CN-122002002-A - Single photon imaging system and method

CN122002002ACN 122002002 ACN122002002 ACN 122002002ACN-122002002-A

Abstract

The application discloses a single photon imaging system and a method, which relate to the field of computational imaging and single pixel imaging, wherein an imaging lens group in the system is used for imaging a target image to a coding disc; the coding disc modulates the light intensity of the target image through the coding pattern area in space; the detection module generates an electric pulse signal according to the light intensity of the target image transmitted by the transmission area in the coding disc; the application can realize single-pixel imaging under extremely weak light conditions.

Inventors

LI MINGFEI
ZHANG YUEXI
ZHAO ZIQING
WU LINGAN
QUAN BAOGANG

Assignees

中国科学院物理研究所

Dates

Publication Date: 20260508
Application Date: 20241216

Claims (10)

1. The single photon imaging system is characterized by comprising an imaging lens group, a coding disc, a detection module, a motor and driving module, a synchronization module, a time digital conversion module and an image reconstruction and display module; the imaging lens group is used for imaging a target image to the coding disc; The coding disc comprises a coding pattern area and a driving area which are arranged on a light-transmitting material substrate, wherein the coding disc is used for modulating the light intensity of a target image in space through the coding pattern area, the coding pattern area comprises a coding pattern constructed based on a cyclic orthogonal matrix, the cyclic orthogonal matrix is constructed according to the pixel size of the target image, and a sector is constructed according to one line of data of the cyclic orthogonal matrix, and the sector comprises a plurality of reflection areas and a plurality of transmission areas; The detection module is used for generating an electric pulse signal according to the light intensity of the target image transmitted by the transmission area in the coding disc and transmitting the electric pulse signal to the time-digital conversion module; The motor and the driving module are connected with the coding disc through the driving area and drive the coding disc to rotate at a constant speed; The synchronous module is used for monitoring the time of one circle of rotation of the coding disc and transmitting synchronous electric pulse signals to the time digital conversion module; The time-to-digital conversion module is used for recording the synchronous electric pulse signals and the electric pulse signals into time events respectively and transmitting the time events to the image reconstruction and display module; The image reconstruction and display module is used for reconstructing and displaying the target image according to the synchronous electric pulse signals and the time events corresponding to the electric pulse signals respectively.
2. The single photon imaging system according to claim 1, wherein the detection module comprises in particular a converging lens and a single photon detector; The converging lens is used for transmitting the light intensity of the transmitted target image to the single photon detector, and the single photon detector is used for generating an electric pulse signal when the light intensity is greater than or equal to the energy of 1 photon.
3. The single photon imaging system according to claim 2, wherein the single photon detector comprises in particular a photomultiplier tube and a geiger-mode avalanche photodiode.
4. The single photon imaging system according to claim 1, wherein the motor and drive module comprises a DC motor and a driver, and the driver adjusts the speed by pulse width modulation technique.
5. The single photon imaging system according to claim 1, wherein the synchronization module comprises an LED and a photodetector, and wherein a code wheel is disposed between the LED and the photodetector.
6. The single photon imaging system according to claim 1, wherein the time-to-digital conversion module comprises a detection circuit comprising a plurality of channels, wherein different channels correspondingly receive the synchronous electric pulse signal and the electric pulse signal and name time events by channel names and time labels respectively.
7. The single photon imaging system according to claim 1, wherein the image reconstruction and display module comprises a processor and a display; the processor is used for reconstructing the target image according to the synchronous electric pulse signals and the time events corresponding to the electric pulse signals respectively; The display is used for displaying the reconstructed target image.
8. A single photon imaging method applied to the single photon imaging system of any one of claims 1-7, the single photon imaging method comprising: imaging the target image to the encoding disk by using the imaging lens group; The method comprises the steps of utilizing a coding disc rotating at a constant speed to spatially modulate light of a target image, utilizing a detection module to generate an electric pulse signal according to the light intensity of the transmitted target image, and simultaneously transmitting the electric pulse signal to a time digital conversion module; The method comprises the steps of monitoring the rotation time of a coding disc for one circle by using a synchronous module, and transmitting synchronous electric pulse signals to a time digital conversion module; the synchronous electric pulse signals and the electric pulse signals are respectively recorded into time events by utilizing a time-to-digital conversion module and are transmitted to an image reconstruction and display module; And reconstructing and displaying the target image by utilizing the image reconstruction and display module to respectively correspond the synchronous electric pulse signals and the electric pulse signals.
9. The method of single photon imaging according to claim 8, wherein the recording of the synchronous electrical pulse signal and the electrical pulse signal as time events by the time-to-digital conversion module, respectively, and transmitting to the image reconstruction and display module, comprises: converting the synchronous electric pulse signal into a time stamp Tag1_i by using a channel CH1 for recording, wherein i represents the revolution of the coding disc; And (3) recording the electric pulse signal conversion arrival time stamp Tag2_j by using a channel CH2, wherein j is the photon number received by the detection module.
10. The method of single photon imaging according to claim 9, wherein the reconstructing and displaying the target image using the image reconstruction and display module for reconstructing and displaying the target image from the time events corresponding to the synchronized electric pulse signal and the electric pulse signal respectively, specifically comprises: Step 1, determining that a time stamp Tag1_i of a channel CH1 is (1, T1 i ) and a time stamp Tag2_j of a channel CH2 is (2, T2 j ),T1 i represents a time stamp corresponding to an ith circle of a turntable, and T2 j represents a time stamp corresponding to a jth photon; Step 2, the time stamp of the channel CH1 and the time stamp of the channel CH2 in each circle of the coded disc are re-corresponding to obtain a time stamp set { T2 j -T1 i ,T2 j+1 -T1 i ,…,T2 j+k -T1 i } in each circle, wherein k represents k time events; Step 3, counting time events according to a time interval Bin to obtain a photon counting distribution data vector { n i ,n 2 ,…,n M } with the length of M, wherein n i represents the photon number obtained by counting in the ith group, the width of the time interval Bin is equal to (T1 i+1 -T1 i )/M, and M is the corresponding coding number of one turn of the coding disc; Step 4, intercepting the obtained photon counting distribution data vector { N i ,n 2 ,…,n M } according to the coding length N, taking the photon counting distribution data vector { N i ,n 2 ,…,n M } as a barrel detector value I b , and carrying out fast Fourier transform on the barrel detector value I b and a first row vector H 1 of a cyclic orthogonal matrix to obtain a reconstructed image vector IMG, wherein N is the length of the cyclic orthogonal matrix, and determining according to the pixel size of a target image; Step 5, the reconstructed image vector IMG is rearranged according to the pixel size of the target image, and then normalization operation is carried out; and 6, repeating the steps 1-5, and superposing the image vectors IMG of each circle to obtain a clear target image and displaying the clear target image.

Description

Single photon imaging system and method Technical Field The application relates to the fields of computational imaging and single-pixel imaging, in particular to a single-photon imaging system and a single-photon imaging method. Background In computational imaging, single pixel imaging techniques, a commonly used spatial modulation device is a digital mirror micromirror device (Digital micromirror devices, DMD) of texas instruments (Texas Instruments, or TI). DMDs require development with complex circuitry and microelectromechanical systems (Micro-Electro-MECHANICAL SYSTEMS, MEMS) processes, and currently only TI companies worldwide have production capabilities. The main parameters of DMD are modulation speed and micromirror size, and currently the fastest possible 32kHz refresh rate, 1920 x 1080 pixel spatial light modulation on the micrometer scale, has been widely used in digital projectors. Although DMD is widely used in computational imaging, structured light illumination, and the like, it has many limitations and disadvantages of use. For example, the power consumption reaches tens of watts in running, the requirement on the working bandwidth of a circuit is as high as tens of gigahertz, and the modulation angle is only 12 degrees, which is not beneficial to optical integration and the like. Aiming at the defects, a scheme for realizing single-pixel imaging by utilizing rotary coding is provided in the prior scheme, a mask pattern is covered on an annular mask to form a light transmission area and an opaque area, space light can be modulated after rotation, and demodulation and imaging are realized by a single-pixel imaging scheme. The method has a modulation speed which is higher than that of the DMD, and can reach the megahertz level, so that the method also has a speed for realizing single-pixel imaging more quickly. The key technical problem of realizing single-pixel imaging by adopting a rotary coding disc is that coding is in one-to-one correspondence with detected signals, the scheme of the current disclosure is that synchronous coding is arranged on the coding disc, a synchronous coding mark rotates for a period of time, collected data is converted into data length according to a period of rotation after being calculated according to a sampling rate, then detection signals equal to the coding length are realized through interpolation, and one-to-one correspondence between the signals and the codes is ensured, so that the image resolving is realized. However, when the rotary encoding disk is used for realizing single-pixel imaging on extremely weak light, particularly the detection signal reaches a single photon level, no signal photons can be detected at certain encoding positions, and the one-to-one correspondence between the encoding and detection signals cannot be ensured by adopting a publicly reported interpolation scheme, namely the realization of single-pixel single-photon imaging based on the rotary encoding disk is not reported at present. The single-pixel single-photon imaging has a very wide application prospect, and particularly has application in the field of very weak light imaging, such as biomedical imaging, night vision imaging and the like. In addition, the single photon detection device has higher time resolution capability, and can realize range gating imaging, for example, the flight time of detecting nanosecond, picosecond and femtosecond light pulses is difficult to realize by a common camera, and an array camera with high time resolution is expensive and has limited detectable wave band, so that single pixel imaging has great advantages in the aspect. Specific application scenes include, but are not limited to, remote detection and imaging of methane gas, security inspection and flaw detection of terahertz wave bands, and the like. In view of the foregoing needs of very low light imaging applications, it is desirable to provide a single-photon imaging system and method for single-pixel single-photon imaging technology based on a rotary encoder disk, so as to enable single-pixel imaging under very low light conditions. Disclosure of Invention The application aims to provide a single photon imaging system and a single photon imaging method, which can realize single pixel imaging under extremely low light conditions. In order to achieve the above object, the present application provides the following solutions: in a first aspect, the application provides a single photon imaging system, which comprises an imaging lens group, a coding disc, a detection module, a motor and driving module, a synchronization module, a time digital conversion module and an image reconstruction and display module; the imaging lens group is used for imaging a target image to the coding disc; The coding disc comprises a coding pattern area and a driving area which are arranged on a light-transmitting material substrate, wherein the coding disc is used for modulating the light intensity of a target