CN112698307B - Single photon imaging radar system - Google Patents
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- CN112698307B CN112698307B CN202011545201.1A CN202011545201A CN112698307B CN 112698307 B CN112698307 B CN 112698307B CN 202011545201 A CN202011545201 A CN 202011545201A CN 112698307 B CN112698307 B CN 112698307B
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- 238000003384 imaging method Methods 0.000 title claims abstract description 71
- 230000003287 optical effect Effects 0.000 claims abstract description 133
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- 238000001514 detection method Methods 0.000 claims abstract description 18
- 239000013307 optical fiber Substances 0.000 claims abstract description 14
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/483—Details of pulse systems
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- Electromagnetism (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
The present disclosure provides a single photon imaging radar system comprising: the signal source is used for generating a synchronous signal and a gating signal; the optical fiber laser is used for receiving the synchronous signal and transmitting laser pulses in response to the synchronous signal; the first optical switch and the second optical switch are used for receiving a gating signal and responding to the gating signal to turn on or off so as to control whether the laser pulse passes through the optical switch or not; the light splitting device is used for receiving the laser pulse transmitted by the first optical switch and transmitting the laser pulse to the optical transceiver plate, or is used for receiving the laser pulse transmitted by the optical transceiver plate and transmitting the laser pulse to the second optical switch; an optical transceiver board; the single photon detector is used for receiving the gating signal and the laser pulse, responding to the gating signal to open or close, responding to the laser pulse to generate a detection signal and transmitting the detection signal to the time-to-digital converter when the single photon detector is opened; and the time digital converter is used for receiving the synchronous signal and the detection signal and recording time information.
Description
Technical Field
The present disclosure relates to the field of lidar, and more particularly, to a single photon imaging radar system.
Background
Laser imaging radar is one of the most widely used precise three-dimensional imaging techniques, and its main principle is to transmit laser pulses to a target area and receive echoes, and to obtain the distance between the target and an emission point by measuring the flight time of photons. And then the three-dimensional image of the target object is obtained by technical means such as scanning the target area.
The prior art is for example a single photon three-dimensional imaging system, as done by a research team at the university of science and technology in china, or a three-dimensional pulsed laser imaging system, as done by a research team at the university of herry-watt in the united kingdom. The above-mentioned technology realizes three-dimensional imaging of the object outside 10km distance, however, they all use the large-caliber telescope as the light beam receiving and transmitting device, its overall structure is complex and bulky, at the same time, the above-mentioned technology is in order to solve the problem of the light beam receiving efficiency, or use the large laser power, or use the long integral time, but these measures have increased the noise at the same time, can't meet the needs of rapid imaging.
Therefore, in the process of realizing the invention, the laser imaging radar system in the related technology is found to have complex and huge structure, portability and no effective noise reduction means, thereby influencing the imaging distance, the imaging speed and the resolution.
Disclosure of Invention
In view of this, the present disclosure provides a single photon imaging radar system.
According to an embodiment of the present disclosure, a single photon imaging radar system includes: the signal source is used for generating a synchronous signal and a gating signal; the fiber laser is used for receiving the synchronous signal and transmitting laser pulses in response to the synchronous signal; the first optical switch and the second optical switch are respectively connected with the optical fiber laser and the light splitting device, the second optical switch is respectively connected with the light splitting device and the single photon detector, and the first optical switch and the second optical switch are used for receiving the gating signal and are turned on or off in response to the gating signal so as to control whether laser pulses pass through the first optical switch and the second optical switch; the optical splitter is configured to receive the laser pulse transmitted by the first optical switch and transmit the laser pulse to the optical transceiver board, or is configured to receive the laser pulse transmitted by the optical transceiver board and transmit the laser pulse to the second optical switch; the optical transceiver board; the single photon detector is configured to receive the gating signal and the laser pulse transmitted by the second optical switch, and to turn on or off in response to the gating signal, where when the single photon detector is turned on, the single photon detector responds to the laser pulse transmitted by the second optical switch, and generates a detection signal to transmit to the time-to-digital converter; and the time-to-digital converter is used for receiving the synchronous signal and the detection signal and recording time information.
According to an embodiment of the present disclosure, the optical transceiver board includes: the light collimation device is used for straightening or coupling laser pulses; scanning means for deflecting the laser pulses; a beam expanding system for changing a beam divergence angle of the laser pulse; and the optical metal substrate is used for defining the light collimation device, the scanning device and the beam expanding system.
According to an embodiment of the present disclosure, the axes of the light collimating means, the scanning means and the beam expanding system are coplanar.
According to an embodiment of the present disclosure, the single photon imaging radar system further comprises: the electric turntable is connected with the optical transceiver plate and used for controlling the direction of the beam expanding system; and the auxiliary camera is used for assisting the single-photon imaging radar system to search for a target object.
According to an embodiment of the present disclosure, the signal source, the fiber laser, the first optical switch, the second optical switch, the spectroscopic device, the single photon detector, and the time-to-digital converter are integrated in a chassis.
According to an embodiment of the present disclosure, the single photon imaging radar system further comprises: and the information processing device is integrated in the case and is used for receiving the time information of the time-to-digital converter and calculating the distance information of the target object according to the time information.
According to an embodiment of the disclosure, the synchronization signal and the gating signal are periodic signals, and a period of the gating signal is greater than a period of the synchronization signal.
According to an embodiment of the disclosure, the gating signal controls the first optical switch to be turned on and the second optical switch and the single photon detector to be turned off in a first half of a period; the gating signal controls the first optical switch to be closed and the second optical switch and the single photon detector to be opened in the second half of a period.
According to an embodiment of the present disclosure, the above-described fiber laser includes: a near infrared pulse fiber laser; the scanning device includes: a micro-electromechanical system galvanometer; the time-to-digital converter includes: PCI-E board card type time-to-digital converter.
According to the embodiment of the disclosure, because the small optical device is used and the reasonable optical design is adopted, the problems of huge volume and complex optical path of the single photon imaging radar system are at least partially overcome, and the effects of integration and practicability are achieved.
Drawings
The above and other objects, features and advantages of the present disclosure will become more apparent from the following description of embodiments thereof with reference to the accompanying drawings in which:
FIG. 1 schematically illustrates a single photon imaging radar system schematic according to the present disclosure;
FIG. 2 schematically illustrates a single photon imaging radar system schematic according to an embodiment of the present disclosure;
FIG. 3 schematically illustrates an integrated single photon imaging radar system schematic in accordance with an embodiment of the present disclosure;
fig. 4 schematically illustrates a prototype system schematic of a single photon imaging radar system according to another embodiment of the present disclosure.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is only exemplary and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and/or the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly formal manner.
Where expressions like at least one of "A, B and C, etc. are used, the expressions should generally be interpreted in accordance with the meaning as commonly understood by those skilled in the art (e.g.," a system having at least one of A, B and C "shall include, but not be limited to, a system having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.). Where a formulation similar to at least one of "A, B or C, etc." is used, in general such a formulation should be interpreted in accordance with the ordinary understanding of one skilled in the art (e.g. "a system with at least one of A, B or C" would include but not be limited to systems with a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).
Embodiments of the present disclosure provide a single photon imaging radar system, comprising: the signal source is used for generating a synchronous signal and a gating signal; the optical fiber laser is used for receiving the synchronous signal and transmitting laser pulses in response to the synchronous signal; the first optical switch is connected with the optical fiber laser and the light splitting device respectively, the second optical switch is connected with the light splitting device and the single photon detector respectively, and the first optical switch and the second optical switch are used for receiving a gating signal and responding to the gating signal to be turned on or turned off so as to control whether laser pulses pass through the first optical switch and the second optical switch; the light splitting device is used for receiving the laser pulse transmitted by the first optical switch and transmitting the laser pulse to the optical transceiver plate, or is used for receiving the laser pulse transmitted by the optical transceiver plate and transmitting the laser pulse to the second optical switch; an optical transceiver board; the single photon detector is used for receiving the gating signal and the laser pulse transmitted by the second optical switch and responding to the gating signal to turn on or turn off, wherein when the single photon detector is turned on, the single photon detector responds to the laser pulse transmitted by the second optical switch to generate a detection signal and transmit the detection signal to the time-to-digital converter; and the time digital converter is used for receiving the synchronous signal and the detection signal and recording time information.
Fig. 1 schematically illustrates a single photon imaging radar system schematic according to the present disclosure.
As shown in fig. 1, the single photon imaging radar system includes a signal source 101, a fiber laser 102, a first optical switch 103, a second optical switch 104, an optical splitter 105, an optical transceiver 106, a single photon detector 107, and a time-to-digital converter 108.
According to an embodiment of the present disclosure, the signal source 101 is used to generate a synchronization signal and a gating signal. The signal source 101 may be any device that can generate multiple stable, controllable signals, including but not limited to a function signal generator, etc.
According to an embodiment of the present disclosure, the fiber laser 102 is configured to receive the synchronization signal and emit a laser pulse in response to the synchronization signal. The fiber laser 102 may be a laser generator in any operating band including, but not limited to, near infrared fiber lasers, and the like.
According to the embodiment of the disclosure, the first optical switch 103 is connected to the fiber laser 102 and the beam splitter 105, the second optical switch 104 is connected to the beam splitter 105 and the single photon detector 107, and the first optical switch 103 and the second optical switch 104 are used for receiving a gating signal and are turned on or off in response to the gating signal so as to control whether the laser pulse passes through the first optical switch 103 and the second optical switch 104.
According to embodiments of the present disclosure, the first optical switch 103 and the second optical switch 104 may be any device having one or more selectable transmission windows and capable of performing interconversion or logic operation on optical signals in an optical transmission line or integrated optical circuit, including, but not limited to, fiber optic switches, and the like. The second optical switch 104 further includes a filtering module, configured to filter noise in the received laser pulse.
According to an embodiment of the present disclosure, the optical splitter 105 is configured to receive the laser pulse transmitted by the first optical switch 103 and transmit the laser pulse to the optical transceiver board 106, or configured to receive the laser pulse transmitted by the optical transceiver board 106 and transmit the laser pulse to the second optical switch 104. The optical splitter 105 may be any device capable of performing the functions of coupling, branching, and distributing optical signals in an optical network system, including, but not limited to, fiber optic splitters, and the like.
According to an embodiment of the present disclosure, the optical transceiver board 106 includes a light collimation device 1061, a scanning device 1062, a beam expanding system 1063, and an optical metal substrate 1064. Light collimating means 1061 is used to collimate or couple the laser pulses including, but not limited to, collimators, convex lens groups, etc. The scanning device 1062, for deflecting the laser pulses, may be any device with fast scanning, transceiving coaxial functions, including but not limited to Micro-Electro-Mechanical System (MEMS) galvanometer. The beam expanding system 1063 is configured to change a beam divergence angle of the laser pulse, so that a light spot of the emitted laser pulse is expanded according to a certain proportion, so that a power density of the laser can be reduced, and safety of the laser is ensured in actual use; beam expanding system 1063 includes, but is not limited to, a beam expander and the like. An optical metal substrate 1064 for holding the light collimating means 1061, the scanning means 1062 and the beam expanding system 1063.
According to an embodiment of the present disclosure, the single photon detector 107 is configured to receive the gating signal and the laser pulse transmitted by the second optical switch 104, and turn on or off in response to the gating signal, where when the single photon detector 107 is turned on, the single photon detector 107 responds to the laser pulse transmitted by the second optical switch 104 to generate a detection signal and transmit the detection signal to the time-to-digital converter 108. The single photon detector 107 is a high sensitivity device, such as an InGaAs single photon avalanche diode or the like, operating in the operating band of the fiber laser 102.
According to an embodiment of the present disclosure, the time-to-digital converter 108 is configured to receive the synchronization signal and the probe signal and record time information.
According to the embodiment of the disclosure, because the small optical device is used and the reasonable optical design is adopted, the problems of huge volume and complex optical path of the single photon imaging radar system are at least partially overcome, and the effects of integration and practicability are achieved.
Fig. 2 schematically illustrates a single photon imaging radar system schematic according to an embodiment of the disclosure.
As shown in fig. 2, in operation of the single photon imaging radar system according to the embodiment of the present disclosure, the fiber laser 102 is triggered by the signal source 101 to generate a laser pulse, and the signal source 101 simultaneously provides a synchronization signal with the same frequency to the time-to-digital converter 108 to record the relative start time of detection. The laser pulse enters the beam splitter 105 through the emission end optical switch 103, and then the light is emitted to free space through the light collimation device 1061, reflected by the scanning device 1062 and expanded by the beam expansion system 1063, and transmitted to the remote target object 204 and reflected. The returned photons are coupled into the optical fiber from the light collimation device 1061 through the same light path, and then enter the single photon detector 107 through the light splitting device 105, the optical switch 104 and the filter device; the single photon detector 107 transmits the received signal to the time-to-digital converter 108 as a timing end signal; the time-to-digital converter 108 transmits the relative start time and the end time obtained in response to the end signal to the information processing device 203, so that the relative distance of the target can be obtained. The scanning device 1062 then scans the different areas of the target object 204 to obtain the relative distances, and further obtain a three-dimensional image of the target object.
According to the single photon imaging radar system of the embodiment of the present disclosure, the single photon detector 107 selects a detection device having a detection sensitivity of a single photon, which can implement laser pulses emitted from the fiber laser 102 that receives an average power of mW level (milliwatt level) at 10 km. The working wavelength of the near infrared band is adopted, the atmospheric transmittance of light with the near infrared band is higher than that of visible light, the atmospheric transmission attenuation is smaller, the light is not easy to be absorbed by human eyes, and the high human eye safety is realized. The use of beam expanding system 1063 expands the outgoing spot, reduces the power density of the laser pulses, and ensures the safety of the single photon imaging radar system of embodiments of the present disclosure.
According to the single photon imaging radar system of the disclosed embodiment, the signal source 101 outputs at least 5 signals, which are respectively synchronous signals for controlling the fiber laser 102 to generate pulses and the time-to-digital converter 108 to record time information, and gate control signals for controlling the optical switches 103 and 104 and the single photon detector 107 at the transmitting and receiving ends. The synchronous signal and the gating signal are periodic signals, and the period of the gating signal is larger than that of the synchronous signal. In order to reduce the noise in the system and improve the duty ratio of the output pulse time, the gating signal controls the first optical switch to be turned on and the second optical switch and the single photon detector to be turned off in the first half of one period; the gating signal controls the first optical switch to be closed and the second optical switch and the single photon detector to be opened in the second half of one period.
The single photon imaging radar system of the embodiments of the present disclosure further includes an electrically powered turret 201. The motorized turret 201 is coupled to the optical transceiver 106 for controlling the pointing of the beam expanding system 1063, and for scenes requiring wide-angle imaging, a device is typically required to change the pointing of the transmitting end of the single photon imaging radar system. For example, there is an unmanned vehicle loaded with the single photon imaging radar system, which is required to perform imaging acquisition of surrounding environment, vehicle and personnel information while the vehicle is traveling, and to achieve this, the single photon imaging radar system is required to be mounted on a turntable capable of rapid rotation.
The single photon imaging radar system of the embodiments of the present disclosure also includes an auxiliary camera 202. And the auxiliary camera is used for assisting the single-photon imaging radar system to search for the target object. For example, in a scene where the target object 204 needs to be imaged, since the view angles of the scanning device 1062 and the beam expanding system 1063 are smaller, it is difficult to find the target object 204 and image it only by the scanning device 1062 itself at the first time, and at this time, the area where the target object 204 is located can be quickly located by the auxiliary camera 202, so that the time required for imaging is reduced. The auxiliary camera 202 may be any device capable of interacting with the information processing apparatus 203 and having an optical information collecting function.
The single photon imaging radar system of the embodiments of the present disclosure further includes an information processing device 203. An information processing device 203 for receiving the time information of the time-to-digital converter and calculating the distance information of the target object according to the time information. The information processing apparatus 203 is an electronic device having information receiving, information processing, information storage, and information output functions, and includes, for example, but is not limited to, a computer, a single-chip microcomputer, and the like.
Fig. 3 schematically illustrates a schematic diagram of an integrated single photon imaging radar system in accordance with an embodiment of the present disclosure.
As shown in fig. 3, according to the integrated single photon imaging radar system of the embodiment of the disclosure, the axes of the light collimation device 1061, the scanning device 1062 and the beam expanding system 1063 are coplanar, the light path part adopts a design of coaxial receiving and transmitting, the light path is simplified, the robustness of the system is improved, the receiving and transmitting calibration process is omitted, the receiving and transmitting light beams are kept overlapped, the adjustment time of the free space light path is saved, and the system has better repeatability and higher stability. The light collimating means 1061, the scanning means 1062 and the beam expanding system 1063 are spatially close together, reducing random noise present in the free space light path, which is not easily disturbed by the outside.
Due to the limitation of the prior art, the inherent divergence angle of the laser exists, so that light spots generated by the fiber laser can become large at a long distance, and the transverse resolution of three-dimensional imaging is poor, and an image becomes blurred. The design of light collimation device 1061 and beam expansion system 1063 allows beam divergence angles on the order of hundred micro radians to enable high lateral resolution in long-range three-dimensional imaging in accordance with an integrated single photon imaging radar system of an embodiment of the present disclosure.
The integrated single-photon imaging radar system of the embodiment of the disclosure adopts a miniaturized and integrated design, wherein most of optical paths adopt optical fibers as transmission media, the optical paths of free space parts are very concise, and the integrated single-photon imaging radar system can be integrated on a small rigid optical metal substrate 1064, thereby being beneficial to improving the optical stability of the system and meeting the practical requirements. Scanning device 1062 employs a two-dimensional MEMS galvanometer having a resonant frequency of up to 1000Hz and a mirror diameter of up to a minimum of 3mm, thus having a small moment of inertia, and allowing for easier high speed rotation. In the specific scanning process, one axis of the two-dimensional MEMS galvanometer works in a resonance mode, the other axis works in a quasi-static mode, and the scanning pattern is in a serpentine shape so as to achieve the fastest scanning speed, and the light path volume is greatly reduced by matching with the small-caliber beam expanding system 1063, so that high scanning imaging frame rate can be realized, and real-time imaging and moving target imaging can be realized.
An integrated single photon imaging radar system according to an embodiment of the present disclosure, wherein an optical metal substrate 1064 is placed on a small tripod 303 housing an electrically powered turret 201. The PCI-E board-card type time-to-digital converter 108 is adopted, and the signal source 101, the fiber laser 102, the first optical switch 103, the second optical switch 104, the optical splitter 105, the single photon detector 107, the time-to-digital converter 108 and the information processing device 203 are integrated in the case 304, so that the system structurally only comprises the case 304, the tripod 303 and the small optical transceiver 106, and the case 304 and the optical transceiver 106 are connected by the flexible electronic cable 301 and the optical fiber 302, thereby having stronger portability.
The integrated single-photon imaging radar system of the embodiment of the disclosure provides a miniaturized system which combines optical fibers and free space, receives and transmits coaxially and scans by utilizing a two-dimensional MEMS vibrating mirror, and greatly reduces the volume of the system. The advantage of high speed of the MEMS galvanometer is utilized, and the three-dimensional image data acquisition speed of a plurality of hertz can be realized. In addition, the system of the embodiment of the disclosure improves noise suppression and detection means, can perform three-dimensional imaging on targets of up to ten kilometers, and has practicability.
Fig. 4 schematically illustrates a prototype system schematic of a single photon imaging radar system according to another embodiment of the present disclosure.
As shown in fig. 4, in the laser emission part of the prototype system of the single photon imaging radar system according to another embodiment of the present disclosure, a near infrared fiber laser 401 is triggered by an FPGA signal source 405 to generate a periodic pulse, and the periodic pulse is emitted from a light collimation device 1061 on an optical transceiver 106 to a free space through an optical switch 103 and a beam splitting device 105, and then reflected by a two-dimensional MEMS galvanometer 409 to an emission system of a beam expanding device 1063, and is emitted onto a target object 204. The FPGA signal source 405 may provide the same reference signal to the time-to-digital converter 108 as the timing start signal.
According to another embodiment of the present disclosure, the near-infrared fiber laser 401 may be a 1550nm wavelength pulse fiber laser with a pulse width of 500ps, or a narrow pulse width nanosecond, sub-nanosecond, picosecond laser with a near-infrared band may be used instead, and the narrow pulse width fiber laser may achieve a higher emission frequency and a lower power density, while meeting the requirements of real-time and safety.
According to another embodiment of the present disclosure, the optical switch 103 may employ a fiber acousto-optic modulator, that is, the fiber AOM402 to suppress spontaneous emission noise when the laser does not pulse, or may use a device having an optical switching function, such as an electro-optic modulator.
According to another embodiment of the present disclosure, the beam splitting device 105 may employ a 2 x 2 fiber optic beam splitter 403, as well as a fiber optic circulator or other exit count fiber optic beam splitter.
According to another embodiment of the present disclosure, light collimation device 1061 may use a fiber collimator 408 or a set of convex lenses.
According to another embodiment of the present disclosure, beam expander 1063 may employ a 1:10 expander to achieve the proper beam divergence angle and receive field of view. The beam expander 1063 may be a kepler type or galilean type beam expander composed of a lens group, and the ratio may be adjusted.
According to another embodiment of the present disclosure, the time to digital converter 108 may employ a board TDC407 of a PCI-E interface, where the board TDC407 has a 13ps count accuracy and is compact. The card TDC407 may be replaced with other devices having similar high-precision time-to-digital conversion functions.
As shown in fig. 4, a portion of a receiving optical path of a prototype system of a single photon imaging radar system according to another embodiment of the present disclosure on an optical transceiver board adopts a design coaxial with a transmitting optical path. The returned signal photons enter the fiber through fiber collimator 408 and enter the receiving end fiber AOM and fiber filter 404 from the other exit of 2 x 2 fiber splitter 403. The signal photons after the filtering process are captured by the single photon detector 107, and the single photon detector 107 transmits the detection signal to the board card TDC407 as a timing end signal, measures the photon flight time and transmits the photon flight time to the computer 406. The two-dimensional MEMS galvanometer 409 scans the target object 204 synchronously to obtain the optical flight path lengths of different scanning points, and the upper computer software of the computer 406 can reconstruct the three-dimensional image of the target object 204.
According to another embodiment of the present disclosure, the optical fiber filters in the optical fiber AOM and the optical fiber filter 404 may be narrow-band optical fiber filters with a center wavelength of 1550nm, so as to suppress the background noise of sunlight in the daytime, and realize the working capacity in the whole day.
According to another embodiment of the present disclosure, the single photon detector 107 may use InGaAs single photon avalanche diodes, or other high sensitivity single photon detectors operating in the near infrared band may be selected.
According to another embodiment of the present disclosure, the fiber AOM and fiber filter 404 and single photon detector 107 are off when the laser is emitting pulses, and the fiber AOM and fiber filter 404 and single photon detector 107 are on when the laser is not emitting pulses. This strategy suppresses local noise caused by the pulses and reduces random errors.
According to another embodiment of the present disclosure, all devices except the optical transceiver board 106, including but not limited to near infrared fiber laser 401, fiber AOM402, 2 x 2 fiber beam splitter 403, fiber AOM and fiber filter 404, FPGA signal source 405, single photon detector 107, computer 406, board TDC407, etc., are integrated into one chassis 304, which is only 290mm x 278mm x 238mm in size. The optical transceiver plate 106 was covered with a black aluminum plate having a height of 11cm, and the dimensions thereof were only 200mm×150mm×10mm. The optical transceiver 106 can be placed on a tripod and connected with the chassis 304 by only one optical fiber and a few electronic cables, and is very simple to install and has extremely high stability when in use.
According to the embodiment of the disclosure, a practical single photon imaging radar system is provided, and the practical requirements of stability, safety, portability and the like can be met. The system adopts an effective optical design, reduces the interference of random factors such as environmental noise, can realize long-distance rapid imaging, has higher resolution, and has simple structure, small size and portability.
The embodiments of the present disclosure are described above. However, these examples are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be made by those skilled in the art without departing from the scope of the disclosure, and such alternatives and modifications are intended to fall within the scope of the disclosure.
Claims (10)
1. A single photon imaging radar system comprising:
the signal source is used for generating a synchronous signal and a gating signal;
the fiber laser is used for receiving the synchronous signal and transmitting laser pulses in response to the synchronous signal;
the first optical switch is connected with the optical fiber laser and the light splitting device respectively, the second optical switch is connected with the light splitting device and the single photon detector respectively, and the first optical switch and the second optical switch are used for receiving the gating signal and responding to the gating signal to be turned on or turned off so as to control whether laser pulses pass through the first optical switch and the second optical switch;
the light splitting device is used for receiving the laser pulse transmitted by the first optical switch and transmitting the laser pulse to the optical transceiver plate, or is used for receiving the laser pulse transmitted by the optical transceiver plate and transmitting the laser pulse to the second optical switch;
the optical transceiver board;
the single photon detector is used for receiving the gating signal and the laser pulse transmitted by the second optical switch and responding to the gating signal to be turned on or turned off, wherein when the single photon detector is turned on, the single photon detector responds to the laser pulse transmitted by the second optical switch to generate a detection signal and transmit the detection signal to the time-to-digital converter; and
the time-to-digital converter is used for receiving the synchronous signal and the detection signal and recording time information.
2. The single photon imaging radar system as claimed in claim 1 wherein said optical transceiver plate comprises:
the light collimation device is used for straightening or coupling laser pulses;
scanning means for deflecting the laser pulses;
a beam expanding system for changing a beam divergence angle of the laser pulse;
and the optical metal substrate is used for fixing the light collimation device, the scanning device and the beam expanding system.
3. The single photon imaging radar system as claimed in claim 2 wherein axes of said light collimation device, said scanning device and said beam expansion system are coplanar.
4. The single photon imaging radar system as claimed in claim 2, further comprising:
and the electric turntable is connected with the optical transceiver plate and used for controlling the direction of the beam expanding system.
5. The single photon imaging radar system as claimed in claim 1, further comprising:
and the auxiliary camera is used for assisting the single-photon imaging radar system to search for a target object.
6. The single photon imaging radar system as claimed in claim 1 wherein the signal source, the fiber laser, the first optical switch, the second optical switch, the light splitting device, the single photon detector and the time-to-digital converter are integrated in a chassis.
7. The single photon imaging radar system as in claim 6 further comprising:
and the information processing device is integrated in the case and is used for receiving the time information of the time-to-digital converter and calculating the distance information of the target object according to the time information.
8. The single photon imaging radar system as claimed in claim 1 wherein the synchronization signal and the gating signal are periodic signals and the period of the gating signal is greater than the period of the synchronization signal.
9. The single photon imaging radar system as claimed in claim 8 wherein said gating signal controls said first optical switch to be on and said second optical switch and said single photon detector to be off for a first half of a cycle; the gating signal controls the first optical switch to be closed and the second optical switch and the single photon detector to be opened in the second half of a period.
10. The single photon imaging radar system as claimed in claim 1, wherein,
the fiber laser includes: a near infrared pulse fiber laser;
the scanning device includes: a micro-electromechanical system galvanometer;
the time-to-digital converter includes: PCI-E board card type time-to-digital converter.
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| CN115932745B (en) * | 2023-02-01 | 2023-06-16 | 中国科学院空天信息创新研究院 | Synchronous control method for azimuth scanning receiving and transmitting space |
| CN116125436B (en) * | 2023-04-17 | 2023-07-04 | 北京航空航天大学 | Integrated coaxial transceiver for single-photon radar and single-photon radar |
| CN116400379B (en) * | 2023-06-08 | 2023-09-12 | 合肥国家实验室 | Three-dimensional imaging system and three-dimensional imaging method of single-photon laser radar |
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