CN113138394A - High-resolution hybrid solid-state imaging laser radar - Google Patents
High-resolution hybrid solid-state imaging laser radar Download PDFInfo
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- CN113138394A CN113138394A CN202110432081.2A CN202110432081A CN113138394A CN 113138394 A CN113138394 A CN 113138394A CN 202110432081 A CN202110432081 A CN 202110432081A CN 113138394 A CN113138394 A CN 113138394A
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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
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- G01S17/89—Lidar systems specially adapted for specific applications for mapping or imaging
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- G—PHYSICS
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- 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
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Abstract
A high-resolution hybrid solid-state imaging laser radar comprises a pulse optical fiber laser, a collimator, a diffraction grating, a 45-degree reflector, a fast reflector, a receiving optical system, a single-photon area array detector driving circuit, a storage, an FPGA and a fast reflector driving circuit. The pulse laser beam forms a laser dot matrix after passing through the diffraction grating, the receiving optical system and the single photon area array detector form an array receiving system, and the FPGA carries out histogram statistical processing on data in the memory to obtain three-dimensional point cloud. The fast reflecting mirror can expand the field angle of the three-dimensional point cloud through stepping motion, and can also realize interpolation fine scanning smaller than the spacing angle of the adjacent laser points of the laser dot matrix through continuous motion. The laser radar has the advantages of high resolution, high imaging frame rate, high measurement precision and long acting distance, and overcomes the defect that the traditional laser radar cannot give consideration to multiple indexes.
Description
Technical Field
The invention belongs to the field of aerospace optical remote sensing, and relates to a high-resolution hybrid solid-state imaging laser radar which can be used for measuring the three-dimensional morphology of a target object.
Background
The laser radar is an effective device for high-precision three-dimensional imaging in the fields of aerospace optical remote sensing, civil surveying and mapping, automatic driving and the like. The current common laser radar mainly comprises a mechanical scanning laser radar, an MEMS scanning laser radar, an area array imaging laser radar, a TOF camera and the like. With the technological progress, the demand for the laser radar is gradually developing toward high resolution, high imaging frame rate, high measurement accuracy, and long range.
Laser radars of various systems have different advantages and disadvantages:
the mechanical scanning laser radar adopts a galvanometer motor or a rotating motor for scanning, and because the scanning speed of the motor is slow, if the high resolution is required, the imaging frame rate is inevitably low. In most applications, the measurement platform is moving, which causes distortion and deformation of the three-dimensional point cloud.
The MEMS scanning laser radar scans by adopting the MEMS oscillating mirror, although the scanning speed is high, the MEMS oscillating mirror adopts the micro-optical-electro-mechanical technology, the driving load capacity is weak, the size of the mirror surface of the MEMS scanning mirror is limited, the divergence angle of the emergent laser beam is large, the transverse resolution of the three-dimensional point cloud of the MEMS scanning laser radar is low, and the resolution of the current commercial MEMS scanning radar is not higher than 0.1 degrees.
The area array imaging laser radar adopts an avalanche photodiode array to carry out flash imaging, the imaging frame rate is very high but is limited by the process level, the array scale of an area array detector is small, the domestic area array detector does not exceed 64 multiplied by 64 at most, and the direct imaging resolution is far from sufficient. The prior art adopts two conventional orthogonal scanning galvanometers to expand the field of view, and has the following disadvantages: first, the scanning speed itself is too slow; secondly, single photon detection needs to perform multiple statistical measurements at the same spatial position, and the structure cannot give consideration to both the lateral resolution and the imaging frame rate. In addition, the pixel size of the currently used single photon area array detector is large, which causes the instantaneous receiving field of view of the laser radar to be large; some systems also add a micro-lens array at the front end of the single-photon area array detector to further expand the instantaneous receiving field of view, and due to the design, when the illumination is strong, a lot of background noise photons can be formed on the single-photon area array detector, so that the target cannot be effectively detected.
The TOF camera adopts an area array detector for intensity detection, the array scale is large, and the acquisition of the high-resolution target three-dimensional morphology can be realized through one-time imaging. It has two disadvantages: firstly, the array scale is too large, the return light energy obtained by each pixel is small and limited by the lighting power of a light source, and the pixel cannot work at a long distance; secondly, the measurement regime determines that the ranging accuracy deteriorates sharply as the working distance becomes longer.
In summary, the laser radar with high resolution, high imaging frame rate, high measurement accuracy and long range has become an urgent need in the commercial and aerospace fields.
Disclosure of Invention
The technical problem solved by the invention is as follows: the defects of the prior art are overcome, and the high-resolution hybrid solid-state imaging laser radar is provided, so that the resolution of three-dimensional imaging can be obviously improved under the premise of high imaging frame rate, high measurement precision and long acting distance.
The technical scheme of the invention is as follows: a high-resolution hybrid solid-state imaging laser radar comprises a pulse optical fiber laser, a collimator, a diffraction grating, a 45-degree reflector, a fast reflector, a receiving optical system, a single-photon area array detector driving circuit, a storage, an FPGA and a fast reflector driving circuit;
the device comprises a pulse optical fiber laser, a collimator and a diffraction grating, wherein a light source consists of the pulse optical fiber laser, the collimator and the diffraction grating, a transmitting-receiving synchronous scanning system consists of a fast reflecting mirror and a fast reflecting mirror driving circuit, a coaxial transmitting-receiving optical path consists of a 45-degree reflecting mirror and a receiving optical system, a detection assembly consists of a single-photon area array detector and a single-photon area array detector driving circuit, and a data processing unit consists of a memory and an FPGA;
pulse laser emitted by the pulse fiber laser forms collimated light beams after passing through the collimator, and the collimated light beams form a laser dot matrix after passing through the diffraction grating; the laser lattice bends the light path by 90 degrees through a 45-degree reflector and emits the light path to a fast reflector, and the bent optical axis is parallel to the optical axis of the receiving optical system; the laser dot matrix can scan in two orthogonal directions through the two-dimensional rotation of the fast reflecting mirror; after being reflected by a fast reflector, the scattered light passing through the target enters a receiving optical system, and the receiving optical system collects the echo light of the target and images the echo light onto a single-photon area array detector at the rear end of the receiving optical system; under the drive of the single-photon area array detector driving circuit, the single-photon area array detector carries out exposure measurement, and each time the single-photon area array detector carries out exposure, time measurement values of all pixels are obtained; the measurement results of multiple exposures are stored in a memory of the system according to the frame number and the pixel number; the fast reflecting mirror is driven by a fast reflecting mirror driving circuit to perform two-dimensional scanning in a multi-step mode or a one-axis step and another-axis periodic triangular wave mode; when the fast reflection mirror scans in a stepping mode, the FPGA carries out histogram statistical processing on data stored in a laser radar memory according to the same pixel number at a stop position to obtain distance information of all pixels corresponding to a space position, and then three-dimensional point cloud which is several times of an instantaneous field angle of a receiving system is obtained through splicing of a plurality of stop positions; when the fast reflecting mirror scans in a mode of one-axis step and another-axis periodic triangular wave, the FPGA obtains an interpolated scanning distance measured value of a non-photosensitive area on the image surface of the detector by utilizing a histogram statistical method of different pixels at the same spatial position, and the interpolated scanning distance measured value is combined with the real-time operation angle of the fast reflecting mirror to obtain a three-dimensional point cloud which is several times of the resolution of the single-photon area array detector.
The angle intervals between the adjacent laser points of the laser dot matrix formed by the diffraction grating are all equal, and the divergence angle of the pulse laser beam is far smaller than the angle intervals between the adjacent points of the laser dot matrix.
The center distances between adjacent pixels of the single-photon area array detector are equal, the pixel distance is far larger than the pixel diameter, and the area of a photosensitive area on the image surface of the detector is far smaller than that of a non-photosensitive area.
And the instantaneous receiving field angle corresponding to each pixel of the single-photon area array detector is consistent with the divergence angle of a single laser spot in a laser dot matrix formed by the diffraction grating.
The time resolution of the single photon area array detector is better than 100 ps.
And a narrow-band filter is arranged at the front end of the receiving optical system, and the central wavelength of the narrow-band filter is consistent with the wavelength of the pulse laser emitted by the pulse fiber laser.
The fast reflecting mirror alternately performs step scanning in two orthogonal directions, steps for 4 times in the X direction, then turns to the Y direction for 1 time, then steps for 4 times in the X direction along the reverse direction, then turns to the Y direction for one time, and reciprocates in such a way, and the staying position of the fast reflecting mirror forms a 5 multiplied by 5 grid; the Y direction is parallel to the optical axis direction of the receiving optical system, and the X direction is parallel to the central axial direction of the diffraction grating.
The fast reflecting mirror moves in a Y axis in a stepping mode and is divided into a small-angle step stage and a large-angle step stage, one-time imaging comprises 4 large steps, and 7 small steps are arranged before the first large step, between the two large steps and after the last large step; and carrying out reciprocating scanning in a periodic triangular wave mode in the X direction, wherein the time interval of adjacent scanning points is the repetition period of laser pulses emitted by the pulse optical fiber laser.
Compared with the prior art, the invention has the following beneficial effects:
(1) the laser radar adopts a mixed solid-state imaging device combining a single-photon area array detector with fast-reflection mirror scanning, and utilizes a histogram statistical method of different pixels at the same spatial position to realize interpolation scanning measurement of a non-photosensitive area on an image surface of the detector, and compared with the traditional mechanical and MEMS scanning laser radar, the longitudinal resolution is improved to 1120 from 128;
(2) the laser radar adopts a single-photon area array detector with high sensitivity and adopts the diffraction grating to improve the laser energy utilization rate, and compared with the traditional mechanical and MEMS scanning laser radar, the action distance is improved from 300m to 600 m;
(3) the laser radar adopts a single-photon area array detector pixel structure with a low filling factor and adopts a receiving optical system with a narrow-band filter, so that background light can be effectively inhibited, and the laser radar has the advantage of working all day long compared with the traditional flash imaging laser radar which can only work under low sunlight illumination;
(4) the laser radar adopts the single-photon area array detector to perform the histogram statistics of the laser echo pulse, and compared with the traditional mechanical and MEMS scanning laser radar for measuring the flight time of single laser pulse, the ranging precision is improved from the level of cm to the level of mm.
Drawings
FIG. 1 is a block diagram of the apparatus of the present invention.
FIG. 2 is a diagram illustrating the optical path of the fast reflecting mirror according to the present invention.
FIG. 3 is a diagram of the pixel distribution and size of the single photon area array detector of the present invention.
Fig. 4 is an overall scanning track diagram of a second embodiment of the present invention, which shows the laser lattice movement positions at two moments.
Fig. 5 is a 7-time small step scanning track of the second embodiment of the present invention, which is a partially enlarged view of fig. 4.
Fig. 6 is a schematic diagram of image plane interpolation scanning measurement according to a second embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Example one
A high-resolution hybrid solid-state imaging laser radar is shown in figure 1, a pulse optical fiber laser 1 emits pulse laser with the center wavelength of 532nm, the repetition frequency of 50kHz, the pulse width of 1ns and the maximum peak power of 10kW, and a pulse laser beam with the diameter of an emergent facula of 15mm and the divergence angle of 0.1mrad is formed through a collimator 2.
The pulsed laser beam passes through the diffraction grating 3 to form a 32 × 32 laser lattice, and the angle intervals Δ θ between adjacent laser spots are all equal, in this embodiment, the angle interval is 0.041 °, and the coverage angle range of the entire laser lattice is 1.312 ° × 1.312 °. The divergence angle of the pulsed laser beam is 0.1mrad, i.e. 0.0057 °, much smaller than the angular separation Δ θ of adjacent spots of the laser lattice.
The laser lattice is incident on a 45-degree reflector 4 at the front end of a receiving optical system 6 from the central direction of the + X axis, the central direction of the light beam is converted into the-Y axis, and then the light beam is incident on a fast reflection mirror 5. The normal direction of the fast reflecting mirror is located in the YOZ plane, the included angles between the normal direction and the + Y axis and the + Z axis are both 45 degrees, and after being reflected by the fast reflecting mirror, the laser beam is emitted to the target 12 from the + Z direction, as shown in FIG. 2. The fast reflection mirror 5 realizes the scanning in two orthogonal directions, and the laser dot matrix can scan in two directions of an X axis and a Y axis through the rotation of the fast reflection mirror.
The scattered light passing through the target 12 is reflected by the fast reflection mirror 5 and enters the receiving optical system 6, and the receiving optical system collects the echo light of the target and images the echo light onto the single photon area array detector 7 at the rear end of the receiving optical system. The number of pixels of the single photon area array detector 7 is 32 × 32, the center distances between adjacent pixels are equal, and in the embodiment, the pixel pitches in both directions are 50 μm. The pixels of the single photon area array detector 7 can be circular or square, in this embodiment, the pixels are circular, the diameter is 7 μm, and the fill factor of the detector is 1.54%, as shown in fig. 3. The total size of the whole image surface of the detector is 1.6mm multiplied by 1.6mm, which corresponds to the coverage angle range of the object laser dot matrix of 1.312 degrees multiplied by 1.312 degrees, and the expression is related to the focal length f of the receiving optical system:
f＝1.6mm/1.312°
the focal length f of the receiving optical system was 69.878 mm.
The instantaneous receiving view field corresponding to each pixel of the single photon area array detector 7 is as follows:
7μm/69.878mm＝0.1mrad。
corresponding to the divergence angle of a single laser spot in the laser lattice. The beneficial effects are that: firstly, all the energy of a single laser point is received by a pixel corresponding to a detector, and no energy loss exists; secondly, the instantaneous receiving field of view of a single pixel is very small, and the received background light intensity is relatively small for a similar device with a larger pixel diameter and a larger instantaneous receiving field of view, so that the background light counting of the single-photon detector can be effectively inhibited.
The front end of the receiving optical system 6 is provided with a narrow-band filter, the central wavelength is 532nm, the wavelength is consistent with the wavelength of pulse laser, the bandwidth is 3nm, and the beneficial effects of the narrow-band filter are that background light is obviously inhibited. The receiving optical system 6 has an optical aperture of 40mm and its optical axis is parallel to the-Y axis.
Under the drive of the single-photon area array detector driving circuit 8, the single-photon area array detector 7 carries out exposure measurement, 128 times of exposure measurement is carried out at a fixed position of the fast reflection mirror, and the exposure period is 20 mu s of the pulse laser repetition period.
Each time the single photon area array detector 7 performs exposure, 1024, that is, 32 × 32 time measurement values are obtained, the time measurement values are digital quantities, in this embodiment, the digital quantity is 10 bits, the time corresponding to each bit is 55ps, and the variation range of the time measurement values is 0-56 ns. 128 exposure measurements, 128 x 1024 time measurements are obtained and stored in the memory 9 of the system according to the frame number 1-128 and the pixel number 1-1024.
The FPGA10 performs histogram statistical processing on the stored data pixel by pixel, and the specific steps of histogram statistics of a certain pixel are as follows:
1) eliminating the frames with the time measurement value of zero corresponding to the pixel;
2) carrying out time measurement value average operation on all the nonzero frames to obtain an average value;
3) eliminating frames with the absolute value of the difference value from the average value larger than a time threshold value time _ th, wherein the time threshold value time _ th is 18, i.e. 990ps in the embodiment;
4) and carrying out average operation on the time measurement values of the residual frames of the pixel to obtain an average value, namely a time measurement statistical value of the pixel at a certain position of the fast reflecting mirror.
Through the above steps, 1024 (i.e., 32 × 32) time measurement statistics are obtained. Through histogram statistics, on one hand, the dark count of the single photon detector is removed from the signal photons, and on the other hand, the time measurement precision is improved through statistical averaging, so that the distance measurement precision is improved. According to a known centroid statistical algorithm, the centroid extraction precision can reach 1/3 or more of the resolution, in the embodiment, the time resolution of the single photon area array detector is 55ps, the time statistical measurement precision reaches 55ps/3 to 18.33ps through histogram statistics, and the corresponding distance measurement precision is 2.75mm (1 sigma).
The total time of 128 exposures and calculations is 128 × 20 μ s ═ 2.56 ms.
Under the drive of the fast reflecting mirror drive circuit 11, the fast reflecting mirror 5 performs stepping motion, the dwell time is 2.56ms, namely the exposure and accumulated measurement time of the single photon area array detector, the motion time of the fast reflecting mirror 5 stepping from one position to the next position is 2.44ms, and then the exposure and accumulated measurement of the next dwell time is continued.
And at the stop position, reading the real-time running angle of the quick reflecting mirror through an angle encoder integrated in the quick reflecting mirror 5, and performing closed-loop control on the quick reflecting mirror by adopting a known PID algorithm to stabilize the angle control precision of the quick reflecting mirror at the stop position within 0.001 degrees. The stepping angle of the fast reflecting mirror is 1.312 degrees at each time, which is consistent with the coverage angle range of the object laser dot matrix. The PID algorithm runs on FPGA 10.
In a three-dimensional imaging period of the laser radar, the fast reflecting mirror 5 is stepped 24 times in total, and exposure and accumulated measurement of 25 stop positions are carried out.
The stepping curve of the quick reflecting mirror is performed alternately in two directions, namely stepping 4 times in the X direction, then turning to the Y direction for stepping 1 time, then stepping 4 times in the reverse direction in the X direction, then turning to the Y direction for stepping once, and the steps are repeated. The dwell positions of the fast reflecting mirrors form a 5 x 5 grid.
Obtaining a 32 multiplied by 32 time measurement statistic value at a stopping position, expanding the time measurement statistic value to a 160 multiplied by 160 time measurement statistic value through the stepping motion of the fast reflecting mirror, fusing the time measurement statistic value and a real-time angle measured by a fast reflecting mirror encoder to obtain a 160 multiplied by 160 three-dimensional point cloud, wherein the total measurement time is 125ms, and the corresponding three-dimensional image frame rate is 8 Hz.
Example two
The hardware devices of the second embodiment are the same as those of the first embodiment, and the difference is in the fast mirror scanning method and the data processing method, and only the difference will be described below.
As shown in fig. 4, the fast reflecting mirror 5 moves in a stepping manner on the Y axis, and is divided into a small-angle step stage and a large-angle step stage, one imaging includes 4 large steps, 7 small steps are provided before the first large step, between two large steps, and after the last large step, the step angle of the large step is 1.312 °, and is consistent with the coverage angle range of the object laser dot matrix. The step angle of the small step is 1/224, i.e. 0.00586 °, which is the three-dimensional imaging angular resolution in the Y-direction, for the large step angle, as shown in fig. 5.
The fast reflection mirror 5 performs reciprocating scanning in the X direction in a periodic triangular wave manner, and the time interval between adjacent scanning points is the laser pulse repetition period, namely 20 μ s. The angular separation of adjacent scan points is equal and the separation angle coincides with the step angle of the small Y-axis step, 0.00586 °. The number of scan points per line in the X direction is 1120, corresponding to a scan angle of about 6.56 °.
The single-photon area array detector 7 performs one exposure after each laser pulse is emitted to obtain 1024 (i.e., 32 × 32) time measurement values, when the next exposure is performed, the X direction has moved 0.00586 °, the imaging position is different from that of the first exposure, and until the eighth exposure is performed, the X direction has moved 0.041 °, which is exactly equal to the receiving angle interval of the adjacent pixels of the single-photon area array detector (pixel distance divided by the focal length of the receiving optical system: 50 μm/69.878 mm: 0.041 °), and at this time, 31 rows of pixels of the detector coincide in spatial position with that of the first exposure, as shown in fig. 6. By analogy, when going to 218 exposures, there are 1 column of pixels that coincide in spatial position with the first exposure. For this column of pixels, a total of 32 exposures are made at this spatial location for 1 st, 8 th, 15 th, … … th, 218 th. Histogram statistics is performed on the 32-time exposure time measurement values, the statistical method is the same as that in the first embodiment, and is not repeated, and the final time measurement statistical value of the row of pixels is finally obtained.
By analogy with the above method, when the exposure numbers 2, 9, 16, … …, and 219 are used, the corresponding spatial position is also used for 32 exposures, histogram statistics is performed on the time measurement values of the 32 exposures, and finally the final time measurement statistic value of the column of pixels is obtained. The spatial angular separation between the row of pixels and the aforementioned pixels is 0.00586 ° of the step angle of the fast reflecting mirror 5 in the X direction.
The beneficial effects of this embodiment are: the self angular resolution of the single-photon area array detector is only 0.041 DEG, the angular resolution is improved to 0.00586 DEG through the thinning scanning of the fast reflecting mirror 5 between the adjacent pixels in the X direction and the thinning stepping motion in the Y direction, and a 1120X 1120 three-dimensional point cloud is formed.
The total number of steps is 39, the fast reflecting mirror 5 makes 39 round trips in the X-axis direction, and the total imaging time is 39 × 1120 × 20 μ s — 874 ms.
By adopting the single-photon detector, the sensitivity of the single-photon detector is far higher than that of an avalanche photodiode working in a linear region, and the three-dimensional imaging with the maximum working distance of 600m under the target reflectivity of 0.2 can be realized.
Compared with the traditional mechanical scanning type laser radar, TOF camera and MEMS scanning laser radar, the hybrid solid-state imaging laser radar has the advantages that the transverse resolution and the longitudinal resolution reach 1120 multiplied by 1120, the action distance reaches 600m, and the indexes are far higher than the indexes of the longitudinal resolution 128 and the action distance 300m of the similar device, and the hybrid solid-state imaging laser radar has obvious advantages.
Those skilled in the art will appreciate that those matters not described in detail in the present specification are well known in the art.
Claims (8)
1. A high resolution hybrid solid state imaging lidar characterized by: the device comprises a pulse fiber laser (1), a collimator (2), a diffraction grating (3), a 45-degree reflector (4), a fast reflector (5), a receiving optical system (6), a single-photon area array detector (7), a single-photon area array detector driving circuit (8), a memory (9), an FPGA (10) and a fast reflector driving circuit (11);
the device comprises a pulse optical fiber laser (1), a collimator (2) and a diffraction grating (3) which form a light source, a fast reflector (5) and a fast reflector driving circuit (11) which form a transceiving synchronous scanning system, a 45-degree reflector (4) and a receiving optical system (6) which form a coaxial transceiving optical path, a single-photon area array detector (7) and a single-photon area array detector driving circuit (8) which form a detection assembly, and a memory (9) and an FPGA (10) which form a data processing unit;
pulse laser emitted by the pulse fiber laser (1) forms collimated light after passing through the collimator (2), and the collimated light forms a laser dot matrix after passing through the diffraction grating (3); the laser lattice converts the light path by 90 degrees through a 45-degree reflector (4) and emits the light path to a fast reflector (5), and the converted optical axis is parallel to the optical axis of a receiving optical system (6); the laser dot matrix can be scanned in two orthogonal directions through the two-dimensional rotation of the fast reflecting mirror (5); the scattered light passing through the target (12) is reflected by the fast reflecting mirror (5) and enters the receiving optical system (6), and the receiving optical system collects the echo light of the target and images the echo light onto the single-photon area array detector (7) at the rear end of the receiving optical system (6); under the drive of a single-photon area array detector driving circuit (8), carrying out exposure measurement on the single-photon area array detector (7), and obtaining time measurement values of all pixels when the single-photon area array detector (7) carries out exposure once; the measurement results of multiple exposures are stored in a memory (9) of the system according to the frame number and the pixel number; the fast reflecting mirror (5) is driven by a fast reflecting mirror driving circuit (11) to carry out two-dimensional scanning in a multi-step mode or a one-axis step and another-axis periodic triangular wave mode; when the fast reflection mirror (5) scans in a stepping mode, the FPGA (10) performs histogram statistical processing on data stored in the laser radar memory (9) at a staying position according to the same pixel number to obtain distance information of all pixels corresponding to space positions, and then three-dimensional point cloud which is several times of the instantaneous field angle of a receiving system is obtained through splicing of a plurality of staying positions; when the fast reflecting mirror (5) scans in a mode of one-axis step and another-axis periodic triangular wave, the FPGA (10) obtains an interpolated scanning distance measurement value of a non-photosensitive area on the image surface of the detector by using a histogram statistical method of different pixels at the same spatial position, and combines the interpolated scanning distance measurement value with the real-time operation angle of the fast reflecting mirror (5) to obtain a three-dimensional point cloud which is several times of the resolution of the single-photon area array detector.
2. A high resolution hybrid solid state imaging lidar according to claim 1, wherein: the angle intervals between the adjacent laser points of the laser dot matrix formed by the diffraction grating (3) are all equal, and the divergence angle of the pulse laser beam is far smaller than the angle intervals between the adjacent points of the laser dot matrix.
3. A high resolution hybrid solid state imaging lidar according to claim 1, wherein: the center distances between adjacent pixels of the single-photon area array detector (7) are equal, the pixel distance is far larger than the pixel diameter, and the area of a photosensitive area on the image surface of the detector is far smaller than that of a non-photosensitive area.
4. A high resolution hybrid solid state imaging lidar according to claim 1, wherein: the instantaneous receiving field angle corresponding to each pixel of the single-photon area array detector (7) is consistent with the divergence angle of a single laser spot in a laser dot matrix formed by the diffraction grating (3).
5. A high resolution hybrid solid state imaging lidar according to claim 1, wherein: the time resolution of the single photon area array detector (7) is better than 100 ps.
6. A high resolution hybrid solid state imaging lidar according to claim 1, wherein: the front end of the receiving optical system (6) is provided with a narrow-band filter, and the central wavelength of the narrow-band filter is consistent with the pulse laser wavelength emitted by the pulse fiber laser.
7. A high resolution hybrid solid state imaging lidar according to claim 1, wherein: the fast reflecting mirror (5) alternately performs step scanning in two orthogonal directions, steps for 4 times in the X direction, then steps for 1 time in the Y direction, then steps for 4 times in the reverse direction in the X direction, and then steps for one time in the Y direction, and the steps are repeated in such a way, and a 5X 5 grid is formed at the stop position of the fast reflecting mirror; the Y direction is parallel to the optical axis direction of the receiving optical system (6), and the X direction is parallel to the central axis direction of the diffraction grating (3).
8. A high resolution hybrid solid state imaging lidar according to claim 7, wherein: the fast reflecting mirror (5) moves in a Y-axis in a stepping mode and is divided into a small-angle step stage and a large-angle step stage, one-time imaging comprises 4 large steps, and 7 small steps are arranged before the first large step, between the two large steps and after the last large step; and performing reciprocating scanning in a periodic triangular wave mode in the X direction, wherein the time interval of adjacent scanning points is the repetition period of the laser pulse emitted by the pulse optical fiber laser (1).
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