An IsCMOS camera dynamic range calibration system

Abstract

The application provides an IsCMOS camera dynamic range calibration system, which comprises an LED calibration light source system, a driving circuit, a notched structure, an enhanced mirror reflection film and an optical fiber; the LED calibration light source system is arranged at an outlet position below a HERD energy meter system; the LED calibration light source system comprises a plurality of groups of LED calibration light sources; the LED calibration light source system comprises a structural panel, the notched structure is arranged on the structural panel, the enhanced mirror reflection film is laid in the notched structure, the optical fiber passes through the notched structure from the enhanced mirror reflection film, a PCB plate assembled with the plurality of groups of LED calibration light sources is covered on the notched structure, each notched structure is configured with an independent group of LED calibration light sources, and the driving circuit matched with the plurality of groups of LED calibration light sources is arranged on the PCB plate. The application solves the problem of HERD energy meter IsCMOS camera large dynamic range calibration.

Description

Technical Field

[0001] This invention belongs to the field of space science, specifically relating to an IsCMOS camera dynamic range calibration system. Background Technology

[0002] Existing camera dynamic range calibration systems include optical fibers, optoelectronic devices, HERD detection facilities, and IsCMOS cameras.

[0003] Optical fiber is a type of glass fiber that can transmit optical signals. It comes in many varieties and is characterized by its flexibility, allowing for easy arrangement. In physical experiments, optical fibers are often used as light-conducting media to guide fluorescence signals generated in crystals to downstream optoelectronic devices. The wavelength range of these fluorescence signals is 400 nm to 760 nm.

[0004] Optoelectronic devices are devices that convert scintillation fluorescence signals into electrical signals based on the photoelectric effect. Common photoelectric conversion devices include photomultiplier tubes, photodiodes, and ICCD cameras. Different optoelectronic devices operate at different wavelengths, meaning they can convert photons of different energies into electrical signals. When charged particles or gamma rays enter a scintillation crystal, they undergo various ionizing radiation effects depending on their energy, generating fluorescence signals. This fluorescence can reach the downstream optoelectronic device directly (through direct coupling between the crystal and the optoelectronic device) or indirectly (through optical fiber propagation), where it is converted into electrical signals through photoelectric conversion.

[0005] The High Energy Radiation Detection Facility (HERD) is a detection facility installed on the Chinese space station for measuring high-energy cosmic rays. It consists of multiple detector subsystems, including a calorimeter (CALO), a FIber Tracker (FIT), a Plastic Scintillation Detector (PSD), a Silicon Charge Detector (SCD), and a Transition Radiation Detector (TRD).

[0006] The most important component of the HERD detection facility is the CALO calorimeter, located in the center. The CALO detector subsystem consists of three parts: a crystal array of 7500 3cm square LYSO crystals, responsible for converting high-energy cosmic ray signals into fluorescence signals; an IsCMOS camera, responsible for reading the fluorescence signals; and a PD system, responsible for reading the fluorescence signals. The fluorescence signals generated by cosmic rays in each LYSO crystal are extracted by fiber optic guides coupled to the upper surface of the crystal. The fiber optic guides have four output ports: one fiber optic port sends the signal to the low-range IsCMOS camera, and another fiber optic port sends the signal to the high-range IsCMOS camera. The other two fiber optic ports are connected to the triggering system. The low-range IsCMOS camera and the high-range IsCMOS camera are identical, except for their operating parameters. The high-range IsCMOS camera has a lower gain factor to facilitate the measurement of signals in a higher energy range.

[0007] Each camera is coupled with a total of 7,500 optical fibers. The particle shower signals generated in the calorimeter reach the camera via these 7,500 fibers, and the camera converts these signals into a two-dimensional digital grayscale image. After the equipment is developed, calibration is required to accurately interpret the detected signals. Furthermore, the entire HERD facility needs to operate in orbit for several years, and the performance of each sub-detector and the IsCMOS camera may change, necessitating periodic calibration. The calibration primarily involves determining the dynamic range of the detectors and the two IsCMOS cameras.

[0008] An IsCMOS camera is a photoelectric detection device comprising a pre-amplifier, a post-amplifier, an image intensifier, and an sCMOS chip. 7500 optical fibers are coupled to the camera via a front-end microplate. Each fiber is coupled to a different region of the camera, and these regions are independent of each other, allowing for individual signal acquisition and amplification. In the HERD calorimeter, fluorescence signals generated by single-particle incident events are transmitted via optical fibers to the IsCMOS camera to form two-dimensional image data. This data is then stored, downloaded, and analyzed. The IsCMOS camera contains a microchannel plate (MCP), where each microchannel functions as a photomultiplier tube, performing photoelectric conversion and signal amplification. Overall, the IsCMOS camera is essentially an assembly of multiple miniature photomultiplier tubes, enabling the simultaneous acquisition of multiple signals.

[0009] In existing technologies, dynamic range calibration involves measuring the input-output relationship curve.

[0010] After the detector is developed, its main purpose is to test unknown signals. For example, if a camera acquires two-dimensional image data, determining the energy and flux represented by this image data requires a pre-calibration process. This involves using signal sources with known energy and flux (or intensity) as input to test the camera's output response. Multiple energy points can be continuously measured from low to high energy. Based on the response results, an input-output relationship curve is established. This curve is the calibration curve, and the range from low to high energy corresponding to the curve is the detector's dynamic range. When using the detector to test unknown signals, as long as the test results are within the dynamic range, that is, within the range covered by the calibration curve, information such as the energy and flux of the unknown signal can be obtained using the calibration curve.

[0011] There are generally two methods for energy calibration. One method involves irradiating the LYSO crystal with rays of different energies (of known energy) to generate fluorescence signals. Based on the test results, the system's response to the known energies can be determined. Combined with simulation methods, the relationship between "input energy" and "output signal" can be established. This allows us to obtain the dynamic range of the camera or CALO subsystem's response to the input signal. Details are as follows:

[0012] The energy of the radiation source is known, and different sources can provide rays with different energies. The beam energy extracted by the accelerator is also known, and the accelerator can provide rays with continuously adjustable energy. These rays with known energies are denoted as E1, E2...En. First, the crystal is irradiated with a ray of energy E1, and the camera's response is denoted as C1; then the crystal is irradiated with a ray of energy E2, and the camera's response is denoted as C2; ...; finally, the crystal is irradiated with a ray of energy En, and the camera's response is denoted as Cn. Using this method, the relationship between the incident energy E and the camera's response can be established. Through this response relationship, the data obtained during the calorimeter's on-orbit operation can be interpreted.

[0013] Besides the calibration method using known-energy rays, LED calibration light sources can also be used to calibrate equipment. LED calibration light sources have adjustable wavelength and power, are small in size, and, with appropriate control circuitry, can generate fluorescence signals very similar to real particle signals. Because LED brightness can be continuously adjusted and the upper limit of light intensity is relatively high, a wide dynamic range can be calibrated. This method can be used when conventional energy methods are unavailable or when separate dynamic range calibration of optoelectronic devices such as cameras is required. This invention is a calibration method for energy meters based on LED calibration light sources.

[0014] During prolonged use, LED calibration light sources may experience changes in light output amplitude due to aging and lifespan variations. Therefore, they cannot be directly used as standard light sources in high-precision testing. A dual-light source calibration method is generally used to calibrate the system's dynamic range. The basic idea of ​​the dual-light source calibration method is to use two light sources (denoted as light source A and light source B) to calibrate the system. Light sources A and B are turned on separately, and the system response result is recorded as A. i B i Then turn on light sources A and B simultaneously and record the system response as AB. i Multiple measurements yielded multiple sets of data A1...A N B1...B N AB1...AB N If the system has a linear response, then A must hold. i +B i =AB i Otherwise, define (A) i +B i -AB i ) / AB i Linearity deviation represents the degree to which the system deviates from a linear response. Using multiple sets of data points, a linearity deviation and the input signal AB can be established. i The relationship between the input signal and the linear deviation is the degree to which different input signals deviate from linearity. This is the result that dynamic range calibration aims to achieve. Using this relationship between the input signal and the linear deviation, the output result can be linearly corrected to obtain a "linear" output. The linear relationship is given by the low-energy calibration. Combining these two relationships, we can understand how much energy corresponds to the result measured by the camera. For example, if the camera measures a grayscale value of 500,000, we first determine whether this grayscale value is in the linear region based on the LED dynamic range calibration relationship. If it is not in the linear region, we determine how much it deviates from the linear region. We then use the dynamic range calibration relationship to multiply the data by a correction factor to correct it to the linear region. Finally, using the energy linear calibration result, we can deduce the energy value of this example.

[0015] In circuit design, there is a type of delay circuit, which is used to postpone or delay the arrival time of a signal. When calibrating a camera using the dual-light source method, this delay circuit can be introduced into the drive circuit.

[0016] The dynamic range calibration method has some drawbacks, as follows:

[0017] a. Limited flexibility in energy selection. The range of available energy levels and particle types for radioactive sources is limited, generally restricting calibration to levels below MeV. Furthermore, energy selection within this range is also limited, confining users to the existing energies of the radioactive source. While accelerator-driven beamlines offer a better option, providing higher energy limits and continuously adjustable energy values ​​(currently reaching several hundred GeV), they are incapable of handling calibration requirements at even higher energies.

[0018] b. It is not convenient to use; the activity of the radioactive source cannot be adjusted, and adjusting the beamline to the appropriate energy and flux requires a great deal of work. Therefore, the total time required to complete the entire calibration work will be very long, the operation procedure will be relatively complex, and multiple people will need to cooperate in a specific environment to complete it.

[0019] c. Difficulty in on-orbit use. This method is also inconvenient for detectors mounted on space stations or satellites. It's difficult to carry multiple radiation sources into space or transport the beam for calibration. Although calibration can be performed using some known sources like Crab during on-orbit flight, suitable options are still limited. Therefore, a convenient and quick calibration method is needed. One alternative is to use LED light to simulate the fluorescence signal produced by real particles for calibration. The size and wavelength of the LED light are adjustable. By selecting an LED with a suitable wavelength and setting a suitable pulse drive current, a pulse of light with equivalent real particle energy can be "generated." Cameras or photoelectric detection devices perform calibration by detecting this equivalent pulse signal. For HERD calorimeters, the dynamic range to be calibrated is relatively large, approximately 1–6000 MIP (1 MIP is equivalent to 200 photoelectrons). Traditional radiation source / ray / cosmic ray methods cannot achieve on-orbit dynamic range calibration.

[0020] d. The camera cannot be calibrated independently. When calibrating using a beam or radiation source, a complete system of "crystal-light guide-camera" must be built to obtain a signal. That is, the calorimeter system as a whole can be calibrated, and the camera performance within the system cannot be calibrated separately. Summary of the Invention

[0021] To address the aforementioned technical problems, this invention provides an IsCMOS camera dynamic range calibration system, which solves the large dynamic range calibration problem of HERD calorimeter IsCMOS cameras, and uses an optical fiber-camera as the calorimeter in the readout system to solve the camera dynamic range calibration problem.

[0022] To achieve the above objectives, the present invention adopts the following technical solution:

[0023] An IsCMOS camera dynamic range calibration system includes an LED calibration light source system, a drive circuit, a grooved structure, an enhanced mirror reflection film, and an optical fiber. The LED calibration light source system is arranged at the exit position directly below the nearly cubic structure composed of 7,500 LYSO crystals in the HERD calorimeter system. The optical fiber is led out from directly below the nearly cubic structure to reach the IsCMOS camera. The LED calibration light source system includes multiple groups of LED calibration light sources. Each LED calibration light source includes a structural panel, on which a grooved structure is provided. An enhanced mirror reflection film is laid in the grooved structure. The optical fiber passes through the enhanced mirror reflection film through the grooved structure. A PCB board equipped with multiple groups of LED calibration light sources covers the grooved structure. Each grooved structure is configured with an independent group of LED light sources. The drive circuit supporting the multiple groups of LED light sources is arranged on the PCB board. The optical fiber passes through the grooved structure and then is led out, thereby integrating the LED calibration light source system onto the HERD calorimeter system.

[0024] Furthermore, the multiple groups of LED calibration light sources are independently driven without interference with each other.

[0025] Furthermore, the light intensity of each group of LED calibration light sources configured for each grooved structure is independently adjustable.

[0026] Furthermore, after the optical fiber is placed in the fixed grooved structure, it is encapsulated with an optical coupling adhesive.

[0027] Furthermore, the enhanced mirror reflection film is an ESR optical reflection film.

[0028] Furthermore, the LED calibration light source adopts the form of a dual-LED calibration light source.

[0029] Furthermore, a delay design is set in the drive circuit.

[0030] Beneficial effects:

[0031] The present invention can effectively solve the coupling problem between multiple optical fibers and optoelectronic conversion devices. Specifically, it has the following advantages:

[0032] a. Simple structure. The present invention occupies very little space. The calibration light source and the primary circuit are integrated on a single PCB board, with a compact structure. The space of the HERD calorimeter is limited, and adopting the present invention will save a large amount of space resources.

[0033] b. High reliability. The present invention uses multiple discrete light sources. These light sources and their drive circuits are independent of each other and can be used as backups for each other. If some light sources fail, other light sources can still calibrate the camera. There is no risk that the calibration system cannot work.

[0034] c. Flexible operation. This invention employs a design where multiple driving circuits independently drive multiple LED light sources. This design allows for flexible configuration of calibration schemes. For example, a line-by-line scanning method can be used to calibrate the camera, or a region-based method can be used, flexibly configured according to real-time power consumption. Attached Figure Description

[0035] Figure 1 Operating mode of the drive circuit when calibrating a camera using the dual-light source method;

[0036] Figure 2 Diagram of HERD energy meter components;

[0037] Figure 3a A top view of an LED calibration light source;

[0038] Figure 3b A side view of an LED calibration light source. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0040] The present invention relates to an IsCMOS camera dynamic range calibration system comprising an LED calibration light source system consisting of multiple LED calibration light sources, a driving circuit, a grooved structure, an enhanced specular reflective film, optical fibers, and optical coupling adhesive. The driving circuit, preferably a PCB board, controls the emission of the multiple LED calibration light sources. The grooved structure is used to house the multiple optical fibers.

[0041] The HERD calorimeter system mainly consists of two parts: a near-cubic structure composed of 7,500 yttrium lutetium silicate crystals, which is responsible for converting cosmic rays into light signals; and an isCMOS camera, which is responsible for converting the light signals into electrical signals. The two are connected by a large number of optical fibers, with the optical signals from the near-cubic structure being transmitted to the isCMOS camera via the fibers.

[0042] Four optical fibers extending from the LYSO (yttrium lutetium silicate) crystal are connected to two IsCMOS cameras and a trigger PMT (photomultiplier tube). When the 7500 optical fibers extend outward from the LYSO crystal array, a suitable location is selected along the fiber path to position the LED calibration light source system. This suitable location is the LYSO crystal array exit position, directly below the HERD calorimeter. The positional relationship between the LED calibration light source system and the optical fibers is shown in Figure 3.

[0043] Due to spatial constraints, the near-cubic structure and the IsCMOS camera are not located adjacent to each other; there is a distance between them. Therefore, an optical fiber is needed to connect them. The optical fiber extends from directly beneath the near-cubic structure to the IsCMOS camera. The LED calibration light source system is also positioned directly beneath the near-cubic structure. The optical fiber needs to pass through the grooved structure in the LED calibration light source system before exiting, thereby integrating the LED calibration light source system into the HERD calorimeter system. The LED calibration light source system includes multiple sets of LED calibration light sources. Figure 2 The microperforated plate in the HERD calorimeter is a structural component that is used to limit the position of the optical fiber and help fix the optical fiber and the IsCMOS camera together.

[0044] The LED calibration light source system is configured as follows: multiple 6cm×4mm×5mm (length×width×depth) grooves are etched on a structural panel. An enhanced specular reflective film, preferably an ESR optical reflective film, is laid within the grooves. An optical fiber passes through the grooves from the enhanced specular reflective film. The grooves are covered by a PCB board on which the LED calibration light source is mounted. When the LED calibration light source is lit, a calibration signal is emitted, enters the optical fiber, and then reaches the IsCMOS camera via the optical fiber.

[0045] The enhanced specular reflective film improves the efficiency of fluorescence collection in optical fibers, ensuring that as much of the calibration fluorescence signal emitted by the LED calibration light source as possible is collected by the optical fiber. Large dynamic range calibration requires the highest possible light intensity, and improved fluorescence collection efficiency is beneficial for achieving large dynamic range calibration targets.

[0046] The density of the grooved structures arranged on the structural panel is seven per 3cm width. Each grooved structure can accommodate three optical fibers, each configured with an independent set of LED calibration light sources. This design facilitates the uniformity of optical signals between different optical fibers. After the calibration signal emitted by the set of LED calibration light sources in each grooved structure is emitted, it is collected by all the optical fibers arranged within the grooved structure. If too many optical fibers are arranged in the grooved structure, such as ten, some fibers may collect more photons than others due to obstruction between fibers, resulting in a problem of non-uniformity in the optical fiber signal. Excessive non-uniformity in the optical fiber signal will affect the width of the calibrable dynamic range. If the uniformity between the optical fibers is good, the dynamic range calibration width of the IsCMOS camera can be made relatively large; if the uniformity between the optical fibers is poor, the dynamic range calibration width of the IsCMOS camera cannot be large, and it will be severely limited by the optical fiber with the worst light collection efficiency.

[0047] The PCB board is equipped with multiple sets of LED calibration light sources and corresponding driving circuits. The PCB board covers the top of the grooved structure (e.g., Figure 3a , Figure 3b As shown, each group of LED calibration light sources corresponds to a grooved structure and three optical fibers within that structure. The PCB board covering the top surface of the grooved structure allows for the positioning of the LED calibration light sources and the configuration of the driving circuit. After the optical fibers are arranged within the grooved structure, they are encapsulated with optical adhesive. This encapsulation protects the optical fibers and ensures the stability of the relationship between the optical fibers, the enhanced specular reflective film, and the LED calibration light source system, thereby guaranteeing the stability of the calibration parameters.

[0048] The IsCMOS camera dynamic range calibration method of the present invention includes the following steps:

[0049] Step (a) Determine the camera area to be calibrated (assuming the area to be calibrated is Z), and check whether the corresponding LED calibration light source and working circuit are normal. Because there are a large number of LED calibration light sources, if all LEDs are powered on at the same time, the power consumption burden will be too large. Generally, a regional calibration method is adopted.

[0050] Step (b) Start the calibration of the driving circuit corresponding to region Z. Turn on the LED calibration light source in group A and record the camera response as A1;

[0051] Step (c) Turn off LED calibration light source A, turn on LED calibration light source B, and record the camera response as B1;

[0052] Step (d) Simultaneously turn on the LED calibration light sources of group A and group B, and record the camera response as AB1;

[0053] Step (e) restarts from step (b), changing the light intensity and obtaining a series of test results (Ai, Bi, AiBi) in order from weakest to strongest; establish the relationship between Ai+Bi-AiBi and AiBi, where i represents the number of groups. The more sampling points, the higher the accuracy of the calibration curve.

[0054] The LED calibration light source system of this invention adopts a near-end positioning design. The LED calibration light source system is positioned at the array exit position of the LYSO crystal. The array exit position is relatively close to the IsCMOS camera (the fiber optic cable length between the LED calibration light source and the IsCMOS camera is approximately 2.2 meters). Positioning the LED calibration light source system in this location reduces the loss of optical signal during fiber propagation, which is beneficial for calibration with a large dynamic range.

[0055] The LED calibration light source system of this invention employs an independent driving design. A large number of LED calibration light source systems are configured at the array exit position of the LYSO crystal to calibrate the IsCMOS camera. Each of these LED calibration light source systems can operate independently without interference. The driving circuit can independently drive each LED calibration light source (not each group), meaning the driving circuit can arbitrarily illuminate any specified LED calibration light source. The advantage of this design is that camera calibration is more flexible, allowing for both full-pixel overall calibration and calibration of only a portion of the area. If some LED calibration light sources fail, the entire LED calibration light source system still retains a certain degree of operational capability and will not fail entirely, thus improving the system's fault tolerance.

[0056] This invention employs an optical fiber grouping and grooving structure design. The grooving structure allows for the grouping of a large number of optical fibers, with each etched groove housing several fibers as a group, and configured with a set of LED light sources. Several fibers within the same groove are illuminated by a set of LED calibration light sources (typically, a set of LED calibration light sources includes multiple LED calibration light sources), resulting in minimal difference in the number of photons received by different fibers. Different groove structures are configured with independent LED calibration light sources, and the light intensity can be independently adjusted. Overall, this design ensures that the dynamic range of the calibration light signal output by each fiber (i.e., the lower limit of the minimum optical signal and the upper limit of the maximum optical signal output by each fiber) is almost identical. In other words, the upper and lower limit ranges of the calibration light signal received by different regions of the IsCMOS camera are essentially the same, allowing for the calibration of the dynamic range of different regions of the IsCMOS camera to be performed with equal magnitude. The IsCMOS camera includes both high-range and low-range IsCMOS cameras.

[0057] This invention employs an optical adhesive encapsulation design. After the optical fiber is placed and fixed in the grooved structure, it is encapsulated with optical coupling adhesive. The advantages are: it can protect the optical fiber; it can solidify the relative structure between the light source, the reflective layer, the optical fiber, and the groove, which can enhance the stability of the optical system and reduce fluctuations; it can improve the optical signal transmission path and enhance transmission efficiency and stability.

[0058] This invention employs a "V"-shaped ESR optical reflective film design. The ESR optical reflective film design serves two purposes: firstly, it improves the collection efficiency of the calibration light signal, increasing the calibrable upper limit of the dynamic range; secondly, it separates the optical fibers. As mentioned earlier, three LYSO crystals are placed in each groove, totaling 12 optical fibers. Six fibers go to the trigger end, six to the IsCMOS camera end, and the signal from the LED calibration light source is only sent to the IsCMOS camera end. Therefore, it is necessary to isolate the six optical fibers leading to the trigger end from the LED calibration light source. This requirement can be met using an ESR optical reflective film. The ESR optical reflective film is an enhanced specular reflective film manufactured by 3M.

[0059] This invention employs a dual-LED calibration light source design. The output of a single LED calibration light source is not very stable, necessitating a dual-light source method for dynamic range calibration. The basic idea of ​​the dual-light source calibration method is to use two light sources (denoted as light source A and light source B) to calibrate the system. Light sources A and B are turned on respectively, and the system response result is recorded as A. i B i Then turn on light sources A and B simultaneously and record the system response as AB. i Multiple measurements yielded multiple sets of data A1...A N B1...B N AB1...AB N If the system has a linear response, then A must hold. i +B i =AB i Otherwise, define (A) i +B i -AB i ) / AB i Linearity deviation represents the degree to which the system deviates from a linear response. Using multiple sets of data points, a linearity deviation and the input signal AB can be established. i The relationship between the input signal and the linear deviation is the degree to which different input signals deviate from linearity. This is the result that dynamic range calibration aims to achieve. Using this relationship between the input signal and the linear deviation, the output result can be linearly corrected to obtain a "linear" output. The linear relationship is given by low-energy calibration. Combining these two relationships, we can understand how much energy corresponds to the result measured by the camera. For example, if the camera measures a grayscale value of 500,000, we first determine whether this grayscale value is in the linear region based on the LED calibration light source dynamic range calibration relationship. If it is not in the linear region, we determine how much it deviates from the linear region. Using the dynamic range calibration relationship, we multiply the data by a correction factor to correct it to the linear region. Then, using the energy linear calibration result, we can deduce the energy value of this instance.

[0060] In this invention, dual-LED calibration requires two independent LED calibration light sources. These two independent LED calibration light sources form a set of LED calibration light sources. This set of independent LED calibration light sources directly illuminates several optical fibers (currently six, but this can be adjusted depending on the situation; it's not a fixed parameter). Because different optical fibers couple to different positions on the IsCMOS camera screen (the screen is large, the pixels are small, and one fiber corresponds to several pixels), a set of LED calibration light sources can be used to calibrate a portion of the IsCMOS camera using the principle of a dual-light source method. For the entire HERD calorimeter array (with approximately 20,000 optical fibers), a large LED calibration light source system composed of many sets of LED calibration light sources is needed to cover a large area of ​​the IsCMOS camera screen. Multiple sets of LED calibration light sources can be arranged on a single structural panel (the number is a variable parameter, flexibly adjusted according to requirements). Each structural panel is covered with a PCB circuit board to power each LED calibration light source and provide the corresponding circuitry.

[0061] This invention employs a signal delay design. LED calibration light sources are somewhat unstable; each time the LED calibration light source is turned off and then on again, a change in signal output amplitude is observed. However, if continuously powered on, the LED calibration light source remains very stable for a period of time (>1 hour). Based on this characteristic of the LED calibration light source, a delay design can be used to replace the power-off operation when using a dual-light source method for camera calibration. Using a delay design in the drive circuit can increase circuit stability and improve calibration efficiency. When using a dual-light source method for calibration, it is generally necessary to complete the test of one energy point according to the working mode of "A on B off --> A off B on --> A on B on", such as... Figure 1 The same test can also be performed using a delay circuit. When using a delay circuit, the specific operating mode is "A on B on (with delay) --> A on B on (no delay)," as follows: Figure 2 When "A on, B on (with delay)", due to the circuit delay, the signal received by the camera can be divided into two sequences: odd-numbered sequences (1, 3, 5...) represent the count of light source A, and even-numbered sequences (2, 4, 6...) represent the count of light source B. Signal acquisition for both lights A and B can be completed in one operation. When both light sources need to be turned on simultaneously, the delay in the drive circuit can be adjusted to zero.

[0062] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dynamic range calibration system for an IsCMOS camera, characterized in that: The system includes an LED calibration light source system, a driving circuit, a grooved structure, an enhanced specular reflective film, and an optical fiber. The LED calibration light source system is positioned at the exit point directly below the near-cubic structure of the HERD calorimeter system, which consists of 7500 LYSO crystals. The optical fiber extends from directly below the near-cubic structure to the IsCMOS camera. The LED calibration light source system comprises multiple sets of LED calibration light sources and includes a structural panel with a grooved structure. An enhanced specular reflective film is laid within the grooved structure. The optical fiber passes through the grooved structure from the enhanced specular reflective film. A PCB board with multiple sets of LED calibration light sources is mounted on the grooved structure, and each grooved structure is configured with an independent set of LED calibration light sources. The PCB board is equipped with a driving circuit that corresponds to the multiple sets of LED calibration light sources. The optical fiber passes through the grooved structure and then extends out, thereby integrating the LED calibration light source system into the HERD calorimeter system.

2. The isCMOS camera dynamic range calibration system according to claim 1, characterized in that: The multiple sets of LED calibration light sources are driven independently and do not interfere with each other.

3. The isCMOS camera dynamic range calibration system according to claim 1, characterized in that: The light intensity of each LED calibration light source in the set of LED calibration light sources configured for each groove structure can be adjusted independently.

4. The isCMOS camera dynamic range calibration system according to claim 1, characterized in that: After the optical fiber is placed and fixed in the grooved structure, it is encapsulated with optical coupling adhesive.

5. The isCMOS camera dynamic range calibration system according to claim 1, characterized in that: The enhanced specular reflective film is an ESR optical reflective film.

6. The isCMOS camera dynamic range calibration system according to claim 1, characterized in that: Each of the multiple sets of LED calibration light sources includes two LED calibration light sources, and each LED calibration light source is driven individually by a driving circuit.

7. The isCMOS camera dynamic range calibration system according to claim 6, characterized in that: The driving circuit incorporates a delay design.

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