A method for continuous acquisition of time-compressed images based on line scan image sensors

Abstract

The present invention provides a method for continuously acquiring time-compressed images based on a line-scan image sensor, which is used to address the technical problem that ultrafast compressed imaging technology for a streak camera of a target scene is limited by the working principle of a streak tube, resulting in a time resolution of picoseconds to sub-nanoseconds and low spatial resolution. The method comprises: selecting a line-scan image sensor with a pixel resolution of M×N; fabricating a pseudo-random mask and covering it on the sensor's photosensitive area; selecting a time-compressed image resolution of M×L to be acquired; imaging the target scene on the sensor's photosensitive area; exposing the target scene and acquiring an image at the start time, with exposure ending at i=0; performing scan output, receiving and recording image data, and completing a line of image output; continuing to acquire an image after the photosensitive area is exposed, with exposure ending at i=i+1; if i≤L, outputting the next line of image 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 a method for continuously acquiring time-compressed images based on a line scanning image sensor. 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 division, and optical path control can achieve femtosecond temporal resolution, but such techniques can only be applied to active imaging systems with illumination. Ultrafast compressed imaging techniques, which use streak cameras to time-shift the target scene, are limited by the operating principle of streak tubes, resulting in temporal resolution in the picosecond to sub-nanosecond range and 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 that uses 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. Instead, a method for continuously acquiring time-compressed images based on a line scan image sensor is provided.

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

[0006] A method for continuously acquiring time-compressed images based on a line scan image sensor is characterized in that it includes the following steps:

[0007] 1] Select a line scan image sensor with a pixel resolution of M×N and set the scanning output period of each line image to T S According to the binary pseudo-random matrix of size M×N, a pseudo-random mask is made and covered on the photosensitive area of the line scan image sensor. The mask is transparent in the area where the matrix element is 1, and is opaque in the area where the matrix element is 0;

[0008] 2] Select the time-compressed image resolution to be acquired: M×L;

[0009] 3] Build an imaging system to image the target scene on the photosensitive area of the line scan image sensor; set the exposure time ΔT E , so that ΔT E ≥TS ;

[0010] 4] Let the starting time be T0. The line scan image sensor exposes the target scene and acquires the initial image at the starting time T0. The exposure time is ΔT0. The end time of this exposure is T1. Then T1 = T0 + ΔT0. Starting from T1, the count i = 0.

[0011] 5] The line scan image sensor performs scanning output, receives and records image data, and completes a line of image output; wherein, during the process of the line scan image sensor scanning and outputting the image data line, the sensor's photosensitive area is still in an exposed state.

[0012] 6] Since the line scan image sensor can continuously perform scanning output and image exposure, after a line of scanning output is completed, the sensor's photosensitive area is exposed to continue image acquisition. The exposure time is (ΔT E -T S ), when the exposure ends, record 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] Complete the image data recording with a resolution of M×L and obtain a time-compressed image of the target scene.

[0014] Furthermore, in step 1], the scanning output period T of the line scanning image sensor is S It is a fixed cycle to facilitate the subsequent decoding work;

[0015] Furthermore, in step 2], when the time-compressed image resolution M×L is selected, L is greater than or equal to 2N, so as to facilitate observation of a larger target scene.

[0016] The beneficial effects of the present invention compared to the prior art are:

[0017] 1. The present invention provides a method for continuously acquiring time-compressed images based on a line scan image sensor. This method achieves high temporal resolution by combining the high-speed output of the line scan image sensor with exposure control. The minimum temporal resolution is the scan output time of the image data row of the line scan image sensor. The system's temporal and spatial resolution parameters are highly selective, and temporal resolution from microseconds to seconds can be achieved.

[0018] 2. The present invention provides a method for continuously acquiring time-compressed images based on a line-scan image sensor. The line-scan image sensor used is combined with spatial coding to acquire time-compressed images. The high-speed continuous scanning output characteristics of the line-scan image sensor are utilized to achieve continuous acquisition of time-compressed images. The resolution of the acquired time-compressed images is highly scalable, and extremely high spatial resolution can be achieved as needed. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a method for continuously acquiring time-compressed images based on a line scan image sensor according to the present invention;

[0020] Figure 2 Schematic diagram of the working principle of the imaging system in step 3 of this method;

[0021] Figure 3 Schematic diagram of the time-compressed image acquisition process in steps 4 to 6 of the present method, wherein (a) indicates exposure of the target scene and initial image acquisition at the starting time T0, (b) indicates the line scan image sensor performs scanning output at time T1, externally receives and records image data, and completes one line of image output, (c) indicates the line scan image sensor performs scanning output at time T2, externally receives and records image data, and completes the second line of image output, and (d) indicates T L At this moment, the line scan image sensor performs scanning output, receives and records image data from the outside, and completes the Lth line image output. DETAILED DESCRIPTION

[0022] 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.

[0023] The present invention is based on a line scan image sensor combined with spatial coding, adopts a method of sensor scanning output and simultaneous exposure accumulation, and utilizes the high-speed continuous image output characteristics and pixel area exposure time adjustable characteristics of the line scan image sensor to achieve continuous acquisition of time-compressed images.

[0024] A time-compressed image continuous acquisition method based on a line scan image sensor, such as Figure 1 As shown, the specific steps include:

[0025] 1] Select a line scan image sensor with a pixel resolution of M×N and set the scanning output period of each line image to T S According to the binary pseudo-random matrix of size M×N, a pseudo-random mask is made and covered on the photosensitive area of the line scan image sensor. The mask is transparent in the area where the matrix element is 1, and is opaque in the area where the matrix element is 0;

[0026] 2] Select the time-compressed image resolution to be acquired: M×L. In order to observe a larger target scene, the value of L can be much larger than the value of N. Preferably, L is greater than or equal to 2N.

[0027] 3] If Figure 2 As shown, an imaging system is constructed to image the target scene (dynamic scene to be measured) on the photosensitive area of the line scan image sensor; the exposure time ΔT is set E , so that ΔT E ≥TS ;

[0028] 4] If Figure 3 As shown, Figure 3 In (a), the starting time is recorded as T0. The line scan image sensor exposes the target scene and acquires the initial image at the starting time T0, and the exposure time is ΔT0.

[0029] 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 line scan image sensor performs scanning output, receives and records image data, and completes a line of image output; the scanning output cycle of each line of image is T S It is a fixed value to facilitate the subsequent decoding work; wherein, during the process of the line scan image sensor scanning and outputting image data rows, the photosensitive area of the sensor is still in an exposure state.

[0030] Specifically, the first exposure end time is recorded as T1, T1 = T0 + ΔT0, Figure 3 (b) in the figure indicates that the line scan image sensor performs scanning output at time T1, receives and records image data from the outside, and completes the output of one line of image; the end time of the second exposure is recorded as T2, T2 = T1 + ΔT1, Figure 3 (c) in the figure indicates that the line scan image sensor performs scanning output at time T2, receives and records image data from the outside, and completes the second line image output; and so on, 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 line scan image sensor performs scanning output, receives and records image data from the outside, and completes the Lth line image output;

[0031] 6] Since the line scan image sensor can continuously perform scanning output and image exposure, after a line of scanning output is completed, the sensor's photosensitive area is exposed to continue image acquisition. Since the line scan image sensor is still in the exposure state during charge transfer output, the exposure time is (ΔT E -T S ); When the exposure ends, execute i=i+1; if i≤L, return to step 5 to output the next line of image; if i>L, execute step 7;

[0032] 7] Complete the image data recording with a resolution of M×L and obtain a time-compressed image of the target scene.

[0033] The present invention provides a method for continuously acquiring time-compressed images based on a line-scan image sensor. The line-scan image sensor used in the method is combined with spatial coding to acquire time-compressed images, which can achieve time resolution from microseconds to seconds. The spatial resolution can be selected according to the size of the line-scan image sensor pixel array as needed, and the system's temporal and spatial resolution parameters are highly selective.

[0034] 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 continuously acquiring time-compressed images based on a line scan image sensor, characterized in that: The following steps are involved: 1] Select a line scan image sensor with a pixel resolution of M×N and set the scanning output period of each line image to T S According to the binary pseudo-random matrix of size M×N, a pseudo-random mask is made and covered on the photosensitive area of the line scan image sensor. The mask is transparent in the area where the matrix element is 1, and is opaque in the area where the matrix element is 0; 2] Select the time-compressed image resolution to be acquired: M×L; 3] Build an imaging system to image the target scene on the photosensitive area of the line scan image sensor; set the exposure time ΔT E , so that ΔT E ≥T S ; 4] Let the starting time be T0. The line scan image sensor exposes the target scene and acquires the initial image at the starting time T0. The exposure time is ΔT0. The end time of this exposure is T1. Then T1 = T0 + ΔT0. Starting from T1, the count i = 0. 5] The line scan image sensor performs scanning output, receives and records image data, and completes a line of image output; 6] After a line of scan output is completed, the photosensitive area of the line scan image sensor is exposed to continue image acquisition. The exposure time is (ΔT E -T S ), when the exposure ends, 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] Complete the image data recording with a resolution of M×L and obtain a time-compressed image of the target scene.

2. The method for continuously acquiring time-compressed images based on a line scan image sensor according to claim 1, characterized in that: In step 1], the scanning output period T of the line scanning image sensor is S For a fixed period.

3. The method for continuously acquiring time-compressed images based on a line scan image sensor according to claim 2, characterized in that: In step 2], when the time-compressed image resolution M×L to be acquired is selected, L is greater than or equal to 2N.

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