A two-dimensional ultrafast imaging device based on spatial domain compression

Abstract

The present invention discloses a two-dimensional ultrafast imaging device based on spatial domain compression, which solves the problem that the CUP based on time domain compression cannot be used for a narrow cathode streak camera. 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 first wedge-shaped optical fiber image sensor, a second wedge-shaped optical fiber image sensor and a narrow cathode streak camera; the incident end of the 4f system corresponds to the target, and the output end is opposite to the first light conversion component; the first light conversion component converts the target light into a first light beam and a second light beam; the second light conversion component converts the second light beam into a third light beam; the narrow cathode streak camera receives the first light beam and the third light beam; the first coding plate is arranged between the first light conversion component and the narrow cathode streak camera, and the second coding plate is arranged between the second light conversion component and the narrow cathode streak camera; the first coding plate and the second coding plate are not correlated, and are connected to the narrow cathode streak camera through the first and second wedge-shaped optical fiber image sensors respectively.

Description

Technical Field

[0001] The invention relates to a compressed ultrafast imaging device, in particular to a two-dimensional ultrafast imaging device based on space domain compression. Background Art

[0002] Ultra-high-speed passive two-dimensional imaging technology is an important means to study basic ultrafast physical phenomena and chemical reactions, such as plasma dynamics research and laser-matter interaction. These processes are not only transient but also non-repeatable, so diagnostic equipment is required to have ultra-fast two-dimensional continuous imaging capabilities. Traditional streak cameras have a time resolution of picoseconds to hundreds of femtoseconds, but their imaging range is limited to one line.

[0003] Compressed ultrafast imaging technology (CUP) realizes the two-dimensional imaging capability of streak cameras by combining compressed sensing algorithms. CUP is currently the fastest passive two-dimensional imaging technology, but the implementation of this technology is based on time domain data compression and reconstruction, which requires the help of a large-array cathode streak camera. However, streak cameras with large-array cathodes limit their own temporal resolution.

[0004] At present, the time resolution of circular cathode streak cameras can reach 200 femtoseconds. However, for cameras with a time resolution of 100 femtoseconds or even faster, the time resolution needs to be sacrificed by sacrificing the spatial resolution outside the axis. The effective imaging area of ​​the current fastest streak camera cathode (C11853-01) is limited to 0.01mm*3mm. Therefore, the CUP based on time domain compression cannot be applied to the fastest narrow cathode streak camera, which limits the development of the time resolution level of ultrafast passive two-dimensional imaging technology. However, some existing ultrafast phenomena such as free electron acceleration and the study of biological photosynthesis mechanisms require imaging equipment to have the diagnostic capability of passive two-dimensional imaging below 100 femtoseconds. Summary of the invention

[0005] The purpose of the present invention is to provide a two-dimensional ultrafast imaging device based on spatial domain compression to solve the technical problem in the prior art that the CUP based on time domain compression cannot be applied to the fastest narrow cathode streak camera, thereby limiting the development of the time resolution level of ultrafast passive two-dimensional imaging technology and resulting in the imaging device not having the passive two-dimensional imaging diagnostic capability below 100 femtoseconds.

[0006] In order to achieve the above-mentioned object, the present invention provides a two-dimensional ultrafast imaging device based on spatial domain compression, which is used for a luminous target, and the target emits target light. The device is special in that it includes a 4f system, a first light conversion element, a second light conversion element, a first coding plate, a second coding plate, a first wedge-shaped optical fiber image sensor, a second wedge-shaped optical fiber image sensor, and a narrow cathode streak camera;

[0007] 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;

[0008] The first light conversion element is used to convert the target light into a first light beam and a second light beam;

[0009] 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;

[0010] The narrow cathode 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;

[0011] The first coding plate is arranged between the first light conversion element and the narrow cathode streak camera, and is located on the optical path of the first light beam, and is connected to the narrow cathode streak camera through a first wedge-shaped optical fiber image sensor;

[0012] The second coding plate is arranged between the second light conversion element and the narrow cathode streak camera, and is located on the optical path of the third light beam, and is connected to the narrow cathode streak camera via a second wedge-shaped optical fiber image sensor;

[0013] The first coding plate is not related to the second coding plate;

[0014] 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.

[0015] Further, the first light conversion component includes a first beam splitter and a reflector;

[0016] 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;

[0017] 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.

[0018] Further, the second light conversion component is a second beam splitter;

[0019] 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.

[0020] Further, it also includes a CCD camera;

[0021] The CCD camera is arranged on the optical path where the fifth light beam is located, and is used for receiving the fifth light beam.

[0022] Furthermore, the narrow cathode streak camera (9) is a narrow cathode streak camera with a time resolution of 100 fs.

[0023] Further, the focal length range of the 4f system is 70-150mm;

[0024] The resolutions of the first wedge-shaped optical fiber image sensor and the second wedge-shaped optical fiber image sensor are both greater than 2048*2048;

[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 size of the second beam splitter is 25*25*25 mm.

[0027] Furthermore, the size of the first beam splitter is 25*25*25 mm.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention first obtains the ultrafast dynamic information of the target through the 4f system, and then divides the target light into the same first light beam and the third light beam through the first light conversion element and the second light conversion element. The first light beam and the third light beam pass through different first coding plates and second coding plates respectively, and realize spatial compression through the first wedge-shaped optical fiber image sensor and the second wedge-shaped optical fiber image sensor, and convert it into a line signal. Finally, the line signal is collected by a narrow cathode streak camera, thereby breaking through the problem of time domain compression ultrafast imaging. The device does not need to expand the cathode imaging area of ​​the narrow cathode streak camera, and can realize the two-dimensional imaging of the narrow cathode streak camera through the compression and reconstruction of the two-dimensional image space dimension.

[0030] 2. The first light conversion element of the present invention adopts a combination of a first beam splitter and a reflector to ensure that the optical path of the target light reaching the first encoding plate is equal to the optical path of the target light reaching the second encoding plate. The structure is simple and easy to implement.

[0031] 3. The present invention also arranges a CCD camera on the optical path where the fifth light beam is located to realize three-channel data acquisition, namely two spatial compression channels and one external CCD channel, thereby ensuring the image reconstruction quality through more data volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of an embodiment of a two-dimensional ultrafast imaging device based on spatial domain compression of the present invention;

[0033] Figure 2 It is a light path diagram of a two-dimensional ultrafast imaging device based on spatial domain compression of the present invention;

[0034] Figure 31 and 1 are schematic diagrams of the ultrafast imaging principle in an embodiment of the present invention, wherein (a) is a schematic diagram of the time domain compression (CUP) principle, and (b) is a schematic diagram of the space domain compression (SCUP) principle.

[0035] Figure Number:

[0036] 1-target, 2-4f system, 3-first light conversion element, 31-first beam splitter, 32-reflector, 4-second light conversion element, 41-second beam splitter, 5-first encoding plate, 6-second encoding plate, 7-first wedge-shaped optical fiber image sensor, 8-second wedge-shaped optical fiber image sensor, 9-narrow cathode streak camera, 10-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 DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, in order to overcome the problem of ultrafast imaging with time domain compression, an embodiment of the present invention provides a two-dimensional ultrafast imaging device based on space domain compression, which is used for an actively luminous target 1. The ultrafast imaging device includes a 4f system 2, a first light conversion component 3, a second light conversion component 4, a first coding plate 5, a second coding plate 6, a first wedge-shaped optical fiber image sensor 7, a second wedge-shaped optical fiber image sensor 8, a narrow cathode streak camera 9 and a CCD camera 10.

[0040] Combination Figure 1 and Figure 2 As shown, the target 1 emits a target light 01, and 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, and the target light 01 can obtain ultrafast dynamic information after passing through the 4f system 2;

[0041] The first light conversion component 3 is used to convert the target light 01 into a first light beam 02 and a second light beam 03; specifically, the first light conversion component 3 includes a first beam splitter 31 and a reflector 32; the first beam splitter 31 is arranged on the light path where the target light 01 is located, 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 light path where the fourth light beam 05 is located, and is used to reflect the fourth light beam 05 to form the first light beam 02. The second light conversion component 4 is a second beam splitter 41, which is arranged on the light path where the second light beam 03 is located, and is used to split 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 size of the first beam splitter 31 and the second beam splitter 41 can be 25*25*25mm.

[0042] The narrow cathode streak camera 9 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 coding plate 5 is arranged between the first beam splitter 31 and the narrow cathode streak camera 9, and is located on the optical path where the first light beam 02 is located, and is connected to the narrow cathode streak camera 9 through the first wedge-shaped optical fiber image sensor 7; the second coding plate 6 is arranged between the second beam splitter 41 and the narrow cathode streak camera 9, and is located on the optical path where the third light beam 04 is located, and is connected to the narrow cathode streak camera 9 through the second wedge-shaped optical fiber image sensor 8; the resolutions of the first wedge-shaped optical fiber image sensor 7 and the second wedge-shaped optical fiber image sensor 8 are both greater than 2048*2048; the CCD camera 10 is arranged on the optical path where the fifth light beam 06 is located, and is used to receive the fifth light beam 06, that is, directly collect the fifth light beam 06, and the narrow cathode streak camera 9 is a narrow cathode streak camera with a time resolution of 100fs.

[0043] It can be understood that the setting of the reflector 32 can make the optical path of the target light 01 reaching the first code plate 5 equal to the optical path of the target light 01 reaching the second code plate 6, and the first light beam 02 and the third light beam 04 simultaneously received by the narrow cathode streak camera 9 have the same initial intensity. In addition, the optical path of the target light 01 reaching the CCD camera 10 is also equal to the optical path of the target light 01 reaching the first code plate 5, so as to ensure that the optical path and initial intensity of the three channels are the same.

[0044] 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, and the first coding plate 5 and the second coding plate 6 respectively adopt two pseudo-random coding modes.

[0045] The principles of the above embodiment are as follows:

[0046] like Figure 3 As shown in (a), the forward model includes three steps: encoding operation C, deflection operation S and superposition operation T. Specifically, first, the three-dimensional dynamic cube I1 (x, y, t) is spatially encoded through a digital mirror device (DMD) or an optical mask, and the encoded information TI1 is then converted into an electronic signal (TSI1) through a circular cathode (Photocathode1). Operator S then performs signal shearing from the encoding cube TI1 to the tilted encoding TSI1 cube through the scanning voltage of a narrow cathode stripe camera. Finally, the tilted encoding TSI1 is overlapped on the CCD along the time direction to become a 2D signal TSCI1. As shown Figure 3 As shown in (b), the main difference between SCUP and CUP is that SCUP adds a spatial superposition operation F before the coding cube enters the narrow cathode streak camera, and the coded signal TI2 is superimposed along the y-axis through the wedge-shaped fiber image sensor (WOFID), which allows the signal to be fully acquired through the narrow cathode. Finally, the measurement data collected by the narrow cathode streak camera is represented as TFSCI2.

[0047] Based on the above principles, the present invention proposes a three-channel data acquisition scheme to ensure the quality of data reconstruction through more auxiliary measurement data. First, ultrafast dynamic information is obtained through a group of lenses (4f system), and then the signal is divided into three identical groups through a combined light conversion component, one of which is directly collected by a CCD camera, and the other two groups of signals pass through different encoding plates and are converted into line signals through a wedge-shaped fiber image sensor (WOFID). The line signal is finally collected by a narrow cathode narrow cathode streak camera. In the combined light conversion component, a square reflector is attached to the back of the first beam splitter to ensure that the three groups of signals have the same optical path. Since each beam signal is obtained by two signal splittings, they have the same initial intensity. Finally, three groups of measurement data can be obtained:

[0048] M1=T1FSCI(x,y,t)

[0049] M2=T2FSCI(x,y,t)

[0050] M3=∫I(x,y,t)dt

[0051] The original three-dimensional dynamic information can be obtained by solving the following optimization problem through the compressed sensing algorithm:

[0052]

[0053] Compared with the traditional CUP technology, the proposed SCUP technology aims to break through the bottleneck of the existing CUP time resolution by combining a faster narrow cathode streak camera. In the future, SCUP can meet the needs of faster imaging diagnosis, such as free electron laser measurement, lattice vibration measurement, etc.

[0054] 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 two-dimensional ultrafast imaging device based on spatial domain compression, for 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 first wedge-shaped optical fiber image sensor (7), a second wedge-shaped optical fiber image sensor (8) and a narrow cathode streak camera (9); 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 narrow cathode streak camera (9) 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 coding plate (5) is arranged between the first light conversion element (3) and the narrow cathode streak camera (9), is located on the optical path of the first light beam (02), and is connected to the narrow cathode streak camera (9) via a first wedge-shaped optical fiber image sensor (7); The second coding plate (6) is arranged between the second light conversion element (4) and the narrow cathode streak camera (9), is located on the optical path of the third light beam (04), and is connected to the narrow cathode streak camera (9) via a second wedge-shaped optical fiber image sensor (8); 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).

2. The two-dimensional ultrafast imaging device based on spatial domain compression 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 two-dimensional ultrafast imaging device based on spatial domain compression according to claim 1 or 2, characterized in that: The second light conversion component (4) is 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 two-dimensional ultrafast imaging device based on spatial domain compression according to claim 3, characterized in that: Also includes a CCD camera (10); The CCD camera (10) is arranged on the optical path where the fifth light beam (06) is located, and is used to receive the fifth light beam (06).

5. The two-dimensional ultrafast imaging device based on spatial domain compression according to claim 4, characterized in that: The narrow cathode streak camera (9) is a narrow cathode streak camera with a time resolution of 100 fs.

6. The two-dimensional ultrafast imaging device based on spatial domain compression according to claim 5, characterized in that: The focal length range of the 4f system (2) is 70-150 mm; The resolutions of the first wedge-shaped optical fiber image sensor (7) and the second wedge-shaped optical fiber image sensor (8) are both greater than 2048*2048; 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.

7. The two-dimensional ultrafast imaging device based on spatial domain compression according to claim 6, characterized in that: The size of the second beam splitter (41) is 25*25*25 mm.

8. The two-dimensional ultrafast imaging device based on spatial domain compression according to claim 2, characterized in that: The size of the first beam splitter (31) is 25*25*25 mm.

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