CN112698307A - Single photon imaging radar system - Google Patents
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- CN112698307A CN112698307A CN202011545201.1A CN202011545201A CN112698307A CN 112698307 A CN112698307 A CN 112698307A CN 202011545201 A CN202011545201 A CN 202011545201A CN 112698307 A CN112698307 A CN 112698307A
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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
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Abstract
The present disclosure provides a single photon imaging radar system, comprising: a signal source for generating a synchronization signal and a gate control signal; the fiber laser is used for receiving the synchronous signal and responding to the synchronous signal to emit laser pulse; the first optical switch and the second optical switch are used for receiving the gate control signal and responding to the gate control signal to be switched on or switched off so as to control whether the laser pulse passes through the optical switches 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 board, or is used for receiving the laser pulse transmitted by the optical transceiver board and transmitting the laser pulse to the second optical switch; an optical transceiver board; the single-photon detector is used for receiving the gate control signal and the laser pulse, responding to the gate control signal to be opened or closed, and responding to the laser pulse to generate a detection signal to be transmitted to the time-to-digital converter when the single-photon detector is opened; and a time-to-digital converter for receiving the synchronization signal and the detection signal and recording time information.
Description
Technical Field
The present disclosure relates to the field of laser radars, and more particularly, to a single photon imaging radar system.
Background
The laser imaging radar is one of the most widely applied precise three-dimensional imaging technologies at present, and the main principle of the laser imaging radar is to emit laser pulses to a target area, receive echoes and obtain the distance between a 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.
There are prior art such as single photon three-dimensional imaging systems as done by the research team at the university of science and technology in china, or three-dimensional pulsed laser imaging systems as done by the research team at the university of herry-watt in england. The above-mentioned technologies realize three-dimensional imaging of objects outside of 10km distance, however, they all adopt large-caliber telescopes as light beam transceiver devices, and their whole structure is complex and bulky, and at the same time, in order to solve the problem of light beam receiving efficiency, or use large laser power, or use long integration time, these measures also increase noise, and cannot meet the requirement of rapid imaging.
Therefore, in the process of implementing the invention, it is found that the laser imaging radar system in the related art has a complex and large structure, is not portable, and has no effective noise reduction means, thereby affecting 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: a signal source for generating a synchronization signal and a gate control signal; the fiber laser is used for receiving the synchronous signal and responding to the synchronous signal to emit laser pulse; a first optical switch and a second optical switch, wherein the first optical switch is connected to the fiber laser and the optical splitting device, respectively, the second optical switch is connected to the optical splitting device and the single photon detector, respectively, and the first optical switch and the second optical switch are configured to receive the gate control signal and turn on or off in response to the gate control signal, so as to control whether a laser pulse passes through the first optical switch and the second optical switch; the optical splitting device is used for receiving the laser pulse transmitted by the first optical switch and transmitting the laser pulse to an optical transceiver board, or is used for receiving the laser pulse transmitted by the optical transceiver board and transmitting the laser pulse to the second optical switch; the above-mentioned optical transceiver board; the single-photon detector is used for receiving the gate control signal and the laser pulse transmitted by the second optical switch and responding to the gate control 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 transmits 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.
According to an embodiment of the present disclosure, the above optical transceiver board includes: the light collimating device is used for collimating or coupling the laser pulse; a scanning device 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 identifying the light collimation device, the scanning device and the beam expanding system.
According to an embodiment of the present disclosure, axes of the light collimating device, the scanning device, 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 board and is used for controlling the pointing direction of the beam expanding system; and the auxiliary camera is used for assisting the single photon imaging radar system to search for the 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 optical splitter, 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 chassis and 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 present disclosure, the synchronization signal and the gate signal are periodic signals, and a period of the gate signal is greater than a period of the synchronization signal.
According to the embodiment of the present disclosure, the gate control 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 a cycle; the gate control 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 cycle.
According to an embodiment of the present disclosure, the above fiber laser includes: a near-infrared pulse fiber laser; the scanning device includes: a micro-electro-mechanical 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 a small-sized optical device is used and a reasonable optical design is adopted, the problems of large volume and complex light path of a single photon imaging radar system are at least partially overcome, and then 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 of the present disclosure with reference to the accompanying drawings, in which:
figure 1 schematically illustrates a single photon imaging radar system according to the present disclosure;
figure 2 schematically illustrates a single photon imaging radar system in accordance with an embodiment of the present disclosure;
FIG. 3 schematically illustrates an integrated single photon imaging radar system in accordance with an embodiment of the present disclosure;
figure 4 schematically illustrates a prototype system schematic of a single photon imaging radar system according to another embodiment of the 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 illustrative only 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 disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not 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 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 is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.
Where a convention analogous to "at least one of A, B and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B and C" would include but not be limited to systems that have 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 convention analogous to "A, B or at least one of C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B or C" would include but not be limited to systems that have 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.).
The embodiment of the present disclosure provides a single photon imaging radar system, including: a signal source for generating a synchronization signal and a gate control signal; the fiber laser is used for receiving the synchronous signal and responding to the synchronous signal to emit laser pulse; 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 gate control signal and responding to the gate control signal to be turned on or turned off so as to control whether the laser pulse passes through the first optical switch and the second 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 board, or is used for receiving the laser pulse transmitted by the optical transceiver board and transmitting the laser pulse to the second optical switch; an optical transceiver board; the single-photon detector is used for receiving the gate control signal and the laser pulse transmitted by the second optical switch and responding to the gate control 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 transmits the detection signal to the time-to-digital converter; and a time-to-digital converter for receiving the synchronization signal and the detection signal and recording time information.
Figure 1 schematically illustrates a single photon imaging radar system 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, a light splitting device 105, an optical transceiver board 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 for generating 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.
In accordance with an embodiment of the present disclosure, fiber laser 102 is configured to receive a synchronization signal and emit laser pulses in response to the synchronization signal. Fiber laser 102 may be a laser generator of any operating wavelength band including, but not limited to, a near infrared fiber laser, and the like.
According to the embodiment of the disclosure, the first optical switch 103 is connected to the fiber laser 102 and the optical splitting device 105, the second optical switch 104 is connected to the optical splitting device 105 and the single photon detector 107, and the first optical switch 103 and the second optical switch 104 are configured to receive a gate control signal and turn on or off in response to the gate control signal, so as to control whether a laser pulse passes through the first optical switch 103 and the second optical switch 104.
According to the embodiment 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 logical operation on optical signals in an optical transmission line or an integrated optical circuit, including but not limited to a fiber optical switch, etc. The second optical switch 104 further includes a filtering module for filtering out noise in the received laser pulse.
According to the 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 is 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 device 105 may be any device capable of coupling, splitting, and distributing optical signals in an optical network system, including but not limited to a fiber optic splitter, and the like.
According to an embodiment of the present disclosure, the optical transceiver board 106 includes a light collimating device 1061, a scanning device 1062, a beam expanding system 1063, and an optical metal substrate 1064. The light collimating device 1061 is used for collimating or coupling the laser pulse, and includes, but is not limited to, a collimator, a convex lens group, and the like. The scanning device 1062 is used for deflecting the laser pulses, and may be any device with fast scanning, transceiving and coaxial functions, including but not limited to a Micro-Electro-Mechanical System (MEMS) galvanometer. The beam expanding system 1063 is used for changing the beam divergence angle of the laser pulse, so that the light spot of the emitted laser pulse is enlarged according to a certain proportion, the power density of the laser can be reduced, and the safety of the laser is ensured in the actual use; the beam expanding system 1063 includes, but is not limited to, a beam expander lens, etc. And an optical metal substrate 1064 for fixing the light collimating device 1061, the scanning device 1062, and the beam expanding system 1063.
According to the embodiment of the present disclosure, single-photon detector 107 is configured to receive the gate signal and the laser pulse transmitted by second optical switch 104, and turn on or off in response to the gate signal, wherein when single-photon detector 107 is turned on, single-photon detector 107 generates a detection signal in response to the laser pulse transmitted by second optical switch 104, and transmits the detection signal to time-to-digital converter 108. The single photon detector 107 is a high sensitivity device operating in the operating band of the fiber laser 102, such as an InGaAs single photon avalanche diode.
According to an embodiment of the present disclosure, the time-to-digital converter 108 is configured to receive the synchronization signal and the detection signal and record time information.
According to the embodiment of the disclosure, because a small-sized optical device is used and a reasonable optical design is adopted, the problems of large volume and complex light path of a single photon imaging radar system are at least partially overcome, and then the effects of integration and practicability are achieved.
Figure 2 schematically illustrates a single photon imaging radar system in accordance with an embodiment of the present disclosure.
As shown in fig. 2, in operation of the single photon imaging radar system of the embodiment of the present disclosure, the fiber laser 102 is triggered by the signal source 101 to generate laser pulses, and the signal source 101 simultaneously gives a synchronous 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 light splitting device 105 through the emitting end optical switch 103, and then the light is emitted to a free space through the light collimating device 1061, reflected by the scanning device 1062 and expanded by the beam expanding system 1063, and then is emitted to the remote target object 204 and reflected. The returned photons are coupled from the light collimating device 1061 into the optical fiber 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 timing time obtained in response to the timing end signal to the information processing apparatus 203, so that the relative distance of the object can be obtained. Then, the scanning device 1062 is enabled to scan rapidly to obtain the relative distances of different areas of the target object 204, so as to obtain a three-dimensional image of the target object.
According to the single photon imaging radar system disclosed by the embodiment of the disclosure, the single photon detector 107 selects a detection device with single photon detection sensitivity, and can receive laser pulses emitted by the fiber laser 102 with mW (milliwatt) average power outside 10 km. The working wavelength of the near-infrared band is adopted, the atmospheric transmittance of the light with the near-infrared wavelength is higher than that of visible light, the atmospheric transmission attenuation is smaller, the absorption of human eyes is not easy, and the safety of the human eyes is high. The beam expanding system 1063 is used for expanding emergent light spots, reducing the power density of laser pulses and ensuring the safety of the single photon imaging radar system in the embodiment of the disclosure.
According to the single photon imaging radar system disclosed by the embodiment of the disclosure, the signal source 101 outputs at least 5 paths of signals, which are respectively a synchronous signal for controlling the fiber laser 102 to generate pulses and the time-to-digital converter 108 to record time information, and a gate control signal 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 internal noise of the system and improve the duty ratio of the output pulse time, the gating signal controls the first optical switch to be opened, and the second optical switch and the single-photon detector to be closed 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 disclosed embodiment further includes an electric turntable 201. The electric turntable 201 is connected to the optical transceiver board 106, and is used to control the pointing direction of the beam expanding system 1063, and for a scene requiring wide-angle imaging, a device capable of changing the pointing direction of the transmitting end of the single photon imaging radar system is usually required. For example, there is an unmanned vehicle equipped with the single photon imaging radar system, which needs to perform imaging acquisition on the surrounding environment, vehicle and personnel information during driving, and for this purpose, the single photon imaging radar system needs to be installed on a turntable capable of performing rapid rotation.
The single photon imaging radar system of the disclosed embodiment further comprises an auxiliary camera 202. And the auxiliary camera is used for assisting the single photon imaging radar system to find the target object. For example, in a scene in which the target object 204 needs to be imaged, since the angle of view of the scanning device 1062 and the beam expanding system 1063 is small, it is difficult to find the target object 204 and image the target object at the first time only by the scanning device 1062 itself, and at this time, the auxiliary camera 202 can be used to quickly locate the area where the target object 204 is located, thereby reducing the time required for imaging. The auxiliary camera 202 may be any device capable of interacting with the information processing apparatus 203 and having an optical information collection function.
The single photon imaging radar system of the embodiment of the present disclosure further includes an information processing apparatus 203. And the information processing device 203 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. The information processing apparatus 203 is an electronic device having functions of information reception, information processing, information storage, and information output, and includes, for example, but is not limited to, a computer, a single chip microcomputer, and the like.
Figure 3 schematically illustrates 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 present disclosure, the axes of the light collimating device 1061, the scanning device 1062, and the beam expanding system 1063 are coplanar, and the light path portion adopts a coaxial receiving and transmitting design, which simplifies the light path, improves the robustness of the system, omits the receiving and transmitting calibration process, keeps the receiving and transmitting light beams overlapped, saves the adjusting time of the free space light path, and has better repeatability and higher stability. The light collimation device 1061, the scanning device 1062 and the beam expanding system 1063 are close to each other in space, so that random noise existing in a free space light path is reduced, and the light path is not easily interfered by the outside.
Due to the limitation of the prior art, the laser has an inherent divergence angle, so that the light spot of the light emitted by the fiber laser becomes large at a long distance, thereby causing the transverse resolution of three-dimensional imaging to be poor and the image to be blurred. According to the integrated single photon imaging radar system, the light collimating device 1061 and the beam expanding system 1063 are designed to enable the divergence angle of the light beam to reach the order of hundreds of microarc, so that high transverse resolution can be achieved during remote three-dimensional imaging.
The integrated single photon imaging radar system of the embodiment of the disclosure adopts a miniaturized and integrated design, wherein most of light paths adopt optical fibers as transmission media, the light paths of the free space part are very simple, and 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. The scanning device 1062 adopts a two-dimensional MEMS galvanometer, which has a maximum resonant frequency of 1000Hz and a minimum mirror diameter of 3mm, thus having a small moment of inertia and being easier to realize high-speed rotation. In a specific scanning process, one shaft of the two-dimensional MEMS galvanometer works in a resonance mode, the other shaft works in a quasi-static mode, scanning patterns are in a snake shape, the fastest scanning speed is achieved, the beam expanding system 1063 with a small caliber is matched, the light path size is greatly reduced, the 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 equipped with a motor-driven turntable 201. A PCI-E board card type time-to-digital converter 108 is adopted, and a signal source 101, an optical fiber laser 102, a first optical switch 103, a second optical switch 104, an optical splitter 105, a single photon detector 107, the time-to-digital converter 108 and an information processing device 203 are all integrated in a case 304, so that the system structurally only comprises the case 304, a tripod 303 and a small optical transceiver board 106, the case 304 and the optical transceiver board 106 are connected through a flexible electronic cable 301 and an optical fiber 302, and the system has strong portability.
The integrated single photon imaging radar system of the embodiment of the disclosure provides a miniaturized system combining optical fibers and free space, coaxially receiving and transmitting, and scanning by using a two-dimensional MEMS galvanometer, and the system volume is greatly reduced. By utilizing the advantage of high speed of the MEMS galvanometer, the three-dimensional image data acquisition speed of several hertz can be realized. In addition, the system of the embodiment of the disclosure is improved in noise suppression and detection means, can perform three-dimensional imaging on the target as far as ten kilometers, and has practicability.
Figure 4 schematically illustrates a prototype system schematic of a single photon imaging radar system according to another embodiment of the disclosure.
As shown in fig. 4, in a laser emission portion of a prototype system of a 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 periodic pulses, and the periodic pulses are emitted from a light collimating device 1061 on an optical transceiver board 106 to a free space through a light switch 103 and a light splitting device 105, and are reflected to a beam expanding device 1063 through a two-dimensional MEMS galvanometer 409 to be emitted to a target object 204. The FPGA signal source 405 will give the time-to-digital converter 108 the same reference signal as the timing start signal.
According to another embodiment of the disclosure, the 1550nm wavelength pulse fiber laser with a pulse width of 500ps can be selected as the near-infrared fiber laser 401, and a narrow pulse width nanosecond, sub-nanosecond and picosecond laser in a near-infrared band can be used as a substitute, so that the narrow pulse width fiber laser can realize higher emission frequency and lower power density, and simultaneously meet the requirements of real-time performance and safety.
According to another embodiment of the present disclosure, the optical switch 103 may employ an optical fiber acousto-optic modulator, that is, the optical fiber AOM402, to suppress the spontaneous emission noise when the laser is not pulsed, or may use a device with an optical switching function, such as an electro-optical modulator.
According to another embodiment of the present disclosure, the optical splitter 105 may employ a 2 × 2 fiber splitter 403, and may also employ a fiber circulator or other exit-number fiber splitter.
According to another embodiment of the present disclosure, the light collimating device 1061 may use the fiber collimator 408 or a convex lens group.
According to another embodiment of the present disclosure, the beam expanding device 1063 may employ a 1: 10 beam expanding mirror to achieve a suitable beam divergence angle and field of view of reception. The beam expanding device 1063 may also be a kepler type or galileo type beam expanding lens composed of lens groups, and the proportion may also be adjusted.
According to another embodiment of the present disclosure, the time-to-digital converter 108 may employ a PCI-E interface board TDC407, and the board TDC407 has a counting accuracy of 13ps and is small in size. The board TDC407 may be replaced by other devices with similar high-precision time-to-digital conversion functions.
As shown in fig. 4, a receiving optical path of a prototype system of a single photon imaging radar system according to another embodiment of the present disclosure is designed to be coaxial with a transmitting optical path on an optical transceiver board. The returned signal photons enter the optical fiber through the optical fiber collimator 408, and enter the optical fiber AOM and the optical fiber filter 404 at the receiving end from the other exit of the 2 × 2 optical fiber splitter 403. The filtered signal photons are captured by the single photon detector 107, the single photon detector 107 transmits detection signals to the board card TDC407 to serve as timing end signals, and the photon flight time is measured and transmitted 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 three-dimensional image of the target object 204 can be reconstructed by using the upper computer software of the computer 406.
According to another embodiment of the present disclosure, the optical fiber AOM and the optical fiber filter in the optical fiber filter 404 may use a narrow-band optical fiber filter with a center wavelength of 1550nm to suppress the sunlight background noise in the daytime, thereby achieving the full-time working capability.
According to another embodiment of the present disclosure, the single photon detector 107 may use an InGaAs single photon avalanche diode, or may use other high-sensitivity single photon detectors operating in the near-infrared band.
According to another embodiment of the present disclosure, fiber AOM and fiber filter 404 and single photon detector 107 are turned off when the laser emits pulses, and fiber AOM and fiber filter 404 and single photon detector 107 are turned on when the laser does not emit pulses. The strategy suppresses local noise caused by the pulse 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 the near infrared fiber laser 401, the optical fiber AOM402, the 2 × 2 optical fiber splitter 403, the optical fiber AOM and the optical fiber filter 404, the FPGA signal source 405, the single photon detector 107, the computer 406, and the board TDC407, are integrated into one chassis 304, and the size thereof is only 290mm × 278mm × 238 mm. The optical transceiver board 106 is covered with a black aluminum plate 11cm in height, and has a size of only 200mm × 150mm × 10 mm. The optical transceiver board 106 may be placed on a tripod and connected to the chassis 304 with only one optical fiber and several electronic cables, which is very simple to install and has very high stability in use.
According to the embodiment of the disclosure, a set of practical single photon imaging radar system is provided, and the practical requirements of stability, safety, portability and the like can be considered. The system adopts effective optical design, reduces the interference of random factors such as environmental noise and the like, can realize long-distance and quick imaging, has higher resolution ratio, and has simple structure, small size and portability.
The embodiments of the present disclosure have been 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 separately above, this does not mean that the measures in the embodiments cannot be used in advantageous combination. The scope of the disclosure is defined by the appended claims and equivalents thereof. Various alternatives and modifications can be devised by those skilled in the art without departing from the scope of the present disclosure, and such alternatives and modifications are intended to be within the scope of the present disclosure.
Claims (10)
1. A single photon imaging radar system comprising:
a signal source for generating a synchronization signal and a gate control signal;
the fiber laser is used for receiving the synchronous signal and responding to the synchronous signal to emit laser pulse;
the first optical switch is connected with the optical fiber laser and the optical splitting device respectively, the second optical switch is connected with the optical splitting device and the single photon detector respectively, and the first optical switch and the second optical switch are used for receiving the gate control signal and responding to the gate control signal to be turned on or turned off so as to control whether the laser pulse passes through the first optical switch and the second optical switch or not;
the optical splitting device is used for receiving the laser pulse transmitted by the first optical switch and transmitting the laser pulse to the optical transceiver board, or is used for receiving the laser pulse transmitted by the optical transceiver board and transmitting the laser pulse to the second optical switch;
the optical transceiver board;
the single-photon detector is used for receiving the gate control signal and the laser pulse transmitted by the second optical switch and responding to the gate control 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 transmits the detection signal to the time-to-digital converter; and
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 of claim 1 in which said optical transceiver panel comprises:
the light collimating device is used for collimating or coupling the laser pulse;
a scanning device 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 of claim 2 in which the axes of said light collimating means, said scanning means and said beam expanding system are coplanar.
4. The single photon imaging radar system of claim 2 further comprising:
and the electric turntable is connected with the optical transceiver board and is used for controlling the pointing direction of the beam expanding system.
5. The single photon imaging radar system of 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 of claim 1 in which said signal source, said fiber laser, said first optical switch, said second optical switch, said beam splitting device, said single photon detector and said time to digital converter are integrated in a chassis.
7. The single photon imaging radar system of claim 6 further comprising:
and the information processing device is integrated in the chassis and 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 of claim 1 in which said synchronization signal and said gate signal are periodic signals and the period of said gate signal is greater than the period of said synchronization signal.
9. The single photon imaging radar system of claim 8 in which said gate control signal controls said first optical switch to be on, said second optical switch and said single photon detector to be off during the 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 one period.
10. The single photon imaging radar system of claim 1,
the fiber laser includes: a near-infrared pulse fiber laser;
the scanning device includes: a micro-electro-mechanical system galvanometer;
the time-to-digital converter includes: PCI-E board card type time-to-digital converter.
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