A transmission-type three-channel compressed ultrafast imaging device

Abstract

The present invention discloses a transmission-type three-channel compressed ultrafast imaging device to solve the problem that the existing compressed ultrafast imaging system cannot flexibly change the dual-coding sampling rate, resulting in low quality of reconstructed images and failure to meet the needs. Specifically, it includes a 4f system, a first light conversion component, a second light conversion component, a first coding plate, a second coding plate, a streak camera CCD camera and a processing unit; the 4f system is located on the target light; the first light conversion component converts the target light into a first light beam and a second light beam; the second light conversion component is arranged on the optical path of the second light beam; the streak camera is arranged on the optical paths of the first light beam and the third light beam; the first coding plate is arranged between the first light conversion component and the streak camera, and is located on the optical path of the first light beam; the second coding plate is arranged between the second light conversion component and the streak camera, and is located on the optical path of the third light beam; the first coding plate is not related to the second coding plate; the processing unit is connected to the output ends of the streak camera and the CCD camera respectively.

Description

Technical Field

[0001] The invention relates to a compressed ultrafast imaging device, in particular to a transmission type three-channel compressed ultrafast imaging device. Background Art

[0002] Compressed ultrafast imaging (CUP) is a new computational imaging technology that combines compressed sensing with streak cameras. Through data encoding, compression and decoding, two-dimensional imaging of streak cameras can be achieved. The data reconstruction process is a pathological inverse process from low-dimensional to high-dimensional recovery. The image reconstruction accuracy restricts the practical application of this technology. The amount of collected data and the signal-to-noise ratio of the system are important factors affecting the accuracy of data reconstruction.

[0003] Streak cameras are imaging devices with ultra-high temporal resolution (ps-fs) and are important research objects in the field of ultrafast optics, inertial confinement fusion, and major scientific devices such as Z-Pinch. However, traditional streak cameras only have one-dimensional spatial imaging capabilities. CUP is a technology that combines streak cameras with compressed sensing theory. By encoding and decoding dynamic information, streak cameras can achieve two-dimensional imaging. That is, CUP randomly selects signal spatial information through a spatial modulation device with a (0, 1) random coding mode, where '1' represents the received signal and '0' represents the blocked signal. At present, spatial modulation devices based on CUP mainly include two forms: digital mirrors (DMD) and optical encoding plates. Among them, DMD is a reflective encoding device. By adjusting the inclination angle of different micro-element mirrors in the DMD, the selection of spatial information encoding is realized. The optical encoding plate is a transmissive encoding device. By randomly plating a chrome layer on the glass, the gating of spatial information encoding is realized.

[0004] In the process of signal acquisition, CUP loses a lot of information due to coding. Therefore, CUP has developed a collection mode based on dual coding channels, which simultaneously obtains the coding of two inclination angles of DMD through a stereo imaging system. Since the two sets of coding information are complementary, the complete information acquisition of the streak camera is achieved. In addition, since the algorithm's reconstruction process of data is a pathological inverse process from two-dimensional to three-dimensional, CUP often combines an external CCD to obtain non-coded integral information to improve the reconstruction accuracy of the algorithm.

[0005] Although the DMD-based CUP system can realize multi-channel data acquisition, the system is a reflective coded imaging system. There are multiple sets of spatially independent reflectors and stereo imaging lenses in the system. In practical applications, the system construction is cumbersome and not conducive to integration. In addition, the system's signal acquisition efficiency and signal-to-noise ratio are low. In addition, the two sets of codes in the system are in a complementary coding state, and the sampling rate of the code cannot be flexibly changed to achieve the best dual-coding combination state. Therefore, the quality of the reconstructed image cannot meet actual needs. Summary of the invention

[0006] The purpose of the present invention is to provide a transmission-type three-channel compressed ultrafast imaging device to solve the technical problems that the existing compressed ultrafast imaging system has a complex structure and cannot flexibly change the dual-coding sampling rate, resulting in low reconstructed image quality and unable to meet practical application requirements.

[0007] In order to achieve the above object, the present invention provides a transmission type three-channel compressed ultrafast imaging device for imaging a luminous target, wherein the target emits target light, and the device is special in that it comprises a 4f system, a first light conversion element, a second light conversion element, a first coding plate, a second coding plate, a streak camera CCD camera and a processing unit;

[0008] The 4f system is located on the target light, with its incident end corresponding to the target and its exit end opposite to the first light conversion element;

[0009] The first light conversion element is used to convert the target light into a first light beam and a second light beam;

[0010] The second light conversion element is disposed on the light path of the second light beam, and is used to convert the second light beam into a third light beam parallel to the first light beam;

[0011] The streak camera is arranged on the optical path where the first light beam and the third light beam are located, and is used to simultaneously receive the first light beam and the third light beam;

[0012] The first coding plate is arranged between the first light conversion element and the streak camera and is located on the light path where the first light beam is located;

[0013] The second coding plate is arranged between the second light conversion element and the streak camera, and is located on the optical path where the third light beam is located;

[0014] The first coding plate is not related to the second coding plate;

[0015] The optical path of the target light to the first encoding plate is equal to the optical path of the target light to the second encoding plate;

[0016] The processing unit is connected to the output ends of the streak camera and the CCD camera respectively, and is used to acquire data from the streak camera and the CCD camera, realize effective reconstruction of the data by an algorithm, and thus obtain target imaging.

[0017] Furthermore, in order to eliminate the optical path difference between the target light and the first encoding plate and the second encoding plate, the present invention makes the following improvements:

[0018] The first light conversion element includes a first beam splitter and a reflector;

[0019] The first beam splitter is arranged on the optical path where the target light is located, and is used to split the target light into a second light beam and a fourth light beam;

[0020] The reflector is arranged on the optical path of the fourth light beam, and is used for reflecting the fourth light beam to form the first light beam.

[0021] Furthermore, the second light conversion element adopts a second beam splitter;

[0022] The second beam splitter is arranged on the optical path of the second light beam, and is used to split the second light beam into a third light beam and a fifth light beam, so that the third light beam is parallel to the first light beam.

[0023] Furthermore, the streak camera is a narrow cathode streak camera.

[0024] Further, the focal length range of the 4f system is 70-150mm;

[0025] The resolution of the first coding plate and the second coding plate are both 250*250, and the material is chrome-plated quartz glass.

[0026] Furthermore, the second beam splitter is a three-dimensional beam splitter, and its size is 25*25*25mm.

[0027] Furthermore, the first beam splitter is a three-dimensional beam splitter, and its size is 25*25*25mm.

[0028] Beneficial effects of the present invention:

[0029] 1. The compressed ultrafast imaging device provided by the present invention is a transmission-type compressed ultrafast imaging device based on an optical encoding plate, which has a simple and stable structure. The first encoding plate and the second encoding plate can set their own sampling rates independently, thereby achieving the optimal combined encoding state to improve the quality of the reconstructed image and meet practical applications.

[0030] 2. The compressed ultrafast imaging device provided by the present invention uses the first light conversion element and the second light conversion element to divide the dynamic scene acquired by the 4f system into the same three-channel information, wherein two channels of information enter the streak camera after passing through the first encoding plate and the second encoding plate respectively, and the information of the other channel enters the external CCD camera, thereby realizing the simultaneous collection of three-channel information. Compared with the prior art, the data sampling rate is effectively improved, the algorithm is effectively reconstructed for data, and the quality of the reconstructed image is further improved.

[0031] 3. The first light conversion element of the present invention adopts a combination of a first beam splitter and a reflector to eliminate the optical path difference between the target light reaching the first encoding plate and the second encoding plate respectively. The structure is simple and ingenious and easy to implement.

[0032] 4. The transmission coding adopted by the present invention can reduce the system complexity, improve the signal-to-noise ratio of the system, and make the whole device structure simple and stable, which is easy to implement. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of an embodiment of a transmission three-channel compressed ultrafast imaging device of the present invention;

[0034] Figure 2 is an optical path diagram of a transmission three-channel compressed ultrafast imaging device of the present invention;

[0035] Reference Numerals in the Drawings:

[0036] 1 - Target, 2 - 4f system, 3 - First light conversion component, 31 - First beam splitter, 32 - Reflecting mirror, 4 - Second light conversion component, 41 - Second beam splitter, 5 - First coding plate, 6 - Second coding plate, 7 - Streak camera, 8 - CCD camera;

[0037] 01 - Target light, 02 - First light beam, 03 - Second light beam, 04 - Third light beam, 05 - Fourth light beam, 06 - Fifth light beam. Detailed Embodiments

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0039] CUP can be represented by the formula y = Ax mathematically;

[0040] wherein, x is the target signal, y is the signal collected by the camera, and A is the projection matrix.

[0041] The projection matrix A ∈ R(M*N), where M << N. Therefore, the algorithm reconstruction is an ill-posed inverse process. The reconstruction process is unstable, and only by obtaining more acquisition data can the instability of the algorithm reconstruction process be reduced and the reconstruction accuracy be improved.

[0042] Currently, most CUP systems based on transmission coding use single coding for acquisition. Due to the low sampling rate, they cannot meet the requirements of the algorithm for high-quality data reconstruction, and it is necessary to develop a multi-channel transmission CUP imaging system.

[0043] For this reason, as Figure 1As shown, an embodiment of the present invention provides a transmission-type three-channel compressed ultrafast imaging device, which is used for an actively luminous target 1, and the target 1 emits a target light 01. The transmission-type three-channel compressed ultrafast imaging device includes a 4f system 2, a first light conversion element 3, a second light conversion element 4, a first coding plate 5, a second coding plate 6, a streak camera 7, a CCD camera 8 and a processing unit.

[0044] The 4f system 2 is located on the target light 01, with its incident end corresponding to the target 1 and its exit end opposite to the first light conversion element 3. The focal length range of the 4f system 2 is 70-150mm. The first light conversion element 3 includes a first beam splitter 31 and a reflector 32. The first beam splitter 31 is arranged on the optical path of the target light 01, and is used to split the target light 01 into a second light beam 03 and a fourth light beam 05. The first beam splitter 31 is a stereoscopic beam splitter, and its size is 25*25*25mm. The reflector 32 is arranged on the optical path of the fourth light beam 05, and is used to reflect the fourth light beam 05 to form the first light beam 02. The second light conversion element 4 adopts a second beam splitter 41 arranged on the optical path of the second light beam 03. The second beam splitter 41 is a stereoscopic beam splitter, and its size is 25*25*25mm. The second beam splitter 41 splits the second light beam 03 into a third light beam 04 and a fifth light beam 06, and makes the third light beam 04 parallel to the first light beam 02. The streak camera 7 is a narrow cathode streak camera, which is arranged on the optical path of the first light beam 02 and the third light beam 04, and is used to simultaneously receive the first light beam 02 and the third light beam 04; the first coding plate 5 is arranged between the first light conversion element 3 and the streak camera 7, and is located on the optical path of the first light beam 02; the second coding plate 6 is arranged between the second light conversion element 4 and the streak camera 7, and is located on the optical path of the third light beam 04; the resolution of the first coding plate 5 and the second coding plate 6 are both 250*250, and the material is chrome-plated quartz glass. The CCD camera 8 is arranged on the optical path of the fifth light beam 06, and is used to receive the fifth light beam 06. The processing unit is connected to the output ends of the streak camera 7 and the CCD camera 8 respectively, and is used to acquire data from the streak camera 7 and the CCD camera 8, and realize the effective reconstruction of the data by the algorithm to obtain the target imaging.

[0045] The resolution of the first coding plate 5 and the second coding plate 6 are both 250*250, and the material is chrome-plated quartz glass. It should be noted that the first coding plate 5 and the second coding plate 6 are not correlated; specifically, the coding of the first coding plate 5 and the second coding plate 6 adopts a coding mode of pseudo-random distribution of "0" and "1", "0" indicates a chrome-plated layer at the pixel, and "1" indicates no chrome-plated layer at the pixel. The first coding plate 5 and the second coding plate 6 respectively use computers to generate two pseudo-random coding modes, and the two sets of coding modes are unrelated.

[0046] It can be understood that the setting of the reflector 32 is to eliminate the optical path difference, that is, due to the setting of the reflector, the optical path from the target light 01 to the first coding plate 5 is lengthened to achieve the purpose of being equal to the optical path from the target light 01 to the second coding plate 6; moreover, the device can also make the optical path from the target light 01 to the CCD camera 8 equal to the optical path from the target light 01 to the first coding plate 5, so that the optical paths of the three channels are all equal; in addition, the target light 01 reaches the first coding plate 5, the second coding plate 6 and the CCD camera 8 through two components, so the initial light intensity of the three channels is equal.

[0047] The optical path process can be summarized as:

[0048] The target light beam 01 is split into a second light beam 03 and a fourth light beam 05 by the first beam splitter 31; the fourth light beam 05 is reflected by the reflector 32 to form a first light beam 02, and the first light beam 02 is collected by the streak camera 7 after passing through the first coding plate 5; the second light beam 03 is split into a third light beam 04 and a fifth light beam 06 by the second beam splitter 41, and the third light beam 04 is collected by the streak camera 7 after passing through the second coding plate 6, and the fifth light beam 06 is directly collected by the CCD camera 8.

[0049] This compressed ultrafast imaging device can achieve high sampling rate data acquisition, thereby realizing effective reconstruction of data by the algorithm; at the same time, transmission coding can also reduce system complexity, improve the system signal-to-noise ratio, and make the entire device structure simple and stable.

[0050] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A transmission-type three-channel compressed ultrafast imaging device for imaging a luminous target (1), wherein the target (1) emits a target light (01), characterized in that: It comprises a 4f system (2), a first light conversion element (3), a second light conversion element (4), a first coding plate (5), a second coding plate (6), a streak camera (7), a CCD camera (8) and a processing unit; The 4f system (2) is located on the target light (01), with its incident end corresponding to the target (1) and its exit end opposite to the first light conversion element (3); The first light conversion element (3) is used to convert the target light (01) into a first light beam (02) and a second light beam (03); The second light conversion element (4) is arranged on the light path of the second light beam (03) and is used to convert the second light beam (03) into a third light beam (04) parallel to the first light beam (02); The streak camera (7) is arranged on the optical path where the first light beam (02) and the third light beam (04) are located, and is used to simultaneously receive the first light beam (02) and the third light beam (04); The first encoding plate (5) is arranged between the first light conversion element (3) and the streak camera (7), and is located on the optical path of the first light beam (02); The second encoding plate (6) is arranged between the second light conversion element (4) and the streak camera (7), and is located on the light path where the third light beam (04) is located; The first coding plate (5) and the second coding plate (6) are not related; The optical path of the target light (01) reaching the first encoding plate (5) is equal to the optical path of the target light (01) reaching the second encoding plate (6); The processing unit is connected to the output ends of the streak camera (7) and the CCD camera (8) respectively, and is used to acquire data from the streak camera (7) and the CCD camera (8) to realize effective reconstruction of the data by an algorithm, thereby obtaining target imaging.

2. The transmission-type three-channel compressed ultrafast imaging device according to claim 1, characterized in that: The first light conversion element (3) comprises a first beam splitter (31) and a reflector (32); The first beam splitter (31) is arranged on the optical path of the target light (01) and is used to split the target light (01) into a second light beam (03) and a fourth light beam (05); The reflector (32) is arranged on the optical path of the fourth light beam (05) and is used to reflect the fourth light beam (05) to form the first light beam (02).

3. The transmission-type three-channel compressed ultrafast imaging device according to claim 1 or 2, characterized in that: The second light conversion element (4) adopts a second beam splitter (41); The second beam splitter (41) is arranged on the optical path of the second light beam (03) and is used to split the second light beam (03) into a third light beam (04) and a fifth light beam (06), so that the third light beam (04) is parallel to the first light beam (02).

4. The transmission-type three-channel compressed ultrafast imaging device according to claim 3, characterized in that: The streak camera (7) is a narrow cathode streak camera.

5. The transmission-type three-channel compressed ultrafast imaging device according to claim 4, characterized in that: The focal length range of the 4f system (2) is 70-150 mm; The resolution of the first coding plate (5) and the second coding plate (6) are both 250*250, and the material is chrome-plated quartz glass.

6. The transmission-type three-channel compressed ultrafast imaging device according to claim 5, characterized in that: The second beam splitter (41) is a three-dimensional beam splitter, and its size is 25*25*25mm.

7. The transmission-type three-channel compressed ultrafast imaging device according to claim 2, characterized in that: The first beam splitter (31) is a three-dimensional beam splitter, and its size is 25*25*25mm.

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