A single photon detection device and fast spectral and imaging system based thereon

Abstract

The application belongs to the field of spectral measurement and imaging, and specifically discloses a single-photon detection device and a rapid spectral and imaging system based on the same. According to the application, a transmission optical fiber spectrometer separates each waveband complex light according to wavelength in space, and couples the photons of different wavelengths into an optical fiber array for time delay, so that the different wavelengths are delayed to different time points and output to a single-photon detection device. The single-photon detection device converts the photons of different wavelengths arriving at the device in time sequence into electrical signals, and obtains the number of photons at different time points after amplification and signal processing, and converts the number of photons into a spectrum. Since the transmission spectrometer can provide higher diffraction efficiency, higher spectral resolution and signal strength, the single-photon detection device can provide a faster and more accurate photon discrimination and photon counting method, and compared with the prior art, the whole can measure the spectrum more quickly, and has higher spectral resolution and signal strength.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of spectral measurement and imaging, and more particularly, relates to a single-photon detection device and a fast spectral and imaging system based thereon. BACKGROUND

[0002] Patent CN115165101A discloses a single-photon sensitivity ultrafast spectral measurement system. On the one hand, the single-photon detector used by the system is a silicon photomultiplier or a SiPM or an avalanche diode array or other single-photon detector array, which can avoid dead time and improve sensitivity. However, the SiPM has a lot of dark noise, and the signal-to-noise ratio is low. The signal sensitivity is easily disturbed by external noise. When multiple photons are continuously incident, it is difficult to distinguish the number of photons after signal superposition. On the other hand, the spectrometer used by the system is a reflection type. Two input optical fibers and an optical fiber array are integrated together. Two sections of optical fibers are input in parallel at the same end with a certain distance. Only one of the two wavebands is on the optical axis, which inevitably causes the other waveband to have spherical aberration, affecting the signal strength and spectral resolution. In addition, the diffraction grating must have an included angle to meet the requirement that the incident light and the diffracted light are in the same optical path. In order to be able to rotate the grating to obtain different wavebands, only a reflection grating insensitive to the incident angle can be used, resulting in low grating diffraction efficiency.

[0003] For the problem of converting optical pulse signals into photon counts, a deconvolution photon counting method has been proposed. However, on the one hand, the deconvolution operation needs to be performed on each data point, resulting in a large amount of calculation. On the other hand, peak fitting is used, which has a certain deviation from the actual peak value. Moreover, during the processing of this method, an overshoot is formed, which reduces the amplitude of the subsequent photons when photons continuously arrive, resulting in inaccurate photon counting results.

[0004] In view of the defects of the reflection spectrometer, a transmission spectrometer has been proposed. However, these transmission spectrometers can only incident one waveband, cannot separate more wavebands in time, and cannot detect a wider spectral range. SUMMARY

[0005] In view of the defects of the prior art, the purpose of the present application is to provide a single-photon detection device and a fast spectral and imaging system based thereon, aiming to solve the problem of limited spectral measurement sensitivity, speed and spectral span.

[0006] The first aspect of the present application relates to a SiPM photon counting method, comprising:

[0007] extracting each peak value in the detected analog voltage signal;

[0008] comparing each peak value and a preset amplitude to identify photon peaks and non-photon peaks;

[0009] For each photon peak, the amplitude difference between the peak amplitude and the amplitude at the start of the photon response is calculated, and the photon number at the peak time is taken as the multiple of the amplitude difference and the single-photon pulse height.

[0010] Preferably, if the amplitude of the analog voltage signal at a certain time is greater than the amplitude at the adjacent time, it is determined as a peak.

[0011] Preferably, if the peak amplitude is greater than a preset amplitude, it is determined as a photon peak, otherwise, it is determined as no photon peak, and the preset amplitude is in the range of (1 / 10 single-photon pulse height, single-photon pulse height).

[0012] Preferably, for each photon peak, the amplitude difference between the peak amplitude and the amplitude at the start of the photon response is calculated, and the photon number at the peak time is taken as the multiple of the amplitude difference and the single-photon pulse height.

[0013] The second aspect of the present application relates to a single-photon detection device, comprising a SiPM-based single-photon detector and a signal processing module.

[0014] The SiPM-based single-photon detector is used to detect a photon pulse event using a SiPM to obtain an analog voltage signal.

[0015] The signal processing module comprises at least one memory for storing a program and at least one processor for entering the program stored in the memory, and when the program stored in the memory is entered, the processor is used to enter the photon counting method as described in the first aspect.

[0016] The third aspect of the present application relates to a multi-channel single-grating transmission fiber spectrometer, comprising a plurality of fiber interfaces, a plurality of collimating elements, a single transmission grating, a focusing element and a multi-mode fiber array; the focusing element is parallel to the multi-mode fiber array and opposite to the transmission grating.

[0017] The i-th complex color light is incident to the i-th collimating element through the i-th fiber interface, and after collimation, it is projected onto the transmission grating, and the projection spots of all channel complex color lights on the transmission grating completely overlap, the center wavelength of the i-th complex color light is greater than the center wavelength of the (i+1)-th complex color light, and the adjacent two complex color light bands are adjacent and equal in length, , The number of fiber interfaces is ;

[0018] The transmission grating separates the signals of different wavelengths in each channel complex color light in space and focuses them onto the multi-mode fiber array through the focusing element, and after the diffraction of each channel complex color light band through the transmission grating, the diffraction light does not exceed the range of the multi-mode fiber array.

[0019] The length difference between adjacent optical fibers in the multi-mode fiber array remains constant, delaying light of different wavelengths to different time points, and merging into a bundle for output;

[0020] The output light beams of the i-th fiber interface and the (i+1)-th fiber interface have a specific included angle, which is the included angle of the light beams focused to the left and right ends of the multi-mode fiber array.

[0021] The fourth aspect of the present application relates to a multi-channel single-grating transmission fiber spectrometer, comprising: a plurality of fiber interfaces, a plurality of collimating elements, a single reflecting element, a single transmission grating, a focusing element, and a multi-mode fiber array; the focusing element is parallel to the multi-mode fiber array and directly opposite the transmission grating;

[0022] The i-th complex color light is incident to the i-th collimating element through the i-th fiber interface, is projected to the reflecting element after collimation, is reflected to the transmission grating again, and the projection spots of all channel complex color lights on the transmission grating are completely overlapped, the center wavelength of the i-th complex color light is greater than the center wavelength of the (i+1)-th complex color light, and the adjacent two complex color light bands are adjacent and equal in length, The number of fiber interfaces is ;

[0023] The transmission grating separates the signals of different wavelengths in each channel complex color light in space and focuses them on the multi-mode fiber array through the focusing element. After the channel complex color light band is diffracted by the transmission grating, the diffracted light does not exceed the range of the multi-mode fiber array;

[0024] The length difference between adjacent optical fibers in the multi-mode fiber array remains constant, delaying light of different wavelengths to different time points, and merging into a bundle for output;

[0025] The output light beams of the i-th fiber interface and the (i+1)-th fiber interface have a specific included angle, which is the included angle of the light beams focused to the left and right ends of the multi-mode fiber array.

[0026] Preferably, the transmission fiber spectrometer further comprises a motorized translation stage for translating the multi-mode fiber array bundle multiple times along the multi-mode fiber arrangement direction, and the distance of each translation is The fiber core diameter is used to measure the light signal at different positions, The number of translations is

[0027] The fifth aspect of the present application relates to a fast spectrum and imaging system based on a single-photon detection device, comprising a laser, an imaging microscope, a light splitting element, n input optical fibers, a transmission fiber spectrometer as described above, and a single-photon detection device;

[0028] The laser emits a pulsed laser beam, which is focused on the sample under test by an imaging microscope to generate a spectral signal, the spectral signal returns to the original path, and is divided into n complex colors by a light splitting element, the center wavelength of the i-th complex color is greater than that of the (i+1)-th complex color, and the adjacent two complex color bands are adjacent and equal in length;

[0029] The i-th input optical fiber is connected to the i-th fiber interface, and the i-th complex color is input into the transmission type fiber spectrometer;

[0030] The n input optical fibers are multi-mode optical fibers with different lengths, and the length difference between adjacent two input optical fibers is greater than the longest optical fiber in the multi-mode optical fiber array;

[0031] The transmission type fiber spectrometer is used to separate the complex color bands in space according to the wavelength respectively, and to couple the photons of different wavelengths into the optical fiber array for time delay, so as to delay the different wavelengths to different time points and output to the single photon detection device;

[0032] The single photon detection device is used to convert the photons of different wavelengths which arrive at different time points into electrical signals, and after amplification and signal processing, the photon numbers at different time points are obtained, which are converted into a spectrum.

[0033] Preferably, the signal processing module is also used for interpolating the spectral intensity collected when the optical fiber array bundle is at different positions.

[0034] Overall, compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects:

[0035] (1) The SiPM photon counting method proposed in the present application, on the one hand, extracts the peak value in the analog signal, compares the peak value amplitude with the preset amplitude, selects the data points with photons, and only counts the photons of the peak value, greatly reduces the data calculation amount, and greatly improves the processing speed; on the other hand, the amplitude difference between the peak value amplitude and the amplitude at the starting time of the photon response is calculated, and the multiple of the amplitude difference and the single photon pulse height is taken as the photon number at the peak value time. This direct linear judgment method removes the influence of peak value change caused by fitting, and the obtained peak value is the actual peak value, so the accuracy is improved. Under the premise of the same data size, compared with the deconvolution method, the counting speed of the method proposed in the present application is improved by about 250 times, and the accuracy is improved by 20%.

[0036] (2) The single photon detection device proposed in the present application combines the SiPM-based single photon detector and the above-mentioned photon counting method, and considers the multi-photon detection characteristics of the SiPM-based single photon detector. The counting method can quickly and accurately distinguish multiple photons arriving at the same time.

[0037] (3) The application provides a multi-channel single-grating transmission fiber spectrometer, a plurality of input fibers are arranged separately from a fiber array, adjacent input fibers are connected to fiber interfaces with a specific angle, and collimated light shares a transmission grating, the specific angle is the angle of the focused light beams at the left and right ends of the multimode fiber array, the different wavebands can be ensured to be on the optical axis at the same time, thereby eliminating spherical aberration, improving spectral resolution and signal strength, and realizing full-waveband spectral detection; compared with a reflection grating, the transmission grating has higher diffraction efficiency; the transmission grating has specific placement requirements, the projection spots of different wavebands on the transmission grating need to be completely overlapped, so that the diffraction light of each waveband passing through the transmission grating can be focused into the multimode fiber array by the lens; the diffraction light of the complex light waveband after diffraction by the transmission grating needs to be within the range of the multimode fiber array, so that the light signal of each wavelength can be collected by the multimode fiber array; the multimode fiber array with an equal-difference length and a single-photon detection device are used to replace a CCD, the sensitivity of photon detection and the accuracy of photon counting are improved, and the spectral measurement speed is improved by more than three orders of magnitude through the multimode fiber array delay detection spectrum method; the application introduces complex light by connecting the input multimode fiber through the fiber interface, compared with the slit incidence, the input end is circular, the signal outside other background light is reduced, the signal-to-noise ratio is improved, and the fiber connection of external equipment is more convenient.

[0038] (4) The application provides a rapid spectrum and imaging system, the transmission spectrometer can provide higher diffraction efficiency, higher spectral resolution and signal strength, the single-photon detection device can provide a faster and more accurate photon discrimination and photon counting method, compared with the prior art, the whole can measure the spectrum more quickly, and has higher spectral resolution and signal strength. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 FIG. 1 is a structure schematic diagram of a rapid spectrum and imaging system based on a single-photon detection device provided by an embodiment of the application.

[0040] Figure 2 FIG. 2 is a structure schematic diagram of a multi-channel single-grating transmission fiber spectrometer provided by an embodiment of the application.

[0041] Figure 3 FIG. 3 is a structure schematic diagram of a multi-channel single-grating transmission fiber spectrometer provided by an embodiment of the application.

[0042] Figure 4 FIG. 4 is a structure schematic diagram of a single-photon detection device provided by an embodiment of the application.

[0043] Figure 5 FIG. 5 is a photon counting result schematic diagram provided by an embodiment of the application. DETAILED DESCRIPTION

[0044] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0045] The term "and / or" in the present application is used to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The symbol " / " in the present application represents the relationship of or, for example, A / B represents A or B.

[0046] The terms "first" and "second" and the like in the specification and claims of the present application are used to distinguish different objects, and are not used to describe the specific order of the objects. For example, the first response message and the second response message are used to distinguish different response messages, and are not used to describe the specific order of the response messages.

[0047] In the embodiments of the present application, the words such as "exemplary" or "for example" are used to mean an example, illustration or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words such as "exemplary" or "for example" are intended to present the relevant concept in a specific manner.

[0048] In the description of the embodiments of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more, for example, a plurality of processing units means two or more processing units, and the like; a plurality of elements means two or more elements, and the like.

[0049] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0050] As shown in Figure 1 The present application discloses a rapid spectrum and imaging system based on a single photon detection device, which comprises a laser, an imaging microscope, a light splitting element, n input optical fibers, a transmission fiber spectrometer and a single photon detection device.

[0051] The laser emits a beam of pulsed laser light, which is focused onto a measured sample by the imaging microscope to generate a spectrum signal. The spectrum signal returns to the original path, is divided into n complex colors by the light splitting element, the center wavelength of the ith complex color is greater than that of the (i+1)th complex color, and the adjacent two complex color bands are adjacent and equal in length.

[0052] The ith input optical fiber is connected to the ith optical fiber interface, and the ith complex color is input to the transmission fiber spectrometer.

[0053] The n input optical fibers are multi-mode optical fibers with different lengths, and the length difference between any two adjacent input optical fibers is greater than the longest optical fiber in the multi-mode optical fiber array.

[0054] The transmission type fiber spectrometer is used for separating each waveband complex light in space according to wavelength, coupling different wavelength photons into the optical fiber array for time delay, delaying different wavelengths to different time, and outputting to the single photon detection device.

[0055] The single photon detection device is used for converting different wavelength photons arriving in time sequence into electrical signals, obtaining photon numbers at different time after amplification and signal processing, and converting into spectrum.

[0056] The working process of the fast spectrum and imaging system is as follows: the laser emits a laser beam, the laser passes through the first dichroic mirror, is scanned by the two-dimensional galvanometer and the third lens group, is focused on the measured sample to generate a spectrum signal, and the spectrum signal returns along the original path; the second dichroic mirror is placed on the signal light path to divide the signal light into two equal and adjacent wavebands; after the waveband signals pass through the optical filter to remove the laser background, the signals are focused into the input optical fiber by the first lens, the optical fiber is input into the transmission type spectrometer, the split signals enter the optical fiber array bundle, and the combined output is processed by the single photon detection device to obtain the spectrum.

[0057] As shown in Figure 2 , the application discloses a multi-channel single-grating transmission type fiber spectrometer, which comprises a plurality of optical fiber interfaces, a plurality of collimating elements, a single transmission type grating, a focusing element and a multi-mode optical fiber array; the focusing element is parallel to the multi-mode optical fiber array and directly opposite to the transmission type grating;

[0058] The i-th complex light is incident on the i-th collimating element through the i-th optical fiber interface, is projected on the transmission type grating after collimation, and the projection spots of all channel complex lights on the transmission type grating completely coincide, the center wavelength of the i-th complex light is greater than the center wavelength of the (i+1)-th complex light, and the wavebands of adjacent two complex lights are adjacent and equal in length, , The number of optical fiber interfaces is equal to the number of collimating elements, ;

[0059] The transmission type grating separates different wavelengths of signals in each channel complex light in space and focuses them on the multi-mode optical fiber array through the focusing element; after the waveband of each channel complex light is diffracted by the transmission type grating, the diffracted light does not exceed the range of the multi-mode optical fiber array;

[0060] The length difference between adjacent optical fibers in the multi-mode optical fiber array is kept constant, different wavelengths of light are delayed to different time, and are gathered into a bundle and output.

[0061] The specific included angle between the i-th fiber interface output light beam and the (i+1)-th fiber interface output light beam is the included angle of the light beams focused to the left and right ends of the multi-mode fiber array.

[0062] The collimating element includes but is not limited to a collimating lens, and the focusing element includes but is not limited to a focusing lens. In an embodiment, the fiber interface is located at the front focal point of the collimating lens, the focusing lens is as close as possible to the transmission grating, and the multi-mode fiber array is located at the rear focal point of the focusing lens.

[0063] Preferably, the collimating lens is an achromatic lens.

[0064] The working process of the multi-channel single-grating transmission fiber spectrometer is as follows: after the light signals of different wave bands input by the optical fibers are collimated by the lens, the light spots are overlapped on the transmission grating. The diffracted light signals are focused by the lens, and the signals of different wavelengths are focused on different positions of the fiber array and then input into the single-photon detection device for detection. Among them, there are multiple fiber inputs at the input end, each fiber input is of a different wavelength, and two adjacent fibers are placed at a specific included angle to hit the light spots on the same position of the transmission grating. Since the wavelengths of the light signals of two adjacent wave bands are different, the diffraction angles are also different, and the specific included angle of the two light signals just compensates for the difference in the diffraction angles, so that the two signals are focused on the same fiber array in space.

[0065] As shown in Figure 3 , the present application discloses a multi-channel single-grating transmission fiber spectrometer, which comprises a plurality of fiber interfaces, a plurality of collimating elements, a single reflecting element, a single transmission grating, a focusing element and a multi-mode fiber array; the focusing element is parallel to the multi-mode fiber array and directly opposite to the transmission grating;

[0066] The i-th complex color light is incident to the i-th collimating element through the i-th fiber interface, is projected to the reflecting element after collimation, is reflected to the transmission grating again, and the projection light spots of all channel complex color lights on the transmission grating are completely overlapped. The center wavelength of the i-th complex color light is greater than that of the (i+1)-th complex color light, and the wave bands of the adjacent two complex color lights are adjacent and equal in length. The number of fiber interfaces is ;

[0067] The transmission grating separates the signals of different wavelengths in each channel complex color light in space and focuses them on the multi-mode fiber array through the focusing element. After the wave band of each channel complex color light is diffracted by the transmission grating, the diffracted light does not exceed the range of the multi-mode fiber array;

[0068] The length difference between adjacent fibers in the multi-mode fiber array is kept constant, the light of different wavelengths is delayed to different time points, and is gathered and output in a bundle.

[0069] The specific included angle between the i-th fiber interface output light beam and the (i+1)-th fiber interface output light beam is the included angle of the light beams focused to the left and right ends of the multi-mode fiber array.

[0070] It should be noted that, Figure 3 Compared with Figure 2 The difference lies in that a reflecting element is added before the transmission grating, which can fold the light path and make the spectrometer structure more compact. The reflecting element includes but is not limited to a mirror.

[0071] Preferably, the transmission fiber spectrometer further comprises an electric translation stage for translating the multi-mode fiber array beam multiple times along the multi-mode fiber arrangement direction, and the distance of each translation is The fiber core diameter is used to measure the light signals at different positions, The number of translations.

[0072] The electric translation stage is used to fine-tune the position of the fiber beam during measurement, so as to measure multiple times between adjacent two fibers, increase the number of measurement points after interpolation, and thus improve the spectral resolution. It should be noted that the electric translation stage is used to move the multi-mode fiber array in the present application, and the multi-mode fiber array is translated multiple times along the multi-mode fiber arrangement direction, and the distance of each translation is The fiber core diameter. In this way, the number of sampling points can be increased by N times in the same spectral range, so that the photons in the fiber gap are also measured, and the spectral resolution is improved.

[0073] As shown in Figure 4 The present application discloses a single photon detection device, which comprises a single photon detector based on SiPM and a signal processing module. The single photon detector based on SiPM is used to detect photon pulse events using SiPM to obtain an analog voltage signal. The signal processing module comprises at least one memory for storing programs and at least one processor for entering the programs stored in the memory. When the programs stored in the memory are entered, the processor is used to enter the following photon counting method: extracting each peak value in the detected analog voltage signal; comparing the amplitude of each peak value with a preset amplitude to identify photon peak values and non-photon peak values; for each photon peak value, calculating the amplitude difference between the peak value amplitude and the amplitude at the starting time of the photon response, and taking the amplitude difference multiplied by the height of a single photon pulse as the photon number at the peak time.

[0074] Preferably, if the amplitude of the analog voltage signal at a certain time is greater than the amplitude at the adjacent time, it is identified as a peak value. It should be noted that the present application identifies the case that the voltage amplitude at a certain time is greater than the amplitude at the adjacent time as a peak value, which will not miss any photons compared with other peak value determination methods.

[0075] Preferably, if the peak amplitude is greater than a preset amplitude, it is determined to have a photon peak, otherwise, it is determined to have no photon peak, and the preset amplitude is in the range of (1 / 10 single photon pulse height, single photon pulse height). It should be noted that the application preferably determines the photon pulse height exceeding a certain proportion as a photon peak, compared with other photon determination methods, noise is not misjudged as a photon, further excluding the peak without photons, reducing the subsequent data calculation amount. It should be noted that the higher the background noise, the higher the selected preset amplitude, in order to exclude the interference of noise on photon counting.

[0076] Preferably, for each photon peak, the difference between the peak amplitude and the amplitude of the photon response starting time is calculated, and the nearest integer multiple of the difference between the amplitude and the single photon pulse height is taken as the photon number at the peak time. The photon response starting time is the peak time minus the response time of the photon detection device. It should be noted that the application preferably determines the photon response starting time according to the peak time and the response time of the photon detection device, and the difference between the peak amplitudes of the two is the multiple of the single photon pulse height as the photon number, avoiding the problem of inaccurate fitting peak of deconvolution method and the interference of overshoot generated when processing, accurately obtaining the actual amplitude of the photon pulse, making the photon counting more accurate.

[0077] Preferably, the signal processing module is also used for interpolating the collected spectral intensity when the fiber array bundle is at different positions. It should be noted that the application measures the spectral signal at different positions several times, interpolates the multiple groups of spectral data to improve the spectral sampling rate, and further improve the spectral resolution.

[0078] Since the multimode fibers of the fiber array are circular, there is a gap between the fibers, resulting in signal waste. The application inserts the signal interpolation method after multiple measurements by moving the electric translation stage, which significantly improves the spectral resolution. Specifically, the electric translation stage is moved N times, and since each fiber of the fiber array bundle can finally obtain a spectral intensity data, a1, a2, a3… are obtained before moving; the second group of data b1, b2, b3… are obtained by moving the electric translation stage (moving distance is 1 / (N+1) fiber core diameter); the third group of data c1, c2, c3… are obtained by moving the electric translation stage again; a1, b1, c1, a2, b2, c2, a3, b3, c3… are finally obtained by interpolation method.

[0079] Preferably, the single photon detection device further comprises a refrigeration device, a refrigeration surface of which is in contact with the SiPM chip and the circuit part, for cooling the chip and the circuit part, so that the SiPM chip works in an ambient temperature of -100℃ to -20℃, thereby greatly reducing the dark noise of the chip and improving the sensitivity of photon detection; and a water-cooled heat dissipation device arranged at the bottom surface of the refrigeration device, for cooling the refrigeration device to ensure the operation of the refrigeration device.

[0080] Preferably, the single photon detection device further comprises an electromagnetic shielding structure, which encapsulates the chip and the circuit part, the power supply, the refrigeration device, the water-cooled heat dissipation device, etc., for shielding the electromagnetic interference and radiation noise from the outside during the single photon detection of the SiPM chip, thereby improving the sensitivity of the chip detection.

[0081] Preferably, the single photon detection device further comprises a signal amplification module, for amplifying the photoelectric current output by the SiPM chip and transmitting to the signal processing module.

[0082] The working process of the single photon detection device is as follows: when the optical signal is incident on the SiPM chip, the SiPM chip converts the optical signal into an electrical signal, the signal amplification module amplifies the photoelectric current to a detectable level, and the signal processing module counts the optical pulse signal to distinguish the number of photons arriving at each moment, thereby obtaining the photon count measured in time sequence. The refrigeration device and the water-cooled heat dissipation device reduce the dark noise of the SiPM chip to a very low level, avoiding interference with single photon counting, and the electromagnetic shielding structure prevents other electromagnetic disturbances from the outside from interfering with signal detection.

[0083] As shown in Figure 5 , the upper half represents the collected analog voltage signal Raw data, and multiple peak values appear on the continuous waveform, and the lower half is the photon counting method proposed in the present application, DDS is the photon number at each peak time, which is essentially a digital signal, and 1 count represents one photon count.

[0084] Raman spectroscopy can make decisive spectral measurements of molecular vibrational transitions and has become an indispensable analytical tool for deciphering molecular structures and their changes in unknown physical and chemical phenomena, as well as fingerprinting metabolic biomarkers and chemicals in complex biological systems with molecular specificity. However, due to the extremely small scattering cross section (typical value σ: 10 -30 cm 2 sr -1Raman spectroscopy has long been known for its weak signal and low throughput (by ten orders of magnitude compared to fluorescence). Over the past few decades, great efforts have been made to improve the sensitivity and speed of Raman spectroscopy. To detect the precious and rarely scattered Raman photons, state-of-the-art Raman spectrometers usually deploy deep cooling (in liquid nitrogen) charge-coupled devices (CCDs) to reduce the dark noise to a negligible level. However, they are affected by readout noise (RON) in the photon-electron conversion and charge-voltage amplification stages. In particular, intensified CCD (ICCD) and electron-multiplying CCD (EMCCD) cameras, which employ ultra-high gain amplification to suppress RON, have become the main alternative to CCDs. However, they are only suitable for low-light applications, with the dynamic range of single-frame exposure limited to one photon. For the latest photomultiplier tubes (PMTs) and single-photon avalanche diode (SPAD) arrays, the noise floor has been reduced to a negligible level, and they mostly work in photon counting and gated mode. However, these photon counting detectors respond to only one photon per laser shot and become blind due to the inherent dead time. Recently, by using dispersion chirp in a long single-mode dispersion fiber, the emerging time-stretched dispersive Fourier transform (TS-DFT) enables Raman band measurements up to MHz. However, all these innovations employ single-mode fibers to realize spectral delay, which limits their nanosecond-level dispersion capabilities. In addition, due to the high coupling loss of single-mode fibers, these methods are not suitable for full-spectrum Raman imaging of highly scattering biological tissues.

[0085] The multi-channel single-grating transmission fiber spectrometer proposed in this application, spectral measurements include Raman, fluorescence and other spectra, especially Raman needs such a sensitive spectrometer. For Raman spectroscopy, this application uses a nanosecond pulsed laser to excite the sample under test at a repetition rate of 1 MHz in less than 0.5 ns, and to spread and measure the excited Raman spectrum in the time interval between excitation pulses, so both the laser power and the spectral measurement time are reduced. Two multimode fibers with a large core of 100 pm and a numerical aperture (NA) of 0.22 are arranged to collect the first Raman band (Band I: -300 cm -1 to 2000 cm -1 ) covering the fingerprint region and the dead zone, and the second Raman band (Band II: 2000 cm -1 to 4300 cm -1). To fully utilize the time capacity, different color Raman photons are spatially separated by a transmission grating and coupled to a multimode fiber array of different lengths assembled instead of a pixel array in a conventional CCD detector to convert the transient Raman spectrum into a time waveform. The multimode fiber array includes but is not limited to the following case: the lengths of 160 multimode fibers are uniformly increased by an arithmetic progression of 0.6 meters (i.e. 0.6, 1.2, 1.8, 2.4 meters...), so that different color Raman photons can be separated by about 3 nanoseconds (0.6 n / c; c: speed of light; n: refractive index of silica, , the specific values vary with morphology and wavelength). Therefore, the spectral range spanned by a single channel is 160 x 3 = 480 nanoseconds, and the spectral span of two channels covering two Raman bands will be 960 nanoseconds, almost occupying the entire 1 microsecond time gap. The single-photon counting detector counts all incident Raman photons in spectral and temporal order after each 1 MHz laser emission. The present application does not need spectral tuning, and performs non-repetitive single spectral measurement at MHz repetition rate, with a complete Raman span (-300 cm -1 to 4300 cm -1 ) covering the fingerprint region, the silent region, the C-H region and the O-H region, thus representing an important step in comprehensively improving sensitivity, speed and spectral span.

[0086] It should be understood that the above device is used to execute the method in the above embodiment, and the corresponding program module in the device, the implementation principle and technical effect are similar to the description in the above method, and the working process of the device can refer to the corresponding process in the above method, which will not be repeated here.

[0087] Based on the method in the above embodiment, the present embodiment provides an electronic device, which can include a processor (Processor), a communications interface (Communications Interface), a memory (Memory) and a communication bus, wherein the processor, the communications interface and the memory complete mutual communication through the communication bus. The processor can call the logical instructions in the memory to execute the method in the above embodiment.

[0088] In addition, the logic instructions in the memory described above can be implemented in the form of a software function unit and sold or used as an independent product, and can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or say the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application.

[0089] Based on the method in the above embodiments, the embodiments of the present application provide a computer readable storage medium, which stores a computer program, and when the computer program runs on a processor, the processor executes the method in the above embodiments.

[0090] Based on the method in the above embodiments, the embodiments of the present application provide a computer program product, and when the computer program product runs on a processor, the processor executes the method in the above embodiments.

[0091] It can be understood that the processor in the embodiments of the present application can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. The general-purpose processor can be a microprocessor or any conventional processor.

[0092] The method steps in the embodiments of the present application can be implemented by means of hardware, or by means of a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in a Random Access Memory (RAM), a flash memory, a Read-only Memory (ROM), a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically EPROM (EEPROM), a register, a hard disk, a mobile hard disk, a CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor, so that the processor can read information from the storage medium, and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can be located in an ASIC.

[0093] In the above embodiments, all or part of the embodiments can be implemented by means of software, hardware, firmware, or any combination thereof. When implemented by means of software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium or transmitted by means of the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by means of a wire (such as coaxial cable, optical fiber, Digital Subscriber Line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. that includes one or more available media sets. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), optical media (such as DVD), or semiconductor media (such as Solid State Disk (SSD)), etc.

[0094] It can be understood that the various numerical numbers involved in the embodiments of the present application are only for the convenience of differentiation, and do not limit the scope of the embodiments of the present application.

[0095] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A SiPM photon counting method, characterized in that, include: Extract the peak values ​​from the detected analog voltage signal; Compare the amplitude of each peak with the preset amplitude to identify peaks with and without photons; For each photon peak, calculate the difference between the peak amplitude and the amplitude at the start of the photon response. Round the difference to the nearest integer multiple of the single-photon pulse height to get the number of photons at the peak. The start of the photon response is the peak time minus the response time of the photon detection device.

2. The photon counting method as described in claim 1, characterized in that, If the amplitude of an analog voltage signal at a certain moment is greater than the amplitude at adjacent moments, it is considered a peak value.

3. The photon counting method as described in claim 1, characterized in that, If the peak amplitude is greater than the preset amplitude, it is considered a photon peak; otherwise, it is considered a no-photon peak. .

4. A single-photon detection device, characterized in that, This includes a SiPM-based single-photon detector and a signal processing module; A single-photon detector based on SiPM is used to detect photon pulse events using SiPM to obtain an analog voltage signal; The signal processing module includes: at least one memory for storing programs; At least one processor is configured to access a program stored in the memory, wherein, when the program stored in the memory is accessed, the processor is configured to access the photon counting method as described in any one of claims 1 to 3.

5. A rapid spectral and imaging system based on a single-photon detection device, characterized in that, Includes a laser, an imaging microscope, a beam splitter, n input optical fibers, a transmission fiber optic spectrometer, and the single-photon detection device as described in claim 4; The laser emits a pulsed laser beam, which is focused onto the sample under test by an imaging microscope to generate a spectral signal. The spectral signal returns along the original path and is split into n polychromatic lights by a beam splitter. The center wavelength of the i-th polychromatic light is greater than the center wavelength of the (i+1)-th polychromatic light, and adjacent polychromatic light bands are adjacent and of equal length. The i-th input fiber is connected to the i-th fiber interface, and the i-th polychromatic light is input into the transmission fiber optic spectrometer. The n input optical fibers are multimode optical fibers of different lengths, and the length difference between any two adjacent input optical fibers is greater than that of the longest fiber in the multimode optical fiber array. The transmission fiber optic spectrometer is used to spatially separate polychromatic light of each band according to wavelength, and couple photons of different wavelengths into the fiber array for delay, delaying different wavelengths to different times and outputting them to the single photon detection device. The single-photon detection device is used to convert photons of different wavelengths that arrive at different times into electrical signals. After amplification and signal processing, the number of photons at different times is obtained and converted into a spectrum.

6. The rapid spectroscopy and imaging system as described in claim 5, characterized in that, The transmission fiber optic spectrometer includes: multiple fiber optic interfaces, multiple collimating elements, a single transmission grating, a focusing element, and a multimode fiber array; the focusing element is parallel to the multimode fiber array and faces the transmission grating. The i-th polychromatic light is incident on the i-th collimating element through the i-th fiber interface, and after collimation, it is projected onto the transmission grating. The projected light spots of all channels of polychromatic light on the transmission grating completely overlap. The center wavelength of the i-th polychromatic light is greater than the center wavelength of the (i+1)-th polychromatic light, and adjacent polychromatic light bands are adjacent and of equal length. , Number of fiber optic interfaces ; The transmission grating spatially separates the signals of different wavelengths in the polychromatic light of each channel and focuses them onto the multimode fiber array through a focusing element. After the polychromatic light band of each channel is diffracted by the transmission grating, the diffracted light does not exceed the range of the multimode fiber array. In a multimode fiber array, the length difference between adjacent fibers remains constant, delaying light of different wavelengths to different times, and then focusing them into a bundle for output. There is a specific angle between the output beam of the i-th fiber interface and the output beam of the (i+1)-th fiber interface. The specific angle is the angle between the beams of the diffracted light focused on the left and right ends of the multimode fiber array.

7. The rapid spectroscopy and imaging system as described in claim 5, characterized in that, The transmission fiber optic spectrometer includes: multiple fiber optic interfaces, multiple collimating elements, a single reflective element, a single transmission grating, a focusing element, and a multimode fiber array; the focusing element is parallel to the multimode fiber array and faces the transmission grating. The i-th polychromatic light is incident on the i-th collimating element through the i-th fiber interface, then projected onto the reflecting element, and finally reflected onto the transmission grating. The projected light spots of all channels of polychromatic light on the transmission grating completely overlap. The center wavelength of the i-th polychromatic light is greater than the center wavelength of the (i+1)-th polychromatic light, and adjacent polychromatic light bands are adjacent and of equal length. Number of fiber optic interfaces ; The transmission grating spatially separates the signals of different wavelengths in the polychromatic light of each channel and focuses them onto the multimode fiber array through a focusing element. After the polychromatic light band of each channel is diffracted by the transmission grating, the diffracted light does not exceed the range of the multimode fiber array. In a multimode fiber array, the length difference between adjacent fibers remains constant, delaying light of different wavelengths to different times, and then focusing them into a bundle for output. There is a specific angle between the output beam of the i-th fiber interface and the output beam of the (i+1)-th fiber interface. The specific angle is the angle between the beams of the diffracted light focused on the left and right ends of the multimode fiber array.

8. The rapid spectroscopy and imaging system as described in claim 6 or 7, characterized in that, The transmission fiber optic spectrometer also includes an electrically driven translation stage, used to translate the multimode fiber array bundle multiple times along the multimode fiber alignment direction, with each translation distance being [distance to be filled in]. Fiber core diameter, used to measure optical signals at different locations. The number of translations.

9. The rapid spectroscopy and imaging system as described in claim 5, characterized in that, The signal processing module is also used to interpolate the spectral intensities collected when the fiber array bundle is in different positions.

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