CN209746131U - Three-dimensional real-time imaging laser radar system based on area array CCD - Google Patents
Three-dimensional real-time imaging laser radar system based on area array CCD Download PDFInfo
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Abstract
The three-dimensional real-time imaging laser radar system based on the area array CCD is characterized by comprising a data processing module, a high-power laser emission assembly, an area array CCD sensor imaging assembly, a power supply conversion module and a PC terminal, wherein the high-power laser emission assembly, the area array CCD sensor imaging assembly, the power supply conversion module and the PC terminal are connected with the data processing module. The system has low cost, can image a moving target, can improve the imaging quality and can improve the imaging real-time property.
Description
Technical Field
The utility model relates to a three-dimensional real-time imaging laser radar technique mainly relates to and utilizes the 2D sensor to realize the laser radar technique of 3D real-time formation of image through indirect TOF imaging method, specifically is three-dimensional real-time imaging laser radar system based on area array CCD.
Background
The three-dimensional imaging radar system can be divided into an active imaging radar and a passive imaging radar according to the acquisition mode of a light source, the passive imaging radar mainly performs imaging by means of natural light, and the passive imaging radar is greatly influenced by natural conditions, so that the research focus at present is basically in the field of the active imaging radar. Because laser has various characteristics such as collimation, little interference from natural light, etc., laser is generally adopted as a light source of an active three-dimensional imaging radar. The optical imaging device comprises detectors such as APD, CCD, ICCD, CMOS and the like, an APD array realizes distance measurement by directly calculating laser flight time, but the resolution ratio is small, the application scene is limited, the ICCD sensor has high resolution ratio, large dynamic range and no special requirements on the measurement environment, the imaging effect is better than that of the CCD sensor, but the system has a large optimization space in the aspects of service life, price cost, volume weight and the like. CMOS sensors are inferior to CCD sensors in both imaging speed and resolution. The CCD sensor has the advantages of high resolution, wide dynamic range, low distortion, small size, light weight, low cost and the like. In the aspect of an imaging algorithm, a TOF imaging algorithm is commonly used, and is divided into a direct TOF method and an indirect TOF method, wherein the direct TOF algorithm is to directly measure round trip time of emitted light and is generally realized by a counter, the indirect TOF method is generally to carry out photon light intensity accumulation, calculate distance by establishing and analyzing a relationship of a light intensity-distance curve, and calculate light flight time by a phase method, so as to calculate distance information of a pixel point. In addition to the above method, the distance measurement can be realized by linear frequency modulation. At present, due to the limitation of the microelectronic technology level, the research on the system structure is still in the theoretical research stage, and the circuit structure is also to be further optimized to improve the stability. The whole application is separated from engineering, and a plurality of theoretical and technical problems need to be solved.
SUMMERY OF THE UTILITY MODEL
The utility model aims at the not enough of prior art, and provide a three-dimensional real-time formation of image laser radar system based on area array CCD. The system has low cost, can image a moving target, can improve the imaging quality and can improve the imaging real-time property.
Realize the utility model discloses the technical scheme of purpose is:
The three-dimensional real-time imaging laser radar system based on the area array CCD is different from the prior art in that the system comprises a data processing module, a high-power laser emission component, an area array CCD sensor imaging component, a power supply conversion module and a PC terminal, wherein the high-power laser emission component is connected with the data processing module, the high-power laser emission component is driven according to square waves, floodlight illumination is carried out on a target area in an imaging view field, and an echo beam of laser reflected by a target reaches the area array CCD sensor imaging component.
The data processing module comprises an FPGA main control chip, an ADC chip conversion circuit connected with the FPGA main control chip, an SDRAM storage chip and a USB transfer port, wherein the digital output end of the ADC chip conversion circuit is connected with the FPGA main control chip so as to be convenient for image processing, the ADC chip adopts an ADC chip with a three-color channel function, the work of later 3D image color recovery is avoided, the SDRAM storage chip is connected with the FPGA main control chip so as to store image data, the USB transfer port is connected with the FPGA main control chip and a PC terminal so as to carry out real-time transmission of the image data and instruction parameters, a 3D image transmits the image data to the PC terminal in the form of the USB transfer port, the data processing module adopts the FPGA technology to carry out image filtering, image weighting and 3D image recovery work, and a parallel bottom layer data processing mechanism is adopted, so that the real-time imaging performance of the system is, and finally, transmitting the processed data to a PC terminal for further correction and display.
The high-power laser emission assembly comprises a laser driving circuit, a laser diode array and an optical beam expanding collimating lens array which are sequentially connected, the high-power laser emission assembly is arranged according to a double-ring structure, the high-power laser emission assembly and an area array CCD sensor imaging assembly carry out same-hole receiving and transmitting, and the optical beam expanding collimating lens array is adopted for amplifying the field angle, so that the detection range is expanded, and the phenomenon of inaccurate detection caused by concentrated laser spots is prevented.
The area array CCD sensor imaging component comprises an area array CCD sensor driving circuit, an area array CCD sensor, a band-pass filter and a telephoto lens which are sequentially connected.
The optical beam expanding and collimating lens array is composed of 32 optical beam expanding and collimating lenses with 20 times of beam expanding function, wherein 16 optical beam expanding and collimating lenses with 20 times of beam expanding function are uniformly arranged in an annular shape, and the 32 optical beam expanding and collimating lenses form a double-annular array structure with different diameters.
The laser diode array is composed of 32 laser diodes, wherein every 16 laser diodes are uniformly arranged in a ring shape, 32 laser diodes form a double-ring array structure with different diameters, the laser diode array and the optical beam expanding collimating lens array are completely consistent in structural arrangement and shape and size and are finally mutually attached together, so that each laser is sent out through the optical beam expanding collimating lens to achieve the effects of beam expanding and collimating, the laser diode array has higher power and quite far difference between the laser wavelength and the natural light wavelength so as to better filter the natural light interference under the action of the band-pass filter, and the laser diode selects a semiconductor laser diode, the utility model discloses the influence on the detection distance is mainly limited by the laser power in a laser emitting component, so the peak power of the selected single laser diode is higher, secondly, the optical beam expanding collimating lens mainly aims at preventing the emitted laser from being too concentrated to cause the reduction of the detection precision, and also to expand the range of laser irradiation.
The laser driving circuit is provided with two MOSFET driving EL7104CS chips, and the two EL7104CS chips respectively drive a ring-shaped laser diode array, so that the rising and falling time delay is low, and the clock rate is high.
The outer diameter of the telephoto lens is consistent with the annular inner diameters of the optical beam expanding and collimating lens array and the laser diode array, so that the telephoto lens is just inserted into the annular inner diameters of the optical beam expanding and collimating lens array and the laser diode array, the purpose of receiving and transmitting laser in the same hole is achieved, and laser is effectively utilized and detection precision is improved.
The diameter of the band-pass filter is consistent with that of the tail end of the telephoto lens and is arranged at the tail end of the telephoto lens so as to completely filter the light passing through the telephoto lens.
The long-focus lens and 32 laser diode arrays in the laser emission assembly form a same-hole receiving and transmitting model, so that echoes generated by the emitted laser diode arrays are effectively recycled by the long-focus lens as far as possible, the detection precision is improved, and when the echoes return to a receiving end, the echoes reach a sensing surface of the area array CCD sensor through the long-focus lens after being filtered by the band-pass filter to remove ambient light, and real-time imaging is carried out under the control of the electronic shutter.
The area array CCD sensor is an area array CCD sensor with a color imaging effect, the large workload is reduced for later image data processing, the photosensitive surface of the area array CCD sensor is just opposite to the non-coated surface of the band-pass filter, the output end of the area array CCD sensor is connected with the analog input end of the ADC chip conversion circuit to acquire color images for digital processing, the area array CCD sensor has high-speed electronic shutter control signals and can form color images in real time, the workload of recovering the color images is eliminated for later color 3D image acquisition, the system efficiency is improved, and meanwhile, the area array CCD sensor adopts a stable power supply conversion system to ensure the stable and efficient work of the area array CCD sensor driving circuit.
The area array CCD sensor driving circuit is formed by adopting a high-speed driving chip and a rectifying chip together, so that the quality of a high-speed electronic shutter time sequence on the area array CCD sensor is ensured, and high-quality imaging is realized.
The power supply conversion module conducts current-voltage conversion under the action of the analog amplification circuit and the power supply conversion chip by leading out a 5V level from the FPGA main control chip so as to meet the current-voltage standard required by each module of the system and ensure stable and effective work of the system.
The power supply conversion module is composed of a voltage conversion circuit composed of a max685 chip and a voltage amplification circuit composed of an LM2924N chip, wherein the voltage conversion circuit composed of the max685 chip mainly provides power support for the area array CCD sensor driving circuit, and the voltage amplification circuit composed of the LM2924N chip mainly provides power support for the laser driving circuit.
the imaging principle of the technical scheme is as follows: in the technical scheme, the flight time of laser echo needs to be known from the recovery of the 3D image from the two-dimensional image generated by the imaging component of the color CCD sensor, and an indirect TOF algorithm is adopted.
The laser diode array generates light pulse strings with the wavelength of lambda, after the light pulse strings are reflected by a target, three light pulses are respectively collected in the exposure time controlled by the electronic shutter, and the collection time interval is tau, then:
t＝t+iΔt
Wherein t0 is the initial gating time, Δ t is the stepping time, i is the natural number serial number, the light intensity accumulation on the color area array CCD sensor can be obtained respectively, the front and back two frames of images collected by the area array CCD image sensor, the light intensity change with the distance is as follows:
Wherein S represents the distance of the target object in the previous image, S' represents the distance of the target object in the next image, c represents the speed of light, t represents time, P (t-2S/c) represents the waveform of the light pulse with the wavelength lambda, g (t) is the power-time function of the gain of the receiver,
The formula shows that the light intensity accumulation of the reflected light of the same point on the same target object on the image sensor is changed along with the integration time, the integration time is related to the pulse transmitting time and the receiving time of the image sensor, the light intensity integration can be carried out on the collected pulse signals on the assumption that the image sensor can carry out the light intensity integration on the same pixel point of the target object after multiple exposures are carried out on the same pixel point, a plurality of trapezoidal integration curve graphs can be obtained on the same pixel point, each integration curve graph has a vertex, a curve can be fitted through a plurality of trapezoidal vertices, so that better measuring accuracy is obtained, the abscissa corresponding to the vertex of the curve is solved according to an image weighting method, the flight time can be known, and the image weighting method is expressed as: assuming that the time delay of the ith time is ti, the light intensity accumulated on the area array CCD image sensor is I (Si), taking out the minimum value min (I (Si)) of a plurality of frames of the same pixel, and letting:
A＝I(S)-min(I(S))
＝∫P(t-2S/c)g(t)dt-min(∫P(t-2S/c)g(t)dt)
The abscissa t is then:
t＝2S/c＝A∑(I(S)-min(I(S)))t
＝A∑(∫P(t-2S/c)g(t)dt-min(∫P(t-2S/c)g(t)dt))t，
in the formula, ti is an integer summation of i times of delay time, A is an Ai summation value Sigma Ai, an abscissa t of a vertex represents the round-trip time of a pulse signal, distance information of a target object can be obtained according to the formula, wherein Z represents the distance information, c represents the flight time of light in vacuum, t is the total time of the light signal in the whole flight process, n is the refractive index of the light in a medium, n is approximately equal to 1 in clean air, and finally, a 3D image is obtained according to the obtained distance information of each pixel point.
The working principle of the technical scheme is as follows: the method comprises the steps of adopting a high-power laser emission assembly to carry out flood lighting on a target area in an imaging view field, driving a laser diode array in the high-power laser emission assembly according to square waves, reflecting laser light by a target and then reaching an imaging assembly of an area array CCD (charge coupled device) sensor, generating light intensity accumulation on the area array CCD image sensor within exposure time controlled by an electronic shutter on the area array CCD image sensor to form a frame of analog image, then reaching a data processing module, converting the image into a digital image through an ADC (analog to digital converter) chip and then storing the digital image in an SDRAM (synchronous dynamic random access memory) storage chip, immediately carrying out image filtering, image weighting and 3D image recovery on an FPGA (field programmable gate array) main control chip in real time, and transmitting the 3D image recovered by the FPGA main control chip to a.
the beneficial effects of this technical scheme are: through a reasonable three-dimensional imaging mechanism, the detection distance is basically only influenced by laser power and a lens focal length, and high-quality imaging can be completed only by an area array CCD image sensor instead of an expensive ICCD sensor; the area array CCD sensor and the ADC chip with the three-color channel are used, so that the image data processing of the data processing module is simpler and faster, the bottom layer parallel processing mechanism of the FPGA main control chip is used for image filtering, image weighting and 3D image recovery, and meanwhile, the USB-to-serial port part of the data processing module uses a USB3.0 serial port for image transmission, so that the frame number is greatly improved, and a moving target can be imaged.
The system has low cost, can image a moving target, can improve the imaging quality and can improve the imaging real-time property.
Drawings
FIG. 1 is a schematic structural diagram of an embodiment;
FIG. 2 is a schematic diagram of imaging timing principle of the system in the embodiment;
The system work flow in the embodiment of fig. 3 is schematic.
In the figure, 1 is a high-power laser emission assembly 2, an area array CCD sensor imaging assembly 3, a data processing module 4, a power supply conversion module 5, a PC terminal 6, an optical beam expanding collimating lens array 7, a laser diode array 8, a laser driving circuit 9, a telephoto lens 10, a band-pass filter 11, an area array CCD sensor 12, an area array CCD sensor driving circuit 13, an ADC chip conversion circuit 14, an SDRAM storage chip 15, a USB-to-serial port 16 and an FPGA main control chip.
Detailed Description
The present invention will be further described with reference to the following drawings and examples, but the present invention is not limited thereto.
example (b):
Referring to fig. 1, the three-dimensional real-time imaging laser radar system based on the area array CCD comprises a data processing module 3, a high-power laser emission component 1 connected with the data processing module 3, an area array CCD sensor imaging component 2, a power conversion module 4 and a PC terminal 5, wherein the high-power laser emission component 1 is driven according to square waves, floodlight illumination is carried out on a target area in an imaging view field, and an echo beam of laser reflected by a target reaches the area array CCD sensor imaging component 2.
the data processing module 3 comprises an FPGA main control chip 16, an ADC chip conversion circuit 13 connected with the FPGA main control chip 16, an SDRAM storage chip 14 and a USB transfer serial port 15, wherein the digital output end of the ADC chip conversion circuit 13 is connected with the FPGA main control chip 16 for image processing, the ADC chip adopts an ADC chip with a three-color channel function, the work of later 3D image color recovery is avoided, the SDRAM storage chip 14 is connected with the FPGA main control chip 16 for storing image data, the USB transfer serial port 15 is connected with the FPGA main control chip 16 and the PC terminal 5 for real-time transmission of image data and instruction parameters, the 3D image transmits the image data to the PC terminal 5 in a USB transfer serial port mode, the data processing module 3 adopts FPGA technology for image filtering, image weighting and 3D image recovery work, and a parallel bottom layer data processing mechanism, so that the real-time imaging performance of the system is greatly improved, and finally, the processed data is transmitted to a PC terminal 5 for further correction and display, and the embodiment adopts a high-speed USB3.0 serial port for transmitting image data, so that the system frame number is greatly improved, and the system stability is also greatly improved.
The high-power laser emission assembly 1 comprises a laser driving circuit 8, a laser diode array 7 and an optical beam expanding collimating lens array 6 which are sequentially connected, the high-power laser emission assembly 1 is arranged according to a double-ring structure, the same-hole receiving and transmitting are carried out with the area array CCD sensor imaging assembly 2, and the optical beam expanding collimating lens array 6 is adopted for amplifying the angle of view, so that the detection range is enlarged, and the phenomenon of inaccurate detection caused by the concentration of laser spots is prevented.
the area array CCD sensor imaging component 2 comprises an area array CCD sensor driving circuit 12, an area array CCD sensor 11, a band-pass filter 10 and a telephoto lens 9 which are connected in sequence.
the optical beam expanding and collimating lens array 6 is composed of 32 optical beam expanding and collimating lenses with 20 times of beam expanding function, wherein 16 optical beam expanding and collimating lenses with 20 times of beam expanding function are uniformly arranged in an annular shape, and the 32 optical beam expanding and collimating lenses form a double-annular array structure with different diameters.
The laser diode array 7 is composed of 32 laser diodes, wherein each 16 laser diodes are uniformly arranged in a ring shape, the 32 laser diodes form a double-ring array structure with different diameters, the model of the laser diode is SPLLL90_3, the laser wavelength is 905nm, the peak power is 70w, 30ns narrow-band pulse can be realized, the laser parameters completely meet the design requirements of the system, the laser diode array 7 and the optical beam expanding and collimating lens array 6 are completely consistent in structural arrangement and shape and size and are finally attached to each other, so that each laser is emitted through the optical collimating and beam expanding lens to achieve the effects of beam expanding and collimating, the power of the laser diode array is larger, the laser wavelength is far away from the natural wavelength, so as to better filter the natural light interference under the effect of a band-pass filter, and the laser diode is a semiconductor laser diode, the influence of the embodiment on the detection distance is mainly limited by the laser power of the laser emitting assembly, so that the peak power of a single laser diode is high, and secondly, the optical beam expanding and collimating lens is mainly used for preventing the detection precision from being reduced due to the fact that the emitted laser is too concentrated and expanding the irradiation range of the laser.
The laser driving circuit 8 is provided with two MOSFET driving EL7104CS chips, and the two EL7104CS chips respectively drive a ring-shaped laser diode array, so that the rising and falling time delay is low, and the clock rate is high.
The outer diameter of the telephoto lens 9 is consistent with the annular inner diameters of the optical beam expanding and collimating lens array 6 and the laser diode array 7, so that the telephoto lens 9 is just inserted into the annular inner diameters of the optical beam expanding and collimating lens array 6 and the laser diode array 7 to achieve the purpose of transmitting and receiving laser in the same hole, the laser is effectively utilized, the detection precision is improved, and the detection distance can reach 100m because the telephoto lens 9 in this embodiment adopts a 50mm fixed-focus lens.
The diameter of the band-pass filter 10 is consistent with the diameter of the tail end of the telephoto lens 9 and is arranged at the tail end of the telephoto lens 9, so that light passing through the telephoto lens 9 is completely filtered, the laser wavelength of the embodiment selects 905nm, a full spectrum diagram of sunlight and a band-pass filter with a band-pass range of 900nm to 910nm in combination with a spectral sensitivity characteristic curve diagram of the area array CCD sensor 11 are comprehensively considered, and the purpose is to filter the interference of ambient light and ensure the effective passing of the laser.
the long-focus lens 9 and 32 laser diode arrays in the laser emission component form a same-hole receiving and transmitting model, so that echoes generated by the emitted laser diode arrays are effectively recycled by the long-focus lens as much as possible, the detection precision is improved, when the echoes return to a receiving end, the echoes reach the sensing surface of the area array CCD sensor through the long-focus lens after passing through a band-pass filter to filter ambient light and are imaged in real time under the control of an electronic shutter, and as the lens needs geometric correction in the error of production and manufacturing, the distortion caused by geometric distortion disappears, and a more accurate detection effect is achieved, the geometric parameters of the lens can be calibrated by using Zhang-Yong calibration, and the actual measurement of the field angle is carried out by using an FOC Chart flat plate.
The area array CCD sensor 11 is an area array CCD sensor with color imaging effect, which reduces a large workload for the later image data processing, taking an area array CCD sensor ICX429AKL as an example, the effective pixel can reach 752X582, the target area 1/2 can realize real-time high resolution imaging, referring to a system imaging time sequence schematic diagram of FIG. 2, area array CCD sensor control signals SUB and VT are respectively responsible for emptying charges in the area array CCD sensor and transferring charges accumulated by light intensity, during the period from the emptying of the charges to the ending of the transferring after the accumulation of the light intensity, namely, during the exposure time of the area array CCD sensor, a laser diode array light source emits laser to reach a target object to generate echo and recycle to the area array CCD sensor to complete primary imaging, namely, the integration of the primary light intensity in time, according to the difference of the detection distance, in order to obtain a better detection effect, according to the system imaging time sequence schematic diagram of FIG. 2, different integration times can be set, namely, multiple exposure imaging is carried out, the photosensitive surface of the area array CCD sensor 11 is just opposite to the non-film-coated surface of the band-pass filter 10, the output end of the area array CCD sensor 11 is connected with the analog input end of the ADC chip conversion circuit 13 to obtain color images for digital processing, and meanwhile, the area array CCD sensor 11 adopts a stable power supply conversion system to ensure the stable and efficient work of the area array CCD sensor driving circuit 12.
By adopting the three-dimensional real-time imaging laser radar system based on the area array CCD manufactured by the embodiment, if the area array CCD sensor 11 with higher resolution and the telephoto lens 9 with larger focal length are adopted, the angular resolution can still be higher, and the detection distance can still be longer.
The area array CCD sensor driving circuit 12 is formed by a high-speed driving chip CXD1267AN and a rectifying chip 74AC04M, so that the quality of a high-speed electronic shutter time sequence on the area array CCD sensor is guaranteed, and high-quality imaging is realized.
the power supply conversion module 4 is used for conducting current-voltage conversion under the action of the analog amplification circuit and the power supply conversion chip by leading out a 5V level from the FPGA main control chip 16 so as to meet the current-voltage standard required by each module of the system and ensure the stable and effective work of the system.
The power conversion module 4 of the embodiment is formed by a digital chip, so that the interference of an analog circuit on the voltage output stability is reduced, and the time sequence working stability of the whole system is improved, the power conversion module 4 is formed by a voltage conversion circuit formed by a max685 chip and a voltage amplification circuit formed by an LM2924N chip, wherein the voltage conversion circuit formed by the max685 chip mainly provides power support for the area array CCD sensor driving circuit 12, and the voltage amplification circuit formed by the LM2924N chip mainly provides power support for the laser driving circuit 8.
Referring to fig. 3, the system work flow is: the method comprises the steps of firstly reading USB equipment, namely a lower computer part of a three-dimensional real-time imaging laser radar system based on an area array CCD, starting the USB equipment, setting the starting time of laser emission of a laser diode array, the light pulse width, the opening and closing time of an area array CCD sensor and the number of repeated integration times on an interface of a PC terminal 5, sending a parameter instruction to the lower computer part of the three-dimensional real-time imaging laser radar system to execute after a system parameter instruction is set, carrying out preprocessing work such as data filtering and image weighting and depth image recovery work when an image acquired by an imaging component of the area array CCD sensor reaches a data processing module, and finally transmitting the acquired 3D image to the PC terminal in real time for further correction and display.
The imaging principle of the example is as follows: recovering a 3D image from a two-dimensional image generated by a color CCD sensor imaging assembly requires knowledge of the time of flight of the laser echo, where an indirect TOF algorithm is employed.
The laser diode array generates light pulse strings with the wavelength of lambda, after the light pulse strings are reflected by a target, three light pulses are respectively collected in the exposure time controlled by the electronic shutter, and the collection time interval is tau, then:
t＝t+iΔt
Wherein t0 is the initial gating time, Δ t is the stepping time, i is the natural number serial number, the light intensity accumulation on the color area array CCD sensor can be obtained respectively, the front and back two frames of images collected by the area array CCD image sensor, the light intensity change with the distance is as follows:
Wherein S represents the distance of the target object in the previous image, S' represents the distance of the target object in the next image, c represents the speed of light, t represents time, P (t-2S/c) represents the waveform of the light pulse with the wavelength lambda, g (t) is the power-time function of the gain of the receiver,
the formula shows that the light intensity accumulation of the reflected light of the same point on the same target object on the image sensor is changed along with the integration time, the integration time is related to the pulse transmitting time and the receiving time of the image sensor, the light intensity integration can be carried out on the collected pulse signals on the assumption that the image sensor can carry out the light intensity integration on the same pixel point of the target object after multiple exposures are carried out on the same pixel point, a plurality of trapezoidal integration curve graphs can be obtained on the same pixel point, each integration curve graph has a vertex, a curve can be fitted through a plurality of trapezoidal vertices, so that better measuring accuracy is obtained, the abscissa corresponding to the vertex of the curve is solved according to an image weighting method, the flight time can be known, and the image weighting method is expressed as: assuming that the time delay of the ith time is ti, the light intensity accumulated on the area array CCD image sensor is I (Si), taking out the minimum value min (I (Si)) of a plurality of frames of the same pixel, and letting:
A＝I(S)-min(I(S))
＝∫P(t-2S/c)g(t)dt-min(∫P(t-2S/c)g(t)dt)
The abscissa t is then:
t＝2S/c＝A∑(I(S)-min(I(S)))t
＝A∑(∫P(t-2S/c)g(t)dt-min(∫P(t-2S/c)g(t)dt))t，
In the formula, ti is an integer summation of i times of delay time, A is an Ai summation value Sigma Ai, an abscissa t of a vertex represents the round-trip time of a pulse signal, distance information of a target object can be obtained according to the formula, wherein Z represents the distance information, c represents the flight time of light in vacuum, t is the total time of the light signal in the whole flight process, n is the refractive index of the light in a medium, n is approximately equal to 1 in clean air, and finally, a 3D image is obtained according to the obtained distance information of each pixel point.
According to the laser ranging principle, the system outputs a depth image with distance information, but not an accurate distance value, and in order to obtain the distance value, the corresponding relation between the depth value and the distance needs to be known, and a depth value-distance curve can be obtained by distance calibration.
the working principle of the embodiment is as follows: a high-power laser emission component 1 is adopted to carry out flood lighting on a target area in an imaging view field, a laser diode array 7 in the high-power laser emission component 1 is driven according to square waves, laser reaches an imaging component of an area array CCD (charge coupled device) sensor after being reflected by a target, light intensity accumulation can be generated on the area array CCD image sensor within the exposure time controlled by an electronic shutter on the area array CCD image sensor to form a frame of analog image, then the image reaches a data processing module 3, the image is converted into a digital image through an ADC (analog to digital converter) chip conversion circuit and then is stored in an SDRAM (synchronous dynamic random access memory) storage chip 14, then image filtering, image weighting and 3D image recovery work are carried out on an FPGA main control chip 16 in real time, and the 3D image recovered by the FPGA main control chip 16 is transmitted to a PC (personal computer.
Claims (10)
1. The three-dimensional real-time imaging laser radar system based on the area array CCD is characterized by comprising a data processing module, a high-power laser emitting assembly, an area array CCD sensor imaging assembly, a power supply conversion module and a PC terminal, wherein the high-power laser emitting assembly, the area array CCD sensor imaging assembly, the power supply conversion module and the PC terminal are connected with the data processing module.
2. The imaging lidar system of claim 1, wherein the data processing module comprises an FPGA main control chip, and an ADC chip conversion circuit, an SDRAM memory chip and a USB serial port connected to the FPGA main control chip, wherein a digital output terminal of the ADC chip conversion circuit is connected to the FPGA main control chip, and the USB serial port is connected to the PC terminal.
3. The imaging lidar system of claim 1, wherein the high power laser transmitter assembly comprises a laser driver circuit, a laser diode array, and an optical beam expanding and collimating lens array connected in series.
4. The imaging lidar system of claim 1, wherein the area array CCD sensor imaging assembly comprises an area array CCD sensor drive circuit, an area array CCD sensor, a band pass filter, and a telephoto lens, connected in series.
5. The imaging lidar system of claim 3, wherein the array of optical beam expanding and collimating lenses comprises 32 pieces of 20-fold beam expanding and collimating lenses, wherein every 16 pieces of 20-fold beam expanding and collimating lenses are uniformly arranged in a ring shape, and the 32 pieces of optical beam expanding and collimating lenses form a double ring array structure with different diameters.
6. the imaging lidar system of claim 3, wherein the laser diode array is composed of 32 laser diodes, wherein each 16 laser diodes are uniformly arranged in a ring shape, the 32 laser diodes form a double ring array structure with different diameters, and the laser diode array and the optical beam expanding collimating lens array are completely consistent in structural arrangement and shape and size and are finally attached to each other.
7. the lidar system of claim 3, wherein the laser driver circuit comprises two MOSFET driver EL7104CS chips, each of which drives a ring-shaped laser diode array, and wherein the two EL7104CS chips are connected to the laser driver circuit.
8. The imaging lidar system of claim 4, wherein an outer diameter of the telephoto lens coincides with an annular inner diameter of each of the array of optical beam expanding and collimating lenses and the array of laser diodes, such that the telephoto lens fits into the annular inner diameters of the array of optical beam expanding and collimating lenses and the array of laser diodes.
9. the lidar system of claim 4, wherein the bandpass filter has a diameter that is substantially coincident with and disposed at an end of the telephoto lens.
10. The imaging lidar system of claim 4, wherein the area array CCD sensor is an area array CCD sensor with color imaging effect, a photosensitive surface of the area array CCD sensor faces a non-coated surface of the band-pass filter, and an output terminal of the area array CCD sensor is connected to an analog input terminal of the ADC chip conversion circuit.
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