An ultrafast time-compressed image acquisition method based on on-chip storage

Abstract

The present invention provides an ultrafast time-compressed image acquisition method based on on-chip storage, which is used to address the technical problem that the ultrafast compression imaging technology of a streak camera for a target scene is limited by the working principle of the streak tube, resulting in a time resolution of the order of picoseconds to sub-nanoseconds and a low spatial resolution. The method of the present invention comprises: selecting pixel areas with pixel resolutions of M×N and M×L as imaging photosensitive areas and imaging storage areas, respectively; making a pseudo-random mask plate to cover the imaging photosensitive area, and covering the imaging storage area with an opaque mask plate; imaging the target scene on the imaging surface of the imaging photosensitive area; exposing the target scene and performing an initial image, and transferring the image of the imaging photosensitive area as a whole by one row along the charge storage transfer direction; after the transfer is completed, exposing the imaging photosensitive area and continuing to acquire the image, and executing i=i+1 after the exposure is completed; if i≤L, outputting the next row of images, and so on until i>L, thereby obtaining a time-compressed image of the target scene.

Description

Technical Field

[0001] The present invention relates to imaging technology, and in particular to an ultrafast time-compressed image acquisition method based on on-chip storage. Background Art

[0002] High-speed imaging technology is an important method for acquiring image test data in modern applied physics research. Especially in the experimental research of high-speed transient physical processes, continuous multiple high-time-resolution images have extremely important application value in explaining physical mechanisms, discovering physical phenomena, and verifying physical laws.

[0003] Traditional computational imaging techniques, based on conventional image sensors, improve the overall performance of imaging systems by introducing coded information into the optical pathways or light sources of the imaging system. In the field of ultrafast imaging, methods such as spectral modulation of the light source through optical refractive index, light sheet segmentation, and optical path control can achieve femtosecond temporal resolution, but such techniques can only be applied to active imaging systems with illumination. Currently, due to limitations in the operating principle of streak tubes, ultrafast compressed imaging techniques that use streak cameras to time-shift the target scene have temporal resolutions in the picosecond to sub-nanosecond range and suffer from low spatial resolution. Summary of the Invention

[0004] The purpose of the present invention is to solve the technical problems that the current ultrafast compressed imaging technology using a streak camera to time-shift the target scene is limited by the working principle of the streak tube, resulting in its time resolution being in the picosecond to sub-nanosecond range and having low spatial resolution, and to provide an ultrafast time compression image acquisition method based on on-chip storage.

[0005] In order to achieve the above objectives, the technical solutions of the present invention are as follows:

[0006] A method for acquiring ultrafast time-compressed images based on on-chip storage is characterized in that it includes the following steps:

[0007] 1] Select a pixel area with a pixel resolution of M×N as the imaging photosensitive area; according to the binary pseudo-random matrix of size M×N, make a pseudo-random mask and cover it on the photosensitive area. The area where the matrix element is 1 is transparent, and the area where the matrix element is 0 is opaque;

[0008] 2] Select a pixel area with a pixel resolution of M×L as the imaging storage area; cover the storage area with an opaque mask;

[0009] 3] Construct an imaging system to image the target scene on the imaging photosensitive area image plane; according to the image charge transfer time Δt, set the exposure time slice ΔT so that ΔT ≥ Δt;

[0010] 4] Let the starting time be T0, and the target scene be exposed and the initial image acquired at T0, with the exposure time being ΔT0; the end time of this exposure is T1, then T1=T0+ΔT0, and starting from T1, the count i=0;

[0011] 5] The image of the imaging photosensitive area is transferred as a whole to the imaging storage area along the charge storage transfer direction. The charge transfer time is Δt.

[0012] 6] After the image charge transfer is completed, the imaging photosensitive area is exposed to continue image acquisition. The exposure time is (ΔT-Δt). When the exposure is completed, execute i=i+1; if i≤L, return to step 5 to output the next line of image; if i>L, execute step 7;

[0013] 7] Output the image information of all pixels in the imaging storage area and the imaging photosensitive area to obtain a time-compressed image of the target scene.

[0014] Furthermore, in step 2], the selected imaging storage area is adjacent to the imaging photosensitive area, so that image data can be transferred from the photosensitive area to the storage area line by line.

[0015] The beneficial effects of the present invention compared to the prior art are:

[0016] 1. The present invention provides an ultrafast time-compressed image acquisition method based on on-chip storage, which achieves high time resolution by combining on-chip charge transfer and exposure control. The minimum time resolution is the on-chip transfer time of the pixel photogenerated charge, which can reach the nanosecond level.

[0017] 2. The present invention provides an ultrafast time-compressed image acquisition method based on on-chip storage, which adopts a method of transferring and exposing the pixel array. The implementation principle is simple, the pixel array has strong scalability, and can achieve high spatial resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of an ultrafast time-compressed image acquisition method based on on-chip storage according to the present invention;

[0019] Figure 2 Schematic diagram of the working principle of the imaging system in step 3 of this method.

[0020] Figure 3 Schematic diagram of the time-compressed image acquisition process in steps 4 to 6 of the present method, wherein (a) indicates exposure and initial image acquisition of the target scene at the starting time T0, (b) indicates that the image of the imaging photosensitive area is transferred as a whole to the imaging storage area along the charge storage transfer direction at time T1, (c) indicates that the image of the imaging photosensitive area is transferred as a whole to the imaging storage area along the charge storage transfer direction at time T2, and (d) indicates that the image of the imaging photosensitive area is transferred as a whole to the imaging storage area along the charge storage transfer direction at time T1. LThe image of the imaging photosensitive area at a moment is transferred as a whole to the imaging storage area along the charge storage transfer direction for one row. DETAILED DESCRIPTION

[0021] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] The present invention is based on an on-chip stored pixel array structure, adopts a method of transferring and exposing the entire pixel array, and utilizes the high-speed transfer characteristics of pixel induced charges within the sensor chip and the adjustable exposure time characteristics of the photosensitive area to achieve the acquisition of ultra-fast time-compressed images.

[0023] An ultrafast time-compressed image acquisition method based on on-chip storage, such as Figure 1 As shown, the specific steps include:

[0024] 1] Select an image sensor with image data transfer and storage characteristics, and select a pixel area with a pixel resolution of M×N as the imaging photosensitive area; create a pseudo-random mask based on an M×N binary pseudo-random matrix and cover it on the imaging photosensitive area. The mask is transparent in areas where the matrix element is 1, and opaque in areas where the matrix element is 0;

[0025] 2] Selecting a pixel area with a pixel resolution of M×L as an imaging storage area; covering the storage area with an opaque mask; in the present invention, the imaging photosensitive area and the imaging storage area are adjacent, so that image data can be transferred from the photosensitive area to the storage area line by line;

[0026] 3] If Figure 2 As shown, an imaging system is constructed to image the target scene (dynamic scene to be measured) on the image plane of the imaging photosensitive area; according to the image charge transfer time Δt, the exposure time ΔT is set so that ΔT ≥ Δt;

[0027] 4] If Figure 3 As shown, the starting time is recorded as T0, Figure 3 (a) in the figure indicates that the target scene is exposed and the initial image is acquired at time T0, and the exposure time corresponding to the starting time is ΔT0;

[0028] 5] The end time of the i-th exposure is recorded as T i ,i=1,2...L,then T i =T i-1 +ΔT i-1 , ΔT i-1 is the exposure time of the i-1th time, each T i The image of the imaging photosensitive area is transferred as a whole to the imaging storage area along the charge storage transfer direction. The charge transfer time is Δt. During the image transfer process, the pixels of the imaging photosensitive area are still in the exposure state.

[0029] Specifically, the first exposure end time is recorded as T1, T1 = T0 + ΔT0, Figure 3 (b) in the figure indicates that the image of the imaging photosensitive area at time T1 is transferred as a whole to the imaging storage area along the charge storage transfer direction; the end time of the second exposure is recorded as T2, T2 = T1 + ΔT1, Figure 3 (c) in the figure indicates that the image of the imaging photosensitive area at time T2 is transferred to the imaging storage area along the charge storage transfer direction. Similarly, the end time of the Lth exposure is recorded as T L , T L =T L-1 +ΔT L-1 , Figure 3 (d) in the equation represents T L The image of the moment imaging photosensitive area is transferred as a whole to the imaging storage area along the charge storage transfer direction for one row;

[0030] 6] After the image charge transfer is completed, the imaging photosensitive area is exposed to continue image acquisition. Since the effective exposure time includes the image charge transfer output time, the exposure time of the image sensor is (ΔT-Δt); when the exposure is completed, execute i=i+1; if i≤L, return to step 5 to output the next line of image; if i>L, execute step 7;

[0031] 7] Output the image information of all pixels in the imaging storage area and the imaging photosensitive area to obtain a time-compressed image of the target scene.

[0032] The present invention provides an ultrafast time-compressed image acquisition method based on on-chip storage. The method of transferring and exposing the pixel array while performing ultrafast time-compressed image acquisition can achieve time resolution from nanoseconds to milliseconds. The spatial resolution can be selected according to the sensor pixel array scale as needed, and the system's temporal and spatial resolution parameters are highly selective.

[0033] The above description is only used to illustrate the technical solution of the present invention, rather than to limit it. For ordinary professional and technical personnel in this field, the specific technical solutions recorded in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents. These modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solution protected by the present invention.

Claims

1. A method for acquiring ultrafast time-compressed images based on on-chip storage, characterized in that: The following steps are involved: 1] Select a pixel area with a pixel resolution of M×N as the imaging photosensitive area; according to the binary pseudo-random matrix of size M×N, make a pseudo-random mask and cover it on the imaging photosensitive area. The area where the matrix element is 1 is transparent, and the area where the matrix element is 0 is opaque; 2] Select a pixel area with a pixel resolution of M×L as an imaging storage area; cover the imaging storage area with an opaque mask; 3] Construct an imaging system to image the target scene on the imaging photosensitive area image plane; According to the image charge transfer time Δt, the exposure time slice ΔT is set so that ΔT ≥ Δt; 4] Let the starting time be T0, and the target scene be exposed and the initial image acquired at T0, with the exposure time being ΔT0; the end time of this exposure is T1, then T1=T0+ΔT0, and starting from T1, the count i=0; 5] The end time of the i-th exposure is recorded as T i ,i=1,2...L,then T i =T i-1 +ΔT i-1 , ΔT i-1 is the exposure time of the i-1th time, each T i The image of the imaging photosensitive area is transferred as a whole to the imaging storage area along the charge storage transfer direction. The charge transfer time is Δt. During the image transfer process, the pixels of the imaging photosensitive area are still in the exposure state. 6] After the image charge transfer is completed, the imaging photosensitive area is exposed to continue image acquisition. The exposure time is (ΔT-Δt). When the exposure is completed, execute i=i+1; if i≤L, return to step 5 to output the next line of image; if i>L, execute step 7; 7] Output the image information of all pixels in the imaging storage area and the imaging photosensitive area to obtain a time-compressed image of the target scene.

2. The method for acquiring ultrafast time-compressed images based on on-chip storage according to claim 1, characterized in that: In step 2], the selected imaging storage area is adjacent to the imaging photosensitive area.

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