Distance measurement system

Abstract

The present application relates to a distance measurement system, including an acousto-optic crystal, a laser emitting device, an ultrasonic emitting device and a signal receiving and processing device, wherein the laser emitting device and the signal receiving and processing device are respectively arranged on opposite sides of the acousto-optic crystal, the ultrasonic emitting device and the target object to be measured are respectively arranged on opposite sides of the acousto-optic crystal, and the laser emitting device and the ultrasonic emitting device are located on adjacent sides of the acousto-optic crystal; the laser emitting device emits laser light to the acousto-optic crystal, the ultrasonic emitting device emits ultrasonic waves to the acousto-optic crystal, and the signal receiving and processing device collects the first diffracted light signal generated by the acousto-optic effect of the ultrasonic wave injected into the acousto-optic crystal and the laser, and collects the second diffracted light signal generated by the acousto-optic effect of the ultrasonic wave returned after reaching the surface of the target object to be measured and the laser, and obtains the time difference of the collection, and obtains the measured distance according to the time difference and the preset ultrasonic propagation speed. The present application has high measurement accuracy and a wide range of applications.

Description

Technical Field

[0001] The present application relates to the field of measurement technology, and in particular to a distance measurement system. Background Art

[0002] With the development of science and technology, non-contact measurement technology has emerged. Non-contact measurement is a measurement method based on photoelectric, electromagnetic and other technologies to obtain the surface parameter information of the object without contacting the surface of the object being measured. For example, for non-contact distance measurement, the distance measurement based on time of flight mainly includes ultrasonic ranging and laser ranging.

[0003] Traditional ultrasonic ranging has low accuracy and large errors. Although laser ranging is better than ultrasonic ranging in terms of ranging accuracy, laser testing is ineffective for transparent and translucent objects. Lasers do not propagate well in turbid liquids, low visibility, and hazy atmospheres, which limits the scope of use of laser ranging. Summary of the invention

[0004] Based on this, it is necessary to provide a distance measurement system that can improve measurement accuracy and has a wide range of applications in response to the above technical problems.

[0005] A distance measurement system, comprising: an acousto-optic crystal, a laser emitting device, an ultrasonic emitting device and a signal receiving and processing device, wherein the laser emitting device and the signal receiving and processing device are respectively arranged on opposite sides of the acousto-optic crystal, the ultrasonic emitting device and a target to be measured are respectively arranged on opposite sides of the acousto-optic crystal, and the laser emitting device and the ultrasonic emitting device are located on adjacent sides of the acousto-optic crystal;

[0006] The laser emitting device emits laser to the acousto-optic crystal, the ultrasonic emitting device emits ultrasonic to the acousto-optic crystal, the signal receiving and processing device collects a first diffraction light signal generated by the acousto-optic effect between the ultrasonic wave injected into the acousto-optic crystal and the laser, and collects a second diffraction light signal generated by the acousto-optic effect between the ultrasonic wave returned after passing through the acousto-optic crystal and the laser in the acousto-optic crystal to reach the surface of the target object to be measured, and obtains the time difference between collecting the first diffraction light signal and the second diffraction light signal, and obtains the measured distance according to the time difference and a preset ultrasonic propagation speed.

[0007] The above-mentioned distance measurement system combines the advantages of traditional ultrasonic distance measurement and laser distance measurement by applying the acousto-optic effect of laser and ultrasonic waves to distance measurement. First, the measured distance is based on ultrasonic propagation. Therefore, under the same flight time accuracy, the speed of sound of ultrasonic waves is only one hundred thousandth of the speed of light, which greatly improves the accuracy of laser distance measurement. Secondly, the acousto-optic effect is used to realize the conversion of ultrasonic signals into optical signals. Based on the acousto-optic effect distance measurement, ultrasonic waves are insensitive to color and light intensity, and can be used to identify transparent, translucent and poorly diffuse objects. It can be used for distance measurement in harsh environments such as darkness, dust or smoke, and strong electromagnetic interference, thereby overcoming environmental sensitivity problems and obtaining high-precision distance measurement in complex environments. Therefore, it can make up for the low accuracy of ultrasonic distance measurement and the environmental sensitivity of laser distance measurement, and has high measurement accuracy and a wide range of applications.

[0008] In one embodiment, the incident direction of the laser and the incident direction of the ultrasonic wave are perpendicular to each other.

[0009] In one embodiment, the laser emitting device is an infrared laser.

[0010] In one embodiment, the ultrasonic emitting device includes an excitation signal controller and an ultrasonic transducer, the excitation signal controller is connected to the ultrasonic transducer, and the ultrasonic transducer is arranged on a side of the acousto-optic crystal opposite to the target object to be measured;

[0011] The excitation signal controller sends a pulse signal to the ultrasonic transducer, and the ultrasonic transducer receives the pulse signal and transmits ultrasonic waves to the acousto-optic crystal.

[0012] In one embodiment, the signal receiving and processing device comprises a photodetector and a computing unit, the photodetector is connected to the computing unit, and the photodetector is arranged on a side of the acousto-optic crystal opposite to the laser emitting device;

[0013] The photoelectric detector receives the first diffracted light signal and records the time to obtain a first moment, and receives the second diffracted light signal and records the time to obtain a second moment; the calculation unit calculates the measured distance according to the first moment, the second moment and the ultrasonic propagation speed.

[0014] In one of the embodiments, the distance measuring system further includes an aperture, which is disposed between the laser emitting device and the acousto-optic crystal, and the laser emitted by the laser emitting device passes through the aperture and then enters the acousto-optic crystal.

[0015] In one embodiment, the above-mentioned ranging system also includes a filter component arranged before the signal receiving and processing device, and the filter component is used to filter the first diffraction light signal and the second diffraction light signal, and the signal receiving and processing device collects the diffraction light signal after filtering by the filter component.

[0016] In one embodiment, the filter assembly includes a first polarizer and a second polarizer, wherein the first polarizer is located between the laser emitting device and the acousto-optic crystal, and the second polarizer is located between the acousto-optic crystal and the signal receiving and processing device.

[0017] In one of the embodiments, the distance measuring system further comprises a lens, and the lens is located between the acousto-optic crystal and the signal receiving and processing device.

[0018] In one of the embodiments, the distance measuring system further includes an adjustable bracket, and the ultrasonic transmitting device is disposed on the adjustable bracket. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 is a schematic structural diagram of a distance measurement system in one embodiment;

[0021] Figure 2 A schematic diagram of the structure of a distance measurement system in another embodiment; DETAILED DESCRIPTION

[0022] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0024] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element, or connected to the other element through an intermediate element. In addition, the "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is transmission of electrical signals or data between the connected objects.

[0025] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" etc. specify the presence of stated features, wholes, steps, operations, components, parts or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof.

[0026] In one embodiment, Figure 1 As shown, a distance measurement system is provided, including: an acousto-optic crystal 110, a laser emitting device 130, an ultrasonic emitting device 150 and a signal receiving and processing device 170; the laser emitting device 130 and the signal receiving and processing device 170 are respectively arranged on opposite sides of the acousto-optic crystal 110, the ultrasonic emitting device 150 and the target object 200 to be measured are respectively arranged on opposite sides of the acousto-optic crystal 110, and the laser emitting device 130 and the ultrasonic emitting device 150 are located on adjacent sides of the acousto-optic crystal 110. For example, taking the acousto-optic crystal 110 as a three-dimensional hexahedron, including the top, bottom, front, back, left and right sides, the laser emitting device 130 is arranged on the back side of the acousto-optic crystal 110, the signal receiving and processing device 170 is arranged on the front side of the acousto-optic crystal 110, the ultrasonic emitting device 150 is arranged on the left side of the acousto-optic crystal 110, and the target object 200 to be measured is arranged on the right side of the acousto-optic crystal 110.

[0027] Among them, the laser emitting device 130 is a device that can emit laser, and the ultrasonic emitting device 150 is a device that can emit ultrasonic waves. The acousto-optic crystal 110 is an acousto-optic coupling medium. When the laser passes through the acousto-optic crystal 110 in the presence of an ultrasonic field, the refractive index of the acousto-optic crystal 110 undergoes periodic changes due to the effect of the ultrasonic field, similar to forming a phase grating. When the laser passes through the phase grating, diffraction occurs, that is, the laser and the ultrasonic wave can produce an acousto-optic effect in the acousto-optic crystal 110 to generate a diffracted light signal.

[0028] The signal receiving and processing device 170 is a device that can detect and process optical signals. Specifically, the laser emitting device 130 emits laser to the acousto-optic crystal 110, and the ultrasonic emitting device 150 emits ultrasonic to the acousto-optic crystal 110; the signal receiving and processing device 170 collects the first diffracted light signal generated by the acousto-optic effect of the ultrasonic wave injected into the acousto-optic crystal 110 and the laser, and collects the second diffracted light signal generated by the acousto-optic effect of the ultrasonic wave returned after passing through the acousto-optic crystal 110 and reaching the surface of the target object 200 to be measured and the laser in the acousto-optic crystal 110, and obtains the time difference between collecting the first diffracted light signal and the second diffracted light signal, and obtains the measured distance according to the time difference and the preset ultrasonic propagation speed. That is, after the laser emitting device 130 emits laser to the acousto-optic crystal 110 and the ultrasonic emitting device 150 emits ultrasonic to the acousto-optic crystal 110, the laser and the ultrasonic produce an acousto-optic effect in the acousto-optic crystal 110 to generate a diffracted light signal as the first diffracted light signal, and the ultrasonic wave passes through the acousto-optic crystal 110 and reaches the surface of the target object 200 to be measured and then returns, and the returned ultrasonic wave again produces an acousto-optic effect with the laser in the acousto-optic crystal 110 to generate a diffracted light signal as the second diffracted light signal; the signal receiving and processing device 170 collects the first diffracted light signal and the second diffracted light signal and obtains the time difference between the two. Specifically, the signal receiving and processing device 170 collects two diffracted light signals within one pulse ultrasound cycle.

[0029] Specifically, the signal receiving and processing device 170 may record the time of receiving the first diffracted light signal and the time of receiving the second diffracted light signal, and calculate the time difference between the two recorded times. It is understood that the signal receiving and processing device 170 may also obtain the time difference in other ways, such as starting the timing when the first diffracted light signal is received and stopping the timing when the second diffracted light signal is received to obtain the time difference.

[0030] The measurement distance refers to the distance to the target object 200. The signal receiving device 170 may calculate the measurement distance using a preset calculation model.

[0031] In the above-mentioned distance measurement system, a laser emitting device 130 and an ultrasonic emitting device 150 are used to emit laser and ultrasonic wave to the acousto-optic crystal 110 respectively, and a signal receiving and processing device 170 collects the first diffracted light signal generated by the acousto-optic effect of the laser and ultrasonic wave and the second diffracted light signal generated by the acousto-optic effect of the ultrasonic wave after reaching the surface of the target object 200 to be measured and returning and reacting with the laser. The measured distance is obtained according to the time difference between the two acquisitions and the preset ultrasonic propagation speed. By applying the acousto-optic effect of laser and ultrasonic wave to the distance measurement, the advantages of traditional ultrasonic distance measurement and laser distance measurement are combined. Combined together, first, the measured distance is based on ultrasonic propagation, so under the same flight time accuracy, the speed of ultrasound is only one hundred thousandth of the speed of light, and the accuracy of laser ranging is greatly improved; secondly, the acoustic-optical effect is used to realize the conversion of ultrasonic signals into optical signals. Based on the acoustic-optical effect, ultrasound is insensitive to color and light intensity, and can be used to identify transparent, translucent and poorly diffuse objects. It can be used for ranging in harsh environments such as darkness, dust or smoke, and strong electromagnetic interference, thereby overcoming environmental sensitivity and obtaining high-precision distance measurement in complex environments. Therefore, it can make up for the low accuracy of ultrasonic ranging and the environmental sensitivity of laser ranging, with high measurement accuracy and a wide range of applications.

[0032] In addition, due to the very fast propagation speed of laser in traditional laser ranging, if short-distance high-precision measurement is to be achieved, a photoelectric detector with a fast response speed is required, which is costly. Compared with traditional laser ranging, the ranging system of the present application has the advantages of low cost and simple structure in terms of accurate ranging over short distances.

[0033] In one embodiment, the acousto-optic crystal 110 is an acousto-optic crystal with an acousto-optic figure of merit higher than a preset value. The preset value can be specifically set to a higher acousto-optic figure of merit according to actual needs. An acousto-optic crystal with a high acousto-optic figure of merit is used as a medium for ultrasonic waves and lasers to produce acousto-optic effects, specifically Bragg diffraction. A high acousto-optic figure of merit helps to improve the efficiency of coupling, increase the intensity of diffracted light signals, and improve the signal-to-noise ratio of signals.

[0034] In one embodiment, the incident direction of the laser and the incident direction of the ultrasonic wave are perpendicular to each other. Specifically, the emission direction of the ultrasonic wave beam can be adjusted so that the ultrasonic wave beam is perpendicular to the laser beam, thereby better generating the acousto-optic effect.

[0035] In one embodiment, the laser emitting device 130 is an infrared laser. An infrared laser is a device that emits infrared laser light, and the infrared laser light beam has a small divergence angle, high brightness, and good use effect.

[0036] In one embodiment, if Figure 2As shown, the distance measurement system further includes an aperture 140 , which is disposed between the laser emitting device 130 and the acousto-optic crystal 110 . The laser emitted by the laser emitting device 130 passes through the aperture 140 and then enters the acousto-optic crystal 110 .

[0037] By using a very small diameter aperture 140, only the center part of the laser beam is allowed to pass through, thereby reducing the diameter of the laser beam. While improving the uniformity of the laser beam, the time for the ultrasonic wave to pass through the laser beam can be shortened, thereby obtaining a more accurate time point, improving the time accuracy of the collected signal, and further improving the accuracy of the distance measurement.

[0038] Specifically, the diaphragm 140 may be an diaphragm with a small hole with adjustable aperture. The size of the laser beam passing through the diaphragm 140 may be adjusted by adjusting the aperture of the small hole, which is easy to operate.

[0039] In one embodiment, reference Figure 2 The ultrasonic emitting device 150 includes an excitation signal controller 151 and an ultrasonic transducer 153. The excitation signal controller 151 is connected to the ultrasonic transducer 153. The ultrasonic transducer 153 is arranged on a side of the acousto-optic crystal 110 opposite to the target object 200 to be measured.

[0040] The excitation signal controller 151 sends a pulse signal to the ultrasonic transducer 153, and the ultrasonic transducer 153 receives the pulse signal and transmits ultrasonic waves to the acousto-optic crystal 110. Specifically, the excitation signal controller 151 controls the high-voltage excitation signal, i.e., the pulse signal, according to the set control parameters. By using the excitation signal controller 151 to control the ultrasonic transducer 153 to transmit ultrasonic waves, the structure is simple.

[0041] In one embodiment, reference Figure 2 The signal receiving and processing device 170 includes a photodetector 171 and a computing unit (not shown). The photodetector 171 is connected to the computing unit and is disposed on a side of the acousto-optic crystal 110 opposite to the laser emitting device 130. The photodetector 171 receives the first diffracted light signal and records the time to obtain a first moment, and receives the second diffracted light signal and records the time to obtain a second moment; the computing unit calculates the measured distance according to the first moment, the second moment and the ultrasonic propagation velocity.

[0042] Specifically, the calculation unit can be based on the formula:

[0043]

[0044] The measured distance is calculated. Wherein, L is the measured distance, V is the ultrasonic propagation velocity, T2 is the second moment, and T1 is the first moment.

[0045] The photoelectric detector 171 is used to detect the diffracted light signal generated by the acousto-optic effect to obtain the time when the ultrasonic wave and the laser emitted by the ultrasonic transducer 153 act in the acousto-optic crystal 110 and the time difference when the ultrasonic wave and the laser act in the acousto-optic crystal 110 after being reflected by the target object 200 to be measured and returned to the acousto-optic crystal 110, and the flight time of the ultrasonic wave is obtained, and the distance of the target object 200 to be measured can be accurately measured in combination with the ultrasonic propagation speed. Compared with the traditional ultrasonic probe, the photoelectric detector 171 has a faster response speed and higher time accuracy to obtain time information, so the distance measurement based on the acousto-optic effect has higher accuracy than the traditional ultrasonic distance measurement.

[0046] Specifically, the photodetector 171 may be a high-frequency single-point photodetector to accurately obtain the time points at which the incident ultrasonic wave and the returning ultrasonic wave successively interact with the laser to generate diffracted light signals, thereby improving the test accuracy.

[0047] In one embodiment, the distance measurement system further includes a filter component disposed before the signal receiving and processing device 170, the filter component is used to filter the first diffracted light signal and the second diffracted light signal, and the signal receiving and processing device 170 collects the diffracted light signal after filtering by the filter component. By using the filter component to filter the diffracted light signal, specifically, the laser signal that has not been diffracted can be filtered out, thereby increasing the signal-to-noise ratio of the diffracted light signal, improving the accuracy of light signal collection, and thus improving the accuracy of distance measurement.

[0048] In one of the embodiments, please refer to Figure 2 The filter assembly includes a first polarizer 181 and a second polarizer 182 . The first polarizer 181 is located between the laser emitting device 130 and the acousto-optic crystal 110 , and the second polarizer 182 is located between the acousto-optic crystal 110 and the signal receiving and processing device 170 .

[0049] Specifically, the laser emitted by the laser emitting device 130 passes through the first polarizer 181 and vertically enters the acousto-optic crystal 110, and the laser is emitted from the acousto-optic crystal 110 and passes through the second polarizer 182. Furthermore, the polarization directions of the first polarizer 181 and the second polarizer 182 are perpendicular. By using two polarizers with perpendicular polarization directions, according to the polarization characteristics of the laser, the laser that does not participate in the acousto-optic effect cannot continuously pass through the two polarizers with perpendicular polarization directions, so that the laser signal that does not diffract can be filtered out, the influence of the incident laser on the diffracted light signal is reduced, and the signal-to-noise ratio of the diffracted light signal is increased.

[0050] In one embodiment, the polarization degree of the laser emitted by the laser emitting device 130 is higher than the preset polarization degree. That is, the laser emitted by the laser emitting device 130 has a higher polarization degree. The higher the polarization degree of the laser, the weaker the optical signal that does not participate in the acousto-optic effect after passing through the two polarizers, and the higher the system signal-to-noise ratio.

[0051] In one of the embodiments, please refer to Figure 2 The above-mentioned distance measurement system further includes a lens 190, which is located between the acousto-optic crystal 110 and the signal receiving and processing device 170. The lens 190 is used to focus the diffracted light signal emitted by the acousto-optic crystal 110, so as to facilitate the signal receiving and processing device 170 to collect it.

[0052] In one embodiment, the distance measurement system further includes an adjustable bracket, and the ultrasonic emitting device 150 is disposed on the adjustable bracket. The adjustable bracket is a bracket whose position can be adjusted, and specifically, the adjustable bracket is a bracket whose angle can be adjusted. By using a bracket with an adjustable angle to fix the ultrasonic emitting gripper 150, specifically to fix the ultrasonic transducer 153, the direction in which the ultrasonic wave enters the acousto-optic crystal 110 can be adjusted, and the convenience of use is high.

[0053] like Figure 2 As shown, a detailed embodiment is used to illustrate the steps of using the ranging system:

[0054] S1: The infrared laser emits laser light, which passes through an aperture 140. The aperture 140 has a small hole with an adjustable aperture, and the diameter of the small hole can be adjusted to be very small. The light beam is adjusted so that the laser light beam passing through the aperture 140 can be transformed into a laser light beam with a diameter consistent with the diameter of the aperture of the aperture 140; the laser light beam then passes through the first polarizer 181 and is transformed into polarized light with a certain polarization direction and vertically enters the acousto-optic crystal 110.

[0055] S2: Adjust the second polarizer 182 and detect it with a laser power meter until the power passing through the two polarizers is the lowest, so that when no ultrasonic wave passes through the acousto-optic crystal 110, the laser power passing through the second polarizer 182 is the lowest.

[0056] S3: Turn on the excitation signal controller 151 to generate a pulse signal to the ultrasonic transducer 153. The excitation signal controller 151 gives a pulse excitation signal to the ultrasonic transducer 153, so that the ultrasonic transducer 153 emits an ultrasonic wave, and adjusts the emission direction of the ultrasonic wave so that the ultrasonic wave is perpendicular to the laser.

[0057] The ultrasonic wave enters the acousto-optic crystal 110, where the ultrasonic wave and the laser produce an acousto-optic effect and generate diffracted light. The diffracted light signal emitted from the acousto-optic crystal 110 passes through the second polarizer 182 to filter out the laser light that has not produced the acousto-optic effect. The diffracted light signal passes through the lens 190 and enters the photodetector 171. The diffracted light signal is acquired by the photodetector 171, and the acquisition time T1 is recorded at the same time.

[0058] S4: The ultrasonic wave is reflected by the target object 200 and returns to the acousto-optic crystal 110, generating an acousto-optic effect with the laser for the second time. The diffracted light signal emitted from the acousto-optic crystal 110 passes through the second polarizer 18 and the lens 190 in sequence and enters the photodetector 171. The diffracted light signal is acquired by the photodetector 171, and the acquisition time T2 is recorded at the same time.

[0059] S5: Finally, the measuring distance is calculated by the calculation unit as follows:

[0060]

[0061] Since the measured distance is half of the product of the ultrasonic propagation speed and the measured ultrasonic flight time, under the same flight time accuracy, the ultrasonic propagation speed is only one hundred thousandth of the speed of light, and the accuracy of the corresponding laser ranging is also greatly improved.

[0062] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0063] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A distance measurement system, characterized in that: include: An acousto-optic crystal, a laser emitting device, an ultrasonic emitting device and a signal receiving and processing device, wherein the laser emitting device and the signal receiving and processing device are respectively arranged on two opposite sides of the acousto-optic crystal, the ultrasonic emitting device and the target object to be measured are respectively arranged on two opposite sides of the acousto-optic crystal, and the laser emitting device and the ultrasonic emitting device are located on two adjacent sides of the acousto-optic crystal; The laser emitting device emits laser to the acousto-optic crystal, the ultrasonic emitting device emits ultrasonic to the acousto-optic crystal, the signal receiving and processing device collects a first diffracted light signal generated by the acousto-optic effect between the ultrasonic wave injected into the acousto-optic crystal and the laser, and collects a second diffracted light signal generated by the acousto-optic effect between the ultrasonic wave returned after passing through the acousto-optic crystal and the laser in the acousto-optic crystal after reaching the surface of the target object to be measured, and obtains a time difference between collecting the first diffracted light signal and the second diffracted light signal, and obtains a measured distance according to the time difference and a preset ultrasonic propagation speed; Wherein, the incident direction of the laser and the incident direction of the ultrasonic wave are perpendicular to each other; and the laser emitting device is an infrared laser.

2. The distance measurement system according to claim 1, characterized in that: The ultrasonic emitting device comprises an excitation signal controller and an ultrasonic transducer, wherein the excitation signal controller is connected to the ultrasonic transducer, and the ultrasonic transducer is arranged on a side of the acousto-optic crystal opposite to the target object to be measured; The excitation signal controller sends a pulse signal to the ultrasonic transducer, and the ultrasonic transducer receives the pulse signal and transmits ultrasonic waves to the acousto-optic crystal.

3. The distance measurement system according to claim 1, characterized in that: The signal receiving and processing device comprises a photodetector and a computing unit, wherein the photodetector is connected to the computing unit and is arranged on a side of the acousto-optic crystal opposite to the laser emitting device; The photoelectric detector receives the first diffracted light signal and records the time to obtain a first moment, and receives the second diffracted light signal and records the time to obtain a second moment; the calculation unit calculates the measured distance according to the first moment, the second moment and the ultrasonic propagation speed.

4. The distance measurement system according to claim 1, characterized in that: It also includes an aperture, which is arranged between the laser emitting device and the acousto-optic crystal. The laser emitted by the laser emitting device passes through the aperture and then enters the acousto-optic crystal.

5. The distance measurement system according to claim 1, characterized in that: It also includes a filter component arranged before the signal receiving and processing device, the filter component is used to filter the first diffracted light signal and the second diffracted light signal, and the signal receiving and processing device collects the diffracted light signal after being filtered by the filter component.

6. The distance measurement system according to claim 5, characterized in that: The filter assembly includes a first polarizer and a second polarizer, wherein the first polarizer is located between the laser emitting device and the acousto-optic crystal, and the second polarizer is located between the acousto-optic crystal and the signal receiving and processing device.

7. The distance measurement system according to claim 1, characterized in that: It also includes a lens, which is located between the acousto-optic crystal and the signal receiving and processing device.

8. The distance measurement system according to claim 1, characterized in that: It also includes an adjustable bracket, and the ultrasonic emitting device is arranged on the adjustable bracket.

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