cannot pass through the first beam splitter 400 into the detection device and can only be reflected by the first beam splitter 400 to continue the subsequent acousto-optic coupling. When the laser passes through the acousto-optic coupling zone for the second time, the acousto-optic coupling is performed for the second time, and the deflection is performed again, and the deflection angles are superimposed.

[0062] The S-polarized light is reflected by the first beam splitter 400 and enters 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, so that the S-polarized light passes through the 1 / 4 wave plate 500 and the acousto-optic coupling region 10, so that the S-polarized light is converted into the second circularly polarized light and undergoes 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 1 / 4 wave plate 500 again, performs the fourth acousto-optic coupling and converts 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 transmits the first beam splitter 400 to obtain a deflected laser, and the deflection angle of the deflected laser is detected by the detection device to obtain the sound pressure information of the acousto-optic coupling region 10. In this embodiment, the laser light is converted back to P polarized light after passing through the 1 / 4 wave plate 500 four times, and can transmit 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 corresponding relationship between the deflection angle of the laser light 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 acousto-optic fusion zone four times to improve the acousto-optic coupling effect, and the deflection angle of the laser is linearly superimposed to increase the deflection angle of the laser, making it easier for the detection device to measure the laser deflection angle.

[0066] In some embodiments of the present 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 reflection 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 by the detection device includes:

[0067] Based on the second beam splitter 300 reflecting the deflected laser to the convex lens 700, 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, obtain the offset of the light spot formed by the deflected laser on the position sensitive detector 800 relative to the origin. In this embodiment, when the laser hits the position sensitive detector 800, an electrical signal will be generated. When the laser hits different positions, the electrical signals will be different. Thus, the offset of the light spot can be detected. The specific structure and working principle of the position sensitive detector 800 are existing mature technologies and will not be elaborated here.

[0069] Obtain the focal length of the convex lens 700, and based on the formula calculate the deflection angle of the deflected laser, where θ is the deflection angle of the deflected laser, d is the offset of the light spot formed by the deflected laser on the position sensitive detector 800 relative to the origin, and f is the focal length of the convex lens 700.

[0070] In this embodiment, by obtaining the offset of the light spot formed by the deflected laser on the position sensitive detector 800 relative to the origin, the deflection angle of the deflected laser can be obtained. In addition, the deflected laser is focused by the convex lens 700 onto the position sensitive detector 800 located on the focal plane of 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 are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. An optical path system for improving the effect of acousto-optic coupling, characterized in that: include: Laser, used for emitting laser light; A first beam splitter is arranged in the light emitting direction of the laser, wherein the beam splitter surface of the first beam splitter is configured to transmit P polarized light and reflect S polarized light; A first reflector, located on the reflected light path of the first beam splitter, wherein a mirror surface of the first reflector forms an angle of 45° with a beam splitter surface of the first beam splitter; A second reflector is located on the transmission light path of the first beam splitter, and the mirror surface of the second reflector forms an angle of 45° with the beam splitter surface of the first beam splitter; A quarter wave plate is disposed between the second reflector and the first beam splitter, and an acousto-optic coupling region is also disposed between the quarter wave plate and the second reflector. The laser generates an acousto-optic effect in the acousto-optic coupling region, so that the propagation path of the laser is offset to generate a deflection angle; The detection device is disposed between the laser and the first beam splitter, and is used to detect the deflection angle of the laser beam returned from the first beam splitter.

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

3. The optical path system for improving the 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 the acoustic-optical coupling effect according to claim 3, characterized in that: A convex lens is arranged 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 deflection angle of the laser after single-shot acousto-optic coupling is: Wherein, d is the offset of the light 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 the acoustic-optical coupling effect according to claim 2, characterized in that: A half-wave plate is arranged between the laser and the second beam splitter, and 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 the acoustic-optical coupling effect according to claim 2, characterized in that: The second beam splitter is a beam splitter prism, and the beam splitter prism is configured so that the light intensity of the transmitted light is greater than the light intensity of the reflected light.

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

8. A sound pressure detection method for improving the acoustic-optical coupling effect, based on the optical path system of claim 1, characterized in that: The method comprises: Perform polarization splitting on the laser based on the first beam splitter to obtain P polarized light; Allow the P polarized light to pass through the quarter wave plate and the acousto-optic coupling region, so that the P polarized light is converted into the first circularly polarized light and the first acousto-optic coupling is performed; Reflecting the first circularly polarized light based on the second reflector, so that the first circularly polarized light passes through the acousto-optic coupling region and the 1 / 4 wave plate again, performing a second acousto-optic coupling and converting the first circularly polarized light into S-polarized light; The S-polarized light is reflected by the first beam splitter and enters the first reflector, the first reflector reflects the S-polarized light back to the first beam splitter, the first beam splitter reflects the S-polarized light again, so that the S-polarized light passes through the 1 / 4 wave plate and the acousto-optic coupling region, the S-polarized light is converted into the second circularly polarized light and the acousto-optic coupling is performed for the third time; Based on the second reflector, the second circularly polarized light is reflected so that the second circularly polarized light passes through the acousto-optic coupling region and the quarter wave plate again, performs the fourth acousto-optic coupling and converts the second circularly polarized light back into P polarized light; The second circularly polarized light is converted back to P polarized light and then transmits 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 zone.

9. A method for detecting sound pressure for improving the effect of acoustic-optical coupling according to claim 8, characterized in that: The detection device comprises: a second beam splitter, a convex lens and a position sensitive detector, wherein the second beam splitter is arranged between the laser and the first beam splitter, the detector is arranged on the reflected light path of the second beam splitter, the convex lens is arranged 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 by the detection device comprises: Reflecting the deflected laser to the convex lens based on the second beam splitter, so that the deflected laser forms a light spot on the position sensitive detector after passing through the convex lens; Based on the position sensitive detector, obtaining an offset of a light spot formed by the deflected laser on the position sensitive detector relative to an origin; Get the focal length of the convex lens, based on the formula The deflection angle of the deflected laser is calculated, wherein θ is the deflection angle of the laser, d is the offset of the light spot formed by the laser on the position sensitive detector relative to the origin, and f is the focal length of the convex lens.

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