Single-photon detection device and rapid spectrum and imaging system based on same

Abstract

The invention belongs to the field of spectral measurement and imaging, and particularly discloses a single-photon detection device and a rapid spectrum and imaging system based on the single-photon detection device. According to the invention, the transmission-type optical fiber spectrometer separates polychromatic light of each wave band in space according to the wavelength, couples photons of different wavelengths into the optical fiber array for time delay, delays different wavelengths to different moments, and outputs the time to the single-photon detection device; the single-photon detection device converts photons of different wavelengths which arrive in time in sequence into electric signals, the number of photons at different moments is obtained after amplification and signal processing, and the photons are converted into spectrums. As the transmission-type spectrometer can provide higher diffraction efficiency, higher spectral resolution and higher signal intensity, and the single-photon detection device can provide a faster and more accurate photon discrimination and photon counting method, compared with the prior art, the spectrum can be measured more quickly on the whole, and higher spectral resolution and higher signal intensity are achieved.

Description

Technical Field

[0001] The present application belongs to the field of spectral measurement and imaging, and more specifically, to a single-photon detection device and a rapid spectral and imaging system based thereon. Background Art

[0002] Patent CN115165101A discloses a single-photon sensitive ultrafast spectral measurement system. On the one hand, the single-photon detector used is a silicon photomultiplier tube or SiPM or an avalanche diode array or other single-photon detector array, which can avoid dead time and improve sensitivity. However, SiPM has a lot of dark noise and a low signal-to-noise ratio; signal sensitivity is easily interfered by external noise; when multiple photons are incident continuously, it is difficult to distinguish the number of photons after signal superposition; on the other hand, the spectrometer used is a reflective type, integrating two input optical fibers and an optical fiber array together, and the two sections of optical fiber input are input in parallel at the same end and a certain distance apart. Only one of the two bands is on the optical axis, which will inevitably lead to spherical aberration in the other band, affecting the signal intensity and spectral resolution; in addition, at this time, the diffraction grating must have an angle to meet the requirement that the incident light and the diffracted light are on the same optical path. In order to be able to rotate the grating to view different bands, only a reflective grating that is insensitive to the incident angle can be used, resulting in a low grating diffraction efficiency.

[0003] In order to solve 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, which leads to a huge amount of calculation. On the other hand, the peak fitting method has a certain deviation from the actual peak value, and overshoot will be generated during the processing of this method, which reduces the amplitude of subsequent photons when photons arrive continuously, resulting in inaccurate photon counting results.

[0004] In view of the defects of reflective spectrometers, transmission spectrometers have been proposed. However, these transmission spectrometers can only input one band, cannot separate more bands in time, and cannot detect a wider spectral range. Summary of the invention

[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 spectroscopy and imaging system based thereon, aiming to solve the problems of limited sensitivity, speed and spectral span of existing spectral measurements.

[0006] A first aspect of the present application relates to a SiPM photon counting method, comprising: Extracting peak values ​​from the detected analog voltage signal; Compare the amplitude of each peak with the preset amplitude to identify the peak with photons and the peak without photons; For each photon peak, the difference between the peak amplitude and the amplitude at the start time of the photon response is calculated, and the multiple of the amplitude difference and the single-photon pulse height is taken as the number of photons at the peak moment.

[0007] Preferably, if the amplitude of the analog voltage signal at a certain moment is simultaneously greater than the amplitude at adjacent moments, it is identified as a peak value.

[0008] Preferably, if the peak amplitude is greater than a preset amplitude, it is identified as a photon peak, otherwise, it is identified as a photon-free peak, and the preset amplitude range is (1 / 10 single-photon pulse height, single-photon pulse height).

[0009] Preferably, for each photon peak, the amplitude difference between the peak amplitude and the amplitude at the start time of the photon response is calculated, and the amplitude difference and the multiple of the single-photon pulse height are rounded up to the nearest integer as the number of photons at the peak moment, and the start time of the photon response is the peak moment minus the response time of the photon detection device.

[0010] A 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; A SiPM-based single photon detector for detecting photon pulse events using SiPM to obtain an analog voltage signal; The signal processing module includes: at least one memory for storing programs; and at least one processor for entering the program stored in the memory. 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.

[0011] 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 multimode fiber array; the focusing element is parallel to the multimode fiber array and directly faces the transmission grating; The i-th complex light is incident on the i-th collimating element through the i-th optical fiber interface, and is projected onto the transmission grating after being collimated, and the projection spots of the complex lights of all channels on the transmission grating completely overlap, the central wavelength of the i-th complex light is greater than the central wavelength of the (i+1)-th complex light, and the adjacent two complex light bands are adjacent and of equal length, , is the number of optical fiber interfaces, ; The transmission grating separates the signals of different wavelengths in the polychromatic light of each channel in space and focuses them onto the multimode optical fiber array through the 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 optical fiber array. The length difference between adjacent optical fibers in a multimode optical fiber array is kept constant, and light of different wavelengths is delayed to different times, gathered into bundles and output; There is a specific angle between the output light beam of the i-th optical fiber interface and the output light beam of the (i+1)-th optical fiber interface, and the specific angle is the angle of the light beams focused by the diffracted light to the left and right ends of the multimode optical fiber array.

[0012] 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 reflection element, a single transmission grating, a focusing element and a multimode fiber array; the focusing element is parallel to the multimode fiber array and directly faces the transmission grating; The i-th complex light is incident on the i-th collimating element through the i-th optical fiber interface, and is projected to the reflecting element after collimation, and then reflected to the transmission grating, and the projection spots of the complex lights of all channels on the transmission grating completely overlap, the central wavelength of the i-th complex light is greater than the central wavelength of the (i+1)-th complex light, and the adjacent two complex light bands are adjacent and of equal length, is the number of optical fiber interfaces, ; The transmission grating separates the signals of different wavelengths in the polychromatic light of each channel in space and focuses them onto the multimode optical fiber array through the 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 optical fiber array. The length difference between adjacent optical fibers in a multimode optical fiber array is kept constant, and light of different wavelengths is delayed to different times, gathered into bundles and output; There is a specific angle between the output light beam of the i-th optical fiber interface and the output light beam of the (i+1)-th optical fiber interface, and the specific angle is the angle of the light beams focused by the diffracted light to the left and right ends of the multimode optical fiber array.

[0013] Preferably, the transmission type optical fiber spectrometer further comprises an electric translation stage for translating the multimode optical fiber array bundle multiple times along the multimode optical fiber arrangement direction, and the distance of each translation is Fiber core diameter to measure optical signals at different locations, is the number of translations.

[0014] A fifth aspect of the present application relates to a rapid spectroscopy and imaging system based on a single-photon detection device, comprising a laser, an imaging microscope, a spectroscopic element, n input optical fibers, a transmission optical fiber spectrometer as described above, and a single-photon detection device; The laser emits a pulsed laser beam, which is focused on the sample to be tested by an imaging microscope to generate a spectral signal. The spectral signal returns along the original path and is split into n complex light beams by a beam splitter. The central wavelength of the i-th complex light beam is greater than the central wavelength of the (i+1)-th complex light beam, and the wavelength bands of two adjacent complex light beams are adjacent and of equal length. The i-th input optical fiber is connected to the i-th optical fiber interface to input the i-th complex light into the transmission optical fiber spectrometer; The n input optical fibers are multimode optical fibers of different lengths, and the length difference between two adjacent input optical fibers is greater than the longest optical fiber in the multimode optical fiber array; The transmission fiber spectrometer is used to separate the polychromatic light of each band in space according to the wavelength, and couple the photons of different wavelengths into the fiber array for delay, delay the different wavelengths to different times, and output them to the single photon detection device; The single-photon detection device is used to convert photons of different wavelengths that arrive successively in time into electrical signals, and after amplification and signal processing, the number of photons at different times is obtained and converted into a spectrum.

[0015] Preferably, the signal processing module is further used to perform interpolation processing on the spectral intensities collected when the optical fiber array bundle is at different positions.

[0016] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: (1) This application proposes a SiPM photon counting method. On the one hand, by extracting the peak value in the analog signal and comparing the peak amplitude with the preset amplitude, the data points with photons are screened out, and only the photon peak is counted, which greatly reduces the amount of data calculation and greatly improves the processing speed. On the other hand, by calculating the difference between the peak amplitude and the amplitude at the start of the photon response, the amplitude difference and the multiple of the single photon pulse height are used as the number of photons at the peak moment. This direct linear judgment method removes the influence of the peak change caused by fitting, and the peak value obtained is the actual peak value. Therefore, the accuracy is improved. Under the premise of the same data size, the method proposed in this application increases the counting speed by about 250 times and the accuracy by 20% compared with the deconvolution method.

[0017] (2) The present application proposes a single-photon detection device that combines a SiPM-based single-photon detector with the above-mentioned photon counting method. Taking into account the multi-photon detection characteristics of the SiPM-based single-photon detector, the counting method can quickly and accurately distinguish multiple photons that arrive at the same time.

[0018] (3) The present application proposes a multi-channel single-grating transmission fiber spectrometer, in which multiple input optical fibers are separated from the optical fiber array. The optical fiber interfaces to which adjacent input optical fibers are connected have a specific angle, and a transmission grating is shared after collimation. The specific angle is the angle of the diffracted light focused onto the light beams at the left and right ends of the multimode optical fiber array, which can ensure that different bands are on the optical axis at the same time, thereby eliminating spherical aberration, improving spectral resolution and signal strength, and realizing full-band spectral detection. Compared with reflective gratings, transmission gratings have higher diffraction efficiency. There are specific requirements for the placement of transmission gratings, which must ensure that the projected light spots of complex light of different bands on the transmission grating completely overlap, thereby ensuring that each band passes through the transmission grating. The diffracted light can be focused into the multimode fiber array through the lens; the diffracted light of the complex light band after diffraction by the transmission grating is required not to exceed 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 equal difference length and the single photon detection device are used instead of CCD to improve the sensitivity of photon detection and the accuracy of photon counting, and the spectrum measurement speed is increased by more than three orders of magnitude through the method of delayed detection of the spectrum by the multimode fiber array; the present application adopts the method of connecting the input multimode fiber with an optical fiber interface to introduce complex light. Compared with the slit incidence, the input end is circular, which reduces the entry of other background light outside the signal, improves the signal-to-noise ratio, and is more convenient when the optical fiber is connected to external equipment.

[0019] (4) This application proposes a fast spectroscopy and imaging system. The transmission spectrometer can provide higher diffraction efficiency, higher spectral resolution and signal intensity. The single-photon detection device can provide a faster and more accurate photon discrimination and photon counting method. Compared with the existing technology, the overall system can measure the spectrum more quickly and has higher spectral resolution and signal intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of a rapid spectroscopy and imaging system based on a single-photon detection device provided in an embodiment of the present application.

[0021] Figure 2 It is a schematic diagram of the structure of a multi-channel single-grating transmission fiber optic spectrometer provided in an embodiment of the present application.

[0022] Figure 3 This is a schematic diagram of the structure of a multi-channel single-grating transmission fiber optic spectrometer provided in an embodiment of the present application.

[0023] Figure 4 It is a schematic diagram of the structure of a single-photon detection device provided in an embodiment of the present application.

[0024] Figure 5 It is a schematic diagram of the photon counting results provided in the embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] The term "and / or" in this application is a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. The symbol " / " in this application indicates that the associated objects are in an or relationship, for example, A / B means A or B.

[0027] The terms "first" and "second" in the specification and claims of this application are used to distinguish different objects rather than to describe a specific order of objects. For example, a first response message and a second response message are used to distinguish different response messages rather than to describe a specific order of response messages.

[0028] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0029] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more than two. For example, multiple processing units refer to two or more processing units, etc.; multiple elements refer to two or more elements, etc.

[0030] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0031] like Figure 1 As shown, the present application discloses a rapid spectroscopy and imaging system based on a single-photon detection device, including a laser, an imaging microscope, a spectroscopic element, n input optical fibers, a transmission optical fiber spectrometer and a single-photon detection device.

[0032] The laser emits a pulsed laser, which is focused onto the sample under test through an imaging microscope to generate a spectral signal. The spectral signal returns along the original path and is split into n complex lights by a spectroscopic element. The central wavelength of the i-th complex light is greater than the central wavelength of the (i+1)-th complex light, and two adjacent complex light bands are adjacent and of equal length.

[0033] The i-th input optical fiber is connected to the i-th optical fiber interface to input the i-th complex light into the transmission optical fiber spectrometer.

[0034] The n input optical fibers are multimode optical fibers with different lengths, and the length difference between two adjacent input optical fibers is greater than the longest optical fiber in the multimode optical fiber array.

[0035] The transmission fiber spectrometer is used to separate the complex light of each band in space according to the wavelength, and couple the photons of different wavelengths into the fiber array for delay, delay the different wavelengths to different times, and output them to the single photon detection device.

[0036] The single-photon detection device is used to convert photons of different wavelengths that arrive successively in time into electrical signals, and after amplification and signal processing, the number of photons at different times is obtained and converted into a spectrum.

[0037] The working process of the rapid spectroscopy and imaging system is as follows: a laser emits a laser beam, which passes through a first dichroic mirror, is scanned by a two-dimensional galvanometer and a third lens group, and is focused on a sample to be tested to generate a spectral signal, and the spectral signal is returned by the original path; a second dichroic mirror is placed on the returning signal light path to split the signal light into two equal and adjacent bands; after the laser background is removed by a filter, the signal of each band is focused into an input optical fiber through a first lens, and the optical fiber is input into a transmission spectrometer, and the split signal enters an optical fiber array bundle, is combined and output to a single-photon detection device for processing to obtain a spectrum.

[0038] like Figure 2 As shown, the present application discloses 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 multimode fiber array; the focusing element is parallel to the multimode fiber array and directly faces the transmission grating; The i-th complex light is incident on the i-th collimating element through the i-th optical fiber interface, and is projected onto the transmission grating after being collimated, and the projection spots of the complex lights of all channels on the transmission grating completely overlap, the central wavelength of the i-th complex light is greater than the central wavelength of the (i+1)-th complex light, and the adjacent two complex light bands are adjacent and of equal length, , is the number of optical fiber interfaces, ; The transmission grating separates the signals of different wavelengths in the polychromatic light of each channel in space and focuses them onto the multimode optical fiber array through the 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 optical fiber array. The length difference between adjacent optical fibers in a multimode optical fiber array is kept constant, and light of different wavelengths is delayed to different times, gathered into bundles and output; There is a specific angle between the output light beam of the i-th optical fiber interface and the output light beam of the (i+1)-th optical fiber interface, and the specific angle is the angle of the light beams focused by the diffracted light to the left and right ends of the multimode optical fiber array.

[0039] 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 one embodiment, the optical fiber interface is located at the front focus of the collimating lens, the distance between the focusing lens and the transmission grating is as small as possible, and the multimode optical fiber array is located at the back focus of the focusing lens.

[0040] Preferably, the collimating lens is an achromatic lens.

[0041] The working process of the multi-channel single-grating transmission fiber spectrometer is as follows: the optical signals of different bands are input through the optical fiber and collimated by the lens, and then hit the transmission grating and the light spots overlap. The diffracted light signal is focused by the lens, and the signals of different wavelengths are focused at different positions of the optical fiber array, and then input into the single-photon detection device for detection. Among them, there are multiple optical fiber inputs at the input end, each optical fiber inputs a different wavelength, and the two adjacent optical fibers are placed at a specific angle to hit the light spot at the same position of the transmission grating. Since the wavelengths of the two adjacent bands of light signals are different, their diffraction angles are different. The specific angle of the two segments of light signals just makes up for the difference in diffraction angles, so that the two segments of signals are spatially focused on the same optical fiber array.

[0042] like Figure 3 As shown, the present application discloses a multi-channel single grating transmission fiber spectrometer, comprising: a plurality of fiber interfaces, a plurality of collimating elements, a single reflection element, a single transmission grating, a focusing element and a multimode fiber array; the focusing element is parallel to the multimode fiber array and directly faces the transmission grating; The i-th complex light is incident on the i-th collimating element through the i-th optical fiber interface, and is projected to the reflecting element after collimation, and then reflected to the transmission grating, and the projection spots of the complex lights of all channels on the transmission grating completely overlap, the central wavelength of the i-th complex light is greater than the central wavelength of the (i+1)-th complex light, and the adjacent two complex light bands are adjacent and of equal length, is the number of optical fiber interfaces, ; The transmission grating separates the signals of different wavelengths in the polychromatic light of each channel in space and focuses them onto the multimode optical fiber array through the 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 optical fiber array. The length difference between adjacent optical fibers in a multimode optical fiber array is kept constant, and light of different wavelengths is delayed to different times, gathered into bundles and output; There is a specific angle between the output light beam of the i-th optical fiber interface and the output light beam of the (i+1)-th optical fiber interface, and the specific angle is the angle of the light beams focused by the diffracted light to the left and right ends of the multimode optical fiber array.

[0043] It should be noted that Figure 3 and Figure 2 The difference is that a reflective element is added in front of the transmission grating, which can fold the light path and make the spectrometer more compact. The reflective element includes but is not limited to a reflector.

[0044] Preferably, the transmission type optical fiber spectrometer further comprises an electric translation stage for translating the multimode optical fiber array bundle multiple times along the multimode optical fiber arrangement direction, and the distance of each translation is Fiber core diameter to measure optical signals at different locations, is the number of translations.

[0045] The electric translation stage is used to fine-tune the position of the optical fiber bundle during measurement, so as to make multiple measurements between two adjacent optical fibers, increase the number of measurement points after interpolation, and thus improve the spectral resolution. It should be noted that the present application preferably uses an electric translation stage to move the multimode optical fiber array, and translates multiple times along the multimode optical fiber arrangement direction, with each translation distance being Fiber core diameter. This can increase the number of sampling points by N times within the same spectral range, so that photons in the fiber gaps can also be measured, improving spectral resolution.

[0046] like Figure 4 As shown, the present application discloses a single-photon detection device, including 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 includes: at least one memory for storing programs; at least one processor for entering the program stored in the memory, when the program stored in the memory is entered, the processor is used to enter the photon counting method described below, including: extracting each peak value in the detected analog voltage signal; comparing each peak amplitude with a preset amplitude to identify photon peaks and non-photon peaks; for each photon peak, calculating the difference between the peak amplitude and the amplitude at the start time of the photon response, and taking the amplitude difference and the multiple of the single-photon pulse height as the number of photons at the peak time.

[0047] Preferably, if the amplitude of the analog voltage signal at a certain moment is greater than the amplitude at adjacent moments, it is identified as a peak. It should be noted that the present application preferably identifies the case where the voltage amplitude is greater than the amplitude at adjacent moments as a peak, and compared with other peak determination methods, no photons will be missed.

[0048] Preferably, if the peak amplitude is greater than the preset amplitude, it is identified as a photon peak, otherwise, it is identified as a photon-free peak, and the preset amplitude value range is (1 / 10 single-photon pulse height, single-photon pulse height). It should be noted that the present application preferably identifies photon pulse heights exceeding a certain proportion as photon peaks. Compared with other photon determination methods, noise will not be mistakenly determined as photons, further excluding peaks without photons, and reducing the amount of subsequent data calculations. It should be noted that the higher the background noise, the higher the preset amplitude selected to eliminate the interference of noise on photon counting.

[0049] Preferably, for each photon peak, the difference between the peak amplitude and the amplitude at the start time of the photon response is calculated, and the amplitude difference is rounded to the nearest integer as a multiple of the single-photon pulse height as the number of photons at the peak moment, and the photon response start time is the peak moment minus the response time of the photon detection device. It should be noted that the present application preferably determines the start time of the photon response based on the peak moment and the response time of the photon detection device, and the difference between the peak amplitudes of the two is taken as a multiple of the single-photon pulse height as the number of photons, avoiding the problem of inaccurate fitting peak of the deconvolution method and the interference of overshoot generated during its processing, accurately obtaining the actual amplitude of the photon pulse, and making the photon counting more accurate.

[0050] Preferably, the signal processing module is also used to interpolate the spectral intensities collected when the optical fiber array bundle is at different positions. It should be noted that the present application measures spectral signals at different positions multiple times and interpolates multiple groups of spectral data to increase the spectral sampling rate and thus improve the spectral resolution.

[0051] Since the multimode optical fiber of the optical fiber array is circular, there are gaps between the optical fibers, resulting in signal waste. In this application, the electric translation stage is moved, and the signal interpolation method is inserted after multiple measurements, which significantly improves the spectral resolution. Specifically, the electric translation stage moves N times, and since each optical fiber in the optical fiber array bundle can eventually obtain a spectral intensity data, the a before movement is obtained. 1 , a 2 , a 3 ...; obtain the second set of data b by moving the electric translation stage (the moving distance is 1 / (N+1) the fiber core diameter) 1 , b 2 , b 3 …; Move the electric translation stage again to obtain the third set of data c 1 , c 2 , c 3 ...; finally obtain a through interpolation 1 , b 1 , c 1 , a 2 , b 2 , c2 , a 3 , b 3 , c 3 ….

[0052] Preferably, the single-photon detection device also includes: a refrigeration device, whose cooling surface is in contact with the SiPM chip and the circuit part, and is used to cool the chip and the circuit, so that the SiPM chip operates in an ambient temperature of -100°C to -20°C, thereby greatly reducing the dark noise of the chip and improving the sensitivity of photon detection; a water-cooled heat sink is arranged on the bottom surface of the refrigeration device, and is used to dissipate heat and cool the refrigeration device to ensure the operation of the refrigeration device.

[0053] Preferably, the single-photon detection device also includes: an electromagnetic shielding structure, a packaged chip and circuit, a power supply, a refrigeration device, a water-cooled heat dissipation device, etc., which are used to shield external electromagnetic interference and radiation noise during the single-photon detection process of the SiPM chip, thereby improving the sensitivity of the chip during detection.

[0054] Preferably, the single photon detection device further comprises: a signal amplification module, which is used to amplify the photocurrent output by the SiPM chip and transmit it to the signal processing module.

[0055] 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 electrical signal amplifies the photocurrent to a detectable level through the signal amplification module, and then the signal processing module counts the optical pulse signal, distinguishes the number of photons arriving at each moment, and obtains the photon count measured along the time sequence. Among them, the refrigeration device and the water-cooling heat dissipation device reduce the dark noise of the SiPM chip to a very low level to avoid interference with the single photon counting, and the electromagnetic shielding structure prevents other external electromagnetic disturbances from interfering with signal detection.

[0056] like Figure 5 As shown, the upper part represents the collected analog voltage signal Raw data, and multiple peaks appear on its continuous waveform. The lower part adopts the photon counting method proposed in this application. DDS is the number of photons obtained at each peak moment. Its essence is a digital signal, and 1 count represents one photon count.

[0057] 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 for 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 -1, ten orders of magnitude smaller than fluorescence), Raman spectroscopy has long been known for weak signals and low throughput. In 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 typically deploy deeply cooled (in liquid nitrogen) charge-coupled devices (CCDs) to reduce dark noise to negligible levels. However, they suffer from 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 leading alternatives to CCDs. However, they are only suitable for low-light applications, with a dynamic range limited to one photon for a single-frame exposure. The noise floor has been reduced to negligible levels for the latest photomultiplier tubes (PMTs) and single-photon avalanche diode (SPAD) arrays, which mostly operate in photon counting and gated modes. However, these photon-counting detectors respond to only one photon per laser shot and are blinded by inherent dead time. Recently, the emerging time-stretched dispersive Fourier transform (TS-DFT) has achieved Raman band measurements up to MHz by using dispersion chirps in long single-mode dispersive fibers. However, all of these innovations use single-mode fibers to achieve spectral delays, which limits their dispersion capabilities to the nanosecond range. In addition, due to the high coupling losses of single-mode fibers, these methods are not suitable for full-spectrum Raman imaging of highly scattering biological tissues.

[0058] The multi-channel single-grating transmission fiber spectrometer proposed in this application measures spectra including Raman, fluorescence and other spectra, especially Raman, which requires such a sensitive spectrometer. For Raman spectroscopy, this application uses a nanosecond pulse laser with a repetition rate of 1 MHz to excite the sample under test in less than 0.5 ns, and expands and measures the excited Raman spectrum in the time interval between the excitation pulses. Therefore, the laser power and the spectrum measurement time are reduced. Two multimode optical fibers with a large inner core of 100 µm and a numerical aperture (NA) of 0.22 are arranged to collect the first Raman band (Band I: -300 cm) covering the fingerprint area and the quiet area. -1 Up to 2000 cm -1 ), and a second Raman band covering the quiet region, CH region, and OH region (Band II: 2000 cm -1 To 4300 cm -1). In order to make full use of the time capacity, Raman photons of different colors are spatially separated by a transmission grating and coupled to a multimode fiber array assembled with different lengths, rather than a pixel array in a traditional CCD detector, to convert the transient Raman spectrum into a time waveform. The multimode fiber array includes but is not limited to the following situations: the lengths of the 160 multimode optical fibers increase uniformly by 0.6 meters in an arithmetic progression (i.e., 0.6, 1.2, 1.8, 2.4 meters...), so Raman photons of different colors can be separated by about 3 nanoseconds in the time domain (0.6 n / c; c: speed of light; n: refractive index of silica, , the specific value varies with morphology and wavelength). Therefore, the spectral range achievable by a single channel spans 160 × 3 = 480 nanoseconds, while the spectral span of two channels covering two Raman bands will be 960 nanoseconds, almost occupying the entire 1 microsecond time interval. The single-photon counting detector counts all incident Raman photons in spectral and temporal order after each 1 MHz laser emission. This application does not require spectral tuning and performs non-repetitive single-shot spectral measurements at a MHz repetition rate. Its full Raman span (-300 cm -1 To 4300 cm -1 ) covers the fingerprint, silent, CH and OH regions, thus representing a major step forward in overall improvement of sensitivity, speed and spectral span.

[0059] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method, which will not be repeated here.

[0060] Based on the method in the above embodiment, the embodiment of the present application provides an electronic device, which may include: a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. The processor may call the logic instructions in the memory to execute the method in the above embodiment.

[0061] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0062] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0063] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0064] It is understandable that the processor in the embodiment of the present application may be a central processing unit (CPU), or 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 may be a microprocessor or any conventional processor.

[0065] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium 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.

[0066] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part 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, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions may be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)), etc.

[0067] It should be understood that the various numerical numbers involved in the embodiments of the present application are only used for the convenience of description and are not used to limit the scope of the embodiments of the present application.

[0068] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A SiPM photon counting method, characterized in that: include: Extracting peak values ​​of the detected analog voltage signal; Compare the amplitude of each peak with the preset amplitude to identify the peak with photons and the peak without photons; For each photon peak, the difference between the peak amplitude and the amplitude at the start time of the photon response is calculated, and the multiple of the amplitude difference and the single-photon pulse height is taken as the number of photons at the peak moment.

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

3. The photon counting method according to claim 1, characterized in that: If the peak amplitude is greater than the preset amplitude, it is determined to be a photon peak, otherwise, it is determined to be a photon-free peak. The preset amplitude range is (1 / 10 single-photon pulse height, single-photon pulse height).

4. The photon counting method according to claim 1, characterized in that: For each photon peak, the amplitude difference between the peak amplitude and the starting time of the photon response is calculated, and the amplitude difference and the multiple of the single-photon pulse height are rounded up to the nearest integer as the number of photons at the peak moment. The starting time of the photon response is the peak moment minus the response time of the photon detection device.

5. A single photon detection device, characterized in that: Includes SiPM-based single-photon detector and signal processing module; A SiPM-based single photon detector for detecting photon pulse events using SiPM to obtain an analog voltage signal; The signal processing module includes: at least one memory for storing a program; At least one processor is used to enter 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 according to any one of claims 1 to 4.

6. A multi-channel single grating transmission fiber spectrometer, characterized in that: include: Multiple fiber interfaces, multiple collimation elements, single transmission gratings, focusing elements, and multimode fiber arrays; The focusing element is parallel to the multimode optical fiber array and directly faces the transmission grating; The i-th complex light is incident on the i-th collimating element through the i-th optical fiber interface, and is projected onto the transmission grating after being collimated, and the projection spots of the complex lights of all channels on the transmission grating completely overlap, the central wavelength of the i-th complex light is greater than the central wavelength of the (i+1)-th complex light, and the adjacent two complex light bands are adjacent and of equal length, , is the number of optical fiber interfaces, ; The transmission grating separates the signals of different wavelengths in the polychromatic light of each channel in space and focuses them onto the multimode optical fiber array through the 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 optical fiber array. The length difference between adjacent optical fibers in a multimode optical fiber array is kept constant, and light of different wavelengths is delayed to different times, gathered into bundles and output; There is a specific angle between the output light beam of the i-th optical fiber interface and the output light beam of the (i+1)-th optical fiber interface, and the specific angle is the angle of the light beams focused by the diffracted light to the left and right ends of the multimode optical fiber array.

7. A multi-channel single grating transmission fiber spectrometer, characterized in that: include: Multiple fiber interfaces, multiple collimating elements, a single reflective element, a single transmissive grating, a focusing element, and a multimode fiber array; The focusing element is parallel to the multimode optical fiber array and directly faces the transmission grating; The i-th complex light is incident on the i-th collimating element through the i-th optical fiber interface, and is projected to the reflecting element after collimation, and then reflected to the transmission grating, and the projection spots of the complex lights of all channels on the transmission grating completely overlap, the central wavelength of the i-th complex light is greater than the central wavelength of the (i+1)-th complex light, and the adjacent two complex light bands are adjacent and of equal length, is the number of optical fiber interfaces, ; The transmission grating separates the signals of different wavelengths in the polychromatic light of each channel in space and focuses them onto the multimode optical fiber array through the 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 optical fiber array. The length difference between adjacent optical fibers in a multimode optical fiber array is kept constant, and light of different wavelengths is delayed to different times, gathered into bundles and output; There is a specific angle between the output light beam of the i-th optical fiber interface and the output light beam of the (i+1)-th optical fiber interface, and the specific angle is the angle of the light beams focused by the diffracted light to the left and right ends of the multimode optical fiber array.

8. The transmission type optical fiber spectrometer according to claim 6 or 7, characterized in that: The transmission type optical fiber spectrometer also includes an electric translation stage for translating the multimode optical fiber array bundle multiple times along the multimode optical fiber arrangement direction, and the distance of each translation is Fiber core diameter to measure optical signals at different locations, is the number of translations.

9. A fast spectroscopy and imaging system based on a single-photon detection device, characterized in that: It comprises a laser, an imaging microscope, a spectroscopic element, n input optical fibers, a transmission optical fiber spectrometer according to any one of claims 6 to 8, and a single photon detection device according to claim 5; The laser emits a pulsed laser beam, which is focused on the sample to be tested by an imaging microscope to generate a spectral signal. The spectral signal returns along the original path and is split into n complex light beams by a beam splitter. The central wavelength of the i-th complex light beam is greater than the central wavelength of the (i+1)-th complex light beam, and the wavelength bands of two adjacent complex light beams are adjacent and of equal length. The i-th input optical fiber is connected to the i-th optical fiber interface to input the i-th complex light into the transmission optical fiber spectrometer; The n input optical fibers are multimode optical fibers of different lengths, and the length difference between two adjacent input optical fibers is greater than the longest optical fiber in the multimode optical fiber array; The transmission fiber spectrometer is used to separate the polychromatic light of each band in space according to the wavelength, and couple the photons of different wavelengths into the fiber array for delay, delay the different wavelengths to different times, and output them to the single photon detection device; The single-photon detection device is used to convert photons of different wavelengths that arrive successively in time into electrical signals, and after amplification and signal processing, the number of photons at different times is obtained and converted into a spectrum.

10. The system according to claim 9, characterized in that The signal processing module is also used to perform interpolation processing on the spectrum intensity collected when the optical fiber array bundle is at different positions.

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