High-precision three-dimensional dynamic contour imaging device and imaging method

Abstract

The invention discloses a high-precision three-dimensional dynamic contour imaging device and method, and belongs to the technical field of three-dimensional imaging, and the device comprises a laser pulse generation system, a beam splitting device, a sampling reflection system, a first composite lens array, a balance cross-correlation adjustment system, a camera assembly, and a data processing system. When the laser pulse generating system generates femtosecond pulse light, the beam splitting device divides the femtosecond pulse light into measurement pulse light and reference pulse light, and the balance cross-correlation adjusting system is used for performing delay adjustment on the measurement pulse light which carries sampling target information and is input again and the reference pulse light which is directly input. A plurality of cross-correlation area array signals are generated and stored in the camera assembly, and the data processing system processes, operates and solves the cross-correlation signals according to data of the camera assembly to obtain three-dimensional information of a sampling target. On the premise that the measuring range is adjustable, high-precision and high-speed measurement can be achieved at the same time.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser three-dimensional imaging, and in particular relates to a high-precision three-dimensional dynamic contour imaging device and an imaging method. Background Art

[0002] A 3D profilometer, also known as a 3D profiler or 3D scanner, is a measuring device that can acquire three-dimensional data about an object's surface. As an important measurement tool in the field of 3D imaging technology, 3D profilometers are widely used in various fields, such as optical metrology, biomedical imaging, and 3D printing.

[0003] However, 3D profilers rely on various optical technologies when in use. Although with the development of optical technology, time-of-flight (ToF) laser ranging technology has been integrated into digital imaging systems, enabling rapid acquisition and real-time processing of full 3D scenes, this method has low detection accuracy due to limitations in temporal resolution and temporal jitter, making it difficult to achieve sub-micron axial resolution and accuracy. To overcome this limitation, researchers have adopted optical sampling technologies based on the photoelectric effect or nonlinear optics, such as interferometric imaging technology using a Michelson interferometer with a moving arm. Although such methods can achieve nanometer-level accuracy in 3D imaging, their measurement range is extremely limited, limiting their application in remote sensing or scenes with a large depth of field.

[0004] In recent years, the advent of optical combs has provided new opportunities for the precise control of coherent light sources in the time and frequency domains. By utilizing the characteristics of time-domain linear optical mutual sampling and frequency-domain multi-longitudinal mode heterodyne interference of dual-comb systems, dual-comb ranging methods can achieve large-scale, dynamic, high-precision absolute distance measurement. However, due to the high complexity and high cost of dual-comb ranging systems, as well as limitations such as high computational load and low refresh rate, the applicability of this method is relatively poor. It can be seen that due to the various defects of various current laser ranging technologies, it is difficult for three-dimensional profilers to achieve a balance between range, rate, sensitivity, field of view, and accuracy, which in turn leads to one or more problems of high computational load, limited range, and poor measurement accuracy in current three-dimensional profilers. Therefore, there is an urgent need to provide a high-precision three-dimensional dynamic profile imaging device and imaging method that can solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned shortcomings by providing a high-precision three-dimensional dynamic profile imaging device and imaging method, aiming to solve the problems of high computational load, limited range, and poor measurement accuracy in the current laser ranging technology of three-dimensional profilometers. To achieve the above-mentioned objectives, the present invention provides the following technical solutions: A high-precision three-dimensional dynamic profile imaging device, comprising a laser pulse generation system, a beam splitting device, a sampling reflection system, a first compound lens array, a balanced cross-correlation adjustment system, a camera assembly, and a data processing system; The laser pulse generating system is used to generate and output femtosecond pulse light to the beam splitting device; The beam splitting device is connected to the laser pulse generating system and is used to split the femtosecond pulse light into a measuring pulse light and a reference pulse light, and output the measuring pulse light and the reference pulse light to the sampling and reconstruction system and the balanced cross-correlation adjustment system respectively; The sampling reflection system includes an imaging range adjustment device and a sampling target; the imaging range adjustment device is used to adjust the imaging range of the measuring pulse light and allow the measuring pulse light to pass through; the sampling target is used to be irradiated by the measuring pulse light so that the measuring pulse light carries information of the sampling target and then reflects; The first composite lens array is used to receive the reflected measurement pulse light, adjust the imaging range of the measurement pulse light, and then output the measurement pulse light to the balanced cross-correlation adjustment system; The balanced cross-correlation adjustment system is used to perform delay adjustment on the received measurement pulse light and reference pulse light, and form and output matching first cross-correlation array signals and second cross-correlation array signals to the camera assembly; The camera assembly is connected to a data processing system; the data processing system is used to process and calculate the first cross-correlation array signal and the second cross-correlation array signal matched in the camera assembly to obtain three-dimensional information of the sampling target.

[0006] Furthermore, the laser pulse generation system includes a continuous laser, an electro-optical modulator, a signal generator, an electric pulse generator, and a compression amplifier; the continuous laser, the electric pulse generator, and the compression amplifier are all connected to the electro-optical modulator; the signal generator is connected to the electric pulse generator; the electro-optical modulator is used to receive the seed light output by the continuous laser and the electrical narrow pulse output by the electric pulse generator, and then modulate the seed light to form a frequency-variable electro-optical comb, which is then output to the compression amplifier.

[0007] Furthermore, the beam splitting device includes a fiber optic beam splitter and a first output coupler and a second output coupler respectively connected to the fiber optic beam splitter; the fiber optic beam splitter is connected to the output end of the compression amplifier; the first output coupler is connected to the input end of the imaging range adjustment device; and the second output coupler is connected to the input end of the balanced cross-correlation adjustment system.

[0008] Furthermore, at the output end of the first output coupler, an imaging range adjustment device and a sampling target are arranged in sequence along the incident path of the measurement pulse light; the imaging range adjustment device includes a sampling lens group, a first polarizing beam splitter, and a second composite lens array connected in sequence; the first polarizing beam splitter is used to refract the reflected measurement pulse light to the first composite lens array.

[0009] Furthermore, the first composite lens array is provided between the sampling reflection system and the balanced cross-correlation adjustment system, and is arranged along a direction perpendicular to the reference pulse light input to the balanced cross-correlation adjustment system.

[0010] Furthermore, the balanced cross-correlation adjustment system includes a second polarizing beam splitter, a first dichroic mirror, a nonlinear large field of view crystal, a second dichroic mirror, a third polarizing beam splitter, a first reflector, a second reflector, a first lens, a second lens, a third lens and a fourth lens; the second polarizing beam splitter, the first dichroic mirror, the nonlinear large field of view crystal, the second dichroic mirror and the third polarizing beam splitter are arranged in sequence along the incident path of the reference pulse light; the first reflector and the second reflector are both arranged at the rear end of the third polarizing beam splitter and on different sides of the third polarizing beam splitter; the third lens and the fourth lens are respectively arranged above the first dichroic mirror and the second dichroic mirror in a direction perpendicular to the incident path of the reference pulse light.

[0011] Furthermore, the camera assembly includes a first high-speed camera and a second high-speed camera; the third lens and the first high-speed camera are arranged in sequence above the first dichroic mirror along a direction perpendicular to the incident path of the reference pulse light; the fourth lens and the second high-speed camera are arranged in sequence above the second dichroic mirror along a direction perpendicular to the incident path of the reference pulse light; the first high-speed camera and the second high-speed camera are both connected to a data processing system.

[0012] A high-precision three-dimensional dynamic contour imaging method, using any of the high-precision three-dimensional dynamic contour imaging devices described above, comprises the following steps: S1: Adjust the imaging range adjustment device and the first compound lens array so that the measurement pulse light can perform near-field high-resolution microscopic imaging or far-field high-blur and large-depth-of-field imaging after irradiating the sampling target; S2: Start the laser pulse generation system to generate femtosecond pulses of equal duration and continuously emitted. The femtosecond pulses are split by a beam splitter to generate a measurement pulse and a reference pulse. The reference pulse is directly output to the balanced cross-correlation adjustment system, while the measurement pulse is irradiated by the imaging range adjustment device to a sampling target, where it is reflected and carries the sampling target information. The measurement pulse then passes through the first composite lens array and enters the balanced cross-correlation adjustment system. S3: The measurement pulse light and the reference pulse light are processed by the balanced cross-correlation adjustment system to generate a first cross-correlation array signal and a second cross-correlation array signal. Then, image information carrying the first cross-correlation array signal and the second cross-correlation array signal is output to the camera system and stored. S4: Use the data processing system to implement a matching alignment strategy for the image information in the camera component, and then extract and match feature points to finally obtain the three-dimensional information of the sampling target.

[0013] Furthermore, in step S4, the matching alignment strategy is a direct matching strategy, an indirect matching strategy or a deep learning strategy.

[0014] Furthermore, in step S4, the processing method of the data processing system is specifically as follows: the data processing system first extracts a plurality of first cross-correlation array signals and a plurality of second cross-correlation array signals recorded by the image information in the camera component, extracts feature points through an algorithm for matching operations, and obtains two matched and aligned first cross-correlation array signals and second cross-correlation array signals; then, pixel intensity subtraction is performed on the corresponding first cross-correlation array signals and second cross-correlation array signals to obtain a first balanced cross-correlation array signal; based on the first balanced cross-correlation array signal, the repetition frequency of the laser pulse generation system is continuously adjusted to thereby generate a plurality of second balanced cross-correlation array signals; the repetition frequency difference of adjacent array signals with an intensity of 0 is extracted from the second balanced cross-correlation array signal; and then, based on a built-in algorithm, the repetition frequency difference is used to solve and obtain the three-dimensional information of the sampling target; wherein the three-dimensional information of the sampling target includes the target distance, velocity, and acceleration.

[0015] The beneficial effects of the present invention are: 1. Combining the imaging device and imaging method proposed in the present invention, the final imaging accuracy can reach nm level, i.e. 10 -8 The imaging device of the present invention, while featuring adjustable range, can significantly improve measurement accuracy compared to traditional far-field imaging methods. Furthermore, while the imaging device of the present invention has an adjustable range, it also extends the measurement range to hundreds of meters, significantly improving the range compared to traditional near-field and far-field imaging methods, which can only reach the millimeter level. The present invention also features high-speed speed measurement, eliminating the effects of bandwidth limitations and environmental noise during measurement. Therefore, the imaging method of the present invention achieves a good balance between measurement accuracy, imaging range adjustment, and measurement speed, enabling both high-precision and high-speed measurements while maintaining an adjustable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the high-precision three-dimensional dynamic contour imaging device provided by the present invention; Figure 2 This is a system principle diagram of the high-precision three-dimensional dynamic contour imaging method provided by the present invention; Figure 3 This is a comparison diagram of the field of view angle simulation of a common nonlinear crystal and a designed nonlinear large field of view crystal in the high-precision three-dimensional dynamic contour imaging method provided by the present invention; Figure 4 In the high-precision three-dimensional dynamic contour imaging method provided by the present invention, the imaging range system is adjusted to form a near-field high-resolution, far-field large field of view, and far-field large depth of field imaging image; Figure 5 It is a graph showing the relationship between the time offset and the balanced optical cross-correlation signal intensity under different pulse width conditions in the high-precision three-dimensional dynamic profile imaging method provided by the present invention; Figure 6 It is an Allan variance diagram of a medium-sensitivity camera obtained when measuring using the high-precision three-dimensional dynamic profile imaging method provided by the present invention.

[0017] In the accompanying drawings: 1. continuous laser; 2. electro-optic modulator; 3. signal generator; 4. electric pulse generator; 5. compression amplifier; 6. fiber optic beam splitter; 7. first output coupler; 8. sampling lens group; 9. first polarizing beam splitter; 10. second compound lens array; 11. sampling target 11; 12. first compound lens array; 13. second output coupler; 14. second polarizing beam splitter; 15. first dichroic mirror; 16. nonlinear large field of view crystal; 17. second dichroic mirror; 18. third polarizing beam splitter; 19. first reflector; 20. second reflector; 21. first high-speed camera; 22. second high-speed camera; 23. first lens; 24. second lens; 25. third lens; 26. fourth lens; 27. data processing system. DETAILED DESCRIPTION

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0019] In the description of the present invention, "first feature" or "second feature" may include one or more of the features.

[0020] In the description of the present invention, "plurality" means two or more.

[0021] In the description of the present invention, a first feature being “on” or “under” a second feature may include the first and second features being in direct contact with each other, or the first and second features not being in direct contact with each other but being in contact with each other via another feature therebetween.

[0022] In the description of the present invention, “on”, “above” and “above” a first feature of a second feature include the first feature being directly above and obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature.

[0023] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," and "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0025] Example 1: See attached Figure 1 A high-precision three-dimensional dynamic profile imaging device, comprising a laser pulse generation system, a beam splitting device, a sampling reflection system, a first compound lens array, a balanced cross-correlation adjustment system, a camera assembly, and a data processing system; The laser pulse generating system is used to generate and output femtosecond pulse light to the beam splitting device; The beam splitting device is connected to the laser pulse generating system and is used to split the femtosecond pulse light into a measuring pulse light and a reference pulse light, and output the measuring pulse light and the reference pulse light to the sampling and reconstruction system and the balanced cross-correlation adjustment system respectively; The sampling reflection system includes an imaging range adjustment device and a sampling target 11; the imaging range adjustment device is used to adjust the imaging range of the measurement pulse light and allow the measurement pulse light to pass through; the sampling target 11 is used to be irradiated by the measurement pulse light so that the measurement pulse light carries information of the sampling target 11 and then reflects; The first composite lens array is used to receive the reflected measurement pulse light, adjust the imaging range of the measurement pulse light, and then output the measurement pulse light to the balanced cross-correlation adjustment system; The balanced cross-correlation adjustment system is used to perform delay adjustment on the received measurement pulse light and reference pulse light, and form and output matching first cross-correlation array signals and second cross-correlation array signals to the camera assembly; The camera assembly is connected to a data processing system; the data processing system is used to process and calculate the first cross-correlation array signal and the second cross-correlation array signal in the camera assembly to obtain three-dimensional information of the sampling target 11.

[0026] As can be seen from the above structure, the laser pulse generation system can output femtosecond pulse light with agile repetition frequency, and its repetition frequency can be continuously adjusted according to demand, which can improve the final imaging accuracy and meet the processing requirements of the data processing system. The beam splitting device is connected to the output end of the laser pulse generation system, and can split the femtosecond pulse light into measurement pulse light and reference pulse light. The sampling reconstruction system and the balanced cross-correlation adjustment system are respectively arranged on the incident paths of the measurement pulse light and the reference pulse light, wherein the sampling reflection system includes an imaging range adjustment device and a sampling target 11. The imaging range adjustment device can adjust the imaging range of the measurement pulse light so that the measurement pulse light can perform near-field high-resolution microscopic imaging or far-field high-blur and large depth of field imaging after irradiating the sampling target 11. The measurement pulse light passes through the imaging range adjustment device along the incident path, irradiates the sampling target 11, and then carries the information of the sampling target 11, returns along the opposite direction of the incident path of the measurement pulse light, passes through the imaging range adjustment device again, and then enters the first compound lens array. The first composite lens array receives the reflected measurement pulse light, adjusts the imaging range of the measurement pulse light again, and then outputs the measurement pulse light to the balanced cross-correlation adjustment system. The present invention utilizes the imaging range adjustment device and the first composite lens array to adjust the imaging range, enabling range adjustment to meet different field of view requirements. Because the reference pulse light enters the balanced cross-correlation adjustment system directly without passing through the sampling reflection system, there is a time difference between the reference pulse light and the measurement pulse light after beam splitting. Delay adjustment of the reference pulse light and the measurement pulse light in the balanced cross-correlation adjustment system enables the balanced optical cross-correlation array generated by the pulse signal to be optimally matched, thereby reducing the complexity and cost of the system. The first and second cross-correlation array signals generated by the balanced cross-correlation adjustment system are output to a camera assembly, which is capable of receiving and storing image information carrying the first and second cross-correlation array signals. Specifically, the camera assembly can include a high-sensitivity, high-speed camera group consisting of one or more CMOS, CCD, ICCD, and EMCCD cameras. Utilizing a highly sensitive, high-speed camera assembly, a cross-correlation array signal with the advantages of a high signal-to-noise ratio, high speed, a large field of view, and a high pixel count can be acquired. The camera assembly is connected to a data processing system, enabling the data processing system to process and calculate the first and second cross-correlation array signals carried by the image information in the camera assembly. Ultimately, based on a built-in algorithm, the required three-dimensional information of the sampled target 11 is accurately determined, achieving high measurement accuracy. Specifically, this three-dimensional information may include target distance, velocity, and acceleration. The three-dimensional dynamic contour imaging device of the present invention has an adjustable field of view, enabling the acquisition of highly accurate measurement parameters while maintaining the required measurement range.In addition, ordinary three-dimensional profilers require multiple scans and calculations to obtain the three-dimensional information of the target, but using the three-dimensional dynamic profile imaging device of the present invention, the three-dimensional information of the sampling target 11 corresponding to the current sampling area can be obtained by a single scan, and the amount of calculation can be greatly reduced, the calculation load can be reduced, and measurement time can be saved.

[0027] Example 2: See attached Figure 1 、 6 . On the basis of Example 1, the laser pulse generating system includes a continuous laser 1, an electro-optical modulator 2, a signal generator 3, an electric pulse generator 4, and a compression amplifier 5; the continuous laser 1, the electric pulse generator 4, and the compression amplifier 5 are all connected to the electro-optical modulator 2; the signal generator 3 is connected to the electric pulse generator 4; the electro-optical modulator 2 is used to receive the seed light output by the continuous laser 1 and the electrical narrow pulse output by the electric pulse generator 4, and then modulate the seed light to form a frequency-variable electro-optical comb, and then output it to the compression amplifier 5. It can be seen from the above structure that the continuous laser 1 can continuously output seed light to the electro-optical modulator 2, and the signal generator 3 can input the electric pulse generator 4 to generate electrical narrow pulses with agile repetition frequency. When electro-optic modulator 2 receives the seed light from continuous laser 1 and the electrical narrow pulses from electrical pulse generator 4, it modulates the seed light into a frequency-variable electro-optical comb. This is then output to compression amplifier 5 for spectrum broadening and compression amplification, producing femtosecond optical pulses. This results in femtosecond pulse output on the order of 1ns-1fs. Specifically, in this laser pulse generation system, the frequency agility of the electrical narrow pulses can be set to 0.1Hz-1GHz, and the frequency agility range can be set to 0.01Hz-100GHz.

[0028] The beam splitting device includes a fiber optic splitter 6 and a first output coupler 7 and a second output coupler 13 connected to the fiber optic splitter 6, respectively. The fiber optic splitter 6 is connected to the output of the compression amplifier 5. The first output coupler 7 is connected to the input of the imaging range adjustment device. The second output coupler 13 is connected to the input of the balanced cross-correlation adjustment system. As can be seen from the above structure, the fiber optic splitter 6 splits the femtosecond pulse light into two beams with an output ratio of 1:1. One beam is the reference pulse light, which is output through the second output coupler 13, and the other beam is the measurement pulse light, which is output through the first output coupler 7.

[0029] At the output end of the first output coupler 7, an imaging range adjustment device and a sampling target 11 are arranged in sequence along the incident path of the measurement pulse light. The imaging range adjustment device includes a sampling lens group 8, a first polarizing beam splitter 9, and a second compound lens array 10 connected in sequence. The first polarizing beam splitter 9 is used to refract the reflected measurement pulse light to the first compound lens array 12. As can be seen from the above structure, the imaging range of the measurement pulse light is adjusted by the sampling lens group 8, the first polarizing beam splitter 9, and the second compound lens array 10. It then illuminates the sampling target 11 and, carrying information about the sampling target 11, is reflected in the direction opposite to the incident path. When the measurement pulse light is reflected by the first polarizing beam splitter 9, it is refracted and then output to the first compound lens array 12.

[0030] The first composite lens array 12 is positioned between the sampling reflection system and the balanced cross-correlation adjustment system, and is arranged perpendicular to the direction in which the reference pulse light enters the balanced cross-correlation adjustment system. As can be seen from the above structure, the arrangement of the first composite lens array 12 enables the imaging range of the reflected measurement pulse light to be readjusted, and the measurement pulse light is then input into the balanced cross-correlation adjustment system in a direction perpendicular to the reference pulse light. Specifically, both the first composite lens array 12 and the second composite lens array 10 can include multiple lenses and microlenses of different models to meet the requirements for adjusting the imaging range.

[0031] The balanced cross-correlation adjustment system includes a second polarizing beam splitter 14, a first dichroic mirror 15, a nonlinear large field of view crystal 16, a second dichroic mirror 17, a third polarizing beam splitter 18, a first reflector 19, a second reflector 20, a first lens 23, a second lens 24, a third lens 25 and a fourth lens 26; the second polarizing beam splitter 14, the first dichroic mirror 15, the nonlinear large field of view crystal 16, the second dichroic mirror 17 and the third polarizing beam splitter 18 are arranged in sequence along the incident path of the reference pulse light; the first reflector 19 and the second reflector 20 are both arranged at the rear end of the third polarizing beam splitter 18 and on different sides of the third polarizing beam splitter 18; the third lens 25 and the fourth lens 26 are respectively arranged above the first dichroic mirror 15 and the second dichroic mirror 17 in a direction perpendicular to the incident path of the reference pulse light.

[0032] From the above structure, it can be seen that Figure 1As shown in the structural diagram, the measurement pulse light and the reference pulse light are combined at the polarization beam splitter 14 to form a combined beam. The combined beam passes through the first lens 23 and the first dichroic mirror 15 and enters the nonlinear large field of view crystal 16 to generate a first sum-frequency cross-correlation signal light. The first sum-frequency cross-correlation signal light carries the first cross-correlation surface array signal. The combined beam, which passes through the nonlinear large field of view crystal 16, is then split into two paths by the second dichroic mirror 17. One path directly passes through the fourth lens 26 and enters the camera assembly, while the other path continues through the second lens 24 and enters the third polarization beam splitter 18. The third polarization beam splitter 18 then decomposes the combined beam into the measurement pulse light and the reference pulse light. The measurement pulse light and the reference pulse light are then reflected by the first reflector 19 and the second reflector 20, respectively, and combined again. They then return to pass through the second lens 24, the second dichroic mirror 17, and the nonlinear large field of view crystal 16, where they generate a second sum-frequency cross-correlation signal light. The second sum frequency cross-correlation signal light carries a second cross-correlation array signal, and the first cross-correlation array signal outputted by the balanced cross-correlation adjustment system is adjusted to match the second cross-correlation array signal.

[0033] Preferably, the nonlinear large field of view crystal 16 is a chirped nonlinear crystal. Figure 3 As shown, if a conventional nonlinear polarization crystal is used, the field of view is approximately 3.5°. However, if a specially designed chirped nonlinear crystal is used, such as one with a period of 17-20 μm, the field of view can be increased to approximately 35°, thereby increasing the number of resolvable elements by a factor of 100. Furthermore, if a larger field of view is desired, other types of nonlinear large-field crystals can be used depending on the field of view requirements.

[0034] The camera assembly includes a first high-speed camera 21 and a second high-speed camera 22; the third lens 25 and the first high-speed camera 21 are arranged in sequence above the first dichroic mirror 15 along a direction perpendicular to the incident path of the reference pulse light; the fourth lens 26 and the second high-speed camera 22 are arranged in sequence above the second dichroic mirror 17 along a direction perpendicular to the incident path of the reference pulse light; the first high-speed camera 21 and the second high-speed camera 22 are both connected to the data processing system 27.

[0035] As can be seen from the above structure, the first high-speed camera 21 and the second high-speed camera 22 respectively receive and store the second sum-frequency cross-correlation signal light and the first sum-frequency cross-correlation signal light, and output the first cross-correlation area array signal and the second cross-correlation area array signal they carry to the data processing system 27 for further processing.

[0036] Preferably, the first high-speed camera 21 and the second high-speed camera 22 can be medium-sensitivity high-speed cameras or high-sensitivity high-speed cameras. The imaging frame rate of the high-sensitivity high-speed camera can be between 1 and 10. 7The imaging sensitivity is at the single-photon level, the imaging pixels range from 10 to 10 million pixels, and the imaging receiving surface is 1mm 2 -800cm 2 , can achieve higher measurement accuracy than ordinary cameras. Figure 6 As shown, the Allan variance of the measurement signal of a medium-sensitivity high-speed camera is measured using the imaging device of the present invention, indicating a high measurement accuracy.

[0037] Example 3: See attached Figures 1 to 6 The present invention also provides a high-precision three-dimensional dynamic contour imaging method, which uses the high-precision three-dimensional dynamic contour imaging device as described in Example 2, and includes the following steps: S1: Adjust the imaging range adjustment device and the first compound lens array 12 so that the measurement pulse light can perform near-field high-resolution microscopic imaging or far-field high-blur and large-depth-of-field imaging after irradiating the sampling target 11; S2: Start the laser pulse generation system to generate femtosecond pulse light of equal duration and continuously emitted; the femtosecond pulse light is split by the beam splitter to form a measurement pulse light and a reference pulse light, respectively; wherein the reference pulse light is directly output to the balanced cross-correlation adjustment system, while the measurement pulse light is irradiated by the imaging range adjustment device on the sampling target 11, acquires and carries information of the sampling target 11 on the reflection, and then enters the balanced cross-correlation adjustment system through the first composite lens array 12; S3: The measurement pulse light and the reference pulse light are processed by the balanced cross-correlation adjustment system to generate a first cross-correlation array signal and a second cross-correlation array signal. Then, image information carrying the first cross-correlation array signal and the second cross-correlation array signal is output to the camera system and stored. S4: Using the data processing system 27 to implement a matching alignment strategy on the image information in the camera assembly, and then through feature point extraction and matching operations, finally obtaining the three-dimensional information of the sampling target 11.

[0038] For step S1, according to the attached Figure 4 The imaging range adjustment device can adjust the imaging range by adjusting the focal length and spacing of the lenses and microlenses in the sampling lens group 8 and the second composite lens array 10. If you want to obtain near-field high-resolution imaging or large depth of field imaging, you can adjust the imaging range adjustment device to an imaging magnification device, wherein the near-field high-resolution imaging is as shown in the attached figure. Figure 4 (1) As shown in the attached figure, the large depth of field imaging Figure 4 (3) As shown, it can achieve meter-level imaging. If it is necessary to obtain a large field of view imaging requirement, the imaging range adjustment device can be adjusted to an imaging beam reduction device to obtain a large field of view imaging resolution, as shown in the attached figure. Figure 4 (2) shown.

[0039] For step S3, Figure 2 (2) is a schematic diagram of the principle of generating balanced cross-correlation signals in a balanced cross-correlation adjustment system. When the measurement pulse light carries the information of the sampling target 11 and enters the balanced cross-correlation adjustment system, the polarization state of the measurement pulse light is perpendicular to that of the reference pulse light, and there is a relative time delay between the measurement pulse light and the reference pulse light. After the measurement pulse light and the reference pulse light are combined, the combined light passes through the nonlinear large field of view crystal 16 during the incidence and reflection, thereby generating two cross-correlation array signals, namely the first cross-correlation array signal and the second cross-correlation array signal. By adjusting the relative delay between the reference pulse light and the measurement pulse light, the matching relationship between the pulse width and the crystal delay can be eliminated to obtain a high-precision, high-sensitivity balanced cross-correlation array signal. As shown in the attached figure Figure 2 (1) With the attached Figure 2 As shown in (3), when the laser pulse generation system scans the repetition frequency, the relative delay change between the reference pulse light and the measurement pulse light will cause the intensity of the two beams of cross-correlated array signal light to change accordingly, and the intensity change process is received and presented by the camera component. In addition, the first high-speed camera 21 and the second high-speed camera 22 in the camera component can both use high-sensitivity high-speed cameras to obtain the intensity change process of the cross-correlated array signal with high signal-to-noise ratio, high speed, large field of view, and high pixel. Among them, the attached Figure 2 (1) is the state diagram of the laser pulse generation system during frequency modulation, and the attached Figure 2 (3) is a signal diagram of different balanced cross-correlation signals generated when the laser pulse generation system is frequency modulated.

[0040] For step S4, as the laser pulse generation system continuously emits, the camera system receives and stores a large number of image information carrying cross-correlation array signals, that is, a large number of photos. Therefore, it is necessary to select a suitable image matching strategy to accurately match and align the first cross-correlation array signal with the corresponding second cross-correlation array signal corresponding to the photo group to eliminate common-mode optical and electrical noise and reduce measurement errors. Then, the built-in algorithm is used to perform feature point extraction and matching operations to finally obtain the three-dimensional information of the sampling target 11.

[0041] Preferably, the matching and alignment strategy is a direct matching strategy, an indirect matching strategy or a deep learning strategy. An image matching strategy is a strategy that finds the content or structure of two images with the same or similar attributes through pixel-level recognition and alignment. Generally speaking, the images to be matched are usually from the same or similar scenes or targets, or other types of image pairs, which have the same shape or semantic information and therefore have a certain degree of matchability. Among them, direct matching strategies, indirect matching strategies or deep learning strategies can all use strategy methods in the prior art. The present invention can select a suitable matching and alignment strategy according to actual detection needs.

[0042] As attached Figure 5 As shown in the figure, the relationship between the balanced cross-correlation signal intensity and the time offset is simulated when the relative delay is fixed at 500fs and the pulse width is 500fs, 1000fs, 1500fs, and 2000fs, respectively. Since the delay time of the nonlinear large field of view crystal 16 is fixed, the delay time of the measurement pulse light and the corresponding reference pulse light input to the balanced cross-correlation adjustment system is not necessarily consistent. This will cause a mismatch between the two delay times, which in turn affects the sensitivity of the balanced cross-correlation signal. Therefore, it is necessary to adjust the two delay times, that is, by continuously adjusting the repetition frequency of the laser pulse generation system to match the optimal delay between the reference pulse light and the measurement pulse light, thereby obtaining the most sensitive first balanced cross-correlation array signal to improve measurement accuracy.

[0043] In addition, in step S4, the processing method of the data processing system is specifically as follows: the data processing system first extracts a plurality of first cross-correlation array signals and a plurality of second cross-correlation array signals recorded by the image information in the camera component, extracts feature points through an algorithm for matching operations, and obtains two matched and aligned first cross-correlation array signals and second cross-correlation array signals; then, pixel intensity subtraction is performed on the corresponding first cross-correlation array signals and second cross-correlation array signals to obtain a first balanced cross-correlation array signal; according to the first balanced cross-correlation array signal, the repetition frequency of the laser pulse generation system is continuously adjusted to thereby generate a plurality of second balanced cross-correlation array signals; the repetition frequency difference of adjacent array signals with an intensity of 0 is extracted from the second balanced cross-correlation array signal; then, according to the built-in algorithm, the repetition frequency difference is used to solve and obtain the three-dimensional information of the sampling target 11; wherein the three-dimensional information of the sampling target 11 includes target distance, velocity, and acceleration.

[0044] The specific implementation method of the data processing system is to use the pulse flight time method to encode the measurement pulse after being reflected by the target object to obtain the distance information to be measured. When the intensity of each pixel point of the obtained balanced cross-correlation array signal is zero, the flight time of the measurement pulse can be locked to an integer multiple of the pulse sequence time domain period, and then the target distance D can be obtained according to the existing calculation method. Then, according to the determined target distance D and the pulse repetition frequency f r The laser pulse generation system is swept at high speed to generate the 1st, 2nd, ..., Mth measurement pulse light signals and 1st, 2nd, ..., Nth, N+1th reference pulse signals. The Mth measurement pulse signal will generate two balanced cross-correlation signals with the Nth reference pulse signal and the N+1th reference pulse signal respectively. The repetition frequencies of the two pulses are f r1 and f r2Then, the zero point of each pixel of the two balanced cross-correlated array signals is obtained by fitting, and the repetition frequency difference Δf of the adjacent array signal intensities of 0 is extracted. The velocity and acceleration information of the sampling target 11 are accurately solved through the built-in calculation formula.

[0045] For example, Δf can be calculated based on the target distance D, and the calculation formula includes: , ; ; Where f is the frequency change caused by the frequency sweep of the laser pulse generation system, Δt is the time interval between two balanced cross-correlation signals when the signal intensity of each pixel is zero, and T is the frequency sweep period. The calculation formulas for target distance, speed, and acceleration include: ; ; ; Where D is the target distance, is the target speed, is the target acceleration, c is the speed of light in vacuum, is a constant, n is the refractive index of air, and Δf is the frequency difference between adjacent zero points of each pixel of the balanced cross-correlation array signal.

[0046] Traditional three-dimensional imaging methods mainly include far-field three-dimensional imaging and near-field three-dimensional imaging. Far-field three-dimensional imaging uses pulse time-of-flight ranging to perform array measurements, and uses the system's internal counter to count the number of clock pulses between the time the pulse laser is emitted and the time the echo signal light arrives to obtain the round-trip time. Its accuracy depends on the frequency of the system's working clock. The general accuracy is between centimeters and millimeters, and due to the existence of dead zones, close-range measurements cannot be performed. Near-field three-dimensional imaging generally uses an interferometer with a moving arm for imaging, but it is limited by coherence distance and slow speed and other issues. Far-field imaging cannot be achieved, and the degree of limitation is relatively large. However, combined with the imaging device and imaging method proposed in the present invention, the final imaging accuracy can reach the nm level, that is, 10 -8 orders of magnitude, compared to traditional far-field imaging methods 10 -3 In terms of precision, the accuracy has been improved by five orders of magnitude, which greatly improves the measurement accuracy. In addition, the imaging range of this method is adjustable, and the measurement range can reach hundreds of meters, which is a significant improvement compared to traditional near-field imaging and far-field imaging methods that can only reach millimeters. In addition, ordinary measurements take several seconds, while the single measurement speed of this method is less than 10 -7In summary, the imaging method of the present invention can achieve a good balance in measurement accuracy, imaging range adjustment, and measurement speed, and can achieve high-precision and high-speed measurement while the range can be adjusted over a wide range.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high-precision three-dimensional dynamic contour imaging device, characterized by: It includes a laser pulse generation system, a beam splitting device, a sampling reflection system, a first compound lens array, a balanced cross-correlation adjustment system, a camera assembly and a data processing system; The laser pulse generating system is used to generate and output femtosecond pulse light to the beam splitting device; The beam splitting device is connected to the laser pulse generating system and is used to split the femtosecond pulse light into a measuring pulse light and a reference pulse light, and output the measuring pulse light and the reference pulse light to the sampling and reconstruction system and the balanced cross-correlation adjustment system respectively; The sampling reflection system includes an imaging range adjustment device and a sampling target; the imaging range adjustment device is used to adjust the imaging range of the measuring pulse light and allow the measuring pulse light to pass through; the sampling target is used to be irradiated by the measuring pulse light so that the measuring pulse light carries information of the sampling target and then reflects; The first composite lens array is used to receive the reflected measurement pulse light, adjust the imaging range of the measurement pulse light, and then output the measurement pulse light to the balanced cross-correlation adjustment system; The balanced cross-correlation adjustment system is used to perform delay adjustment on the received measurement pulse light and reference pulse light, and form and output matching first cross-correlation array signals and second cross-correlation array signals to the camera assembly; The camera assembly is connected to a data processing system; the data processing system is used to process and calculate the first cross-correlation array signal and the second cross-correlation array signal matched in the camera assembly to obtain three-dimensional information of the sampling target.

2. The high-precision three-dimensional dynamic contour imaging device according to claim 1, characterized in that: The laser pulse generating system includes a continuous laser, an electro-optical modulator, a signal generator, an electric pulse generator, and a compression amplifier; The continuous laser, electric pulse generator, and compression amplifier are all connected to the electro-optical modulator; the signal generator is connected to the electric pulse generator; the electro-optical modulator is used to receive the seed light output by the continuous laser and the electrical narrow pulse output by the electric pulse generator, and then modulate the seed light to form a frequency-variable electro-optical comb, which is then output to the compression amplifier.

3. The high-precision three-dimensional dynamic contour imaging device according to claim 2, characterized in that: The beam splitting device includes a fiber beam splitter and a first output coupler and a second output coupler respectively connected to the fiber beam splitter; the fiber beam splitter is connected to the output end of the compression amplifier; the first output coupler is connected to the input end of the imaging range adjustment device; and the second output coupler is connected to the input end of the balanced cross-correlation adjustment system.

4. The high-precision three-dimensional dynamic contour imaging device according to claim 3, characterized in that: At the output end of the first output coupler, an imaging range adjustment device and a sampling target are arranged in sequence along the incident path of the measurement pulse light; the imaging range adjustment device includes a sampling lens group, a first polarizing beam splitter, and a second composite lens array connected in sequence; the first polarizing beam splitter is used to refract the reflected measurement pulse light to the first composite lens array.

5. The high-precision three-dimensional dynamic contour imaging device according to claim 4, characterized in that: The first composite lens array is provided between the sampling reflection system and the balanced cross-correlation adjustment system, and is arranged along a direction perpendicular to the reference pulse light input to the balanced cross-correlation adjustment system.

6. The high-precision three-dimensional dynamic contour imaging device according to claim 1, characterized in that: The balanced cross-correlation adjustment system includes a second polarizing beam splitter, a first dichroic mirror, a nonlinear large field of view crystal, a second dichroic mirror, a third polarizing beam splitter, a first reflector, a second reflector, a first lens, a second lens, a third lens and a fourth lens; the second polarizing beam splitter, the first dichroic mirror, the nonlinear large field of view crystal, the second dichroic mirror and the third polarizing beam splitter are arranged in sequence along the incident path of the reference pulse light; the first reflector and the second reflector are both arranged at the rear end of the third polarizing beam splitter and on different sides of the third polarizing beam splitter; the third lens and the fourth lens are respectively arranged above the first dichroic mirror and the second dichroic mirror in a direction perpendicular to the incident path of the reference pulse light.

7. The high-precision three-dimensional dynamic contour imaging device according to claim 6, characterized in that: The camera assembly includes a first high-speed camera and a second high-speed camera; the third lens and the first high-speed camera are arranged in sequence above the first dichroic mirror along a direction perpendicular to the incident path of the reference pulse light; the fourth lens and the second high-speed camera are arranged in sequence above the second dichroic mirror along a direction perpendicular to the incident path of the reference pulse light; the first high-speed camera and the second high-speed camera are both connected to a data processing system.

8. A high-precision three-dimensional dynamic contour imaging method, characterized in that: The high-precision three-dimensional dynamic contour imaging device according to any one of claims 1 to 7 comprises the following steps: S1: Adjust the imaging range adjustment device and the first compound lens array so that the measurement pulse light can perform near-field high-resolution microscopic imaging or far-field high-blur and large-depth-of-field imaging after irradiating the sampling target; S2: Start the laser pulse generation system to generate femtosecond pulses of equal duration and continuously emitted. The femtosecond pulses are split by a beam splitter to generate a measurement pulse and a reference pulse. The reference pulse is directly output to the balanced cross-correlation adjustment system, while the measurement pulse is irradiated by the imaging range adjustment device to a sampling target, where it is reflected and carries the sampling target information. The measurement pulse then passes through the first composite lens array and enters the balanced cross-correlation adjustment system. S3: The measurement pulse light and the reference pulse light are processed by the balanced cross-correlation adjustment system to generate a first cross-correlation array signal and a second cross-correlation array signal. Then, image information carrying the first cross-correlation array signal and the second cross-correlation array signal is output to the camera system and stored. S4: Use the data processing system to implement a matching alignment strategy for the image information in the camera component, and then extract and match feature points to finally obtain the three-dimensional information of the sampling target.

9. The high-precision three-dimensional dynamic contour imaging method according to claim 8, characterized in that: In step S4, the matching alignment strategy is a direct matching strategy, an indirect matching strategy or a deep learning strategy.

10. The high-precision three-dimensional dynamic contour imaging method according to claim 8, characterized in that: In step S4, the processing method of the data processing system is specifically as follows: The data processing system first extracts a number of first cross-correlation array signals and a number of second cross-correlation array signals recorded by the image information in the camera component, extracts feature points through an algorithm and performs matching operations to obtain two matched and aligned first cross-correlation array signals and second cross-correlation array signals; then, pixel intensity subtraction is performed on the corresponding first cross-correlation array signals and the second cross-correlation array signals to obtain a first balanced cross-correlation array signal; based on the first balanced cross-correlation array signal, the repetition frequency of the laser pulse generation system is continuously adjusted to generate a plurality of second balanced cross-correlation array signals; the repetition frequency difference between adjacent array signals with an intensity of 0 is extracted from the second balanced cross-correlation array signal; and then, based on the built-in algorithm, the repetition frequency difference is used to solve and obtain the three-dimensional information of the sampling target; wherein the three-dimensional information of the sampling target includes the target distance, velocity and acceleration.

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