Portable Kilometer-level Strobe Imaging System

Abstract

The present invention provides a portable kilometer-level gated imaging system, which includes a laser, a beam expander, and a gated camera assembly. The gated camera assembly includes a gated camera, a filter, and an imaging lens arranged in sequence. The imaging lens is arranged parallel to the beam expander. The gated camera is connected to the laser and performs synchronous delay control on the laser. The gated camera includes an imaging module, a gating module, a gain module, and a timing module. The imaging module at least includes a photocathode and a detector. When receiving a shooting signal to perform gated imaging, the timing module sends a trigger signal to the laser, and the laser emits laser pulses to irradiate the target. The timing module is set to adjust the delay time of the gating pulse signal of the photocathode, so that when the laser echo signal reflected by the target reaches the photocathode, the photocathode is turned on, the gated camera is gated and turned on, and the detector acquires an image and sends the image when the gated camera is gated and turned on. The present invention adopts a compact design, reduces the volume and weight, and is convenient to carry.

Description

Technical Field

[0001] The present invention relates to the field of imaging technology, and particularly to a portable kilometer-level gated imaging system. Background Art

[0002] Under harsh weather conditions, such as thick fog, smoke, rain or snow, traditional penetration imaging technologies, such as lidar and infrared thermal imaging, although have achieved certain improvement in imaging effects, still have shortcomings in terms of portability, energy consumption control and cost-effectiveness. First, traditional penetration imaging devices are large in size and heavy in weight due to the inclusion of large optical components, high-power lasers and complex signal processing units. This not only increases the difficulty of transportation and deployment, but also limits their application on mobile platforms such as drones, vehicles or carried on foot. Secondly, high power consumption is another problem that needs to be solved urgently. Especially in the field operation where the power supply is limited, the high energy consumption of traditional systems has become the main obstacle restricting their continuous working ability and efficiency improvement. Summary of the Invention

[0003] An embodiment of the present invention provides a portable kilometer-level gated imaging system. The gated camera cooperates with the laser to achieve efficient capture and accumulation of the target echo signal; the laser and the gated camera are reasonably arranged to reduce the system volume and weight and lower the overall power consumption of the system.

[0004] A portable kilometer-level gated imaging system provided by an embodiment of the present invention includes:

[0005] A laser for emitting laser pulses;

[0006] An expander connected to the laser for expanding the diameter of the laser pulses emitted by the laser and outputting uniform laser pulses;

[0007] A gated camera assembly for capturing the echo signal reflected after the laser pulses irradiate the target and outputting the acquired image, including a gated camera, a filter and an imaging lens arranged in sequence. The gated camera, the filter and the imaging lens form a confocal receiving optical path. The imaging lens is arranged parallel to the expander. The gated camera is connected to the laser to perform synchronous delay control on the laser;

[0008] The gated camera includes an imaging module, a gating module, a gain module and a timing module; the imaging module acquires the image formed by focusing the echo signal reflected by the target; the imaging module at least includes a photocathode and a detector; the timing module sends a trigger signal to the laser; the timing module sends a gating pulse signal to the photocathode through the gating module;

[0009] When a shooting signal is received to select imaging, the timing module sends a trigger signal to the laser, and the laser emits laser pulses to irradiate the target. Set the timing module to adjust the delay time of the gating module sending the gating pulse signal to the photocathode, so that when the laser echo signal reflected by the target reaches the photocathode, the photocathode is turned on, that is, the gated camera is in the gated-on state; the detector acquires an image and sends the image when the gated camera is in the gated-on state.

[0010] Preferably, it further includes a computer, and the computer is connected to the gated camera to acquire the image output by the gated camera and perform image processing; the computer converts multiple slice images corresponding to time into a gray value change sequence curve corresponding to time, and the peak of the gray value change sequence curve indicates the target; calculate the relative position of the target according to the time corresponding to the peak.

[0011] Preferably, the laser pulses emitted by the laser, the echo signals reflected by the target, and the gating pulse signals sent to the photocathode have the same frequency; the distance of the target relative to the gated camera is calculated by the following formula:

[0012] ,

[0013] where, is the distance of the target relative to the gated camera; is the delay time when the photocathode is turned on when the laser echo signal reflected by the target reaches the photocathode, which is equal to the delay time of the gating module sending the gating pulse signal to the photocathode; is the pulse width of the gating pulse signal sent to the photocathode; is the pulse width of the laser pulses emitted by the laser; is the speed of light.

[0014] Preferably, there are two targets located at different distances, and the distances of the two targets relative to the gated camera are calculated by the following formula:

[0015] ,

[0016] ,

[0017] where, is the distance of the first target relative to the gated camera; is the distance of the second target relative to the gated camera; is the delay time when the photocathode is turned on when the laser echo signal reflected by the first target reaches the photocathode; is the delay time when the photocathode is turned on when the laser echo signal reflected by the second target reaches the photocathode; is the pulse width of the gating pulse signal sent to the photocathode; is the pulse width of the laser pulse emitted by the laser; is the speed of light.

[0018] Preferably, it further includes a housing, the housing includes a bottom plate and a shell, the shell covers the bottom plate and forms a receiving space between the shell and the bottom plate; the laser, the beam expander, the gating camera, the filter and the imaging lens are all arranged on the bottom plate and located in the receiving space; one end of the shell is provided with a front cover plate, the other end is provided with a closed rear cover plate, the front cover plate is provided with a borosilicate protective glass, and the beam expander and the imaging lens are arranged in parallel at one end close to the borosilicate protective glass.

[0019] Preferably, a cooling fan is arranged at the bottom of the bottom plate, and the cooling fan corresponds to the laser.

[0020] Preferably, the laser is a high-repetition-rate nanosecond pulse laser, the laser is connected to the beam expander through an optical fiber to transmit laser pulses, the working wavelength of the laser pulses is 860nm, the frequency is continuously adjustable within the range of 0Hz - 100KHz, the pulse width is continuously adjustable within the range of 10ns - 200ns, and the peak output power is 1200W.

[0021] Preferably, the detector includes an sCMOS chip. Among them, sCMOS is the abbreviation of scientific CMOS (scientific-grade CMOS); CMOS is the abbreviation of Complementary Metal-Oxide-Semiconductor (complementary metal oxide semiconductor). The frequency of the gating pulse signal of the photocathode of the gating camera is continuously adjustable within the range of 0Hz - 300KHz, and can be turned on multiple times within the single exposure cycle of the sCMOS chip of the detector.

[0022] Preferably, the effective clear aperture of the beam expander is 75mm, the divergence angle is continuously adjustable within the range of 0.44° - 5.15°, the imaging lens is a Cassegrain lens with a focal length of 500mm, and the clear aperture of the imaging lens is 95mm.

[0023] Preferably, the filter is an 860nm narrow-band filter, and the bandwidth of the filter is 20nm.

[0024] Compared with the prior art, the technical solution of the embodiment of the present invention has beneficial effects.

[0025] For example, the portable kilometer-level gated imaging system provided by the present invention includes a laser, a beam expander, and a gated camera assembly. The gated camera assembly includes a gated camera, a filter, and an imaging lens arranged in sequence. By precisely synchronizing the delay of the photocathode gating of the laser and the gated camera through the gated camera timing module and the gating module, when the laser echo signal reflected by the target reaches the photocathode, the photocathode is opened, that is, the gated camera is in the gated open state. The detector acquires an image when the gated camera is in the gated open state, achieving penetration imaging of kilometer-level targets; adopting a compact design, reasonably arranging the positions of core devices such as the laser and the gated camera, reducing the system volume and weight, and lowering the overall power consumption of the system.

[0026] For another example, image processing is performed on the image output by the gated camera; multiple slice images corresponding to time are converted into a sequence curve of gray value changes corresponding to time, and the peaks of the sequence curve of gray value changes indicate the target; the relative position of the target is calculated according to the time corresponding to the peak; without the need to equip an additional rangefinder, the device volume is reduced to a certain extent, not only obtaining the image information of the target, but also obtaining the position information of the target, improving the efficiency of on-site operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Internal structure diagram of the portable kilometer-level gated imaging system of the present invention;

[0028] Figure 2 Structure diagram of the portable kilometer-level gated imaging system of the present invention;

[0029] Figure 3 Structure diagram of the portable kilometer-level gated imaging system of the present invention from another angle;

[0030] Figure 4 Hardware structure diagram of the portable kilometer-level gated imaging system of the present invention;

[0031] Figure 5 Schematic diagram of the laser pulse propagation process of the portable kilometer-level gated imaging system of the present invention;

[0032] Figure 6 Gated imaging timing diagram of the portable kilometer-level gated imaging system of the present invention;

[0033] Figure 7 Schematic diagram of the push-scanning space of the portable kilometer-level gated imaging system of the present invention for multiple targets;

[0034] Figure 8 Sequence curve of the gray value change of the image of the present invention for push-scanning multiple targets;

[0035] Figure 9This is the curve of the change sequence of the image gray value after the multi-target push-scan adjustment of the starting time and the push-scan step time in the present invention;

[0036] Figure 10 This is the schematic diagram of the change of the time overlap between the laser pulse and the photocathode gating pulse in the present invention.

[0037] Explanation of reference numerals:

[0038] 1 - Beam expander; 2 - Laser; 3 - Gated camera; 4 - Filter; 5 - Imaging lens; 6 - Computer; 7 - Outer shell; 8 - Adapter ring;

[0039] 31 - Imaging module; 32 - Gating module; 33 - Gain module; 34 - Timing module; 311 - Detector; 312 - Photocathode;

[0040] 71 - Base plate; 72 - Housing; 73 - Front cover plate; 74 - Borosilicate protective glass; 75 - Rear cover plate; 76 - Cooling fan. Detailed implementation manners

[0041] To make the objectives, features, and beneficial effects of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention with reference to the accompanying drawings. It can be understood that the following described detailed implementation manners are only used to explain the present invention and are not intended to limit the present invention. Also, in the figures, the same or similar reference numerals may be used to refer to the same or similar elements in different embodiments, and the descriptions of the same or similar elements in different embodiments and the descriptions of the elements, features, effects, etc. of the prior art may also be omitted.

[0042] Refer to Figures 1 to 10 , the embodiment of the present invention provides a portable kilometer-level gated imaging system.

[0043] Specifically, the portable kilometer-level gated imaging system provided by the embodiment of the present invention includes:

[0044] A laser 2 for emitting laser pulses;

[0045] A beam expander 1 connected to the laser 2 for expanding the diameter of the laser pulses emitted by the laser 2 and outputting uniform laser pulses;

[0046] The gated camera component captures the echo signal reflected after the laser pulse irradiates the target and outputs the acquired image, including a sequentially arranged gated camera 3 (for example, an IsCMOS gated camera, where IsCMOS is short for Isolated CMOS), a filter 4, and an imaging lens 5. The filter 4 is arranged in an adapter ring 8 connecting the gated camera 3 and the imaging lens 5. The gated camera 3, the filter 4, and the imaging lens 5 form a confocal receiving optical path. The imaging lens 5 is arranged parallel to the beam expander 1. The gated camera 3 is connected to the laser 2 (for example, the gated camera 3 has a trigger port reserved and is connected to the trigger laser 2 through a wire) to perform synchronous delay control on the laser 2;

[0047] The gated camera 3 includes an imaging module 31, a gating module 32, a gain module 33, and a timing module 34; the imaging module 31 acquires the image formed by focusing the echo signal reflected from the target; the imaging module 31 at least includes a photocathode 312 and a detector 311 (for example, an sCMOS detector), and the timing module 34 sends a trigger signal to the laser 2; the timing module 34 sends a gating pulse signal to the photocathode 312 through the gating module 32;

[0048] In a specific implementation, the imaging module further includes an MCP (Micro Channel Plate, abbreviated as MCP), a fluorescent screen, and a coupling light cone. The photocathode, the MCP, and the fluorescent screen form an image intensifier. The image intensifier cooperates with the gain module to amplify weak optical signals, and at the same time cooperates with the gating module 32 to achieve time-resolved imaging, that is, slice imaging; the image intensifier and the detector 311 are connected through optical cone coupling.

[0049] When the imaging is gated upon receiving the shooting signal, the timing module 34 sends a trigger signal to the laser 2. The laser 2 emits a laser pulse to irradiate the target. The timing module 34 is set to adjust the delay time of the gating module 32 sending the gating pulse signal to the photocathode 312, so that when the laser echo signal reflected from the target reaches the photocathode 312, the photocathode 312 is turned on, that is, the gated camera 3 is in a gated-on state; the detector 311 acquires an image and sends the image when the gated camera 3 is in a gated-on state. The image is received by the software on the computer side and is displayed in real time, realizing the penetration imaging of kilometer-level targets.

[0050] In some embodiments, it further includes a housing 7, which includes a bottom plate 71 and a housing body 72. The housing body 72 covers the bottom plate 71 and forms a receiving space therebetween; the laser 2, the beam expander 1, the gated camera 3, the filter 4 and the imaging lens 5 are all disposed on the bottom plate 71 and within the receiving space; one end of the housing body 72 is provided with a front cover plate 73, and the other end is provided with a closed rear cover plate 75. A borosilicate protective glass 74 is provided on the front cover plate 73. The beam expander 1 and the imaging lens 5 are arranged in parallel at one end close to the borosilicate protective glass 74. With a compact design, the positions of core devices such as the laser 2 and the gated camera 3 are reasonably arranged, reducing the system volume and weight and lowering the overall power consumption of the system.

[0051] In a specific implementation, the overall dimensions of the housing 7 are 372mm * 139mm * 214mm, the weight is 6.5 kg, the power supply voltage of the laser 2 and the gated camera 3 is 12V, the current is 3A, and the power consumption of the entire system is only 72W.

[0052] In some embodiments, a cooling fan 76 is provided at the bottom of the bottom plate 71, and the cooling fan 76 is disposed corresponding to the laser 2.

[0053] In some embodiments, the laser 2 is a high-repetition-rate nanosecond pulsed laser. The laser 2 transmits laser pulses to the beam expander 1 through an optical fiber. The working wavelength of the laser pulses is 860 nm, the frequency is continuously adjustable within the range of 0 Hz - 100 KHz, the pulse width is continuously adjustable within the range of 10 ns - 200 ns, and the peak output power is 1200W.

[0054] In some embodiments, the detector 311 includes an sCMOS chip. The gated pulse signal frequency of the photocathode 312 of the gated camera 3 is continuously adjustable within the range of 0 Hz - 300 KHz and can be turned on multiple times within the single exposure period of the sCMOS chip of the detector 311 (i.e., the single-frame exposure time of the detector 311).

[0055] In some embodiments, the effective clear aperture of the beam expander 1 is 75 mm, the divergence angle is continuously adjustable within the range of 0.44° - 5.15°, the imaging lens 5 is a Cassegrain lens with a focal length of 500 mm, and the clear aperture of the imaging lens 5 is 95 mm.

[0056] In some embodiments, the filter 4 is an 860 nm narrow-band filter, and the bandwidth of the filter 4 is 20 nm, effectively filtering ambient stray light.

[0057] In some embodiments, a computer 6 is further included. The computer 6 is connected to the gated camera 3, acquires the images output by the gated camera 3, and performs image processing. The computer 6 converts multiple slice images corresponding to time into a sequence curve of gray value changes corresponding to time. The peaks of the sequence curve of gray value changes indicate the target object. The relative position of the target object is calculated according to the time corresponding to the peak.

[0058] In some embodiments, the laser pulse emitted by the laser 2, the echo signal reflected by the target object, and the gated pulse signal sent to the photocathode 312 have the same frequency. The distance of the target object relative to the gated camera 3 is calculated by the following formula:

[0059] ,

[0060] where, is the distance of the target object relative to the gated camera 3; is the delay time when the photocathode is turned on when the laser echo signal reflected by the target object reaches the photocathode 312, which is equal to the delay time of the gated module 32 sending the gated pulse signal to the photocathode 312; is the pulse width of the gated pulse signal sent to the photocathode 312; is the pulse width of the laser pulse emitted by the laser 2; is the speed of light.

[0061] In some embodiments, there are two target objects at different distances. The distances of the two target objects relative to the gated camera 3 are calculated by the following formula:

[0062] ,

[0063] ,

[0064] where, is the distance of the first target object relative to the gated camera 3; is the distance of the second target object relative to the gated camera 3; is the delay time when the photocathode is turned on when the laser echo signal reflected by the first target object reaches the photocathode 312; is the delay time when the photocathode is turned on when the laser echo signal reflected by the second target object reaches the photocathode 312; is the pulse width of the gated pulse signal sent to the photocathode 312; is the pulse width of the laser pulse emitted by the laser 2; is the speed of light.

[0065] The principle of gated imaging and the calculation principle of the distance of the target object relative to the gated camera will be described below with reference to the accompanying drawings.

[0066] Please refer toFigure 5 and Figure 6 When there is no target in the field of view of the gated camera 3, even if the gated camera 3 starts gated imaging, the ambient scattered light backscattered from the background area, i.e., the non-target area, generally presents a relatively uniform distribution and does not cause significant intensity fluctuations. However, once a target appears, due to the unique absorption and reflection characteristics of the target material to the laser pulse, the light intensity of the laser echo signal reflected by the target will show a significant jump. The laser 2 emits a laser pulse towards the target, and during the laser propagation process, it will be scattered by various particles in the air. These scattered rays are non-target noise light. Therefore, during this period, the photocathode 312 of the gated camera 3 is in the gated off state. When the laser echo signal reflected by the target reaches the photocathode 312, the photocathode 312 is turned on. At this time, the gated camera 3 is in the gated on state, realizing gated imaging of the target.

[0067] The laser pulse signal, the target object reflected echo signal, and the gated pulse signal sent to the photocathode 312 all have the same frequency. is the pulse width of the laser pulse; It is the pulse width of the echo signal reflected by the target when the laser irradiates the target. , is the time required for the laser pulse front to be reflected by the target object and reach the gated camera 3, Multiply by the ambient light speed is the actual distance between the target object and the gated camera 3; is the pulse width of the gate pulse signal of the photocathode 312; The delay time from the laser echo signal reflected by the target object to the photocathode 312 when the photocathode is turned on satisfies the following formula when the target object is gated for imaging:

[0068] ,

[0069] The distance of the target object relative to the gated camera 3 can be calculated :

[0070] ,

[0071] When the target is too far away and the target echo signal is too weak, the single-frame exposure accumulation function of the gated camera 3 can be used to open the photocathode 312 multiple times within the single-frame exposure time of the detector 311 to improve the signal-to-noise ratio of the target signal.

[0072] See Figure 7, control the delay time for opening the photocathode 312 of the gated camera 3, perform slice imaging on the space by the method of layer-by-layer push-scanning of slices, obtain the backscattered light slices of the environmental background and the effective slices of the target object, and step by step collect the imaging signals of the effective target area for detecting one or more target objects at unknown distances. During the entire sequence push-scanning process, two-dimensional image information at different distances is obtained, including the slice image information of the target object and the slice image information of the backscattered light of the environmental background; through Figure 8 and Figure 9 Once the sequence push-scanning delay times of targets at different distances are obtained in the way of Figure 5 and Figure 6 gating working principle, combined with Figure 8 , Figure 9 and Figure 10 fine control of relevant parameters can be carried out to obtain fine imaging slices of multiple specific targets at different distances.

[0073] Please refer to Figure 8 , convert the slice image information of the target object and the slice image information of the backscattered light of the environmental background into a sequence curve of gray value changes corresponding to time. The wave peaks of the sequence curve of gray value changes indicate the target objects, and the abscissa represents the gating delay time of the photocathode 312. Since the trigger inherent delay of the laser 2 is greater than the inherent delay of the photocathode 312 to open the door, it is necessary to use the starting moment of the laser emission as the time reference starting point of the sequence push-scanning, denoted as , and are the delay values at the wave peaks of the gray values of the sequence curves corresponding to the first target object and the second target object respectively during the sequence push-scanning process of the gated camera 3. The distances of the two target objects relative to the gated camera 3 are:

[0074] ,

[0075] ,

[0076] By the sequence push-scanning delay times corresponding to multiple wave peaks, the distance parameters between multiple different target objects can be quickly obtained, and at the same time, the image information of target objects at different distances can be obtained, so as to obtain kilometer-level target parameter information in terms of time and space.

[0077] Please refer to Figure 9 , approach the effective target area where the target object is located. When controlling the delay time for opening the photocathode 312 of the gated camera 3 and collecting the imaging signals of the effective target area step by step by the method of layer-by-layer push-scanning of slices, set a relatively large value close to the left side of the target at the starting scanning time of the sequence, and set a value close to the right side of the target at the end scanning time of the sequence., while reducing the sequence push-scan step time value , reduce and , further improve the precision of slicing, making the distances of the two targets relative to the gated camera 3 more accurate, which is more conducive to extracting effective target signals.

[0078] Please refer to Figure 10 , the intensity of the actual laser pulse presents a Gaussian bell curve. Controlling the gating opening signal of the photocathode 312, that is, the gating pulse signal controlling the opening of the photocathode 312, is actually an electrical pulse signal. There are rising and falling edges in the electrical pulse signal. When the gate width of the gating opening signal of the photocathode 312 needs to be opened extremely narrow, it can also be considered that the waveform of the opening signal presents a Gaussian bell curve. In the figure, it is assumed that is greater than , at time Tm, when the photocathode 312 opens, it is just at the moment before the effective target laser echo signal to be measured is not captured; at time Tm+1, based on the delay of the photocathode 312 opening relative to time Tm, it is delayed by an additional ∆Tstep time to open, that is, Tm+1 = Tm + ∆Tstep. At this time, when the photocathode 312 opens, it just receives the starting part of the rising edge of the laser echo signal pulse; and so on. At time Tmid, the waveform of the laser echo pulse can just completely contain the signal of the delayed opening of the photocathode 312, and the center of the gating opening signal is just aligned with the center of the laser pulse. At this time, when the photocathode 312 opens, it can capture the maximum value of the intensity of the laser echo signal; at times Tn-1 and Tn, they are the last moments when the gating opening signal of the photocathode 312 and the laser echo signal are synchronized in time, that is, Tn = Tm + (n - m)∆Tstep, and it is also the end part of the falling edge of the pulse of the photocathode 312 receiving the target laser echo signal. From the area of the shaded region of the overlapping part of the laser pulse and the gating opening signal of the photocathode 312 from none to the right, then to the maximum value, and then continue to decrease until there is no overlap. If the step time value ∆Tstep of the entire sequence push-scan process is small enough, then when the sequence push-scan image generated by slicing is converted into a gray value curve display, it will also present a Gaussian bell curve. If the reflectivity of the target to be measured itself is relatively strong, then the gray value at the peak of the corresponding gray value curve will be larger. As long as there are no interfering objects with extremely strong reflectivity in the non-target space except for the target to be measured during the entire sequence push-scan process, then as long as one sequence push-scan is performed, the Figure 9 shown sequence push-scan gray value curve graph can be obtained, and thus the distances of different targets can be calculated according to the number of peaks of the curve and the corresponding time positions; therefore, reducing the sequence push-scan step time value ∆Tstep and improving the precision of slicing are beneficial to improving the push-scan efficiency, beneficial to extracting the target, and improving the measurement precision of the target distance; although it is assumed that is greater than , but if is less than The same conclusion will also be obtained.

[0079] In summary, the portable kilometer-level gated imaging system provided by the present invention includes a laser 2, a beam expander 1, and a gated camera assembly. The gated camera assembly includes a gated camera 3, a filter 4, and an imaging lens 5 arranged in sequence. By precisely synchronizing the delay of the laser 2 and the photocathode 312 gating of the gated camera 3 through the timing module 34 and the gating module 32 of the gated camera 3, when the laser echo signal reflected by the target reaches the photocathode 312, the photocathode 312 is opened, that is, the gated camera 3 is in the gated open state; the detector 311 acquires an image when the gated camera 3 is in the gated open state, realizing the penetration imaging of kilometer-level targets; adopting a compact design, reasonably arranging the positions of core devices such as the laser 2 and the gated camera 3, reducing the system volume and weight, and reducing the overall power consumption of the system.

[0080] Furthermore, the present invention performs image processing on the images output by the gated camera 3; converts multiple slice images corresponding to time into a sequence curve of gray value changes corresponding to time, and the peaks of the sequence curve of gray value changes indicate the target; calculates the relative position of the target according to the time corresponding to the peak; does not require an additional rangefinder, reducing the device volume to a certain extent, not only obtaining the image information of the target, but also obtaining the position information of the target, improving the efficiency of on-site operations.

[0081] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present invention disclosed, even when describing a single embodiment relative to a specific feature. The feature examples provided in the present invention disclosure are intended for illustration rather than limitation, unless otherwise stated. In specific implementations, according to actual needs and when technically feasible, the technical features of one or more dependent claims can be combined with the technical features of the independent claim, and can be combined in any appropriate manner rather than only through the specific combinations listed in the claims from the technical features of the corresponding independent claims.

[0082] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined by the claims.

Claims

1. A portable kilometer-level gated imaging system, characterized in that: include: a laser for emitting laser pulses; a beam expander connected to the laser to expand the diameter of the laser pulse emitted by the laser and output uniform laser pulses; A gated camera assembly captures the echo signal reflected from the target after the laser pulse is irradiated and outputs the acquired image, comprising a gated camera, a filter, and an imaging lens arranged in sequence. The gated camera, the filter, and the imaging lens form a confocal receiving optical path. The imaging lens is arranged in parallel with the beam expander. The gated camera is connected to the laser to perform synchronous delay control on the laser. a computer connected to the gated camera to acquire images output by the gated camera and perform image processing; the computer converts the multiple slice images corresponding to time into a grayscale value change sequence curve corresponding to time, wherein the peak of the grayscale value change sequence curve indicates the target object; and calculates the relative position of the target object based on the time corresponding to the peak; The gated camera includes an imaging module, a gate module, a gain module, and a timing module; the imaging module acquires an image formed by focusing the echo signal reflected from the target; the imaging module includes at least a photocathode and a detector; the timing module sends a trigger signal to the laser; the timing module sends a gated pulse signal to the photocathode through the gate module; When receiving a shooting signal to select imaging, the timing module sends a trigger signal to the laser, and the laser emits a laser pulse to illuminate the target object. The timing module is set to adjust the delay time of the gate control module sending the gate control pulse signal to the photocathode, so that when the laser echo signal reflected by the target object reaches the photocathode, the photocathode is turned on, that is, the gate control camera is in the gated on state; the detector acquires and sends the image when the gate control camera is in the gated on state; The laser pulse emitted by the laser, the echo signal reflected by the target, and the gated pulse signal sent to the photocathode have the same frequency; the distance of the target relative to the gated camera is calculated using the following formula: , The two targets are located at different distances, and the distances between the two targets and the gated camera are calculated using the following formula: , , in, is the distance of the target object relative to the gated camera; The delay time for the photocathode to be turned on when the laser echo signal reflected by the target reaches the photocathode is equal to the delay time for the gating module to send the gating pulse signal to the photocathode; is the pulse width of the gate pulse signal sent to the photocathode; is the pulse width of the laser pulse emitted by the laser; is the speed of light; is the distance of the first target object relative to the gated camera; is the distance of the second target object relative to the gated camera; The delay time for the photocathode to be turned on when the laser echo signal reflected by the first target reaches the photocathode; is the delay time of the photocathode turning on when the laser echo signal reflected by the second target reaches the photocathode; the starting moment of the laser emission is used as the time reference starting point of the sequence push scan, which is recorded as ; The intensity of the laser pulse presents a Gaussian bell curve; when the imaging signal is collected by pushing the slice layer by layer, a value close to the left side of the target is set at the start scanning time of the sequence , set a value close to the right side of the target at the end scan time of the sequence , while reducing the sequence push-scan step time value ∆Tstep, reducing and .

2. The portable kilometer-level gated imaging system according to claim 1, characterized in that: The housing further comprises a bottom plate and a shell, wherein the shell cover is arranged on the bottom plate and forms a storage space with the bottom plate; the laser, the beam expander, the gate-controlled camera, the filter and the imaging lens are all arranged on the bottom plate and located in the storage space; a front cover is provided at one end of the shell, and a closed rear cover is provided at the other end, a borosilicate protective glass is provided on the front cover, and the beam expander and the imaging lens are arranged in parallel at one end close to the borosilicate protective glass.

3. The portable kilometer-level gated imaging system according to claim 2, characterized in that: A heat dissipation fan is provided at the bottom of the base plate, and the heat dissipation fan is provided corresponding to the laser.

4. The portable kilometer-level gated imaging system according to claim 1, characterized in that: The laser is a high repetition rate nanosecond pulse laser, which is connected to the beam expander via an optical fiber to transmit laser pulses. The laser pulse operating wavelength is 860nm, the frequency is continuously adjustable in the range of 0Hz-100KHz, the pulse width is continuously adjustable in the range of 10ns-200ns, and the peak output power is 1200W.

5. The portable kilometer-level gated imaging system according to claim 1, characterized in that: The detector includes an sCMOS chip, and the gate pulse signal frequency of the photocathode of the gated camera is continuously adjustable within the range of 0 Hz-300 KHz, and can be opened multiple times within a single exposure cycle of the sCMOS chip of the detector.

6. The portable kilometer-level gated imaging system according to claim 1, characterized in that: The effective clear aperture of the beam expander is 75 mm, and the divergence angle is continuously adjustable within the range of 0.44°-5.15°. The imaging lens is a Cassegrain lens with a focal length of 500 mm, and the clear aperture of the imaging lens is 95 mm.

7. The portable kilometer-level gated imaging system according to claim 1, characterized in that: The filter is an 860nm narrowband filter, and the bandwidth of the filter is 20nm.

Images