Single-photon single-pixel imaging method based on average pulse number estimation intensity

Abstract

The invention discloses a single-photon single-pixel imaging method based on average pulse number estimation intensity. The method comprises the following steps: recording each single-photon event; averaging the recorded pulse number of each single photon event to obtain an average pulse number of different photon numbers; performing intensity estimation by using the average pulse number of different photon numbers to obtain average pulse number estimation intensity, and performing information recovery on the target object to obtain an image of the target object; based on the image of the target object, the imaging quality of the target object is evaluated by calculating different image quality indexes. An image is restored by counting the number of pulses before each photon arrives and averaging. In an experiment, only one single-photon avalanche diode is used as a single-photon detector to obtain photon information, the high efficiency of the method under the low-light condition is proved, and compared with a traditional time correlation single-photon counting imaging method, the method can achieve information recovery of a target object through fewer photons.

Description

Technical Field

[0001] The invention belongs to the technical field of single-photon single-pixel imaging, and in particular relates to a single-photon single-pixel imaging method based on average pulse number intensity estimation. Background Art

[0002] Traditional imaging technology methods are affected by absorption, scattering, turbulence and complex light-matter interaction effects during the propagation process, making it difficult to obtain clear underwater images. Single-pixel imaging has the characteristics of high sensitivity, anti-interference and wide working wavelength. It has significant advantages in weak light, special bands and improving imaging distance, and is expected to become the next generation of information acquisition technology that is focused on development. However, the current single-pixel imaging method lacks in-depth research on the physical mechanism of imaging scattering, resulting in poor information recovery and time-consuming sampling time, making it difficult to obtain dynamic real-time information recovery of the target object, which seriously restricts the promotion and application of this technology in underwater imaging detection.

[0003] Single-photon single-pixel imaging technology uses highly sensitive single-photon detectors to detect single photon events. This high sensitivity enables the technology to perform effective imaging in environments with extremely weak light intensity, which is difficult to achieve in conventional optical imaging technology. Single-photon detectors can record the time of arrival of photons on an extremely short time scale, which not only enables single-photon detectors to capture fast dynamic events, but also enables single-photon detectors to have high temporal resolution imaging capabilities. In addition, single-photon single-pixel imaging technology also has strong penetration capabilities. In many application scenarios, single-photon detectors can effectively penetrate obstacles, thereby achieving imaging of deep structures or distant targets. This feature makes single-photon single-pixel imaging technology have broad application potential in biomedicine, environmental monitoring, astronomical observation and other fields. Single-photon single-pixel imaging can also be combined with other imaging technologies (such as super-resolution microscopy, quantum imaging technology, etc.) to further improve the spatial resolution and temporal resolution of imaging. Through multimodal imaging, image data of different scales can be obtained simultaneously, thereby achieving a more comprehensive and accurate imaging effect. With the continuous development of quantum technology, single-photon single-pixel imaging technology is expected to be widely used in more fields, promoting scientific research and technological innovation.

[0004] In the process of implementing the technical method of the embodiment of the present invention, the inventors of the present application have found at least the following technical problems in the prior art: Traditional time-correlated single-photon counting imaging methods require a large number of photons to effectively recover the information of the target object. Since each photon event must be accurately recorded in time, the amount of data generated by the time-correlated single-photon counter is very large, resulting in high storage requirements, complex data processing, and high computational overhead. In addition, since photon events need to be counted and processed one by one, the imaging speed is slow, especially when facing high-intensity or rapidly changing signals, it is often difficult to obtain real-time high-quality images. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a single-photon single-pixel imaging method based on the average pulse number to estimate the intensity. Different from the traditional time-correlated single-photon counting imaging method, this method can use fewer photons to achieve information recovery of the target object.

[0006] To achieve the above object, the present invention adopts the following technical solution: A single-photon single-pixel imaging method for estimating intensity based on average pulse number comprises the following steps: Step S1, the pulse light emitted by the supercontinuum pulse laser is irradiated onto the digital micromirror device through the attenuator and the beam expander, the substrate illumination pattern on the digital micromirror device encodes the incident light, which is focused and transmitted by the first lens to irradiate the target object, and the photon signal transmitted by the target object is received by the single photon avalanche diode through the second lens and input into the TCSPC module to record each single photon event; Step S2, averaging the number of pulses of each recorded single photon event to obtain the average number of pulses with different photon numbers; Step S3, using the average pulse number of different photon numbers to perform intensity estimation to obtain the average pulse number estimation intensity, and performing information recovery on the target object to obtain an image of the target object; Step S4: Based on the image of the target object, the imaging quality of the target object is evaluated by calculating different image quality indicators.

[0007] Optionally, the average number of pulses in step S2 is expressed as: , In the above formula, Indicates The first The number of pulses before the photon arrives, M represents the total number of photons, Indicates The average number of pulses corresponding to the base illumination pattern.

[0008] Optionally, the average pulse number estimation intensity described in step S3 is expressed as: , In the above formula, Indicates The total intensity of the base illumination pattern, Indicates The average number of pulses corresponding to the base illumination pattern.

[0009] Optionally, the image representation of the target object in step S3 is: , In the above formula, An image representing the target object, K Indicates the number of base lighting patterns, Indicates The intensity value of the base lighting pattern, Indicates The average number of pulses corresponding to the base illumination pattern, Indicates The average intensity of the substrate illumination patterns.

[0010] Optionally, the image quality assessment index in step S4 is specifically the variance of the grayscale value of the image pixels and the Brenner value of the image.

[0011] Optionally, the formula for the variance of the grayscale value of the image pixel is: , In the above formula, represents the variance of the grayscale values ​​of the image pixels within the selected range, a represents the total number of pixels within the selected range, Indicates the coordinates in The gray value of the pixel, Represents the average grayscale value of pixels within the selected range.

[0012] Optionally, the formula for the Brenner value of the image is: , In the above formula, b represents the Brenner value of the image, Indicates the coordinates in The gray value of the pixel, Indicates the horizontal coordinate of the pixel point within the selected range. Indicates the vertical coordinate of the pixel points within the selected range.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with the traditional time-correlated single-photon counting imaging method, the single-photon single-pixel imaging method based on the average pulse number to estimate the intensity of the present invention has a faster imaging speed and can face high-intensity or rapidly changing signals to achieve real-time high-quality image acquisition. Because in the single-photon single-pixel imaging method based on the average pulse number to estimate the intensity of the present invention, the time-correlated single-photon counter does not need to record each photon event, and the amount of data generated is small, resulting in low storage requirements, simple data processing, low computational overhead, and easy real-time analysis. The single-photon single-pixel imaging method based on the average pulse number to estimate the intensity of the present invention reduces the impact of background noise to a certain extent, especially when the background signal is strong, it can still provide a clearer image.

[0014] 2. The single-photon single-pixel imaging method of the present invention, which estimates the intensity based on the average number of pulses, provides important theoretical and technical guidance for the application field of ultra-low light imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of an experimental optical path of a single-photon single-pixel imaging method for estimating intensity based on average pulse number in an embodiment of the present invention; Figure 2 is a time sequence diagram of a photon signal and a synchronization signal recorded by a time-correlated single photon counter in an embodiment of the present invention; Figure 3 is an image reconstruction result diagram obtained through experiments in an embodiment of the present invention; Figure 4 A comparison diagram of the imaging effects of the single-photon single-pixel imaging method based on the average pulse number intensity estimation method in the embodiment of the present invention and the traditional time-correlated single-photon counting imaging method; Figure 5 In the embodiment of the present invention Figure 3 Brenner values ​​from (a) to (g) in the figure; In the figure: 1-supercontinuum pulse laser; 2-attenuator; 3-beam expander; 4-time-correlated single-photon counter; 5-digital micromirror device; 6-first lens; 7-target object; 8-second lens; 9-single-photon avalanche diode; 10-computer; 11-front view of the target object. DETAILED DESCRIPTION

[0016] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0017] Example like Figure 1 As shown, the computer 10 is connected to the digital micromirror device 5 and the time-correlated single photon counter 4. The pulse light emitted by the supercontinuum pulse laser 1 with a repetition rate of 5 MHz is irradiated onto the digital micromirror device 5 through the attenuator 2 and the beam expander 3. The computer 10 controls the parameters of the digital micromirror device 5 to project the encoded substrate illumination pattern. The substrate illumination pattern on the digital micromirror device 5 encodes the incident light, which is focused and transmitted through the first lens 6 to irradiate the target object 7. The photon signal transmitted by the target object 7 is received by the single photon avalanche diode 9 as a single photon detector through the second lens 8, and input into the TCSPC (Time-Correlated Single Photon Counting) module of the time-correlated single photon counter 4. The synchronization signal of the pulse light is input into the SYNC-IN channel of the time-correlated single photon counter 4, and the synchronization signal of the substrate illumination pattern of the digital micromirror device 5 is input into the M1 channel of the time-correlated single photon counter 4 to keep the synchronization of the entire system. The data of the time-correlated single photon counter 4 is fed back to the computer 10, and the computer 10 recovers the information of the target object 7. The front view 11 of the target object is a front projection view of the target object 7 .

[0018] Furthermore, if Figure 2 As shown, the number of pulses of photons corresponding to each substrate illumination pattern is recorded. For each substrate illumination pattern, the photons projected from the target object are recorded by a single-photon avalanche diode; then the digital signal is fed to a time-correlated single-photon counter, which simultaneously receives synchronization signals from a digital micromirror device and a pulsed light source. Next, the intensity is estimated using the average number of pulses with different photon numbers, where the average number of pulses is expressed as: , In the above formula, Indicates The first The number of pulses before the photon arrives, M represents the total number of photons, Indicates The average number of pulses corresponding to the base illumination pattern.

[0019] The average pulse number estimated intensity is expressed as: , In the above formula, Indicates The total intensity of the base illumination pattern, Indicates The average number of pulses corresponding to the base illumination pattern.

[0020] Specifically, by intensity estimation Correlation measurement with the substrate illumination pattern to restore the image of the target object , the image of the target object is represented as: = , In the above formula, An image representing the target object, K Indicates the number of base lighting patterns, Indicates The intensity value of the base lighting pattern, Indicates The average number of pulses corresponding to the base illumination pattern, Indicates The average intensity of the substrate illumination patterns.

[0021] like Figure 3 As shown, Figure 3 Images (a) to (f) are images of the target object obtained by using the single-photon single-pixel imaging method that estimates the intensity using the average pulse number. Figure 3 The image (g) is an image of the target object obtained using the time-correlated single photon counting imaging method. Figure 3 The number of photons used in images (a) to (g) are 10, 100, 200, 300, 400, 500, and 584, respectively. Figure 3 The image (h) in the figure shows the position of the target pattern in the reconstructed image. The coordinates of point A in the black frame are (200, 370), and the coordinates of point B are (390, 200), indicating that the range of the target pattern is x =200 to x =390, y =200 to y =370.

[0022] Furthermore, the imaging effect of the single-photon single-pixel imaging method based on the average pulse number estimation intensity is evaluated by calculating different image quality indicators. The variance of the grayscale value of the image pixel and the Brenner value of the image are calculated to evaluate the imaging quality of the target object. The formula for calculating the variance of the grayscale value of the image pixel is: , In the above formula, represents the variance of the grayscale values ​​of the image pixels within the selected range, a represents the total number of pixels within the selected range, For coordinates in The gray value of the pixel, Represents the average grayscale value of pixels within the selected range.

[0023] Figure 4 This is a comparison diagram of the imaging effects of the single-photon single-pixel imaging method based on the average pulse number intensity estimation method of the present invention and the traditional time-correlated single-photon counting imaging method, indicating that Figure 3 The images (a) to (g) in the figure are the variances of the grayscale values ​​of the pixels at y=230, y=260, y=290, y=320, and y=350, respectively. The grayscale value of each pixel has been normalized, and the horizontal axis represents the number of photons. Figure 4 It can be seen that the single-photon single-pixel imaging method of the present invention based on the average pulse number intensity estimation can achieve the image restoration effect of 100 photon information as the traditional time-correlated single-photon counting method using 584 photon information.

[0024] Figure 5 for Figure 3 The Brenner values ​​of images (a) to (g) in the figure. The formula of the Brenner value of an image is expressed as: , In the above formula, b represents the Brenner value of the image, Indicates the coordinates in The gray value of the pixel, Indicates the horizontal coordinate of the pixel point within the selected range. Indicates the vertical coordinate of the pixel points within the selected range.

[0025] Depend on Figure 5 It can be seen that the single-photon single-pixel imaging method based on the average pulse number to estimate the intensity is superior to the traditional time-correlated single-photon counting imaging method to a certain extent. Specifically, compared with the traditional time-correlated single-photon counting imaging method, the single-photon single-pixel imaging method based on the average pulse number to estimate the intensity can use fewer photons to achieve information recovery of the target object.

[0026] It should be understood that the above description of the preferred embodiment is relatively detailed and cannot be regarded as limiting the scope of patent protection of the present invention. Under the enlightenment of the present invention, ordinary technicians in this field can also make substitutions or modifications without departing from the scope of protection of the claims of the present invention, which all fall within the scope of protection of the present invention. The scope of protection requested for the present invention shall be based on the attached claims.

Claims

1. A single-photon single-pixel imaging method based on average pulse number intensity estimation, characterized in that: The following steps are involved: Step S1, the pulse light emitted by the supercontinuum pulse laser is irradiated onto the digital micromirror device through the attenuator and the beam expander, the substrate illumination pattern on the digital micromirror device encodes the incident light, which is focused and transmitted by the first lens to irradiate the target object, and the photon signal transmitted by the target object is received by the single photon avalanche diode through the second lens and input into the TCSPC module to record each single photon event; Step S2, averaging the number of pulses of each recorded single photon event to obtain the average number of pulses with different photon numbers; Step S3, using the average pulse number of different photon numbers to perform intensity estimation to obtain the average pulse number estimation intensity, and performing information recovery on the target object to obtain an image of the target object; Step S4: Based on the image of the target object, the imaging quality of the target object is evaluated by calculating different image quality indicators.

2. The method according to claim 1, characterized in that The average number of pulses described in step S2 is expressed as: ， In the above formula, Indicates The first The number of pulses before the photon arrives, M represents the total number of photons, Indicates The average number of pulses corresponding to the base illumination pattern.

3. The method according to claim 1, characterized in that The average pulse number estimation intensity described in step S3 is expressed as: ， In the above formula, Indicates The total intensity of the base illumination pattern, Indicates The average number of pulses corresponding to the base illumination pattern.

4. The method according to claim 1, characterized in that: The image of the target object in step S3 is represented as: ， In the above formula, An image representing the target object, K Indicates the number of base lighting patterns, Indicates The intensity value of the base lighting pattern, Indicates The average number of pulses corresponding to the base illumination pattern, Indicates The average intensity of the substrate illumination patterns.

5. The method according to claim 1, characterized in that The image quality evaluation index in step S4 is specifically the variance of the grayscale value of the image pixels and the Brenner value of the image.

6. The method according to claim 5, characterized in that The formula for the variance of the grayscale value of the image pixel is: ， In the above formula, represents the variance of the grayscale values ​​of the image pixels within the selected range, a represents the total number of pixels within the selected range, Indicates the coordinates in The gray value of the pixel, Represents the average grayscale value of pixels within the selected range.

7. The method according to claim 5, characterized in that The formula for the Brenner value of the image is: ， In the above formula, b represents the Brenner value of the image, Indicates the coordinates in The gray value of the pixel, Indicates the horizontal coordinate of the pixel point within the selected range. Indicates the vertical coordinate of the pixel points within the selected range.

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