A stripe camera-based surface scanning time-of-flight three-dimensional imaging system and method

Abstract

The present invention relates to a time-of-flight ranging system and method, and particularly to a surface-scanning time-of-flight three-dimensional imaging system and method based on a streak camera. It solves the technical problems of low resolution in TOF distance measurement based on traditional single-photon detection devices and slow speed in line-scanning three-dimensional imaging based on streak cameras. The system of the present invention includes an illumination unit, a signal acquisition unit, a data processing unit, and a synchronization control unit; the illumination unit is used to illuminate the imaging area of the target to be measured to generate an echo signal; the signal acquisition unit includes a coupled imaging device, an optical fiber conversion device, an optical fiber transmission module, and a streak camera; the echo signal is coupled and imaged by the coupled imaging device, and the area array optical fiber is converted into a line array optical fiber by the optical fiber conversion device, and then sent to the streak camera through the optical fiber transmission module to output a streak image; the streak image is processed by the data processing unit to obtain a three-dimensional image. At the same time, the present invention also provides a surface-scanning time-of-flight three-dimensional imaging method based on a streak camera.

Description

Technical Field

[0001] The present invention relates to a time-of-flight ranging system and method, and particularly to a surface-scanning time-of-flight three-dimensional imaging system and method based on a streak camera. Background Art

[0002] Traditional direct time-of-flight ranging technology uses pulsed light as an illumination source and uses a single-photon detection device coupled with a time-correlated single-photon counting circuit to record the arrival time of echo photons to deduce the distance information of the target, and has developed rapidly especially in the fields such as lidar. However, the distance measurement resolution of the time-of-flight ranging technology is determined by the time resolution of the detection device. The time resolution of a single-photon detection device is usually in the sub-nanosecond order, and the corresponding distance resolution is in the centimeter to hundred-millimeter order, which is difficult to meet the fine measurement requirements of the three-dimensional morphology of the target at the millimeter or even sub-millimeter level (see Heinrichs R., Aull B.F., Marino R M., et al. Three-dimensional laser radar with SPAD arrays. Laser Radar Technology and Applications VI. International Society for Optics and Photonics, 2001, 4377: 106-118.; and Wang F., Zhao Y., Zhang Y., et al. Range accuracy limitation of pulse ranging systems based on Geiger mode single-photon detectors. Applied Optics, 2010, 49(29): 5561-5566.).

[0003] The streak camera is a one-dimensional ultrafast imaging device with a time resolution on the picosecond or even femtosecond scale. In time-of-flight (TOF) ranging, it can achieve a distance measurement resolution of sub-millimeters. However, in the traditional three-dimensional imaging method of the streak camera for TOF, the streak camera needs to perform line scanning to measure the three-dimensional topography of the target to be measured, resulting in a problem of slow imaging speed (see Zhaodong C., Rongwei F., Guangchao Y., Tong L., Jiayu G., Zhigang Z., et al. Depth resolution improvement of streak tube imaging lidar system using three laser beams. Chin Opt Lett. 2018; 16: 041101.). For example, for a streak camera with a frame rate of 10 Hz, it takes 10 s to obtain a depth image of 100×100 pixels, which is not conducive to three-dimensional imaging of high-speed dynamic targets and limits its further application. There is an urgent need to develop a three-dimensional imaging method with a high distance resolution on the sub-millimeter scale and high speed that meets the requirements of TOF ranging technology. Summary of the Invention

[0004] The object of the present invention is to solve the technical problems of low TOF distance measurement resolution based on traditional single-photon detection devices and slow three-dimensional imaging speed of line scanning based on streak cameras, and to provide a surface scanning time-of-flight three-dimensional imaging system and method based on a streak camera.

[0005] The technical solution of the present invention is as follows:

[0006] A surface scanning time-of-flight three-dimensional imaging system based on a streak camera, characterized in that it includes an illumination unit, a signal acquisition unit, a data processing unit, and a synchronization control unit;

[0007] The illumination unit includes a pulsed laser module, a beam scanning module, and a beam expansion module;

[0008] The pulsed laser module is used to generate pulsed light;

[0009] The beam scanning module is arranged on the optical path of the pulsed light and is used to perform two-dimensional scanning on the pulsed light and adjust the direction of the pulsed light so that it is incident on the target to be measured;

[0010] The beam expansion module is arranged between the beam scanning module and the target to be measured. The beam expansion module expands the pulsed light and then irradiates it to the area of the target to be measured, and the target to be measured generates an echo signal;

[0011] The signal acquisition unit includes a displacement scanning imaging module, an optical fiber transmission module, and a streak camera;

[0012] The displacement scanning imaging module includes a coupling imaging device and an optical fiber conversion device;

[0013] The coupling imaging device and the optical fiber conversion device are arranged in sequence along the echo signal path. The echo signal is coupled and imaged on the optical fiber conversion device by the coupling imaging device, and the optical fiber conversion device converts the formed target two-dimensional image into a one-dimensional image;

[0014] The incident end and the outgoing end of the optical fiber transmission module are respectively connected to the optical fiber conversion device and the streak camera;

[0015] The data processing unit is electrically connected to the streak camera, and is used for processing the streak image output by the streak camera, and obtaining a three-dimensional image according to the time-of-flight ranging principle;

[0016] The synchronization control unit is electrically connected to the pulsed laser module, the beam scanning module and the streak camera respectively.

[0017] Furthermore, the displacement scanning imaging module further includes a displacement scanning device; the coupling imaging device and the optical fiber conversion device are both arranged on the displacement scanning device, and the displacement scanning device is used for displacing the coupling imaging device and the optical fiber conversion device as a whole to align with the area to be imaged of the target to be measured; the displacement scanning device is electrically connected to the synchronization control unit.

[0018] Furthermore, the time resolution of the streak camera is in the picosecond to femtosecond order of magnitude;

[0019] The pulse width of the pulsed light is from picosecond to femtosecond, and the pulse jitter is less than 100 ps;

[0020] The trigger pulse jitter emitted by the synchronization control unit is less than 100 ps.

[0021] Furthermore, the optical fiber conversion device is composed of an optical fiber bundle. Among them, the signal receiving end is arranged in a planar array of the optical fiber bundle, and the signal output end is arranged in a linear array of the optical fiber bundle. The optical fiber bundle is used for transmitting optical signals in the visible spectral range of 400 - 700 nm; the optical fiber conversion device converts a target two-dimensional image with a size of [RN, CN] into a one-dimensional image with a size of [1, RN×CN], where RN×CN corresponds to the number of pixels in the slit direction of the streak camera, within the range of 1000 - 5000 pixels, and RN and CN are positive integers greater than 1.

[0022] Furthermore, the time resolution of the streak camera is less than 10 ps, and the single-pixel scanning time is less than 6 ps; the optical fiber conversion device is composed of a photonic crystal fiber bundle.

[0023] Furthermore, the coupling imaging device is an imaging lens. According to the different target imaging distances and resolutions, the imaging lens can be a fixed-focus lens, an adjustable-focus lens, a microscope or a telecentric lens.

[0024] At the same time, the present invention also provides a surface scanning time-of-flight three-dimensional imaging method based on a streak camera, which adopts the above-mentioned surface scanning time-of-flight three-dimensional imaging system based on a streak camera, and its special feature is that it includes the following steps:

[0025] Step 1) The pulse laser module emits pulse light to illuminate the imaging area of ​​the target to be measured, generating an echo signal;

[0026] Step 2) the echo signal is coupled to the optical fiber conversion device through the coupling imaging device; the optical fiber conversion device converts the target two-dimensional image with a size of [RN, CN] into a one-dimensional image with a size of [1, RN×CN], where RN×CN corresponds to the number of pixels in the slit direction of the streak camera, within the range of 1000-5000 pixels, and RN and CN are positive integers greater than 1; the one-dimensional image is transmitted through the optical fiber transmission module and enters the streak camera; the streak camera performs time scanning imaging on the one-dimensional image signal and outputs a streak image;

[0027] Step 3) The image data processing unit processes the fringe image according to the time-of-flight ranging principle and reconstructs a two-dimensional depth image of the target, that is, obtains a three-dimensional image.

[0028] Furthermore, the method further comprises step 4):

[0029] A displacement scanning device is used to perform multiple overall displacements on the coupled imaging device and the optical fiber conversion device. Each displacement scans the imaging area of ​​the target to be measured to generate a fringe image. N scans generate N fringe images. The image data processing unit processes the N scanning areas to generate three-dimensional images, which are then spliced ​​to generate a large-field-of-view three-dimensional image.

[0030] Furthermore, step 1) is specifically as follows: the pulse laser module emits pulse light with a pulse width of picoseconds to femtoseconds, the pulse light is adjusted in direction by the beam scanning module, and then enters the beam expansion module, and the beam expansion module expands the pulse light and irradiates it to the imaging area of ​​the target to be measured.

[0031] Further, step 3) is specifically as follows: the fringe image comprises two axes, one of which is a spatial axis for collecting one-dimensional optical fiber signals, and the other is a time axis for recording the time t at which the echo signal at each spatial position arrives. 0 The time difference Δt=tt 0 , calculate the depth information of each spatial position d=cΔt / 2, where c is the speed of light; and then obtain a three-dimensional image based on the conversion relationship from a two-dimensional image to a one-dimensional image in the optical fiber conversion device.

[0032] Beneficial effects of the present invention:

[0033] 1. A three-dimensional imaging system for surface scanning time-of-flight based on a streak camera according to the present invention combines an imaging device, an optical fiber conversion device and a streak camera, scans a surface optical fiber array, and can convert a two-dimensional image of the surface optical fiber array into a one-dimensional image of a linear optical fiber array, achieving the measurement of larger targets, greatly improving the speed of three-dimensional imaging of the streak camera time-of-flight. Compared with the three-dimensional imaging speed of traditional cameras, it is increased by about 10 times. It can also effectively utilize the effective imaging area in the slit direction, maximize the function of the streak camera, and ensure the consistency of the lateral spatial resolution of the three-dimensional image. In addition, by using a streak camera with a time resolution in the picosecond to femtosecond range, a depth measurement resolution in the sub-millimeter to micrometer range can be ensured.

[0034] 2. A three-dimensional imaging system for surface scanning time-of-flight based on a streak camera according to the present invention can use a displacement scanning imaging module to perform multiple overall displacements on the coupled imaging device and the optical fiber conversion device, and perform surface scanning imaging on the target to be measured each time a displacement is made, so as to obtain three-dimensional imaging of a larger range of the target.

[0035] 3. A method for three-dimensional imaging of surface scanning time-of-flight based on a streak camera according to the present invention is simple to operate, has a fast imaging speed and high imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of a three-dimensional imaging system for surface scanning time-of-flight based on a streak camera in a specific embodiment of the present invention;

[0037] Figure 2 It is a schematic diagram of the optical fiber conversion device in the displacement scanning imaging module converting the surface array arranged optical fibers into linear array arranged optical fibers.

[0038] Reference numerals: 1 - illumination unit, 2 - signal acquisition unit, 3 - data processing unit, 4 - synchronization control unit, 5 - pulsed laser module, 6 - beam scanning module, 7 - beam expansion module, 8 - target to be measured, 9 - displacement scanning imaging module, 10 - optical fiber transmission module, 11 - streak camera, 12 - coupled imaging device, 13 - optical fiber conversion device, 14 - displacement scanning device. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The technical solutions of the present invention will be further described below in conjunction with the drawings and embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the concept and scope of the technical solutions of the present invention shall be covered within the protection scope of the present invention.

[0040] A three-dimensional imaging system for surface scanning time-of-flight based on a streak camera according to the present invention, as Figure 1 shown, includes an illumination unit 1, a signal acquisition unit 2, a data processing unit 3 and a synchronization control unit 4.

[0041] The illumination unit 1 includes a pulsed laser module 5, a beam scanning module 6, and a beam expansion module 7. Among them, the pulsed laser module 5 is used to generate pulsed light with a pulse width in the picosecond to femtosecond range and a pulse jitter less than 100 picoseconds; the beam scanning module 6 is arranged on the pulsed light path, and the beam scanning module 6 is used to perform two-dimensional scanning on the pulsed light and adjust the direction of the pulsed light so that it is incident on the target to be measured 8; the beam expansion module 7 is arranged between the beam scanning module 6 and the target to be measured 8, and the beam expansion module 7 is used to expand the pulsed light and irradiate the imaging area of the target to be measured 8. After the beam expansion module 7 expands the pulsed light and irradiates the imaging area of the target to be measured 8, the target to be measured 8 generates an echo signal.

[0042] The signal acquisition unit 2 includes a displacement scanning imaging module 9, an optical fiber transmission module 10, and a streak camera 11. Among them, the displacement scanning imaging module 9 includes a coupled imaging device 12, an optical fiber conversion device 13, and a displacement scanning device 14; the coupled imaging device 12 is used to couple and image the echo signal of the target to be measured 8 on the optical fiber conversion device 13. The coupled imaging device 12 and the optical fiber conversion device 13 are arranged in sequence along the echo signal path, and the coupled imaging device 12 and the optical fiber conversion device 13 are respectively installed on the displacement scanning device 14. The displacement scanning device 14 is used to displace the coupled imaging device 12 and the optical fiber conversion device 13 as a whole to align with the imaging area of the target to be measured 8. The echo signal is coupled and imaged on the optical fiber conversion device 13 by the coupled imaging device 12, and the optical fiber conversion device 13 converts the formed two-dimensional target image into a one-dimensional image. As Figure 2 shown, the optical fiber conversion device 13 is composed of an optical fiber bundle. The signal receiving end is an array arrangement of the optical fiber bundle surface, and the signal output end is a linear array arrangement of the optical fiber bundle. The two-dimensional array size of the surface array optical fiber arrangement of the optical fiber conversion device 13 is [RN, CN], and it is converted into a one-dimensional image by the optical fiber conversion device 13. The linear array optical fiber arrangement size is [1, RN×CN], where RN×CN corresponds to the number of pixels in the slit direction of the streak camera and is in the range of 1000 - 5000 pixels. RN and CN are positive integers greater than 1. The coupled imaging device 12 is an imaging lens, and according to the different target imaging distances and resolutions, a fixed-focus lens, an adjustable-focus lens, a microscope, or a telecentric lens can be selected; the optical fiber bundle can transmit optical signals in the visible spectral range of 400 - 700 nm. In this embodiment, the optical fiber conversion device 13 is composed of a photonic crystal optical fiber bundle. The optical fiber transmission module 10 contains RN×CN optical fibers. The incident end and the output end of the optical fiber transmission module 10 are respectively connected to the optical fiber conversion device 13 and the streak camera 11. The optical fiber transmission module 10 is used to transmit the linear array optical fiber signal output by the optical fiber conversion device 13 to the streak camera 11. The time resolution of the streak camera 11 is in the picosecond to femtosecond order of magnitude, and the time resolution of the streak camera 11 is less than 10 ps, and the single-pixel scanning time is less than 6 ps, which can ensure a distance resolution of sub-millimeter. The streak camera 11 is used to perform time-scanning imaging on the linear array optical fiber signal and then output a streak image.

[0043] The data processing unit 3 is electrically connected to the streak camera 11, and is configured to process the streak image output by the streak camera 11 and reconstruct the three-dimensional image of the target according to the time-of-flight ranging principle. The synchronization control unit 4 is electrically connected to the pulsed laser module 5, the beam scanning module 6, the streak camera 11, and the displacement scanning device 14 respectively, and is used to control the synchronization among the pulsed laser module 5, the beam scanning module 6, the displacement scanning device 14, and the streak camera 11 in the system. The trigger pulse jitter emitted by the synchronization control unit 4 is less than 100 ps.

[0044] Meanwhile, the present invention also provides a surface scanning time-of-flight three-dimensional imaging method based on a streak camera, which is implemented by using the surface scanning time-of-flight three-dimensional imaging system of the present invention, and includes the following steps:

[0045] Step 1) The pulsed laser module 5 emits pulsed light to irradiate the imaging area of the target 8 to be measured, generating an echo signal;

[0046] The pulsed laser module 5 emits pulsed light with a pulse width ranging from picoseconds to femtoseconds. After the direction of the pulsed light is adjusted by the beam scanning module 6, the pulsed light enters the beam expander module 7, and the beam expander module 7 expands the pulsed light and then irradiates the imaging area of the target 8 to be measured.

[0047] Step 2) The echo signal is coupled and imaged on the fiber optic conversion device 13 by the coupled imaging device 12; the fiber optic conversion device 13 converts the two-dimensional image of the target with the two-dimensional array size of the surface array fiber [RN, CN] into a one-dimensional image with the one-dimensional array size of the linear array fiber [1, RN×CN]; after being transmitted by the fiber optic transmission module 10, the one-dimensional image enters the streak camera 11; the streak camera 11 performs time scanning imaging on the one-dimensional signal and outputs a streak image;

[0048] Step 3) The image data processing unit 3 processes the streak image according to the time-of-flight ranging principle and reconstructs the two-dimensional depth image of the target, that is, the three-dimensional image. Specifically: the streak image includes two axes, one of which is the spatial axis for collecting the one-dimensional fiber optic signal, and the other is the time axis for recording the time t when the echo signals at each spatial position arrive. According to the time difference Δt = t - t 0 of the echo signal arrival time t and the pulse emission time t 0 , the depth information d = cΔt / 2 at each spatial position is calculated, where c is the speed of light; then, according to the conversion relationship from the two-dimensional image to the one-dimensional image in the fiber optic conversion device, the three-dimensional image can be obtained.

[0049] Step 4) The displacement scanning imaging module 14 can be used to perform area scanning imaging on the target to be measured 8, so as to obtain three-dimensional imaging of a larger range of the target. Specifically: the displacement scanning device 14 is used to perform multiple overall displacements on the coupled imaging device 12 and the optical fiber conversion device 13. Each time, the imaging area of the target to be measured 8 is scanned and imaged to generate a fringe image. N scans generate N fringe images. After being processed by the image data processing unit 3, three-dimensional images of N scanning areas are generated. The three-dimensional images of the N scanning areas are stitched together to generate a large-field-of-view three-dimensional image.

[0050] For example, if a three-dimensional image of 100×100 pixels needs to be generated, assuming that the frame rate of the fringe camera 11 is 10 Hz and the effective imaging pixels in the slit spatial axis direction of the fringe image are 1000 pixels. If the traditional line-scanning fringe camera time-of-flight three-dimensional imaging method is used, 100 scans are required, and the acquisition time of a single-frame three-dimensional image is 10 s. Moreover, there is a problem of inconsistent resolutions in the x and y directions. The scanning direction resolution is the scanning step size, and the slit direction resolution is the dynamic imaging resolution of the fringe camera. If the area-scanning fringe camera time-of-flight three-dimensional imaging method provided by the present invention is used, assuming that the size of the area-scanning optical fiber array corresponds to 100×10 pixels, then after being converted into a line optical fiber array, it corresponds to 1×1000 pixels. The effective imaging pixels on the slit of the fringe camera can be effectively utilized, and the spatial resolutions in the x and y directions can also be ensured to be consistent. Both are determined by the dynamic imaging slit direction resolution of the fringe camera 11 and the optical fiber size. And only 10 scans are required to reconstruct a three-dimensional image of 100×100 pixels, and the acquisition time of a single-frame three-dimensional image is 1 s.

[0051] Therefore, by adopting the area-scanning time-of-flight three-dimensional imaging system and method based on a fringe camera of the present invention, on the basis of the fringe camera, the area-scanning method using an optical fiber array is used to replace the line-scanning method, which can maximize the function of the fringe camera, effectively improve the utilization efficiency of the imaging target surface, can ensure the imaging resolution at a sub-millimeter distance, and at the same time can increase the three-dimensional imaging speed of the traditional line-scanning fringe camera by about 10 times, providing an effective means for high-precision high-speed three-dimensional imaging of high-speed targets.

Claims

1. A surface scanning time-of-flight three-dimensional imaging system based on a streak camera, characterized in that: it includes an illumination unit (1), a signal acquisition unit (2), a data processing unit (3) and a synchronization control unit (4); the illumination unit (1) includes a pulsed laser module (5), a beam scanning module (6), and a beam expansion module (7); the pulsed laser module (5) is used to generate pulsed light; the beam scanning module (6) is arranged on the pulsed light optical path, and is used to perform two-dimensional scanning on the pulsed light and adjust the direction of the pulsed light so that it is incident on the target to be measured (8); the beam expansion module (7) is arranged between the beam scanning module (6) and the target to be measured (8), and the beam expansion module (7) expands the pulsed light and then irradiates it to the imaging area of the target to be measured (8), and the target to be measured (8) generates an echo signal; the signal acquisition unit (2) includes a displacement scanning imaging module (9), an optical fiber transmission module (10) and a streak camera (11); the displacement scanning imaging module (9) includes a coupling imaging device (12) and an optical fiber conversion device (13); the coupling imaging device (12) and the optical fiber conversion device (13) are arranged in sequence along the echo signal path, the echo signal is coupled and imaged on the optical fiber conversion device (13) by the coupling imaging device (12), and the optical fiber conversion device (13) converts the two-dimensional image of the target formed thereon into a one-dimensional image; the incident end and the output end of the optical fiber transmission module (10) are respectively connected to the optical fiber conversion device (13) and the streak camera (11); the data processing unit (3) is electrically connected to the streak camera (11), and is used to process the streak image output by the streak camera (11), and obtain a three-dimensional image according to the time-of-flight ranging principle; the synchronization control unit (4) is electrically connected to the pulsed laser module (5), the beam scanning module (6) and the streak camera (11) respectively.

2. A surface scanning time-of-flight three-dimensional imaging system based on a streak camera according to claim 1, characterized in that: the displacement scanning imaging module (9) further includes a displacement scanning device (14); the coupling imaging device (12) and the optical fiber conversion device (13) are both arranged on the displacement scanning device (14), and the displacement scanning device (14) is used to displace the coupling imaging device (12) and the optical fiber conversion device (13) as a whole to align with the imaging area of the target to be measured (8); the displacement scanning device (14) is electrically connected to the synchronization control unit (4).

3. A surface scanning time-of-flight three-dimensional imaging system based on a streak camera according to claim 1 or 2, characterized in that: the time resolution of the streak camera (11) is in the picosecond to femtosecond order of magnitude; the pulse width of the pulsed light is from picoseconds to femtoseconds, and the pulse jitter is less than 100 ps; the trigger pulse jitter emitted by the synchronization control unit (4) is less than 100 ps.

4. A surface scanning time-of-flight three-dimensional imaging system based on a streak camera according to claim 3, characterized in that: The fiber optic conversion device (13) consists of a fiber optic bundle. Among them, the signal receiving end is arranged in a planar array of the fiber optic bundle, and the signal output end is arranged in a linear array of the fiber optic bundle. The fiber optic bundle is used to transmit optical signals in the visible spectral range of 400 - 700 nm; The fiber optic conversion device (13) converts a target two-dimensional image with dimensions [RN, CN] into a one-dimensional image with dimensions [1, RN×CN], where RN×CN corresponds to the number of pixels in the slit direction of the streak camera and is in the range of 1000 - 5000 pixels. RN and CN are positive integers greater than 1.

5. A planar scanning time-of-flight three-dimensional imaging system based on a streak camera according to claim 4, characterized in that: The time resolution of the streak camera (11) is less than 10 ps, and the single-pixel scanning time is less than 6 ps; The fiber optic conversion device (13) consists of a photonic crystal fiber bundle.

6. A planar scanning time-of-flight three-dimensional imaging system based on a streak camera according to claim 5, characterized in that: The coupled imaging device (12) is an imaging lens. According to different target imaging distances and resolutions, the imaging lens selects a fixed-focus lens, an adjustable-focus lens, a microscope, or a telecentric lens.

7. A planar scanning time-of-flight three-dimensional imaging method based on a streak camera, using a planar scanning time-of-flight three-dimensional imaging system according to any one of claims 1 - 6, characterized in that, including the following steps: Step 1) The pulsed laser module (5) emits pulsed light to irradiate the imaging area of the target to be measured (8), generating an echo signal; Step 2) The echo signal is coupled and imaged on the fiber optic conversion device (13) through the coupled imaging device (12); the fiber optic conversion device (13) converts a target two-dimensional image with dimensions [RN, CN] into a one-dimensional image with dimensions [1, RN×CN], where RN×CN corresponds to the number of pixels in the slit direction of the streak camera and is in the range of 1000 - 5000 pixels. RN and CN are positive integers greater than 1; the one-dimensional image is transmitted through the fiber optic transmission module (10) and then enters the streak camera (11); the streak camera (11) performs time scanning imaging on the one-dimensional image signal and outputs a streak image; Step 3) The image data processing unit (3) processes the streak image according to the time-of-flight ranging principle to reconstruct the target two-dimensional depth image, that is, to obtain a three-dimensional image.

8. A planar scanning time-of-flight three-dimensional imaging method based on a streak camera according to claim 7, characterized in that, further including Step 4): Using the displacement scanning device (14) to perform multiple overall displacements on the coupled imaging device (12) and the fiber optic conversion device (13). Each time of displacement scans the imaging area of the target to be measured (8) to generate a streak image. N scans generate N streak images. After being processed by the image data processing unit (3), three-dimensional images of N scanning areas are generated and stitched to generate a large-field-of-view three-dimensional image.

9. A planar scanning time-of-flight three-dimensional imaging method based on a streak camera according to claim 8, characterized in that, Step 1) Specifically: The pulsed laser module (5) emits pulsed light with a pulse width ranging from picoseconds to femtoseconds. After the direction of the pulsed light is adjusted by the beam scanning module (6), it enters the beam expander module (7), and the beam expander module (7) expands the pulsed light and irradiates it onto the imaging area of the target to be measured (8).

10. A three-dimensional imaging method for surface scanning time-of-flight based on a streak camera according to claim 9, characterized in that, Step 3) Specifically: The stripe image contains two axes, one of which is the spatial axis for collecting one-dimensional optical fiber signals, and the other is the time axis for recording the time t when the echo signals at each spatial position arrive. According to the time difference Δt = t - t 0 between the time t when the echo signal arrives and the pulse emission time t 0 , the depth information d = cΔt / 2 at each spatial position is calculated, where c is the speed of light; According to the conversion relationship from a two-dimensional image to a one-dimensional image in the optical fiber conversion device (13), a three-dimensional image is obtained.

Images