A high spatio-temporal resolution imaging system and imaging method based on wavelength multiplexing

Abstract

The present invention provides a high spatio-temporal resolution imaging system and imaging method based on wavelength multiplexing, which are used to solve the technical problems existing in the existing imaging technology based on high-speed framing cameras, such as the decrease in imaging resolution, large electronic noise, or the problems existing in the serial laser shadow active imaging technology, such as the inconsistency of the field of view between multiple frames, the easy mutual interference between imaging frames, and the low anti-interference ability and stability of the system. The high spatio-temporal resolution imaging system based on wavelength multiplexing of the present invention couples the pulsed lasers emitted by multiple high-energy nanosecond pulsed lasers with different wavelengths through multiple dichroic mirrors, enables the multiple pulsed lasers to propagate on the same optical path, forms a composite pulse sequence and then irradiates the target to be measured, ensuring the consistency of the imaging field of view; at the same time, each detector can only receive the imaging light pulse with a corresponding wavelength through the beam splitting module and the corresponding narrowband filter, realizing the wavelength multiplexing of the imaging light pulses.

Description

Technical Field

[0001] The present invention relates to an imaging system and an imaging method, and in particular, to a high spatio-temporal resolution imaging system and an imaging method based on wavelength multiplexing. Background Art

[0002] High-speed imaging technology uses a high-speed camera system to instantaneously record images of an object's high-speed motion and rapid deformation. After processing and analysis, parameters such as the position, morphology, and motion of the object at different times can be obtained. It is an important technical means for studying ultrafast phenomena and has been widely applied in fields such as high-speed collision, flow field diagnosis, and energetic material testing. With the continuous progress of technology, the frame rate of traditional high-speed cameras used in high-speed imaging has been increased to over one million frames per second, which is of great significance for capturing dynamic processes within an extremely short time. However, the frame rate of a high-speed camera is inversely proportional to the number of pixels. The spatial resolution of existing high-speed cameras with a frame rate of one million frames per second can only reach tens of thousands of pixels, posing a severe challenge to application scenarios that require simultaneous acquisition of high spatio-temporal resolution.

[0003] Currently, the most representative high spatio-temporal resolution imaging technologies include imaging technology based on a high-speed framing camera and serial laser shadow active imaging technology. The imaging technology based on a high-speed framing camera separately images the same object onto multiple image intensifier detectors through common aperture framing or wavefront framing. Each image intensifier detector is independently exposed through timing control, thereby achieving high-speed imaging. Although the imaging technology based on a high-speed framing camera improves the time resolution to a certain extent, it relies on an image intensifier detector for low-light amplification and imaging, resulting in a decrease in imaging resolution and introducing a large amount of electronic noise. The serial laser shadow active imaging technology abandons the image intensifier and instead uses multiple high-energy pulsed lasers to actively irradiate the target to be measured. Through timing control, multiple detectors respectively receive their corresponding detection pulses, thereby achieving high spatio-temporal resolution imaging. Although the serial laser shadow active imaging technology avoids problems such as resolution degradation and electronic noise caused by the image intensifier, it brings three problems: First, each high-energy pulsed laser and its corresponding detector are not coaxial and cannot share an optical system, resulting in inconsistent fields of view between multiple frames; Second, in the serial laser shadow active imaging technology, the wavelengths of multiple pulsed lasers are the same, and the detectors at the detection end often simultaneously receive pulsed lasers at different times, resulting in easy interference between imaging frames; Third, the serial laser shadow active imaging system is complex and large in volume, reducing the anti-interference ability and stability of the system. Summary of the Invention

[0004] The object of the present invention is to solve the technical problems existing in the existing imaging technology based on high-speed framing cameras, such as the decrease in imaging resolution, large electronic noise, or the problems existing in the serial laser shadow active imaging technology, such as the inconsistent field of view between multiple frames, the easy mutual interference between imaging frames, and the low anti-interference ability and stability of the system, and to provide a high spatio-temporal resolution imaging system and imaging method based on wavelength multiplexing.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A high spatio-temporal resolution imaging system based on wavelength multiplexing, characterized in that it includes a wavelength multiplexing unit, a laser beam expander, an imaging unit, and a timing control unit;

[0007] The wavelength multiplexing unit includes M high-energy nanosecond pulse lasers with different wavelengths and M - 1 dichroic mirrors, where M ≥ 2; the transmission surface of the first dichroic mirror is located on the pulsed laser output optical path of the first high-energy nanosecond pulse laser, and the reflection surface is located on the pulsed laser output optical path of the second high-energy nanosecond pulse laser, and the light pulses transmitted and reflected by the first dichroic mirror are coaxial; when M ≥ 3, the transmission surface of the i-th dichroic mirror is located on the optical path of the light pulse transmitted through the (i - 1)-th dichroic mirror, and the reflection surface is located on the pulsed laser output optical path of the (i + 1)-th high-energy nanosecond pulse laser, and the light pulses transmitted and reflected by the i-th dichroic mirror are coaxial, i = 2,..., M - 1;

[0008] The pulsed lasers with M different wavelengths generate a composite pulse sequence after passing through M - 1 dichroic mirrors;

[0009] The laser beam expander is located on the optical path of the composite pulse sequence, and the object to be measured is located on the transmission optical path of the composite pulse sequence after passing through the laser beam expander, for forming an object light pulse sequence carrying object information;

[0010] The imaging unit includes an imaging optical system at the detection end, a beam splitting module, and M detectors;

[0011] The imaging optical system at the detection end is located on the transmission optical path of the object light pulse sequence, for forming an imaging light pulse sequence; the beam splitting module is located on the transmission optical path of the imaging light pulse sequence, for splitting the imaging light pulse sequence into M paths; the M detectors are respectively located on the transmission optical paths of the M paths of imaging light pulse sequences;

[0012] A narrowband filter is respectively arranged at the front end of each detector; the light passing ranges of the M narrowband filters are all different, and the wavelengths corresponding to the light passing ranges are respectively in one-to-one correspondence with the pulsed laser wavelengths of the M high-energy nanosecond pulse lasers, for enabling each detector to only receive the imaging light pulses corresponding to the wavelengths;

[0013] The timing control unit is electrically connected to M high-energy nanosecond pulse lasers and M detectors respectively, and is used to synchronously control the laser emission time of each high-energy nanosecond pulse laser and the shutter time of the corresponding detector according to preset timing parameters.

[0014] Furthermore, the beam splitting module includes M - 1 beam splitters;

[0015] The first beam splitter is located on the transmission optical path of the imaging light pulse sequence and is used to divide the imaging light pulse sequence into a first reflected light and a first transmitted light; when M≥3, the j-th beam splitter is located on the optical path of the (j - 1)-th transmitted light and is used to divide the corresponding transmitted light into a j-th reflected light and a j-th transmitted light, where j = 2,..., M - 1; the first M - 1 detectors are respectively located on the transmission optical paths of the first to the (M - 1)-th reflected lights, and the M-th detector is located on the transmission optical path of the (M - 1)-th transmitted light.

[0016] Furthermore, the sum of the angle between the beam splitting surface of the j-th beam splitter and the laser optical axis incident on its beam splitting surface and the angle between the beam splitting surface of the (j - 1)-th beam splitter and the laser optical axis incident on its beam splitting surface is 180°, where j = 2,..., M - 1.

[0017] Furthermore, the beam splitting module is a pyramid;

[0018] M reflectors are arranged on the pyramid, which are located on the transmission optical path of the imaging light pulse sequence and are used to divide the imaging light pulse sequence into M paths through the M reflectors on it.

[0019] Furthermore, the sum of the angle between the transmission surface of the i-th dichroic mirror and the laser optical axis incident on its transmission surface and the angle between the transmission surface of the (i - 1)-th dichroic mirror and the laser optical axis incident on its transmission surface is 180°, where i = 2,..., M - 1. This setting is convenient for integration and thus realizes the miniaturization of the imaging system.

[0020] Furthermore, a knife edge is arranged in the detection end imaging optical system to realize high spatio-temporal resolution laser schlieren imaging.

[0021] Furthermore, the optical depth of the narrowband filter > 5 and the optical bandwidth ≤ 3nm.

[0022] Furthermore, the timing control unit is implemented by a digital pulse signal generator DG645; the detector uses a CCD or a CMOS camera.

[0023] Furthermore, M = 4.

[0024] In addition, the present invention also provides a high spatio-temporal resolution imaging method based on wavelength multiplexing, which is characterized in that it includes the following steps:

[0025] Step 1: Set up a high spatio-temporal resolution imaging system based on wavelength multiplexing as described above;

[0026] Step 2: Turn on M high-energy nanosecond pulse lasers, and adjust the poses and parameters of M - 1 dichroic mirrors, a laser beam expander, an imaging optical system at the detection end, and M - 1 beam splitters, so that the optical pulses transmitted through the M - 1 dichroic mirrors, the laser beam expander, the imaging optical system at the detection end, and the optical pulses transmitted through the M - 1 beam splitters are coaxial;

[0027] Step 3: The timing control unit synchronously controls the laser emission time of each high-energy nanosecond pulse laser and the shutter time of the corresponding detector according to the preset timing parameters, so that pulsed lasers of different wavelengths generate a composite pulse sequence after passing through the M - 1 dichroic mirrors. After the composite pulse sequence irradiates the target to be measured, the target optical pulse sequence carrying the target information passes through the imaging optical system at the detection end and then is incident coaxially to the beam splitting module in sequence. After passing through the beam splitting module, it passes through M narrowband filters respectively, so that the corresponding detectors at the back end receive the imaging optical pulses of the corresponding wavelengths, and the images of the target to be measured at M different moments are obtained.

[0028] The beneficial effects of the present invention compared with the prior art are as follows:

[0029] 1. A high spatio-temporal resolution imaging system based on wavelength multiplexing provided by the present invention couples pulsed lasers emitted by multiple high-energy nanosecond pulse lasers of multiple different wavelengths through multiple dichroic mirrors, enables multiple pulsed lasers to propagate on the same optical path, forms a composite pulse sequence and then irradiates the target to be measured, ensuring the consistency of the imaging field of view; at the same time, multiple detectors are provided at the detection end, and narrowband filters matching each high-energy nanosecond pulse laser are provided in front of each detector. Through the beam splitting module and the corresponding narrowband filters, each detector can only receive an imaging optical pulse of a corresponding wavelength, realizing the wavelength multiplexing of the imaging optical pulses. The present invention abandons image intensifier detectors, and the imaging resolution can reach tens of millions of pixels, and the imaging field of view is consistent. By precisely controlling the emission time of pulsed lasers of different wavelengths and the shutter time of the corresponding detectors, high time resolution and high spatial resolution imaging are ensured.

[0030] 2. A high spatio-temporal resolution imaging system based on wavelength multiplexing provided by the present invention has a simple structure, strong anti-interference ability, and wide applicability.

[0031] 3. In the present invention, the angles between the transmission surfaces of each dichroic mirror and the laser optical axis incident on its transmission surface and the angles between the beam splitting surfaces of the beam splitters and the laser optical axis incident on its beam splitting surface can be set to reasonably arrange multiple high-energy nanosecond pulse lasers and multiple detectors, which is convenient for integration and realizes the miniaturization of the imaging system.

[0032] 3. The high spatio-temporal resolution imaging method based on wavelength multiplexing provided by the present invention is simple to operate and highly practical, and can be widely applied to fields such as high-speed collision, flow field diagnosis, and energetic material testing for high spatio-temporal resolution imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. 1 is a schematic diagram of Embodiment 1 of a high spatio-temporal resolution imaging system based on wavelength multiplexing of the present invention.

[0034] The reference numerals are as follows:

[0035] 1 - High-energy nanosecond pulse laser, 2 - High-energy nanosecond pulse laser, 3 - High-energy nanosecond pulse laser, 4 - High-energy nanosecond pulse laser, 5 - First dichroic mirror, 6 - Second dichroic mirror, 7 - Third dichroic mirror, 8 - Laser beam expander, 9 - Target to be measured, 10 - Imaging optical system at the detection end, 11 - First beam splitter, 12 - Second beam splitter, 13 - Third beam splitter, 14 - Narrowband filter, 15 - Narrowband filter, 16 - Narrowband filter, 17 - Narrowband filter, 18 - First detector, 19 - Second detector, 20 - Third detector, 21 - Fourth detector. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0036] In order to make the advantages and features of the present invention clearer, the following further describes the present invention in detail with reference to the drawings and specific embodiments.

[0037] Embodiment 1

[0038] As shown in Figure 1 FIG. 1, a high spatio-temporal resolution imaging system based on wavelength multiplexing includes a wavelength multiplexing unit, a laser beam expander 8, an imaging unit, and a timing control unit. Among them, the wavelength multiplexing unit includes four high-energy nanosecond pulse lasers with different wavelengths and three dichroic mirrors. The four high-energy nanosecond pulse lasers with different wavelengths serve as illumination light sources and coaxial output to form a composite pulse sequence after passing through the three dichroic mirrors.

[0039] The four high-energy nanosecond pulse lasers are respectively denoted as High-energy nanosecond pulse laser 1, High-energy nanosecond pulse laser 2, High-energy nanosecond pulse laser 3, and The high-energy nanosecond pulse laser 4, and at the same time, the three dichroic mirrors are respectively denoted as the first dichroic mirror 5, the second dichroic mirror 6, and the third dichroic mirror 7. The transmission surface of the first dichroic mirror 5 is located on the outgoing light path of the pulsed laser of the high-energy nanosecond pulse laser 1, and the reflection surface is located on the outgoing light path of the pulsed laser of the high-energy nanosecond pulse laser 2, and the optical pulse after the pulsed laser of the high-energy nanosecond pulse laser 1 is transmitted through the first dichroic mirror 5 is coaxial with the optical pulse after the pulsed laser of the high-energy nanosecond pulse laser 2 is reflected by the first dichroic mirror 5 and exits. The transmission surface of the second dichroic mirror 6 is located on the light path of the optical pulse transmitted or reflected through the first dichroic mirror 5, and the reflection surface is located on the outgoing light path of the pulsed laser of the high-energy nanosecond pulse laser 3, and the optical pulse after being transmitted through the second dichroic mirror 6 is coaxial with the optical pulse after the pulsed laser of the high-energy nanosecond pulse laser 3 is reflected by the second dichroic mirror 6 and exits. The transmission surface of the third dichroic mirror 7 is located on the light path of the optical pulse transmitted or reflected through the second dichroic mirror 6, and the reflection surface is located on the outgoing light path of the pulsed laser of the high-energy nanosecond pulse laser 4, and the optical pulse after being transmitted through the third dichroic mirror 7 is coaxial with the optical pulse after the pulsed laser of the high-energy nanosecond pulse laser 4 is reflected by the third dichroic mirror 7 and exits. The pulsed laser with a wavelength of is sequentially transmitted through the first dichroic mirror 5, the second dichroic mirror 6, and the third dichroic mirror 7 and then irradiates the target to be measured 9. The pulsed laser with a wavelength of is reflected by the first dichroic mirror 5 and then sequentially transmitted through the second dichroic mirror 6 and the third dichroic mirror 7 and then irradiates the target to be measured 9. The pulsed laser with a wavelength of is reflected by the second dichroic mirror 6 and then transmitted through the third dichroic mirror 7 and then irradiates the target to be measured 9. The pulsed laser with a wavelength of is reflected by the third dichroic mirror 7 and then irradiates the target to be measured 9. The pulsed laser with a wavelength of , the pulsed laser with a wavelength of , the pulsed laser with a wavelength of , the pulsed laser with a wavelength of are output coaxially through the three dichroic mirrors after being time-sequentially controlled by the time-sequence control unit to form a composite pulse sequence.

[0040] The laser beam expander 8 is located on the transmission light path of the composite pulse sequence, and the target to be measured 9 is located on the transmission light path of the composite pulse sequence after being transmitted through the laser beam expander 8, and is used to form a target optical pulse sequence carrying target information after passing through the target to be measured 9.

[0041] The imaging unit includes a detection - end imaging optical system 10, a beam - splitting module, and four detectors. Among them, the number of detectors is the same as the number of high - energy nanosecond pulse lasers, and the detectors can be high - performance CCD or CMOS cameras. The detection - end imaging optical system 10 is located on the transmission optical path of the target optical pulse sequence and is used to form an imaging optical pulse sequence. By adding a knife - edge, etc. in the detection - end imaging optical system 10, high - spatiotemporal - resolution laser schlieren imaging can be achieved.

[0042] In this embodiment, the beam - splitting module adopts a wave - front splitting mode, that is, the beam - splitting module is set as three beam splitters. The three beam splitters are sequentially denoted as the first beam splitter 11, the second beam splitter 12, and the third beam splitter 13, and the four detectors are respectively denoted as the first detector 18, the second detector 19, the third detector 20, and the fourth detector 21. The first beam splitter 11 is located on the transmission optical path of the imaging optical pulse sequence and is used to divide the imaging optical pulse sequence into a first transmitted beam and a first reflected beam. The second beam splitter 12 is located on the transmission optical path of the first transmitted beam and is used to divide the corresponding transmitted beam into a second transmitted beam and a second reflected beam. The third beam splitter 13 is located on the transmission optical path of the second transmitted beam and is used to divide the corresponding transmitted beam into a third transmitted beam and a third reflected beam. The first detector 18 is located on the transmission optical path of the first reflected beam, the second detector 19 is located on the transmission optical path of the second reflected beam, the third detector 20 is located on the transmission optical path of the third reflected beam, and the fourth detector 21 is located on the transmission optical path of the third transmitted beam.

[0043] A high - performance narrow - band filter is respectively arranged at the front ends of the first detector 18, the second detector 19, the third detector 20, and the fourth detector 21. It only allows light pulses of one wavelength to pass through, and light pulses of the other three wavelengths are filtered out; the high - performance narrow - band filter refers to a narrow - band filter with an optical depth > 5 and a through - light bandwidth ≤ 3 nm. The through - light ranges of the four narrow - band filters are all different, and the wavelengths corresponding to their through - light ranges are respectively in one - to - one correspondence with the pulse laser wavelengths of the four high - energy nanosecond pulse lasers, and are used to enable each detector to only receive the imaging optical pulses of the corresponding wavelength. In this embodiment, the wavelength corresponding to the through - light range of the narrow - band filter at the front end of the first detector 18 is , denoted as narrow - band filter 14, the wavelength corresponding to the through - light range of the narrow - band filter at the front end of the second detector 19 is , denoted as narrow - band filter 15, the wavelength corresponding to the through - light range of the narrow - band filter at the front end of the third detector 20 is , denoted as narrow - band filter 16, the wavelength corresponding to the through - light range of the narrow - band filter at the front end of the fourth detector 21 is , denoted as Narrowband filter 17. In the present invention, the positions of the narrowband filters do not need to correspond one by one to the positions of the high-energy nanosecond pulse lasers.

[0044] The timing control unit is electrically connected between the four high-energy nanosecond pulse lasers and the four detectors respectively, and is used to synchronously control the laser emission time of each high-energy nanosecond pulse laser and the shutter time of the corresponding detector according to the preset timing parameters. Cooperating with the corresponding narrowband filters can effectively ensure that each detector accurately detects the imaging light pulse of the corresponding wavelength, and realize the target imaging at different times. The timing control unit adopts a precision timing control unit, and its control accuracy can reach the nanosecond or even picosecond level. In this embodiment, a digital pulse signal generator DG645 is preferably used to implement it. The present invention abandons the CCD or CMOS camera based on an image intensifier, can achieve tens of millions of pixels, and realizes high-time-resolution and high-space-resolution imaging.

[0045] Except For the high-energy nanosecond pulse laser 1, the other three high-energy nanosecond pulse lasers can be arranged on the same side or on both sides. At the same time, the three dichroic mirrors are arranged along the same horizontal plane, and the angle between the transmission surface of each dichroic mirror and the laser optical axis incident on the transmission surface can be any angle from 0 to 180°. For the sake of system integration and miniaturization, in this embodiment, it is preferred The high-energy nanosecond pulse laser 1 is arranged horizontally. The high-energy nanosecond pulse laser 2 and The high-energy nanosecond pulse laser 4 are arranged on the same side and perpendicular to The setting direction of the high-energy nanosecond pulse laser 1. The high-energy nanosecond pulse laser 3 is also perpendicular to The setting direction of the high-energy nanosecond pulse laser 1, but it is different from The high-energy nanosecond pulse laser 2 and The high-energy nanosecond pulse laser 4 is on a different side. Correspondingly, the sum of the angles between the transmission surfaces of two adjacent dichroic mirrors and the laser optical axis incident on the corresponding transmission surface is 180°, that is, the sum of the angle between the transmission surface of the second dichroic mirror 6 and the laser optical axis incident on its transmission surface and the angle between the transmission surface of the first dichroic mirror 5 and the laser optical axis incident on its transmission surface is 180°, and the sum of the angle between the transmission surface of the third dichroic mirror 7 and the laser optical axis incident on its transmission surface and the angle between the transmission surface of the second dichroic mirror 6 and the laser optical axis incident on its transmission surface is 180°.

[0046] Correspondingly, the setting principle of the detectors is similar to that of the high-energy nanosecond pulse lasers, and the setting principle of the beam splitters is similar to that of the dichroic mirrors, which will not be elaborated here one by one.

[0047] At the same time, the present invention also provides a high spatio-temporal resolution imaging method based on wavelength multiplexing, which specifically includes the following steps:

[0048] Step 1: Set up the above-mentioned high spatio-temporal resolution imaging system based on wavelength multiplexing.

[0049] Step 2: Turn on four high-energy nanosecond pulsed lasers, and adjust the poses and parameters of three dichroic mirrors, laser beam expander 8, imaging optical system 10 at the detection end, and three beam splitters, so that the optical pulses transmitted through the three dichroic mirrors, laser beam expander 8, imaging optical system 10 at the detection end, and the optical pulses transmitted through the three beam splitters are coaxial, and complete the system debugging. During debugging, the four high-energy nanosecond pulsed lasers can be turned on simultaneously, or two adjacent high-energy nanosecond pulsed lasers can be turned on simultaneously for sequential debugging.

[0050] Step 3: The timing control unit synchronously controls the laser emission time of each high-energy nanosecond pulsed laser and the shutter time of the corresponding detector according to the preset timing parameters, so that pulsed lasers of different wavelengths generate a composite pulse sequence after passing through the three dichroic mirrors. After the composite pulse sequence irradiates the target to be measured 9, the target optical pulse sequence carrying the target information passes through the imaging optical system 10 at the detection end, and is incident on the three beam splitters coaxially in sequence. After being reflected by the first beam splitter 11, the second beam splitter 12, the third beam splitter 13 and transmitted through the third beam splitter 13, the corresponding first detector 18, second detector 19, third detector 20, and fourth detector 21 at the back end receive the imaging optical pulses of the corresponding wavelengths through four narrow-band filters, and obtain the images of the target to be measured at four different times.

[0051] Embodiment 2

[0052] The difference between this embodiment and Embodiment 1 is only that the beam splitting module adopts a common aperture beam splitting mode, that is, the beam splitting module is implemented by a quadrangular pyramid. The specific principle is as follows: Four reflecting mirrors are arranged on the quadrangular pyramid, and the quadrangular pyramid is located on the transmission optical path of the imaging optical pulse sequence, and is used to divide the imaging optical pulse sequence into four paths through the four reflecting mirrors on it. The four imaging optical pulse sequences pass through the corresponding narrow-band filters to enable the first detector 18, second detector 19, third detector 20, and fourth detector 21 to receive the imaging optical pulses of the corresponding wavelengths.

[0053] The present invention relates to a high spatio-temporal resolution imaging system based on wavelength multiplexing, which uses pulsed lasers of multiple different wavelengths and couples them through corresponding dichroic mirrors to ensure that the multiple pulsed lasers propagate on the same optical path and are irradiated onto the target to be measured through the same laser beam expander 8. The pulsed laser carrying the target information after passing through the target to be measured is imaged onto different optical paths by a quadrangular pyramid. At the same time, corresponding narrowband filters are arranged in front of the detectors on each optical path, so as to ensure that each detector can only receive light pulses of one wavelength. The present invention not only realizes high time resolution and high spatial resolution imaging, but also ensures the consistency of the imaging field of view. The overall system structure is simple, the anti-interference ability is improved, the applicability is enhanced, and it has broad application prospects and important practical value in the fields of high-speed collision, flow field diagnosis, energetic material testing, etc. In the present invention, by increasing the number of high-energy nanosecond pulsed lasers and corresponding detectors, eight or even sixteen high spatio-temporal resolution images can be realized.

[0054] As mentioned above, it is only used to illustrate the technical solution of the present invention, rather than to limit it. For those of ordinary professional skills in the art, the specific technical solution recorded in the above embodiments can be modified, or some of the technical features can be equivalently replaced, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. A high spatiotemporal resolution imaging system based on wavelength multiplexing, characterized in that: It comprises a wavelength multiplexing unit, a laser beam expansion device (8), an imaging unit and a timing control unit; The wavelength multiplexing unit comprises M high-energy nanosecond pulse lasers of different wavelengths and M-1 dichroic mirrors, M≥2; the transmission surface of the first dichroic mirror is located on the pulse laser output light path of the first high-energy nanosecond pulse laser, the reflection surface is located on the pulse laser output light path of the second high-energy nanosecond pulse laser, and the light pulses transmitted and reflected by the first dichroic mirror are coaxial; when M≥3, the transmission surface of the i-th dichroic mirror is located on the light path of the light pulse after being transmitted by the i-1-th dichroic mirror, the reflection surface is located on the pulse laser output light path of the i+1-th high-energy nanosecond pulse laser, and the light pulses transmitted and reflected by the i-th dichroic mirror are coaxial, i=2,...,M-1; M pulsed lasers of different wavelengths pass through M-1 dichroic mirrors to generate a composite pulse sequence; The laser beam expansion device (8) is located on the optical path of the composite pulse sequence, and the target to be measured (9) is located on the transmission optical path of the composite pulse sequence after passing through the laser beam expansion device (8), so as to form a target optical pulse sequence carrying target information; The imaging unit comprises a detection end imaging optical system (10), a light splitting module and M detectors; The detection end imaging optical system (10) is located on the transmission optical path of the target optical pulse sequence and is used to form an imaging optical pulse sequence; the light splitting module is located on the transmission optical path of the imaging optical pulse sequence and is used to split the imaging optical pulse sequence into M paths; the M detectors are respectively located on the transmission optical paths of the M paths of the imaging optical pulse sequence; A narrowband filter is disposed at the front end of each detector; the light transmission ranges of the M narrowband filters are different, and the wavelengths corresponding to the light transmission ranges are matched one by one with the pulse laser wavelengths of the M high-energy nanosecond pulse lasers, so that each detector only receives imaging light pulses of the corresponding wavelength; The timing control unit is electrically connected to the M high-energy nanosecond pulse lasers and the M detectors respectively, and is used to synchronously control the laser emission time of each high-energy nanosecond pulse laser and the shutter time of the corresponding detector according to preset timing parameters.

2. The high spatiotemporal resolution imaging system based on wavelength multiplexing according to claim 1, characterized in that: The light splitting module includes M-1 beam splitters; The first beam splitter is located on the transmission optical path of the imaging light pulse sequence, and is used to split the imaging light pulse sequence into the first reflected light and the first transmitted light; when M≥3, the jth beam splitter is located on the optical path of the j-1th transmitted light, and is used to split the corresponding transmitted light into the jth reflected light and the jth transmitted light, j=2,...,M-1; the first M-1 detectors are respectively located on the transmission optical paths of the first to M-1th reflected light, and the Mth detector is located on the transmission optical path of the M-1th transmitted light.

3. The high spatiotemporal resolution imaging system based on wavelength multiplexing according to claim 2, characterized in that: The sum of the angle between the j-th beam splitter surface and the laser optical axis incident thereon and the angle between the j-1-th beam splitter surface and the laser optical axis incident thereon is 180°, j=2,...,M-1.

4. The high spatiotemporal resolution imaging system based on wavelength multiplexing according to claim 1, characterized in that: The light splitting module is a pyramid; The pyramid is provided with M reflectors, which are located on the transmission light path of the imaging light pulse sequence and are used to divide the imaging light pulse sequence into M paths through the M reflectors thereon.

5. A high spatiotemporal resolution imaging system based on wavelength multiplexing according to any one of claims 1 to 4, characterized in that: The sum of the angles between the i-th dichroic mirror transmission surface and the laser optical axis incident thereon and the angles between the i-1-th dichroic mirror transmission surface and the laser optical axis incident thereon is 180°, i=2,...,M-1.

6. The high spatiotemporal resolution imaging system based on wavelength multiplexing according to claim 5, characterized in that: The detection end imaging optical system (10) is provided with a knife edge for realizing high temporal and spatial resolution laser schlieren imaging.

7. The high spatiotemporal resolution imaging system based on wavelength multiplexing according to claim 1, characterized in that: The optical depth of the narrowband filter is greater than 5, and the light transmission bandwidth is less than or equal to 3nm.

8. The high spatiotemporal resolution imaging system based on wavelength multiplexing according to claim 2, characterized in that: The timing control unit is implemented by a digital pulse signal generator DG645; The detector adopts a CCD or CMOS camera.

9. The high spatiotemporal resolution imaging system based on wavelength multiplexing according to claim 1, characterized in that: The M=4.

10. A high spatiotemporal resolution imaging method based on wavelength multiplexing, characterized in that: The following steps are involved: Step 1, constructing a high spatiotemporal resolution imaging system based on wavelength multiplexing as described in any one of claims 1 to 9; Step 2, turning on M high-energy nanosecond pulse lasers, adjusting the positions and parameters of M-1 dichroic mirrors, the laser beam expansion device (8), the detection end imaging optical system (10), and the M-1 beam splitters, so that the light pulses transmitted through the M-1 dichroic mirrors, the laser beam expansion device (8), the detection end imaging optical system (10), and the light pulses transmitted through the M-1 beam splitters are coaxial; Step 3, the timing control unit synchronously controls the laser emission time of each high-energy nanosecond pulse laser and the shutter time of the corresponding detector according to the preset timing parameters, so that the pulse lasers of different wavelengths pass through M-1 dichroic mirrors to generate a composite pulse sequence. After the composite pulse sequence is irradiated onto the target to be measured (9), the target light pulse sequence carrying the target information passes through the imaging optical system (10) at the detection end, and then coaxially incident on the spectroscopic module in sequence. After being split by the spectroscopic module, the corresponding detectors at the back end respectively pass through M narrow-band filters to receive the imaging light pulses of the corresponding wavelengths, thereby obtaining the imaging of the target to be measured at M different times.

Images