CN111006754A - Scanning type multi-channel coherent laser pickup method and device - Google Patents
Scanning type multi-channel coherent laser pickup method and device Download PDFInfo
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Abstract
The invention discloses a scanning type multichannel coherent laser pickup method and a device, wherein a cooperative target is correspondingly arranged at each position in a target area, the position of the pickup target in the target area is captured and tracked through a video, then an output light beam of a laser light source is divided into a local oscillator light beam and an emission light beam through a beam splitter, the emission light beam is directionally emitted to the cooperative target in the position area, an echo light beam of the cooperative target is received, the echo light beam and the local oscillator light beam are coherently received to obtain signal data, the signal data are transmitted to a main control computer, and the main control computer obtains voice information of the signal data through voice information demodulation. The invention can carry out laser pickup on a pickup target in motion, realizes audio and video synchronous monitoring, has good space selectivity, and has the characteristics of strong anti-noise interference capability, long interception distance, high precision and clear voice.
Description
Technical Field
The invention relates to the technical field of laser pickup, in particular to a scanning type multi-channel coherent laser pickup method and a device.
Background
Audio monitoring becomes an important component of security systems in places such as squares, airports, stations, parks, meeting places and the like, and is an important means for dealing with group emergencies such as prison violent movement and terrorist activities in public places. The sound collection part is the core of the audio monitoring system and mainly collects the sound on site through the vibration of the sound. Because outdoor long distance pickup has strong environmental noise interference, traditional microphone sound collector effect is not good, and the implementation degree of difficulty is very big.
The laser pickup device transmits laser beams to a target, detects nano-level weak vibration signals on the surface of the target caused by sound pressure in a real-time non-contact manner, demodulates the signals and acquires object micro-vibration information, thereby realizing the acquisition of remote passive voice signals.
According to the detection system division, laser pickup can be roughly divided into three types: a positive reflection type laser intensity detection method, a speckle image detection method, and a coherent laser detection method. The positive reflection type laser intensity detection method has the advantages of complex operation, single target type, low detection sensitivity and weak environmental interference resistance, so that the positive reflection type laser intensity detection method cannot play a good role in voice information acquisition; the speckle image detection method utilizes the intensity change of speckle interference to acquire voice information, and although the method is simple to operate and high in sensitivity, the method has high emitted laser power, can cause certain damage to a human body and has weak environmental interference resistance; the coherent laser detection method comprises a homodyne system and a heterodyne system, has the advantages of high sensitivity, high measurement range, quick real-time response, multiple target object types, simplicity in operation and the like, and becomes the main technical means at present, but the detection mode is point-to-point, only accurate voice information can be acquired when a pickup target is in a static state, and when the pickup target moves, the accuracy of the acquired voice is greatly reduced, so that the coherent laser detection method is not suitable for being used in security places such as squares, stations, prisons and the like.
Disclosure of Invention
The invention aims to provide a scanning type multi-channel coherent laser sound pickup method and a device. The invention can carry out laser pickup on a pickup target in motion, has good space selectivity, and also has the characteristics of strong anti-noise interference capability, long interception distance, high precision and clear voice.
The technical scheme of the invention is as follows: a scanning type multi-channel coherent laser pickup method is characterized in that cooperative targets are arranged at a plurality of positions in a target area, and the cooperative targets are used for responding to voice vibration of the surrounding environment; the output light beam of the laser light source is divided into a local oscillation light beam and an emission light beam through a beam splitter, the emission light beam is directionally emitted to a cooperative target which carries out voice vibration response on the pickup target in the position area, the echo light beam of the cooperative target is received, the echo light beam and the local oscillation light beam are coherently received to obtain signal data, the signal data are transmitted to a main control computer, and the main control computer obtains voice information of the signal data through voice information demodulation.
In the scanning type multichannel coherent laser pickup method, the main control computer demodulates the voice information, corrects the signal data, obtains the weak vibration phase of the object surface through arc tangent phase discrimination after correction, and obtains the voice information sensed by the cooperative target through a unwrapping algorithm.
According to the scanning type multichannel coherent laser pickup method, the video data collected by the video capture device and used for tracking the pickup target are sent to the processor, the processor analyzes the pixel coordinate of the target from the received video data, the processor enables the video capture device to aim at the mobile pickup target by driving the pan-tilt servo mechanism according to the pixel coordinate, and meanwhile, the laser pickup device selects the cooperative target closest to the pickup target for voice reception.
In the foregoing scanning multichannel coherent laser pickup method, the echo light beam and the local oscillator light beam enter a 2 × 490 ° optical bridge to perform orthogonal coherent reception, and the optical field is expressed as:
wherein R isN(t) is caused by sound pressure sensed by the echo beamWeak vibration amplitude of object surface, f0Is the laser carrier frequency, c is the speed of light, phiSIs the noise phase of the echo beam, phiLOIs the noise phase of the local oscillator beam;
t is time; eS_NIs the echo beam amplitude; eLO_NIs the local oscillator beam amplitude;
the four outputs after being mixed by the 2 × 490 ° optical bridge are respectively:
wherein phiN_noiseIs the noise phase; i isSIs a direct current quantity related to the echo beam; i isOIs the direct current quantity related to the local oscillator beam;
the in-phase signal and the orthogonal signal with the orthogonal characteristic output by the optical bridge are respectively received by the photoelectric balance detector; the in-phase signal and the orthogonal signal output by the photoelectric balance detector are respectively as follows:
wherein k isinPhotoelectric balance detector response rate, k, of in-phase signalquIs the photoelectric balance detector responsivity of the quadrature signal;
if the response rates of the photodetectors of the in-phase signal and the quadrature signal are consistent, the weak vibration phase of the surface of the object can be obtained by arc tangent phase splitting:
wherein phi isN_noiseIs the noise phase;
finally, reconstructing the voice signal R of the output beam through the unwrapping algorithmN(t)。
In the foregoing scanning multichannel coherent laser pickup method, the echo light beam and the local oscillator light beam enter a 2 × 2180 ° optical bridge for orthogonal coherent reception, and the optical field is expressed as:
wherein R isN(t) is the amplitude of the weak vibration of the surface of the object caused by the sound pressure sensed by the echo beam, f0Is the laser carrier frequency, fshiftIs the amount of frequency shift of the local oscillator beam, c is the speed of light, phiSIs the noise phase of the emitted light beam, phiLOIs the noise phase of the local oscillator beam;
t is time; eS_NIs the echo beam amplitude; eLO_NIs the local oscillator beam amplitude;
the two outputs after being mixed by the 2 × 2180 ° optical bridge are respectively:
wherein phiN_noiseIs the noise phase; i isSIs a direct current quantity related to the echo beam; i isOIs the direct current quantity related to the local oscillator beam;
the two paths of output are received and output by a photoelectric balance detector, and the output data is as follows:
where k is the photoelectric equilibrium detector responsivity, φN_noiseIs the noise phase;
the output data of the photoelectric balance detector is converted into digital data through an analog-to-digital converter, and finally the digital data is acquired by one channel of a data acquisition unit, meanwhile, the other channel of the data acquisition unit acquires a digital driving signal of a frequency shifter, and the acquired data is input into a data processing unit for processing: first, quadrature baseband signals are obtained by quadrature demodulation, which is expressed as:
if the response rates of the photoelectric balance detectors of the in-phase signal and the quadrature signal are consistent, obtaining the weak vibration phase of the object surface by arc tangent phase splitting:
wherein phi isN_noiseIs the noise phase;
finally, reconstructing the voice signal R of the output beam through the unwrapping algorithmN(t)。
In the scanning type multichannel coherent laser pickup method, the transmission of the echo light beam is realized by transmitting the emission light beam to the optical circulator and then transmitting the emission light beam to the light beam scanner through the optical telescope, and the light beam scanner and a cooperative target focus to form directional emission of the emission light beam; the directional emission is carried out by fixing the light beam scanner on the scanning holder, rotating the scanning holder and then matching with the rotating double optical wedges; the optical telescope receives the echo beams of the cooperative target and finally transmits the echo beams to the optical bridge through the optical circulator.
The device for realizing the scanning type multi-channel coherent laser pickup method comprises a laser light source, wherein the laser light source is connected with an optical circulator through a beam splitter;
the output end of the optical circulator is sequentially connected with an optical telescope and a light beam scanner, and the light beam scanner is connected with passive devices arranged at various positions in a target area; the optical circulator and the beam splitter are connected with an optical bridge together, and the optical bridge is a 2 x 490-degree optical bridge; the optical bridge is connected with an analog-to-digital converter through a photoelectric balance detector, and the analog-to-digital converter is connected with a main control computer through a data acquisition unit; the main control computer is also connected with the light beam scanner.
The device for realizing the scanning type multi-channel coherent laser pickup method comprises a laser light source, wherein the laser light source is connected with an optical circulator and a frequency shifter through a beam splitter;
the output end of the optical circulator is sequentially connected with an optical telescope and a light beam scanner, and the light beam scanner is connected with passive devices arranged at various positions in a target area; the optical circulator and the frequency shifter are connected with an optical bridge together, and the optical bridge is a 2 x 2180-degree optical bridge; the optical bridge is connected with an analog-to-digital converter through a photoelectric balance detector, and the analog-to-digital converter is connected with a main control computer through a data acquisition unit; the data acquisition unit is also connected with the digital output of the frequency shifter; the main control computer is also connected with the light beam scanner.
In the device, a polarizer is further arranged between the laser light source and the beam splitter; and a laser amplifier is also arranged between the beam splitter and the optical circulator.
The device, the cooperative target of which is a passive device, comprises a substrate layer for fixing, an intermediate layer and a waterproof layer; the surface of the middle layer is coated with a low-acoustic-resistance diaphragm made of high-reflection materials; the waterproof layer is a waterproof sound-transmitting film made of PE materials.
Compared with the prior art, the invention correspondingly arranges a cooperative target at each position in the target area, and the laser sound pick-up selects the cooperative target closest to the pickup target for voice reception by capturing and tracking the pickup target position in the target area through the video; then dividing an output light beam of the laser light source into a local oscillation light beam and an emission light beam through a beam splitter, directionally emitting the emission light beam to a cooperative target which carries out voice vibration response on the pickup target in the position area, receiving an echo light beam of the cooperative target, carrying out coherent reception on the echo light beam and the local oscillation light beam to obtain signal data, and transmitting the signal data to a main control computer, wherein the main control computer obtains voice information of the signal data through voice information demodulation; therefore, the invention covers the area through a plurality of cooperative targets, so that the emitted light beam can be emitted to the plurality of cooperative targets in different time periods, thereby flexibly realizing the optimized laser pickup of the pickup target in motion and having good space selectivity; when the echo light beams of the cooperative target are obtained, the voice information is obtained by coherent reception of the local oscillation light beams and the echo light beams and demodulation of the voice information by the main control computer. The invention can realize audio and video synchronous monitoring and has the characteristics of strong anti-noise interference capability, long interception distance, high precision and clear voice. In addition, the invention has the characteristics of simple overall structure and simple and convenient system operation, and has good application prospect.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic diagram of the beam scanner of the present invention;
FIG. 3 is a schematic diagram of a cooperative target architecture of the present invention;
fig. 4 is a sound pickup flowchart;
FIG. 5 is a schematic structural diagram of an apparatus in embodiment 3 of the present invention.
The labels in the figures are: 1. a laser light source; 2. a beam splitter; 3. an optical circulator; 4. an optical telescope; 5. a light beam scanner; 6. a passive device; 7. an optical bridge; 8. a photoelectric balance detector; 9. an analog-to-digital converter; 10. a data acquisition unit; 11. a main control computer; 13. A polarizer; 14. a laser amplifier; 15. a base layer; 16. an intermediate layer; 17. a waterproof layer; 18. a frequency shifter.
Detailed Description
The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.
Example 1: a scanning type multichannel coherent laser pickup method includes setting a cooperative target at each position in a target area, capturing and tracking the position of the pickup target in the target area through video, dividing an output light beam of a laser light source into a local oscillator light beam and an emission light beam through a beam splitter, directionally emitting the emission light beam to a cooperative target 6 in the position area for carrying out voice vibration response on the pickup target, receiving an echo light beam of the cooperative target, carrying out coherent reception on the echo light beam and the local oscillator light beam to obtain signal data, transmitting the signal data to a main control computer, and demodulating the signal data by the main control computer to obtain voice information of the signal data.
Example 2: a device of a scanning type multichannel coherent laser pickup method is shown in figure 1 and comprises a laser light source 1, wherein the laser light source 1 adopts a 1550nm single-mode narrow-linewidth continuous optical fiber laser safe to human eyes, the linewidth of the laser is 10kHz, the output power is 20mW, and the optical fiber output has isolation protection; a polarizer 13 is arranged between the laser light source 1 and the beam splitter 2; the optical fiber coupling output light beam firstly passes through the polarizer 13, the polarization extinction ratio is ensured to be more than 25dB, and the polarization direction can be controlled to rotate; the laser light source 1 is connected with an optical circulator 3 through a beam splitter 2; the beam splitter 2 is a 1 × 2 fiber polarization beam splitter, and the polarization states of two paths of light emitted by the light beam of the laser source through the 1 × 2 fiber polarization beam splitter are horizontal polarization (P light) and vertical polarization (S light), respectively. The emergent polarization direction is changed by adjusting the polarizer 13, the light intensity of two paths output by the 1 multiplied by 2 optical fiber polarization beam splitter is ensured to be 10:90, a P light branch is used as a transmission light beam, and an S light branch is used as a local oscillation light beam;
the output end of the optical circulator 3 is sequentially connected with an optical telescope 4 and a light beam scanner 5, a laser amplifier 14 is further arranged between the beam splitter 2 and the optical circulator 3, the laser amplifier 14 (erbium-doped fiber amplifier) amplifies the light beam and the light beam, the light beam enters the optical circulator 3, the optical circulator 3 is composed of a laser collimator, a polarization beam splitter, a Faraday optical rotator and a half-wave plate, the Faraday optical rotator rotates the polarization state of horizontal polarized light by 45 degrees, the slow axis of the half-wave plate and the incident polarization state form 22.5 degrees, the polarization state of transmitted polarized light can be rotated by 90 degrees, and the polarization state of received light is kept unchanged. The horizontally polarized emitted light passes through a Faraday rotator and a half-wave plate, and the polarization state is changed into vertical polarization; the main control computer 11 is connected with the light beam scanner 5 and is used for controlling the light beam direction of the rotary double-optical-wedge scanner and realizing the fast and accurate switching between different cooperative targets so as to achieve the purpose of changing the detection channel. As shown in fig. 2, the beam scanner 5 is a rotary dual-wedge beam scanner, the rotary dual-wedge structure is composed of two identical circular wedges, the two wedges are placed in parallel and independently rotate around the same axis, the azimuth angle of the emergent beam is related to the rotation angles of the two wedges, the pitch angle is only related to the included angle between the two wedges, and is unrelated to the absolute positions of the two wedges, and the emitting direction of the laser beam can be changed by controlling the rotation angles of the two wedges, so that the directional emission of the laser beam is realized. The beam scanner 5 is connected with cooperative targets 6 arranged at various positions in a target area; the said cooperation target is a passive device, the passive device is an electronic component which can display its characteristic without external power supply, the passive device mainly includes resistance, capacitance, inductance, converter, graduator, matching network, resonator, filter, mixer and switch, etc., and is available on the market, and is the most conventional and common device in microwave video, as shown in fig. 3, the said passive device also can include a base layer 15 for fixing, an intermediate layer 16 and a waterproof layer 17; the surface of the intermediate layer 16 is coated with a low-acoustic-resistance diaphragm made of a high-reflection material, so that the high-acoustic-resistance diaphragm has high sensitivity; the waterproof layer 17 is a waterproof sound-transmitting film made of PE material, has a uniform submicron and internally interconnected microporous structure inside, and has good sound transmission and waterproof performance and good infrared laser transmission. As shown in fig. 4, at a certain moment, after determining the pickup target, capturing or tracking the position of the pickup target by video, then sending a light beam to point to a cooperative target (passive device) in the position area responding to the pickup target voice vibration, the optical telescope 4 and the cooperative target forming a unique detection channel, when the pickup target moves away from the current position area, capturing the latest position of the pickup target by video again, sending the light beam to point to the cooperative target (passive device) in the latest position area responding to the pickup target voice vibration, after receiving the echo beam of the cooperative target, passing through a polarization beam splitter, inputting a 2 × 490 ° optical bridge and a photoelectric balanced detector 8 with a local oscillator beam to realize orthogonal coherent reception, the bandwidth of the photoelectric balanced detector 8 being 100MHz, and direct current coupling; the echo light beam and the local oscillator light beam enter a 2 x 490-degree optical bridge for orthogonal coherent reception, and the optical field is expressed as:
wherein R isN(t) is the amplitude of the weak vibration of the surface of the object caused by the sound pressure sensed by the echo beam, f0Is the laser carrier frequency, c is the speed of light, phiSIs the noise phase of the echo beam, phiLOIs the noise phase of the local oscillator beam;
t is time; eS_NIs the echo beam amplitude; eLO_NIs the local oscillator beam amplitude;
the four outputs after being mixed by the 2 × 490 ° optical bridge are respectively:
wherein phiN_noiseIs the noise phase; i isSIs a direct current quantity related to the echo beam; i isOIs the direct current quantity related to the local oscillator beam;
the optical bridge 7 is connected with an analog-to-digital converter 9 through a photoelectric balance detector 8, and the analog-to-digital converter 9 is connected with a main control computer 11 through a data acquisition device 10; the analog signals of the in-phase channel and the orthogonal channel output by the photoelectric balance detector 8 are collected by a dual-channel data acquisition card (data collector 10), the sampling rate of each channel is 500MHz, the in-phase signal and the orthogonal signal with the orthogonal characteristic output by the optical bridge are respectively received by the photoelectric balance detector 8, and the in-phase signal and the orthogonal signal output by the photoelectric balance detector are respectively:
wherein k isinPhotoelectric balance detector response rate, k, of in-phase signalquIs the photoelectric balance detector responsivity of the quadrature signal;
and finally, inputting data into a main control computer 11, wherein after the main control computer performs smooth filtering and least square nonlinear correction, if the response rates of the photodetectors of the in-phase signal and the quadrature signal are consistent, the corrected data is subjected to inverse tangent phase discrimination to obtain the weak vibration phase of the surface of the object:
wherein phi isN_noiseIs the noise phase;
finally, reconstructing the voice signal R of the output beam through the unwrapping algorithmNAnd (t) finally, outputting the voice signal and the video synchronously.
Example 3: the device of the scanning type multichannel coherent laser pickup method is shown in fig. 5 and comprises a laser light source 1, wherein the laser light source 1 adopts a 1550nm single-mode narrow-linewidth continuous optical fiber laser safe to human eyes, the linewidth of the laser is 10kHz, the output power is 20mW, and the optical fiber output has isolation protection; a polarizer 13 is arranged between the laser light source 1 and the beam splitter 2; the optical fiber coupling output light beam firstly passes through the polarizer 13, the polarization extinction ratio is ensured to be more than 25dB, and the polarization direction can be controlled to rotate; the laser light source 1 is connected with an optical circulator 3 and a frequency shifter 18 through a beam splitter 2; the beam splitter 2 is a 1 × 2 fiber polarization beam splitter, and the polarization states of two paths of light emitted by the light beam of the laser source through the 1 × 2 fiber polarization beam splitter are horizontal polarization (P light) and vertical polarization (S light), respectively. The emergent polarization direction is changed by adjusting the polarizer 13, the light intensity of two paths output by the 1 multiplied by 2 optical fiber polarization beam splitter is ensured to be 10:90, a P light branch is used as a transmission light beam, and an S light branch is used as a local oscillation light beam;
the output end of the optical circulator 3 is sequentially connected with an optical telescope 4 and a light beam scanner 5, a laser amplifier 14 is further arranged between the beam splitter 2 and the optical circulator 3, the laser amplifier 14 (erbium-doped fiber amplifier) amplifies the light beam and the light beam, the light beam enters the optical circulator 3, the optical circulator 3 comprises a polarization beam splitter, a Faraday optical rotator and a half-wave plate, the Faraday optical rotator rotates the polarization state of horizontal polarized light by 45 degrees, the slow axis of the half-wave plate and the incident polarization state form 22.5 degrees, the polarization state of transmitted polarized light can be rotated by 90 degrees, and the polarization state of received light is kept unchanged. The horizontally polarized emitted light passes through a Faraday rotator and a half-wave plate, and the polarization state is changed into vertical polarization; the main control computer 11 is connected with the light beam scanner 5 and is used for controlling the light beam direction of the rotary double-optical-wedge scanner and realizing the fast and accurate switching between different cooperative targets so as to achieve the purpose of changing the detection channel. As shown in fig. 2, the beam scanner 5 is a rotating dual-wedge beam scanner, the rotating dual-wedge structure is composed of two identical circular wedges, which are placed in parallel and rotate independently around the same axis, the azimuth angle of the emergent beam is related to the rotation angles of the two wedges, the pitch angle is only related to the included angle between the two wedges, and is unrelated to the absolute positions of the two wedges, and the emitting direction of the laser beam can be changed by controlling the rotation angles of the two wedges, so that the directional emission of the laser beam is realized. The beam scanner 5 is connected with cooperative targets 6 arranged at various positions in a target area; comprises a base layer 15 for fixing, an intermediate layer 16 and a waterproof layer 17; the surface of the intermediate layer 16 is coated with a low-acoustic-resistance diaphragm made of a high-reflection material, so that the high-acoustic-resistance diaphragm has high sensitivity; the waterproof layer 17 is a waterproof sound-transmitting film made of PE material, has a uniform submicron and internally interconnected microporous structure inside, and has good sound transmission and waterproof performance and good infrared laser transmission. As shown in fig. 4, at a certain moment, after determining the pickup target, capturing or tracking the position of the pickup target by video, then sending a light beam to point to a cooperative target (passive device) in the position area, which responds to the voice vibration of the pickup target, the optical telescope 4 and the cooperative target form a unique detection channel, when the pickup target moves away from the current position area, capturing the latest position of the pickup target by video again, sending a light beam to point to the cooperative target (passive device), which responds to the voice vibration of the pickup target, in the latest position area, passing through a polarization beam splitter after receiving the echo light beam of the cooperative target, inputting a 2 × 2180 ° optical bridge and a photoelectric balance detector 8 with a local oscillation light beam to realize orthogonal coherent reception, and the bandwidth of the photoelectric balance detector 8 is 100MHz and is in direct current coupling; the local oscillator beam is first shifted in frequency by the frequency shifter 18, and then enters the 2 × 2180 ° optical bridge with the echo beam for orthogonal coherent reception, where the optical field is expressed as:
wherein R isN(t) is the amplitude of the weak vibration of the surface of the object caused by the sound pressure sensed by the echo beam, f0Is the laser carrier frequency, fshiftIs the amount of frequency shift of the local oscillator beam, c is the speed of light, phiSIs the noise phase of the emitted light beam, phiLOIs the noise phase of the local oscillator beam;
t is time; eS_NIs the echo beam amplitude; eLO_NIs the local oscillator beam amplitude;
the two outputs after being mixed by the 2 × 2180 ° optical bridge are respectively:
wherein phiN_noiseIs the noise phase; i isSIs a direct current quantity related to the echo beam; i isOIs the direct current quantity related to the local oscillator beam;
a signal;
the optical bridge 7 is connected with an analog-to-digital converter 9 through a photoelectric balance detector 8, and the analog-to-digital converter 9 is connected with a main control computer 11 through a data acquisition device 10; the analog signals of the in-phase channel and the orthogonal channel output by the photoelectric balance detector 8 are collected by a dual-channel data acquisition card (data collector 10), the sampling rate of each channel is 500MHz, the in-phase signal and the orthogonal signal with the orthogonal characteristic output by the optical bridge are respectively received by the photoelectric balance detector 8, and the in-phase signal and the orthogonal signal output by the photoelectric balance detector are respectively:
where k is the photoelectric equilibrium detector responsivity, φN_noiseIs the noise phase;
the output data of the photoelectric balance detector is converted into digital data through an analog-to-digital converter, and finally is acquired by one channel of the data acquisition unit, meanwhile, the other channel of the data acquisition unit acquires a digital driving signal of the frequency shifter 18, and the acquired data is input into the main control computer 11:
first, quadrature baseband signals are obtained by quadrature demodulation, which is expressed as:
if the response rates of the photoelectric balance detectors of the in-phase signal and the quadrature signal are consistent, obtaining the weak vibration phase of the object surface by arc tangent phase splitting:
wherein phi isN_noiseIs the noise phase;
reconstruction of the speech signal R of the output beam by means of an unwrapping algorithmN(t)；
And finally, synchronously outputting the voice signal and the video.
Claims (10)
1. The scanning type multi-channel coherent laser pickup method is characterized in that: setting cooperative targets at a plurality of positions in a target area, wherein the cooperative targets are used for responding to voice vibration of the surrounding environment; the output light beam of the laser light source is divided into a local oscillation light beam and an emission light beam through a beam splitter, the emission light beam is directionally emitted to a cooperative target which carries out voice vibration response on the pickup target in the position area, the echo light beam of the cooperative target is received, the echo light beam and the local oscillation light beam are coherently received to obtain signal data, the signal data are transmitted to a main control computer, and the main control computer obtains voice information of the signal data through voice information demodulation.
2. The scanning multichannel coherent laser pickup method according to claim 1, characterized in that: the main control computer demodulates the voice information, corrects the signal data, obtains the weak vibration phase of the object surface by the inverse tangent phase discrimination after the correction, and obtains the voice information inducted by the cooperative target by the unwrapping algorithm.
3. The scanning multichannel coherent laser pickup method according to claim 1, characterized in that: the video capturing and pickup target tracking method comprises the steps that video data collected by a video capturing device are sent to a processor, the processor analyzes pixel coordinates of a target from the received video data, the processor enables the video capturing device to aim at the moving pickup target by driving a pan-tilt servo mechanism according to the pixel coordinates, and meanwhile a laser pickup selects a cooperative target closest to the pickup target to receive voice.
4. The scanning multichannel coherent laser pickup method according to claim 1, characterized in that: the echo light beam and the local oscillator light beam enter a 2 x 490-degree optical bridge for orthogonal coherent reception, and the optical field is expressed as:
wherein R isN(t) is the amplitude of the weak vibration of the surface of the object caused by the sound pressure sensed by the echo beam, f0Is the laser carrier frequency, c is the speed of light, phiSIs the noise phase of the echo beam, phiLOIs a local oscillator beamThe noise phase of (1);
t is time; eS_NIs the echo beam amplitude; eLO_NIs the local oscillator beam amplitude;
the four outputs after being mixed by the 2 × 490 ° optical bridge are respectively:
wherein phiN_noiseIs the noise phase; i isSIs a direct current quantity related to the echo beam; i isOIs the direct current quantity related to the local oscillator beam;
the in-phase signal and the orthogonal signal with the orthogonal characteristic output by the optical bridge are respectively received by the photoelectric balance detector, and the in-phase signal and the orthogonal signal output by the photoelectric balance detector are respectively:
wherein k isinPhotoelectric balance detector response rate, k, of in-phase signalquIs the photoelectric balance detector responsivity of the quadrature signal;
if the response rates of the photodetectors of the in-phase signal and the quadrature signal are consistent, the weak vibration phase of the surface of the object can be obtained by arc tangent phase splitting:
wherein phi isN_noiseIs the noise phase;
finally, reconstructing the voice signal R of the output beam through the unwrapping algorithmN(t)。
5. The scanning multichannel coherent laser pickup method according to claim 1, characterized in that: the echo light beam and the local oscillator light beam enter a 2 x 2180-degree optical bridge for orthogonal coherent reception, and the optical field is expressed as:
wherein R isN(t) is the amplitude of the weak vibration of the surface of the object caused by the sound pressure sensed by the echo beam, f0Is the laser carrier frequency, fshiftIs the amount of frequency shift of the local oscillator beam, c is the speed of light, phiSIs the noise phase of the emitted light beam, phiLOIs the noise phase of the local oscillator beam;
t is time; eS_NIs the echo beam amplitude; eLO_NIs the local oscillator beam amplitude;
the two outputs after being mixed by the 2 × 2180 ° optical bridge are respectively:
wherein phiN_noiseIs the noise phase; i isSIs a direct current quantity related to the echo beam; i isOIs the direct current quantity related to the local oscillator beam;
the two paths of output are received and output by a photoelectric balance detector, and the output data is as follows:
where k is the photoelectric equilibrium detector responsivity, φN_noiseIs the noise phase;
the output data of the photoelectric balance detector is converted into digital signals through an analog-to-digital converter, and finally, the digital signals are acquired by one channel of a data acquisition unit, meanwhile, the other channel of the data acquisition unit acquires digital driving signals of a frequency shifter, and the acquired data are input into a data processing unit for processing: first, quadrature baseband signals are obtained by quadrature demodulation, which is expressed as:
if the response rates of the photoelectric balance detectors of the in-phase signal and the quadrature signal are consistent, obtaining the weak vibration phase of the object surface by arc tangent phase splitting:
wherein phi isN_noiseIs the noise phase;
finally, reconstructing the voice signal R of the output beam through the unwrapping algorithmN(t)。
6. The scanning multichannel coherent laser pickup method according to claim 1, characterized in that: the transmission of the echo light beam is realized by transmitting the emitted light beam to the optical circulator and then transmitting the emitted light beam to the light beam scanner through the optical telescope, and the light beam scanner and a cooperative target focus to form directional emission of the emitted light beam; the directional emission is carried out by fixing the light beam scanner on the scanning holder, rotating the scanning holder and then matching with the rotating double optical wedges; the optical telescope receives the echo beams of the cooperative target and finally transmits the echo beams to the optical bridge through the optical circulator.
7. The device for realizing the scanning type multi-channel coherent laser pickup method as claimed in any one of claims 1 to 4, characterized in that: the laser device comprises a laser light source (1), wherein the laser light source (1) is connected with an optical circulator (3) through a beam splitter (2);
the output end of the optical circulator (3) is sequentially connected with an optical telescope (4) and a light beam scanner (5), and the light beam scanner (5) is connected with cooperative targets (6) arranged at various positions in a target area; the optical circulator (3) and the beam splitter (2) are connected with an optical bridge (7), and the optical bridge (7) is a 2 x 490-degree optical bridge; the optical bridge (7) is connected with an analog-to-digital converter (9) through a photoelectric balance detector (8), and the analog-to-digital converter (9) is connected with a main control computer (11) through a data acquisition unit (10); the main control computer (11) is also connected with the light beam scanner (5).
8. The device for realizing the scanning type multichannel coherent laser pickup method according to claim 5, characterized in that: the laser device comprises a laser light source (1), wherein the laser light source (1) is connected with an optical circulator (3) and a frequency shifter (18) through a beam splitter (2);
the output end of the optical circulator (3) is sequentially connected with an optical telescope (4) and a light beam scanner (5), and the light beam scanner (5) is connected with cooperative targets (6) arranged at various positions in a target area; the optical circulator (3) and the frequency shifter (18) are connected with an optical bridge (7), and the optical bridge (7) is a 2 × 2180-degree optical bridge; the optical bridge (7) is connected with an analog-to-digital converter (9) through a photoelectric balance detector (8), and the analog-to-digital converter (9) is connected with a main control computer (11) through a data acquisition unit (10); the data acquisition unit (10) is also connected with a frequency shifter (18); the main control computer (11) is also connected with the light beam scanner (5).
9. The apparatus of claim 7 or 8, wherein: a polarizer (13) is arranged between the laser light source (1) and the beam splitter (2); and a laser amplifier (14) is also arranged between the beam splitter (2) and the optical circulator (3).
10. The apparatus of claim 7 or 8, wherein: the cooperative target (6) is a passive device and comprises a substrate layer (15) for fixing, an intermediate layer (16) and a waterproof layer (17); the surface of the intermediate layer (16) is coated with a low-acoustic-resistance diaphragm made of high-reflection materials; the waterproof layer (17) is a waterproof sound-transmitting film made of PE materials.
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Effective date of registration: 20220921 Address after: Room 1803, No. 12, Lane 333, Hongshi Road, Juyuan New District, Jiading District, Shanghai, 201800 Patentee after: Sun Jianfeng Address before: 310053 room 701, block B, 581 torch Avenue, Puyan street, Binjiang District, Hangzhou City, Zhejiang Province Patentee before: HANGZHOU ILIDAR TECHNOLOGY CO.,LTD. |