CN119469439A

CN119469439A - Optical path device of visible near infrared detector array test and calibration system

Info

Publication number: CN119469439A
Application number: CN202411208798.9A
Authority: CN
Inventors: 刘冰; 傅雨婷; 郑福
Original assignee: National Space Science Center of CAS
Current assignee: National Space Science Center of CAS
Priority date: 2024-08-30
Filing date: 2024-08-30
Publication date: 2025-02-18

Abstract

The embodiment of the disclosure discloses an optical path device of a visible near-infrared detector array test calibration system, which comprises a single photon source module, a visible light generation module and an optical focusing module, wherein the single photon source module is used for generating near-infrared photons, the visible light generation module is used for generating visible light, and the optical focusing module adopts a coaxial optical path and is used for focusing photons output by the single photon source module and visible light output by the visible light generation module to a photosensitive surface of a to-be-detected probe detector array.

Description

Light path device of visible near infrared detector array test calibration system

Technical Field

The disclosure relates to the technical field of measurement calibration, in particular to an optical path device of a visible near infrared detector array test calibration system.

Background

Single photon avalanche photodiodes are semiconductor optoelectronic devices with internal photocurrent gain, with the ability to detect extremely weak optical signals at single photon energy levels. The avalanche effect is a mechanism for causing PN junction breakdown, and utilizes the avalanche multiplication of photocurrent obtained by the impact ionization effect of photo-generated carriers in the depletion layer of the diode. When the bias voltage is high enough, the electron hole pairs generated by impact ionization can be heated by the electric field continuously and generate new hole electron pairs, then the new hole-electron pairs can be further impact ionized to generate more hole-electron pairs, the continuous impact ionization greatly increases carriers, and finally avalanche current is formed under the action of the electric field, so that the single photon avalanche photodiode works in a geiger mode (also called a single photon mode). The internal gain of the single photon avalanche photodiode in this mode can reach over 106.

However, the different parameters of the existing SPAD device are needed to be completed together by means of different measuring instruments, a universal source meter and a peripheral circuit, the precision of the universal source meter is high, the price is high, and the high precision is far beyond the requirement of a SPAD device testing system. Therefore, the development of the integrated detector test calibration system with high precision, low cost and easy operation is very significant.

Disclosure of Invention

This disclosure is provided in part to introduce concepts in a simplified form that are further described below in the detailed description. This disclosure is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

The embodiment of the disclosure provides an optical path device of a visible near-infrared detector array test calibration system, which comprises a single photon source module, a visible light generation module, an optical focusing module and a control module, wherein the single photon source module is used for generating near-infrared photons, the visible light generation module is used for generating visible light, the optical focusing module adopts a coaxial optical path and is used for focusing photons output by the single photon source module and the visible light output by the visible light generation module to a photosensitive surface of a to-be-tested probe detector array, the test calibration system comprises a high-voltage bias circuit and an array scanning module, the high-voltage bias circuit is used for providing high-voltage bias for the to-be-tested detector array, the array scanning module is used for scanning detectors in the to-be-tested detector array and outputting electric signals, the array fixing module is used for fixing the to-be-tested detector array, and the control module is used for generating performance parameters of the to-be-tested detector array based on the electric signals.

In some embodiments, the single photon source module is configured to output a pulsed single photon source, where the output laser pulses are attenuated to 0.1 photons per pulse by an adjustable attenuator.

In some embodiments, the optical focusing module comprises a microscope positioned in the XY direction and focused in the Z direction with an adjustment accuracy of 1 μm.

In some embodiments, the laser detector further comprises an aperture diaphragm, the aperture diaphragm can translate along the XY direction, the size of the aperture diaphragm is smaller than the entrance pupil of the microscope lens, and the incident angle of the laser incident on the detector array to be detected also changes along with the translation process of the aperture diaphragm.

In some embodiments, the optical focusing module comprises the first beam splitter prism and a second beam splitter prism, wherein the first beam splitter prism is arranged between the aperture diaphragm and the optical focusing module and is used for guiding laser photons or visible light to the optical focusing module, and the second beam splitter prism is arranged for guiding visible light to the first beam splitter prism.

In some embodiments, the detector array to be detected is further provided with a CCD, and the near infrared photons and visible light observed by the CCD are focused on the detector array to be detected by the same microscope lens.

In some embodiments, a CCD and illumination LEDs are used to focus the light source onto the photosensitive surface of the array to be tested prior to testing.

In some embodiments, the single photon source module receives the synchronization signals sent by the control circuit, the control module generates two paths of synchronization signals, the first path of synchronization signals couples the periodic narrow gating pulse to the detector array to be tested to drive the detector array to be tested, and the second path of synchronization signals synchronizes to the single photon source module to align the narrow gating pulse with the optical signals generated by the single photon source module.

In some embodiments, when the test calibration system is in a dark count test state, the single photon source in the light path device is in a closed state, wherein the dark count rate is generated by transmitting the obtained pulse signals to the control module by the signal extraction and identification module when the detector array to be tested is in a dark room and no light is added, counting the number of pulses of the count pulses by the control module to obtain the dark count, and generating the dark count rate based on the dark count.

In some embodiments, when the test calibration system is in a light count rate test state or a post-pulse probability test state, the single photon source in the light path device is in an on state, wherein the light count rate is generated by receiving one or more photons in the detection gate by the detector array to be tested, transmitting the obtained pulse signals to the control module by the signal extraction and discrimination in an edge latch mode, counting the number of pulses of the pulses by the control module to obtain the light count, and generating the light count rate based on the light count, wherein the post-pulse probability is generated by receiving one or more photons in the detection gate by the detector array to be tested, transmitting the obtained pulse signals to the control module by the signal extraction and discrimination in a double gate mode, counting the number of pulses of the counted pulses by the control module to obtain the post-pulse number, and generating the post-pulse probability based on the post-pulse number.

Drawings

The above and other features, advantages, and aspects of embodiments of the present disclosure will become more apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. The same or similar reference numbers will be used throughout the drawings to refer to the same or like elements. It should be understood that the figures are schematic and that elements and components are not necessarily drawn to scale.

FIG. 1 is a schematic diagram of an optical path device of a first visible near infrared detector array test calibration system provided by an embodiment of the present application;

FIG. 2 is a schematic diagram of a first visible near infrared detector array test calibration system provided by an embodiment of the present application.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure have been shown in the accompanying drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustration purposes only and are not intended to limit the scope of the present disclosure.

It should be understood that the various steps recited in the method embodiments of the present disclosure may be performed in a different order and/or performed in parallel. Furthermore, method embodiments may include additional steps and/or omit performing the illustrated steps. The scope of the present disclosure is not limited in this respect.

The term "including" and variations thereof as used herein are intended to be open-ended, i.e., including, but not limited to. The term "based on" is based at least in part on. The term "one embodiment" means "at least one embodiment," another embodiment "means" at least one additional embodiment, "and" some embodiments "means" at least some embodiments. Related definitions of other terms will be given in the description below.

It should be noted that the terms "first," "second," and the like in this disclosure are merely used to distinguish between different devices, modules, or units and are not used to define an order or interdependence of functions performed by the devices, modules, or units.

It should be noted that references to "one", "a plurality" and "a plurality" in this disclosure are intended to be illustrative rather than limiting, and those of ordinary skill in the art will appreciate that "one or more" is intended to be understood as "one or more" unless the context clearly indicates otherwise.

In view of the above problems, embodiments of the present application provide the following embodiments to solve.

Referring to fig. 1, an overall view of an optical path device of a test calibration system for a visible near-infrared detector array (the arrow in fig. 1 indicates the propagation direction of light) may include a single photon source module for generating near-infrared photons, a visible light generation module for generating visible light, and an optical focusing module for focusing photons output by the single photon source module and visible light output by the visible light generation module onto a photosensitive surface of a test detector array by using coaxial optical paths.

The test calibration system comprises a high-voltage bias circuit, an array scanning module, an array fixing module and a control module, wherein the high-voltage bias circuit is used for providing high-voltage bias for a detector array to be tested, the array scanning module is used for scanning detectors in the detector array to be tested and outputting electric signals, the array fixing module is used for fixing the detector array to be tested, and the control module is used for generating performance parameters of the detector array to be tested based on the electric signals. As an example, the visible near infrared detector array test calibration system shown in fig. 1 may include a high voltage bias circuit (1), an optical focusing module (2), an APD array scanning module (3), a signal extraction and discrimination module (4), a single photon source module (5), an FPGA control module (6), a human-computer interaction interface (7), and a TEC refrigeration module.

A single photon source module capable of generating a single photon, i.e., a single quantum of light. In the fields of quantum communications and precision measurement, single photon sources are very important. The technical effect is that single photons with high purity and high stability can be provided for experiments or tests.

The visible light generating module can generate visible light, namely light waves which can be perceived by human eyes. Visible light is necessary in many applications, such as illumination, display, and optical testing. A stable and controllable visible light source can be provided.

The optical focusing module adopts a coaxial light path design and can focus light generated by the single photon source module and the visible light generating module to a point. Coaxial optical path means that the beams propagate along the same axis, helping to improve the focusing accuracy. This allows accurate focusing of light onto the photosensitive surface of the detector array for effective testing.

A high voltage bias circuit capable of providing high voltage power to the detector array. In some photodetectors, high voltages are required to improve their performance or to perform specific tests. Thus, the required high voltage can be stably provided, and the performance of the detector array in the test process is ensured.

And the array scanning module is used for scanning each detector in the detector array and outputting corresponding electric signals. The scanning may be physically moving or electronically. The performance of each detector can thus be detected, providing data for subsequent analysis.

The array fixing module is used for fixing the detector array, ensuring the position stability in the test process and avoiding influencing the test result due to movement. Thereby ensuring stability and repeatability of the detector array during testing.

The control module is responsible for receiving the electrical signals output by the array scanning module and generating performance parameters of the detector array based on the signals. The control module may contain data processing and analysis software to evaluate the performance of the detector. Thereby providing a comprehensive assessment of detector array performance, helping to optimize design and improve performance.

A pulsed single photon source refers to a single photon source capable of outputting a single photon in the form of a pulse. The pulsed output allows accurate photon generation at specific points in time, which is important for experiments and applications requiring time resolution.

The laser pulse is a beam of light emitted by the laser in a short time, with high energy and short duration. In a single photon source, a laser pulse may be used to generate a single photon.

The adjustable attenuator may adjust the light intensity, typically for reducing the intensity of the light. The adjustable attenuator is used to reduce the number of photons in the laser pulse.

The 0.1 photon per pulse means that after the attenuator treatment, each laser pulse contains about only 0.1 photon. This is a very low photon count, meaning that on average only one tenth of the chance exists for one photon per pulse, which helps achieve accurate control at the single photon level.

Therefore, through the adjustable attenuator, the accurate control of the output of the single photon source can be realized, the number of photons in each pulse can be reduced, the noise caused by a multi-photon event can be reduced, and the signal to noise ratio of the system can be improved. By adjusting the attenuator, different experimental conditions and requirements can be adapted, and the flexibility of experiments is provided. In general, this technique can provide powerful support for precision experiments and applications requiring single photons or very low photon numbers.

Microscope-a microscope is an optical instrument used to observe minute objects or details. In optical testing and precision operation, the microscope may provide high resolution imaging.

XY positioning refers to the ability of the microscope to move in two directions (X-axis and Y-axis) in the horizontal plane. XY orientation allows the microscope to be precisely aligned with the sample or target area.

Z-direction focusing refers to the ability of a microscope to adjust in the vertical direction (Z-axis) for changing the focal length to ensure the sharpness of the image. Z-direction focusing is a key to achieving accurate focusing.

The adjustment accuracy is 1 μm, which means that the movement and adjustment of the microscope in three directions of XYZ can reach an accuracy of 1 micrometer (μm). 1 micron is equal to one thousandth of a millimeter and is a very fine scale, i.e. the system has very high positioning and focusing accuracy.

Thus, high resolution imaging can be achieved, the microscope can achieve very fine imaging, the high precision of XY positioning and Z focusing allows the microscope to be precisely aligned to the target area, ensuring the accuracy of the test or operation. The high precision of the adjustment capability enables the microscope to accommodate different samples or test conditions, providing greater flexibility. The high-precision adjusting system can ensure the repeatability of each operation and improve the reliability of experiments or tests. Quick and accurate positioning and focusing can reduce the setting time and improve the working efficiency.

The light path device further includes an aperture stop. An aperture stop is an optical element for limiting or adjusting the diameter of a light beam entering an optical system. By varying the size of the aperture, the intensity and focusing characteristics of the beam can be controlled.

Translation in the XY direction, which means that the aperture stop can be moved in the X-axis and Y-axis directions on the horizontal plane to change the incident position or shape of the light beam.

The entrance pupil of a microscope lens, which is the opening in the optical system that receives light, is typically located at the front end of the microscope lens. The aperture stop is smaller in size than the entrance pupil, meaning that it can condition the beam without completely blocking the light.

The angle of incidence refers to the angle between the light ray and the normal to the surface of the detector array to be measured. Varying the angle of incidence can affect the distribution and reflection characteristics of the light on the detector.

Therefore, the aperture diaphragm can accurately control the size of the light beam entering the system, and is beneficial to optimizing the focusing effect and the light beam quality. The aperture diaphragm is translated along the XY direction, so that the light beam can be positioned at different positions, and the method is suitable for different testing or operation requirements. Translation of the aperture stop results in a change in the angle of incidence, which can be used to study the response of the detector array to different angles of incidence, or to adjust the interaction of the beam with the detector. By precisely controlling the angle of incidence, the performance of the detector array may be more accurately tested and evaluated, especially in applications where angular dependence needs to be considered. The ability of the aperture stop to move provides a variety of experiments, allowing researchers to explore detector performance under different conditions. By adjusting the aperture stop, the beam quality and focusing characteristics of the entire optical system can be optimized, thereby improving the overall performance of the system.

The optical focusing module is responsible for focusing light of different wavelengths (e.g., laser photons and visible light) to a specific point or region.

A dichroic prism is an optical element that is capable of dividing an incident light beam by wavelength or direction. In this description, a dichroic prism is used to direct light of different wavelengths to the correct path.

And a first beam splitter prism, which is one of the optical focusing modules, disposed between the aperture stop and the optical focusing module. Its function is to direct laser photons or visible light to an optical focusing module.

And a second light-splitting prism, which is another light-splitting prism, provided at another position in the optical system for guiding the visible light to the first light-splitting prism.

Thus, by using the beam splitter prism, the optical path can be effectively managed, and the transmission of the laser photons and the visible light can be ensured to follow a predetermined path.

The use of a beam splitting prism provides a flexible way to control and adjust the optical path to accommodate different test or application requirements. By accurately directing the beam to the optical focus module, the accuracy and quality of focus can be improved. The splitting prism allows the system to process light at multiple wavelengths simultaneously, which is useful for applications where simultaneous analysis or testing of different types of light is required. By reasonably configuring the beam splitter prism, the performance of the whole optical system can be optimized, and the accuracy and reliability of the test or experiment can be improved.

A CCD (Charge-Coupled Device) is a semiconductor Device capable of converting light into an electric signal.

Thus, CCDs have high resolution and can provide clear images, which is important for accurate testing and calibration of the detector array. By focusing the visible and near infrared photons using the same microscope lens, precise alignment of the two types of light on the detector array can be ensured, thereby enabling simultaneous observation. By intensively processing the test of visible light and near infrared light, the equipment configuration and the test time can be reduced, and the test efficiency can be improved.

An illumination LED, light emitting Diode (LIGHT EMITTING Diode), is used here as a light source to provide the illumination required for testing.

Focusing refers to the process of concentrating light into a point or small area so as to precisely irradiate onto the photosensitive surface of the detector array to be measured.

The photosensitive surface of the array to be tested, which refers to the portion of the detector array that is sensitive to light, is the area that receives and converts the optical signal into an electrical signal.

Before testing, the preparation work is needed before formally testing the performance of the detector array.

Thus, the use of illumination LEDs can provide a stable and uniform light source, ensuring consistent illumination conditions on the photosurface. The light source is focused by the CCD and the illumination LED before the test, so that the photosensitive surface of the detector array to be tested can be ensured to be accurately and uniformly illuminated. The test accuracy is improved, and the variable in the test process can be reduced and the accuracy and reliability of the test result are improved by accurately controlling the illumination condition. And the test flow is optimized, and the light source focusing is carried out before the test, so that the test flow is optimized, and the smooth test is ensured. The configuration is high in adaptability, the system is allowed to adapt to different testing conditions and requirements, and the flexibility of the system is improved. By prefocusing the light source, the adjustment time in the test process can be reduced, and the test efficiency can be improved. The CCD can be used for monitoring and calibrating the focusing condition of the light source, and ensures the consistency and repeatability of the test conditions.

The combined use of CCD and illumination LED provides a high-efficiency and accurate light source control means for the light path device of the visible near infrared detector array test calibration system, which is beneficial to improving the quality and efficiency of the test.

Control circuitry, an electronic system that is responsible for generating control signals, is used to coordinate and drive the various components throughout the test system.

And the synchronous signal is used for ensuring that the operations of different parts in the system are synchronously performed.

Periodic narrow gating pulses refer to pulse signals of short duration that are periodically generated by the control module for controlling the test process of the detector array.

Coupling refers to the process of delivering a synchronization signal to the detector array under test. The transmission or reception of the signal is controlled by the gating pulse.

Therefore, through two paths of synchronous signals generated by the control module, the accurate synchronization of the operation of the detector array and the single photon source module is ensured. The synchronization mechanism allows the detector array to receive the optical signal at precise times, thereby improving the accuracy and reliability of the test. The control module can generate and manage multiple paths of synchronous signals, and the control capability of the test process is enhanced.

The system design allows independent synchronous control of the different parts, providing greater flexibility and adaptability. By means of the synchronous signals, the start and the end of the test can be accurately controlled, and the whole test flow is optimized. The synchronization mechanism helps to reduce errors caused by time dyssynchrony and ensures the accuracy of test results.

The dark count test state is a test state in which the system does not receive an external light source for measuring the noise level of the detector in the absence of light.

The off state refers to a single photon source that does not generate photons during the dark count test, i.e., does not operate.

The darkroom is a completely dark environment and is used for isolating an external light source and ensuring that the test is not interfered by the external light.

The signal extraction and discrimination module is responsible for receiving signals from the detector array and extracting and discriminating useful pulse signals therefrom.

And the control module is responsible for coordinating and controlling the testing process, including statistics and analysis data.

Pulse signal-the signal detected by the detector array, typically represented as an electrical pulse.

Dark counts, counts produced by the detector array due to noise or other non-optical signal sources in the absence of an external light source.

The dark count rate, the number of dark counts per unit time, is an important parameter in evaluating the noise level of the detector.

Thus, the dark count test allows to evaluate the noise level of the detector in the absence of light, which is crucial for testing the performance of the detector. By measuring the dark count rate, the system design can be optimized to reduce noise and improve signal to noise ratio. Dark count testing provides a method of calibrating the detector array to ensure accuracy in practical applications. The measurement of dark count rate helps to analyze and compare the performance of different detectors. By testing in the darkroom, the interference of the external light source can be controlled, and the accuracy of the test result is ensured. The control module provides a reliable method for statistics and analysis of the pulse signal to determine the dark count rate.

An optical count rate test state, a test state in which a single photon source is turned on and emits photons to a detector array for measuring the response frequency of the detector array to optical signals.

The post-pulse probability test state is a specific test state for measuring the probability that the detector will produce an additional pulse after receiving a photon, which is typically related to the post-pulse effect of the detector.

An on state, meaning that the single photon source is operating during a light count rate test or a post pulse probability test, producing photons.

The detector array under test, referred to as the detector array under test, will respond to the photon signal and generate an electrical pulse.

A detection gate, a window of time defined in the test, and a detector array responsive to the photon signal only during that time.

Signal extraction and discrimination is responsible for receiving signals from the detector array and extracting and discriminating useful pulse signals therefrom.

The edge latch mode uses the edge (rising edge or falling edge) of the signal to trigger the latch, thereby capturing and transmitting the pulse signal.

The double gating method, which uses two time gates to determine whether a pulse signal is within a specific time window, is commonly used to measure the post-pulse probability.

Light counts, the number of photons received by the detector array within the detection gate.

The light count rate, the number of light counts per unit time, is an important parameter in assessing the response frequency of the detector array to light signals.

Post pulse count, the number of additional pulses generated after the detector array receives a photon in the detection gate.

The probability of the rear pulse, the ratio of the number of rear pulses to the total light count, is used to evaluate the rear pulse effect of the detector.

Thus, by controlling the single photon source on and off, measurements of dark counts and light counts, respectively, can be made to more accurately assess the performance of the detector. The light count rate and the post-pulse probability are key parameters for evaluating the performance of the detector, and help to understand the sensitivity and reliability of the detector. The edge latch approach and the double gating approach provide an efficient signal processing technique that ensures that only the signal that meets the conditions is counted.

Referring to fig. 2, the near infrared detector array test calibration system may include a high voltage bias circuit (1), an optical focusing module (2), an APD array scanning module (3), a signal extraction and identification module (4), a single photon source module (5), an FPGA control module (6), a man-machine interface (7), and a TEC refrigeration module.

The optical focusing module (2) adopts a coaxial light path, 1550nm irradiation laser and visible light observed by CCD are focused on the measured APD array (3) by the same microscope lens. The optical focusing (2) system in the system adopts a coaxial light path, 1550nm irradiation laser and visible light observed by a CCD are focused on the detected APD array (3) by the same microscope lens, the detected visible near infrared single photon detector SPAD is arranged on an XYZ three-dimensional translation stage, XY orientation and Z orientation focusing can be carried out, the adjusting precision can reach 1 mu m, an aperture diaphragm capable of translating in the XY direction is arranged on an intermediate light path of 1550nm laser, the size of the aperture diaphragm is smaller than that of the entrance of the microscope lens, the incident angle of the laser incident on the APD array (3) is changed along with the aperture diaphragm in the translation process, and the position of a light spot is unchanged.

The APD array scanning module (3) can realize an all-parallel array integration method for integrating a plurality of APD pixels. The data of pixels with a certain address are selected by a row-column decoder and output to an on-chip bus, the on-chip controller sequentially traverses the pixel addresses of the whole array, the whole frame of data is uploaded through an off-chip bus, the read-out frame rate is limited to a certain extent by the bus bandwidth, and a UART bus implementation mode is selected and mainly comprises a sending module TRASMITTER, a receiving module Receiver, a receiving FIFO with depth of 16, a sending FIFO with depth of 16, a register list, a state control interrupt register module and the like. Facing the array circuitry is a register list (Reg File) where the data read by the array is stored in the corresponding location in the list and then uploaded through TRASMITTER. Parameters such as authentication voltage, frame rate, gate control setting and the like are set for the chip through a UART by a man-machine interaction interface (7).

The high-voltage bias circuit (1) is connected with the APD array (3) to provide high-voltage bias. The voltage conversion is realized, the input voltage is converted into direct current voltage and is output to the APD array (3), so that the voltage is ensured to be under the avalanche voltage of the APD array (3) when the provided bias voltage is stable; the high voltage bias circuit (1) may be a dc-dc conversion circuit or an ac-dc conversion circuit.

The FPGA control module (6) generates periodic narrow gate pulses, the periodic narrow gate pulses are coupled to the APD array (3) to drive the detector, and meanwhile, the FPGA control module (6) generates another synchronous pulse signal, the synchronous pulse signal passes through the single photon source module (5) to 0.1 single photons per pulse, and the synchronous pulse signal is coupled to a photosensitive surface of the APD array (3) through optical fibers.

The signal obtained by the signal extraction and identification module (4) after APD array scanning (3) is amplified by a high-speed amplifier, and the amplified signal is connected to an ECL high-speed comparator with adjustable identification voltage for comparison and identification and then connected to an FPGA control module (6) for reading and counting. The extraction and identification module (4) adopts a passive quenching mode to work SPADs in a gate control geiger mode, avalanche signals generated in the gate control with photons are firstly sampled through a 50 omega resistor, the sampled signals are amplified through a high-speed amplifier, the amplified signals are connected into an ECL high-speed comparator with adjustable identification voltage for comparison and identification, so that a pure avalanche signal is output corresponding to the avalanche, a capacitor peak response is generated when periodic gate control pulses are loaded to two ends of the SPADs due to the junction capacitance effect of the SPADs p-n junction, error counting is formed, the avalanche signals are also overlapped on the capacitor peak response noise signals, so that the avalanche signals are difficult to extract, an edge latching mode is adopted, the avalanche signals generated when photons are incident are latched through the comparator, and the high level obtained through comparison of the avalanche signals is connected into the FPGA control module (6) for reading counting.

The FPGA control module (6) is connected with the human-computer interaction interface (7), the pulse width and the repetition frequency of the gating signal generated by the FPGA control module (6) can be modified through the human-computer interaction interface (7), and the data of dark count, light count, post pulse and the like obtained by processing of the FPGA control module (6) are sent to the human-computer interaction interface (7) for display. In order to avoid error counting caused by spike pulse noise generated when loading gating pulse on SPDs, a latch pulse is provided for an ECL comparator in a signal extraction and identification module (4) when avalanche signals are extracted, the latch edge of the ECL comparator is finely aligned with the center of the avalanche signals through IO DELAY, and the high level of the ECL comparator is kept to the rising edge of the next gating pulse signal of the FPGA, so that the error of establishing the holding time is avoided when the counting module in the FPGA counts. The pulse signal LASERDRIVER of the synchronous laser is driven by the DCM clock to divide the frequency and is adjustable in the full gating pulse period. When the avalanche level is detected, the HOLDFF dead time is set so that the gating pulse signal is at a low level, the dead time being adjustable in steps of 10ns in the range of 9ns to 1009 ns.

In this embodiment, since more types of FPGA control modules, high-voltage bias circuits, single photon source modules, and TEC refrigeration are available, the specific implementation manner related to this embodiment uses a PDL 800-B synchronous laser from PicoQuant, a FVA-3150 variable attenuator from EXFO as the single photon source module, a Virtex 5-series FPGA from Xilinx, an IT6834 high-voltage bias power supply from ite and an LTC1923TEC controller from Linear Technology as the example effect description. The laser driver PDL 800-B is a single-channel dual-mode driver of LDH series and LDH-FA series picosecond pulse laser heads (375-1990 nm) and PLS series subnanosecond pulse LEDs (255-600 nm), different lasers or LED heads are connected, the wavelength can be replaced, an internal oscillator has two user-selected fundamental frequencies which are 80MHz and 1MHz respectively and can be controlled by external trigger signals, the laser pulse is up to 10MHz, the variable attenuator FVA-3150 has three attenuation modes which can be selected, an absolute mode (comprising insertion loss), a relative mode (relative to a reference value of 0.00 dB) or an X+B mode (relative to the display of any selected reference value), the high-voltage bias power supply IT6834 has a resolution of 10mV/10mA, the precision is less than 0.1% +38mV/0.1% +15mA, the LTC1923 controller integrates all necessary control circuits and two groups of complementary output drivers to drive a full bridge, so that a temperature of the dual-channel TEC can be controlled accurately and stably, and accurately controlling the temperature of a laser can be controlled by a temperature system of a dual-channel system.

The method comprises the steps of focusing a light spot on a photosensitive surface of an APD array through an optical focusing and three-dimensional adjustable optical displacement platform, providing a stable bias high voltage VP lower than breakdown voltage VBR for the APD array by a direct current high voltage power supply, coupling a gating signal Vpulse with the repetition frequency of 100KHz and the gating amplitude of 3.3V to the APD array by the FPGA, enabling the N pole voltage of the APD array to be quickly increased to a level of tens of volts higher than the breakdown voltage VBR, enabling the APD to enter a geiger mode working state, synchronously triggering a laser by an FPGA system, attenuating emergent pulse laser to 0.1 photon per pulse, irradiating the APD photosensitive surface to generate an avalanche signal, and enabling the N pole voltage of the APD to be quickly returned to the voltage VP lower than the breakdown voltage VBR when the gating pulse becomes low level, so as to play a quenching role.

Because of the capacitance effect of APD, when the periodic gate pulse is loaded to the two ends of APD, the capacitance spike response is generated to form error count, and the avalanche signal is superimposed on the capacitance spike response noise signal to make the avalanche signal extraction difficult.

And setting the number of pulse trains generated by each gating signal through a human-computer interaction interface, wherein dark counts can be obtained when the APD array is not illuminated, and the light counts and the number of rear pulses can be obtained when the APD array receives photons in a detection gate. The man-machine interaction interface can set the gating pulse width, the gating pulse repetition frequency and the gating pulse string number through the FPGA, and process and display the test results of dark count, light count, post pulse and the like, so that the performance calibration of the APD array can be realized.

The human-computer interaction interface (7) in the system can adjust and set parameters related to the SPAD, communicate with the FPGA control module (6) through the USB, and feed back the FPGA count value to the human-computer interaction interface (7) for display and storage.

TEC refrigeration in the system realizes 0.1 ℃ precision control of an APD array through a TEC controller, and can adapt to different working voltages of 5-12V and different types of semiconductor refrigeration sheets of 6A maximum.

The foregoing description is only of the preferred embodiments of the present disclosure and description of the principles of the technology being employed. It will be appreciated by persons skilled in the art that the scope of the disclosure referred to in this disclosure is not limited to the specific combinations of features described above, but also covers other embodiments which may be formed by any combination of features described above or equivalents thereof without departing from the spirit of the disclosure. Such as those described above, are mutually substituted with the technical features having similar functions disclosed in the present disclosure (but not limited thereto).

Moreover, although operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of the present disclosure. Certain features that are described in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are example forms of implementing the claims.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. An optical path apparatus for a detector array test calibration system, comprising:

a single photon source module for generating near infrared photons;

the visible light generation module is used for generating visible light;

The optical focusing module adopts a coaxial light path and is used for focusing photons output by the single photon source module and visible light output by the visible light generation module to a photosensitive surface of the to-be-detected probe detector array;

the test calibration system comprises a high-voltage bias circuit, an array scanning module, an array fixing module and a control module, wherein the high-voltage bias circuit is used for providing high-voltage bias for a detector array to be tested, the array scanning module is used for scanning detectors in the detector array to be tested and outputting electric signals, the array fixing module is used for fixing the detector array to be tested, and the control module is used for generating performance parameters of the detector array to be tested based on the electric signals.

2. The optical path apparatus of claim 1, wherein the single photon source module is configured to output a pulsed single photon source, and the output laser pulse is attenuated to 0.1 photons per pulse by an adjustable attenuator.

3. The optical path apparatus according to claim 1, wherein the optical focusing module includes a microscope positioned in XY direction and focused in Z direction with an adjustment accuracy of 1 μm.

4. The optical path apparatus according to claim 3, further comprising an aperture stop translatable in XY directions, the aperture stop having a size smaller than an entrance pupil of the microlens;

in the process of translating the aperture diaphragm, the incident angle of the laser incident on the detector array to be detected also changes.

5. The light path apparatus of claim 1, wherein the optical focusing module comprises the first and second beam splitting prisms;

the first beam splitting prism is arranged between the aperture diaphragm and the optical focusing module and is used for guiding laser photons or visible light to the optical focusing module;

the second light-splitting prism is provided for guiding the visible light to the first light-splitting prism.

6. The optical path device according to claim 1, further comprising a CCD;

near infrared photons and visible light observed by the CCD are focused on the detector array to be detected by the same microscope lens.

7. The light path apparatus of claim 6, wherein the CCD and illumination LED are used to focus the light source onto the photosensitive surface of the array to be tested prior to testing.

8. The optical path device according to claim 1, wherein the single photon source module receives a synchronization signal transmitted from a control circuit;

The control module generates two paths of synchronous signals, the first path of synchronous signals couples the periodic narrow gating pulse to the detector array to be detected to drive the detector array to be detected, and the second path of synchronous signals are synchronously transmitted to the single photon source module so as to align the narrow gating pulse with the optical signals generated by the single photon source module.

9. The optical path device according to claim 1, wherein,

When the test calibration system is in a dark counting test state, the single photon source in the light path device is in a closed state;

The dark count rate is generated by transmitting the obtained pulse signals to the control module by the signal extraction and identification module when the detector array to be detected is in the darkroom and no light is added, counting the pulse number of the pulse to obtain the dark count by the control module, and generating the dark count rate based on the dark count.

10. The optical path device according to claim 1, wherein,

When the test calibration system is in a light counting rate test state or a rear pulse probability test state, a single photon source in the light path device is in an on state;

The optical counting rate is generated by the following steps that one or more photons are received in a detection gate by a detector array to be detected, and the pulse signals obtained by the edge latch mode are transmitted to a control module by signal extraction and identification;

The post-pulse probability is generated by receiving one or more photons in a detection gate by a detector array to be detected, transmitting an obtained pulse signal to a control module by a double-gate method through signal extraction and identification, counting the number of pulses of the counted pulses by the control module to obtain the post-pulse number, and generating the post-pulse probability based on the post-pulse number.