A performance test system for a broadband gap filter

Abstract

The application discloses a kind of performance test systems of wide band gap filter, it is related to optical element performance test technical field, including multi-working-condition dynamic environment simulation unit, for producing temperature variation sequence and laser irradiation sequence in the cavity of measured filter;Full parameter synchronous optical test unit is used for real-time acquisition of the light signal that is transmitted through filter and is reflected by filter during the operation of the multi-working-condition dynamic environment simulation unit.The performance test system of the wide band gap filter, by the data acquisition ability of dynamic succession, so that the performance degradation trend of filter in actual service environment can be restored, avoid the information loss and positioning error caused by discretization test, solve the problem that test result is too optimistic, cannot accurately predict service life.

Description

Technical Field

[0001] This invention relates to the field of optical component performance testing technology, specifically a performance testing system for wide bandgap filters. Background Technology

[0002] Chinese invention patent CN117232786A discloses a system and method for testing the deep cutoff transmittance of a solar-blind filter. This method uses a light source to generate mixed-color light, which is then dispersed by a monochromator to obtain monochromatic light. A quasi-parallel beam is then obtained through an optical collimator, and a photon counter records the number of photons arriving per second, thereby calculating the transmittance of the filter at a specific wavelength. This system provides a dark environment through a dark box, effectively suppressing stray light interference and achieving high-precision measurement of weak light signals in the deep cutoff band, offering advantages such as high testing accuracy and small error. However, this method only tests a single transmittance parameter of the solar-blind filter, and the entire testing process is completed under static conditions at room temperature, with the sample always in an ideal environment of constant temperature and humidity and no external light irradiation. This testing mode is fundamentally out of touch with the actual service scenarios of wide-bandgap filters in practical applications. For example, in space optical remote sensing, filters must withstand wide-range temperature changes caused by day-night cycles. The refractive index and coefficient of thermal expansion of the filter material drift with temperature, leading to a shift in the center wavelength. In high-power laser systems, filters experience localized temperature rises under continuous laser irradiation, altering their spectral bandwidth and damage threshold. The dynamic coupling effect of temperature and laser interaction, along with the synchronous evolution of multiple parameters such as reflectivity, cutoff depth, center wavelength shift, and laser damage threshold, cannot be obtained using existing single-parameter static testing systems. More importantly, current methods involve disassembling and reassembling samples to measure different parameters on different devices. This discretization not only introduces positioning errors and surface contamination risks but also loses continuous dynamic information about performance degradation under multiple operating conditions. This results in overly optimistic test results, making it impossible to accurately predict the filter's service life in actual use.

[0003] Therefore, how to synchronously simulate the coupled working environment of wide-range temperature changes and high-power laser loading within the same test system, and to acquire real-time and continuous multi-parameter co-evolution data such as spectral bandwidth, center wavelength shift, cutoff depth, and laser damage threshold of wide-bandgap filters under this dynamic condition, has become a technical bottleneck restricting their performance evaluation and reliability verification. To address this, the present invention aims to solve the problem of integrated, real-time, and continuous co-detection of multiple key spectral performance parameters of wide-bandgap filters under dynamic multi-condition coupling. Summary of the Invention

[0004] The purpose of this invention is to provide a performance testing system for wide bandgap filters to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a performance testing system for wide bandgap filters, comprising:

[0006] The multi-condition dynamic environment simulation unit is used to generate temperature change sequences and laser irradiation sequences within the cavity where the filter under test is located.

[0007] The full-parameter synchronous optical testing unit is used to acquire light signals transmitted through the filter and reflected by the filter in real time during the operation of the multi-condition dynamic environment simulation unit, and to calculate spectral performance parameters including center wavelength, spectral bandwidth, cutoff depth, transmittance, and reflectance.

[0008] A cross-coupled collaborative control unit is electrically connected to the multi-condition dynamic environment simulation unit and the full-parameter synchronous optical test unit, respectively. It is used to use the temperature value and laser energy value monitored in real time by the multi-condition dynamic environment simulation unit as trigger signals to control the full-parameter synchronous optical test unit to perform optical signal acquisition at a specific environmental state point. At the same time, it uses the center wavelength offset calculated in real time by the full-parameter synchronous optical test unit as a feedback parameter to dynamically adjust the wavelength scanning step size and integration time of the full-parameter synchronous optical test unit, forming an adaptive compensation closed loop for optical detection.

[0009] The cross-coupled collaborative control unit also integrates a closed-loop iterative test module, which is configured to perform the following progressive test process: first, perform a full-parameter baseline scan; second, excite stepwise according to the preset temperature-laser composite loading curve and collect dynamic responses in real time; third, dynamically adjust the acquisition parameters of the full-parameter synchronous optical test unit according to the center wavelength offset to perform dynamic compensation test; fourth, calculate multi-parameter indicators and compare them with preset thresholds; fifth, when the thresholds are not met, automatically shrink the operating range and refine the step amplitude to perform a second iterative test.

[0010] Preferably, the dynamic compensation test specifically involves: when the cross-coupled collaborative control unit determines that the rate of change of the center wavelength offset exceeds a preset rate threshold, controlling the full-parameter synchronous optical test unit to reduce the wavelength scanning step size from a normal step size to a fine step size, while simultaneously extending the integration time from a normal integration time to a long integration time; the normal step size is one wavelength point per nanometer, the fine step size is one wavelength point per zero-nanometer, the normal integration time is 100 milliseconds, and the long integration time is 500 milliseconds.

[0011] Preferably, the multi-parameter index includes the center wavelength temperature coefficient, laser damage threshold, and comprehensive performance degradation factor. The comprehensive performance degradation factor is equal to the sum of the ratio of the maximum decrease in peak transmittance to the initial peak transmittance, the ratio of the maximum degradation in cutoff depth to the initial cutoff depth, and the ratio of the maximum broadening of spectral bandwidth to the initial spectral bandwidth.

[0012] Preferably, the multi-condition dynamic environment simulation unit includes a wide-temperature-range temperature control module and a high-power laser loading module. The temperature control module has a temperature control range of -40 degrees Celsius to 120 degrees Celsius, and the laser loading module outputs pulsed laser energy density ranging from 0.1 joules per square centimeter to 100 joules per square centimeter.

[0013] Preferably, the full-parameter synchronous optical testing unit includes a broadband composite light source, a dual-path differential detection optical path, and a multi-channel synchronous detector group. The dual-path differential detection optical path splits the incident light into two paths: a reference light and a sample light, which are synchronously received by the reference detector and the sample detector, respectively.

[0014] Preferably, the preset thresholds in the closed-loop iterative test module include the center wavelength temperature coefficient threshold, the laser damage threshold, and the comprehensive performance attenuation factor threshold. When any index fails to meet the corresponding threshold, the cross-coupled collaborative control unit automatically shrinks the temperature scanning range to the sensitive sub-interval corresponding to the index, and reduces the temperature step amplitude and laser energy step amplitude within the sub-interval to half of the original value.

[0015] Preferably, when the threshold is still not met after two iterations of testing, the cross-coupled collaborative control unit outputs the failure boundary conditions of the filter, which include the maximum tolerance temperature and the critical laser energy density.

[0016] Preferably, the cross-coupled collaborative control unit includes a central processing unit, a signal acquisition card, and a drive circuit, wherein the central processing unit runs a closed-loop iterative control algorithm.

[0017] Preferably, it also includes a data output module, which is connected to the cross-coupled collaborative control unit and is used to output a test report containing multi-parameter dynamic evolution curves and failure boundary conditions.

[0018] A performance testing method for a wide bandgap filter, applied to the system described above, includes the following steps:

[0019] S1: Install the filter to be tested into the multi-condition dynamic environment simulation unit;

[0020] S2: The cross-coupled collaborative control unit controls the full-parameter synchronous optical test unit to perform the first full-parameter baseline scan to obtain the initial spectral parameters;

[0021] S3: According to the preset temperature-laser composite loading curve, the multi-condition dynamic environment simulation unit applies temperature changes and laser irradiation step by step, while the full-parameter synchronous optical test unit collects dynamic spectral responses in real time at each environmental state point; and during the test, the wavelength scanning step size and integration time of the full-parameter synchronous optical test unit are dynamically adjusted according to the center wavelength offset calculated in real time to complete the dynamic compensation test.

[0022] S4: The cross-coupled collaborative control unit calculates multiple parameter indicators and compares them with preset thresholds. If all indicators meet the thresholds, a qualified evaluation result is output. If they do not meet the thresholds, the operating condition range is automatically narrowed and the step size is refined to perform a second iteration test until the final evaluation result or failure boundary condition is output.

[0023] This invention provides a performance testing system for wide bandgap filters. It has the following advantages:

[0024] This system achieves synchronous dynamic capture of multispectral parameters under coupled conditions of temperature changes and high-power laser loading. Through a cross-coupling design of a multi-condition dynamic environment simulation unit and a full-parameter synchronous optical testing unit, the system enables the real-time acquisition of multiple parameters, including transmittance, reflectance, center wavelength, spectral bandwidth, and cutoff depth, while the filter is subjected to wide-range temperature change sequences and pulsed laser irradiation sequences. Unlike traditional methods that require disassembling and reassembling samples to measure different parameters on different devices and only obtain discrete data points under static conditions at room temperature, this system comprehensively records the entire evolution of the filter's spectral performance under the combined effects of temperature and laser on the same continuous time axis within the same device. Testers can directly obtain the continuous shift curve of the center wavelength with increasing temperature, the attenuation trajectory of peak transmittance with increasing laser energy density, and the changes in cutoff depth and spectral bandwidth under coupled conditions. This dynamic and continuous data acquisition capability allows for the accurate reproduction of the filter's performance degradation trend in actual service environments, avoiding information loss and positioning errors caused by discrete testing, and solving the shortcomings of overly optimistic test results and inaccurate prediction of service life.

[0025] Through an asymmetric design involving closed-loop iteration and threshold adaptation, a refined quantitative assessment of the failure boundary of non-conforming products is achieved. By integrating a closed-loop iterative testing module into the cross-coupled collaborative control unit, when one or more indicators fail to meet the preset threshold in the initial test, the system does not simply output a non-conforming conclusion. Instead, it automatically identifies the sub-range of operating conditions most sensitive to performance degradation, narrows the temperature scan range to this sub-range, and reduces the temperature step size and laser energy step size to half of their original values, performing a second refined iterative test. If the threshold is still not met after the second iteration, specific failure boundary conditions are output, including the maximum withstand temperature and critical laser energy density. This mechanism is fundamentally different from the conventional approach of "full-range equal-step testing, only providing a binary conclusion of pass or fail." The failure boundary information provided by this system can guide material improvement and process optimization of filters. This quantitative boundary output defines the reliable operating range of filters in practical engineering applications such as space optical remote sensing and high-power laser systems, enhancing the practical value of test results for product development and quality control. Attached Figure Description

[0026] Figure 1 This is an iterative flowchart of the performance testing system for the wide bandgap filter of the present invention;

[0027] Figure 2 This is a diagram showing the working state of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example: Please refer to Figure 1 and Figure 2This invention provides a technical solution: a performance testing system for wide bandgap filters, comprising a multi-condition dynamic environment simulation unit, a full-parameter synchronous optical testing unit, and a cross-coupled collaborative control unit. The multi-condition dynamic environment simulation unit includes a sealed test chamber, the inner wall of which is coated with a black matte coating with an absorptivity greater than 0.95%. A temperature control platform, consisting of a semiconductor cooling chip and a resistance heating wire, is installed at the bottom of the chamber. This platform uses a PID controller to stabilize the temperature at any set value within the range of -40°C to 120°C, with temperature fluctuations not exceeding ±0.2°C. A sample fixing base is installed above the temperature control platform, with a light-transmitting hole at its center. A high-power laser loading interface is also fixed on the side of the chamber. This interface connects to an external pulsed laser via optical fiber. The laser outputs a laser with a wavelength of 1064 nanometers, a pulse width of 10 nanoseconds, and an energy density adjustable range from 0.1 joules per square centimeter to 100 joules per square centimeter. A beam homogenizer is installed at the laser loading interface outlet to shape the laser spot into a uniform circular spot with a diameter of two millimeters, which is then vertically irradiated onto the central area of ​​the filter under test.

[0030] The full-parameter synchronous optical testing unit is located outside the cavity and is connected to the sample optical path inside the cavity through two deep ultraviolet high-transmittance quartz windows. This unit contains a broadband composite light source, consisting of a deuterium lamp, a halogen tungsten lamp, and a deep ultraviolet light-emitting diode array. These three components are selected by an electrically operated switching wheel, outputting a continuous spectral range of 190 nm to 2500 nm. The light emitted from the light source enters a dual-path differential detection optical path after passing through a collimating lens: the first path is the reference path, directly received by the reference detector; the second path is the sample path, passing sequentially through the front window, the test filter, and the rear window before being received by the sample detector. Both the reference detector and the sample detector employ a three-channel combination: photomultiplier tubes are used in the 190 nm to 320 nm wavelength range, silicon photodiodes in the 320 nm to 1100 nm wavelength range, and indium gallium arsenide photodiodes in the 1100 nm to 2500 nm wavelength range. The output signals of all detectors are simultaneously connected to a 16-bit analog-to-digital converter with a sampling frequency of 100 kHz.

[0031] The cross-coupled collaborative control unit consists of a field-programmable gate array (FPGA), an embedded microprocessor, and multiple driver circuits. The FPGA is responsible for synchronously acquiring the voltage signals of the reference detector and the sample detector, and calculating the transmittance and reflectance at each wavelength in real time. The embedded microprocessor runs the control program for the closed-loop iterative test module. This control program executes the test according to the following progressive flow:

[0032] The first step involves controlling the full-parameter synchronous optical testing unit to scan the entire spectrum from 190 nanometers to 2,500 nanometers in a step of one wavelength point per nanometer, with the temperature control platform set at 25 degrees Celsius and the laser loading interface closed. This process yields initial baseline data, including the initial center wavelength, initial spectral bandwidth, initial peak transmittance, and initial cutoff depth.

[0033] The second step involves coupling excitation according to a preset composite loading curve. This curve is divided into a heating phase and a laser irradiation phase. In the heating phase, the temperature control platform raises the temperature from 25 degrees Celsius to 120 degrees Celsius at a rate of 10 degrees Celsius per minute, pausing for 30 seconds after each 10-degree increase. At each pause, the cross-coupled collaborative control unit uses the real-time temperature value as a trigger signal to control the full-parameter synchronous optical test unit to perform a multi-wavelength rapid acquisition at that temperature point, with an acquisition time of one second. The embedded microprocessor calculates the center wavelength offset and peak transmittance change in real time based on the acquired data. After the heating phase ends, the temperature control platform maintains a constant temperature of 120 degrees Celsius. The laser irradiation phase then begins: the laser loading interface starts with an energy density of 5 joules per square centimeter, increasing by 2 joules per square centimeter each time, outputting single-pulse lasers sequentially. After each pulse is output, the full-parameter synchronous optical test unit is immediately triggered to acquire transmittance and reflectance, and calculate the relative decrease in transmittance and reflectance.

[0034] The third step is dynamic compensation testing. During the heating phase, when the embedded microprocessor detects that the rate of change of the center wavelength shift is greater than 0.005 nanometers per degree Celsius, the wavelength scanning step size of the full-parameter synchronous optical test unit at subsequent temperature points is adjusted from one point per nanometer to one point per 0.1 nanometers. At the same time, the integration time is extended from 100 milliseconds to 500 milliseconds to obtain high-density spectral data in the region of rapid center wavelength drift.

[0035] The fourth step involves multi-parameter calculation and threshold comparison. After completing the entire testing process, the embedded microprocessor automatically calculates three indicators: the center wavelength temperature coefficient, calculated by dividing the center wavelength offset within each temperature interval of the heating phase by the maximum value of the temperature interval; the laser damage threshold, calculated by taking the minimum laser energy density value that causes a permanent decrease in transmittance exceeding 0.5%; and the comprehensive performance attenuation factor, which is equal to the maximum decrease in peak transmittance divided by the initial peak transmittance, plus the maximum degradation of the cutoff depth divided by the initial cutoff depth, plus the maximum broadening of the spectral bandwidth divided by the initial spectral bandwidth. The preset qualified thresholds are: center wavelength temperature coefficient not greater than 0.01 nanometers per degree Celsius, laser damage threshold not less than 10 joules per square centimeter, and comprehensive performance attenuation factor not greater than 0.15.

[0036] Step 5: Adaptive Iterative Testing. If any of the three indicators fails to meet the corresponding threshold, the cross-coupled collaborative control unit automatically identifies the sensitive interval corresponding to the failed indicator. For example, if the center wavelength temperature coefficient exceeds the standard, the sub-interval of 20°C to 60°C with the highest center wavelength offset change rate is locked; if the laser damage threshold fails to meet the standard, the sub-interval of one joule per square centimeter before and after the first occurrence of a transmittance decrease exceeding 0.3% of the energy density is locked. Then, the temperature scanning range of the temperature control platform is narrowed to this sub-interval, and the temperature step size is reduced from 10°C to 2°C, and the laser energy density step size is reduced from two joules per square centimeter to one joule per square centimeter. Steps 2 to 4 are executed again. If all indicators meet the threshold after the second iteration, a qualified conclusion is output; if they still do not meet the threshold, the failure boundary conditions of the filter are output, namely the maximum withstand temperature and the critical laser energy density, which are respectively taken as the temperature at which the indicator first exceeds the standard and the laser energy density at which the first permanent transmittance decrease exceeds 0.5%.

[0037] Through the coordinated operation of the above-mentioned units and control processes, the testing system can acquire the evolution data of the spectral performance parameters of the filter in real time and continuously under the dynamic environment of temperature change and laser loading coupling, and automatically provide a refined failure boundary for unqualified samples.

[0038] The wide bandgap filter of the present invention refers to a bandpass filter with a spectral bandwidth greater than 50 nm and a center wavelength covering the ultraviolet to near-infrared band, or a filter made of a wide bandgap semiconductor material with a band width greater than 3.0 eV.

[0039] Inside the embedded microprocessor of the cross-coupled collaborative control unit, a rate threshold register is pre-stored. The center wavelength offset change rate threshold set in this register is 0.005 nanometers per degree Celsius. During the heating phase of the test system, the embedded microprocessor receives the center wavelength calculation results reported every 0.5 seconds from the full-parameter synchronous optical test unit in real time, calculates the difference between two adjacent reported values, and divides this difference by the actual temperature change within the time interval corresponding to 0.5 seconds to obtain the current real-time rate value.

[0040] The embedded microprocessor compares the real-time rate value with the value of 0.005 nanometers per degree Celsius in the rate threshold register. When the real-time rate value is less than or equal to the threshold, the full-parameter synchronous optical test unit operates according to the conventional acquisition parameters, with a wavelength scan step of one wavelength point per nanometer and an integration time of one hundred milliseconds per point. When the real-time rate value exceeds 0.005 nanometers per degree Celsius, the embedded microprocessor immediately sends a parameter switching command to the grating drive controller and detector preamplifier of the full-parameter synchronous optical test unit.

[0041] This parameter switching command causes the grating drive controller to switch the wavelength scanning step size from one point per nanometer to one point per 0.1 nanometers (i.e., the second value is 0.1 nanometers). Simultaneously, this command switches the integration time setting of the detector preamplifier from 100 milliseconds to 500 milliseconds (i.e., the fourth value is 500 milliseconds). The parameter switching operation is completed within ten milliseconds of receiving the rate exceeding the limit signal. The switched acquisition parameters remain in effect until the embedded microprocessor determines that the real-time rate value has fallen below 0.005 nanometers per degree Celsius and remains below the threshold for three consecutive determinations. Only then does it revert to the normal parameters of one point per nanometer and one hundred milliseconds integration time.

[0042] To smooth the switching boundaries and avoid data interruption due to frequent switching, the embedded microprocessor also sets a hysteresis interval: a switch is triggered when the real-time rate value exceeds 0.005 nanometers per degree Celsius, and normal parameters are restored only when the real-time rate value falls below 0.004 nanometers per degree Celsius three times consecutively. This hysteresis interval effectively eliminates repeated switching when the rate value fluctuates near the threshold.

[0043] Within the temperature range where parameter switching is effective, the density of spectral data points acquired by the full-parameter synchronous optical testing unit is increased from one point per nanometer to ten points per nanometer, and the integration time for each data point is extended to five times the conventional value. This results in spectral curves with higher signal-to-noise ratio and finer wavelength resolution in the rapid center wavelength drift segment. These encrypted spectral data are fed into an embedded microprocessor to calculate the center wavelength shift, spectral bandwidth change, and peak transmittance attenuation gradient within this temperature range, providing more accurate input data for subsequent multi-parameter calculations and threshold comparisons.

[0044] Inside the embedded microprocessor of the cross-coupled collaborative control unit, there is a parameter calculation module. After completing the entire temperature-laser coupling test process, this module automatically calculates three multi-parameter indicators, namely the center wavelength temperature coefficient, the laser damage threshold, and the comprehensive performance attenuation factor.

[0045] The center wavelength temperature coefficient is calculated as follows: extract the center wavelength value calculated at each temperature node in the heating segment; for each pair of adjacent temperature nodes, subtract the center wavelength value of the previous node from the center wavelength value of the latter node to obtain the center wavelength offset; divide the offset by the temperature difference between the two nodes to obtain the center wavelength change rate within the temperature interval; after traversing all temperature intervals, take the maximum value of the change rate of each interval as the center wavelength temperature coefficient, with the unit being nanometers per degree Celsius.

[0046] The laser damage threshold is calculated as follows: During the laser irradiation period, the energy density value of each pulse and its corresponding relative decrease in transmittance are recorded. The relative decrease in transmittance is defined as the difference between the peak transmittance measured after the pulse and the initial peak transmittance before laser irradiation, divided by the initial peak transmittance. Starting from the lowest energy density, the relative decrease in transmittance is checked pulse by pulse. When this decrease first exceeds 0.5%, the energy density value corresponding to that pulse is determined as the laser damage threshold, in joules per square centimeter. If the transmittance decrease for all pulses does not exceed 0.5%, the maximum tested energy density is used as the reported value.

[0047] The comprehensive performance degradation factor is calculated as follows: First, three degradation quantities are extracted from the entire testing process. The maximum decrease in peak transmittance is the difference between the lowest peak transmittance and the initial peak transmittance during the entire testing process. The maximum degradation in cutoff depth is the difference between the minimum cutoff depth and the initial cutoff depth during the entire testing process. The maximum broadening of spectral bandwidth is the difference between the maximum spectral bandwidth and the initial spectral bandwidth during the entire testing process. Then, each of the above three degradation quantities is divided by its corresponding initial value to obtain three dimensionless relative degradation ratios. The comprehensive performance degradation factor is equal to the sum of the relative degradation ratios of peak transmittance, cutoff depth, and spectral bandwidth. This factor is used to characterize the overall performance degradation degree of the filter under multi-condition coupling; a larger value indicates more severe performance degradation. This factor is compared with a preset threshold of 0.15 to determine whether the filter meets the qualification standard.

[0048] The multi-condition dynamic environment simulation unit consists of a sealed test chamber, a wide-temperature-range temperature control module installed inside the chamber, and a high-power laser loading module fixed to the side wall of the chamber.

[0049] The testing chamber is made of aluminum alloy, with its inner wall coated with a black anodized layer with an absorptivity of 0.96% to reduce stray light reflection from the inner wall. A sample mounting door is located on one side of the chamber, with a deep ultraviolet high-transmittance quartz observation window installed on it. Optical apertures are respectively opened on the front and rear walls of the chamber, each sealed with a 2-millimeter-thick quartz window with a transmittance greater than 90% in the deep ultraviolet band, used for testing the incident and exit beams.

[0050] The wide-range temperature control module includes a thermoelectric cooler, a resistance heating wire, a temperature sensor, and a PID controller. The thermoelectric cooler is attached to the bottom outer surface of the cavity, with its cold end facing inwards and its hot end facing the external heat sink. The resistance heating wire is embedded in a heat-conducting plate on the inner wall of the cavity. The temperature sensor is a platinum resistance thermometer, with its probe extending into the cavity near the sample holder. The PID controller receives the resistance signal from the temperature sensor at its input, and its output is connected to the power supply for the thermoelectric cooler and the solid-state relay for the resistance heating wire. The target temperature set within the PID controller can be adjusted arbitrarily within the range of -40°C to 120°C, with an actual temperature control accuracy of ±0.3°C. When the set temperature is lower than the ambient temperature, the PID controller activates the thermoelectric cooler, controlling the direction of the DC current to achieve cooling; when the set temperature is higher than the ambient temperature, the PID controller activates the resistance heating wire, adjusting the heating power to achieve heating. The heating rate is adjusted via PID parameters, reaching a maximum of 15°C per minute, and the cooling rate can reach a maximum of 8°C per minute.

[0051] The high-power laser loading module includes a laser interface, an optical fiber transmission line, a beam homogenizer, and a laser power meter. The laser interface, located on the cavity sidewall, uses a standard SMA fiber optic connector for connecting an independently configured pulsed laser with an output wavelength of 1064 nm, a pulse width of 10 nanoseconds, and a repetition frequency adjustable between single triggering and 1 Hz. The optical fiber transmission line is a multimode silica fiber with a core diameter of 600 micrometers and a length of one meter. The beam homogenizer, mounted inside the cavity interface, contains a lens group and a rectangular aperture, shaping the divergent light output from the fiber into a uniform circular spot with a diameter of 2 mm and an energy non-uniformity of less than 5%. The beam homogenizer's exit port is directly opposite the center of the filter under test on the sample holder, with a distance of 15 mm from the filter surface. The laser power meter uses a thermopile probe, mounted on a movable bracket between the beam homogenizer and the filter, and is used to calibrate the incident laser energy density before formal testing. During calibration, the power meter probe is moved into the optical path to measure the single-pulse energy. The energy density value is calculated by combining the energy density with the spot area. After calibration, the probe is moved out of the optical path. The energy density is adjusted by changing the pump voltage or attenuation plate group of the laser. The adjustment range is from 0.1 joules per square centimeter to 100 joules per square centimeter, with a step accuracy of 0.5 joules per square centimeter.

[0052] The temperature control module and the high-power laser loading module can operate independently or in tandem according to a preset timing sequence. In tandem mode, the temperature control module first stabilizes the cavity temperature at a set value, and then the laser loading module outputs a single pulse or a sequence of pulses. The two are coordinated and scheduled by a cross-coupled control unit to achieve composite loading of temperature and laser.

[0053] The full-parameter synchronous optical testing unit consists of three parts connected sequentially: a broadband composite light source, a dual-path differential detection optical path, and a multi-channel synchronous detector group.

[0054] The broadband composite light source is installed in a sealed light source box, the inner wall of which is coated with a diffuse reflection coating. The composite light source comprises three independent light source elements: the first is a deuterium lamp with an output spectral range of 190 nm to 400 nm, used for excitation in the deep ultraviolet band; the second is a halogen tungsten lamp with an output spectral range of 350 nm to 2500 nm, used for excitation in the visible to near-infrared band; and the third is a deep ultraviolet light-emitting diode array, consisting of six LEDs with center wavelengths of 190 nm, 210 nm, 230 nm, 250 nm, 270 nm, and 290 nm, used to enhance the light source energy in the deep ultraviolet band. The three light source elements are fixed at three positions on an electric turntable driven by a stepper motor, which automatically switches the light source according to the test wavelength. An integrating sphere and a homogenizing rod are sequentially installed at the light outlet of the light source box. The integrating sphere has an inner diameter of 50 mm and its inner wall is coated with barium sulfate. The homogenizing rod is made of quartz, is 30 mm long, and has a 5 mm x 5 mm square cross-section. After passing through the integrating sphere and homogenizing rod, the illuminance uniformity of the emitted light spot reaches 98%.

[0055] The dual-path differential detection optical path includes a beam splitter, a reference optical path, and a sample optical path. The beam splitter is a UV fused silica beam splitter with a splitting ratio of 50:50 and an incident angle of 45 degrees. The incident surface of the beam splitter receives a collimated beam from a broadband composite light source and splits it into two equal paths: a reflected path as the reference beam and a transmitted path as the sample beam. The reference beam propagates in a straight line, passes through a neutral density filter, and then enters the reference detector. The sample beam passes sequentially through an adjustable aperture and a pair of mirrors, then through the front quartz window of the test cavity, the filter under test, and the rear quartz window, finally entering the sample detector. The aperture of the adjustable aperture can be continuously adjusted within the range of 0.5 mm to 10 mm to match the aperture of filters of different sizes. Both mirrors are UV-enhanced mirrors with an aluminum-coated film, exhibiting a reflectivity greater than 92% in the 200 nm to 2500 nm wavelength range.

[0056] The multi-channel synchronous detector array comprises a reference detector and a sample detector, both with identical structures. Each detector integrates three independent detection elements, arranged in parallel according to their wavelength bands: the first detection element is a photomultiplier tube with a photosensitive surface diameter of eight millimeters and a response wavelength range of 160 nm to 320 nm, used for signal reception in the deep ultraviolet band; the second detection element is a silicon photodiode with a photosensitive surface of 10 mm x 10 mm square and a response wavelength range of 320 nm to 1100 nm, used for signal reception in the visible to near-infrared band; the third detection element is an indium gallium arsenide photodiode with a photosensitive surface diameter of three millimeters and a response wavelength range of 900 nm to 2600 nm, used for signal reception in the infrared band. The outputs of the three detection elements are connected to their respective preamplifiers, which have adjustable gain levels of 10⁴, 10⁵, and 10⁶ times.

[0057] An electrically driven filter wheel is installed between the beam splitter and the reference detector, and between the last-stage reflector in the sample optical path and the sample detector. Six long-pass filters with different cutoff wavelengths are mounted on each filter wheel: 220 nm, 350 nm, 500 nm, 850 nm, 1200 nm, and 1800 nm cutoffs, used to suppress higher-order stray light that may be generated after the monochromator or grating beam splitting. The switching of the electrically driven filter wheels is automatically executed by the cross-coupled collaborative control unit according to the current test wavelength.

[0058] All six output channels of the reference detector and sample detector—three channels for the reference path and three channels for the sample path—are connected to a single 16-bit analog-to-digital converter (ADC). This ADC features six synchronous sample-and-hold circuits with a maximum sampling frequency of 200 kHz, triggered by the same external clock to ensure complete synchronization of the reference and sample signal acquisition times. After converting the analog voltage signal into a digital quantity, the ADC transmits it via a parallel data bus to the field-programmable gate array (FPGA) of the cross-coupled co-control unit for subsequent transmittance and reflectance calculations.

[0059] Within the embedded microprocessor of the closed-loop iterative testing module, three preset qualification threshold parameters are stored in three independent registers. The center wavelength temperature coefficient threshold is 0.01 nanometers per degree Celsius, the laser damage threshold is 10 joules per square centimeter, and the overall performance attenuation factor threshold is 0.15. These thresholds are preset by the system according to the typical engineering application requirements of wide bandgap filters and are loaded at the start of each test.

[0060] After the initial execution of the complete temperature-laser coupling test procedure, the embedded microprocessor compares the calculated center wavelength temperature coefficient, laser damage threshold, and overall performance attenuation factor with their corresponding register thresholds. If all three indicators meet the threshold requirements, a pass conclusion is directly output without triggering the iterative process. If any indicator fails to meet its corresponding threshold, the sensitive sub-region identification and parameter shrinkage process is triggered.

[0061] The identification methods for sensitive sub-intervals are set separately for different indicators:

[0062] When the center wavelength temperature coefficient exceeds the limit, the embedded microprocessor retrieves the center wavelength data stored at each temperature node in the heating phase. It calculates the center wavelength offset rate within each temperature interval, identifies the temperature range covered by the three consecutive temperature intervals with the highest offset rates, and extends each end of this range outwards by five degrees Celsius to define a sensitive sub-interval. For example, if the three temperature intervals with the highest offset rates cover 30 to 50 degrees Celsius, the sensitive sub-interval is determined to be 25 to 55 degrees Celsius.

[0063] For cases where the laser damage threshold is not met, the embedded microprocessor retrieves the relative decrease in transmittance at each pulse energy density within the laser irradiation segment. It identifies the energy density value corresponding to the pulse where the relative decrease in transmittance first exceeds 0.3%, and defines the sensitive sub-interval as a range of one step before and after this energy density value, i.e., two joules per square centimeter. For example, if the decrease first exceeds 0.3% at twelve joules per square centimeter, the sensitive sub-interval is determined to be between ten joules and fourteen joules per square centimeter.

[0064] For cases where the overall performance degradation factor exceeds the standard, the embedded microprocessor analyzes the change curves of the three degradation quantities: peak transmittance, cutoff depth, and spectral bandwidth, finds the interval with the largest slope of each curve, takes the union of the temperature ranges of the three intervals, and then extends the union outward by five degrees Celsius at both ends to form the sensitive sub-interval.

[0065] After identifying the sensitive sub-region, the cross-coupled collaborative control unit automatically narrowed the temperature scan range for subsequent iterative tests from the original -40°C to 120°C to this sensitive sub-region. Simultaneously, the original temperature step size was reduced from 10°C to 5°C, half the original value; the original laser energy step size was reduced from 2 joules per square centimeter to 1 joule per square centimeter, also half the original value. This reduction in step size doubled the test density within the sensitive sub-region, resulting in higher resolution performance evolution data.

[0066] After parameter adjustments are completed, the cross-coupling collaborative control unit restarts the closed-loop iterative test module, performing a second temperature-laser coupling test only within the shrunken sensitive sub-interval with a reduced step size. The remaining procedures for the second test are the same as the first test, including dynamic compensation testing and multi-parameter index calculation. After the second test, the calculated indices are compared again with preset thresholds. If the thresholds are met, a pass conclusion is output and the second test data is recorded; if they are still not met, failure boundary conditions are output, and iteration stops.

[0067] The embedded microprocessor of the cross-coupled collaborative control unit includes a failure boundary condition determination and output module. This module is triggered after the completion of the second iteration test. The second iteration test refers to the process of re-executing the temperature-laser coupling test within the sensitive sub-interval with a reduced step size and recalculating the multi-parameter indicators.

[0068] After the second iteration of the test, the embedded microprocessor compares the newly calculated center wavelength temperature coefficient, laser damage threshold, and overall performance attenuation factor with their respective preset register thresholds. If any one of the three indicators still fails to meet the corresponding threshold, the filter under test is determined to have failed the qualification test, and the failure boundary condition extraction process begins.

[0069] The failure boundary conditions include two specific parameters: the maximum withstand temperature and the critical laser energy density.

[0070] The maximum tolerance temperature is extracted as follows: The embedded microprocessor retrieves the center wavelength offset data calculated at all temperature nodes in the heating phase, and checks the rate of change of the center wavelength offset point by point, starting from the lowest temperature node. When the center wavelength offset rate within a certain temperature interval exceeds 0.005 nanometers per degree Celsius for two consecutive intervals, the starting temperature of that interval is recorded as the abnormal starting temperature. The maximum tolerance temperature is the abnormal starting temperature minus two degrees Celsius, which serves as the upper limit of the filter's tolerance in terms of center wavelength stability. If the center wavelength offset rate never exceeds 0.005 nanometers per degree Celsius, the maximum tolerance temperature is not output, but a "not detected" flag is output instead.

[0071] The critical laser energy density is extracted as follows: The embedded microprocessor retrieves the relative decrease in transmittance data for each pulse energy density within the laser irradiation segment. Starting from the lowest energy density, each point is checked sequentially. When the relative decrease in transmittance first exceeds 0.5%, the energy density value corresponding to that pulse is recorded as the critical laser energy density. If the relative decrease in transmittance never exceeds 0.5%, the maximum laser energy density achieved in the test is added to a step value of two joules per square centimeter as the reported critical laser energy density, with an "extrapolated value" label appended.

[0072] After the failure boundary conditions are extracted, the embedded microprocessor packages the two parameters in a standardized format and sends them to the data output module via a serial communication interface. The data output module generates a test report containing the failure boundary conditions, clearly indicating "failed the qualification test" along with the corresponding maximum withstand temperature and critical laser energy density values. For example, a test report for a filter might state: "Failed the qualification test; maximum withstand temperature is 58 degrees Celsius; critical laser energy density is 11 joules per square centimeter." This report provides quantitative basis for improving the filter's engineering design and addressing operational limitations in practical applications.

[0073] The cross-coupled collaborative control unit consists of three parts: a central processing unit, a signal acquisition card, and a drive circuit, which are connected by an internal bus. The central processing unit runs a closed-loop iterative control algorithm.

[0074] The central processing unit (CPU) uses an STM32H743 ARM microcontroller with a clock frequency of 400 MHz, and has two megabytes of flash memory and one kilobyte of random access memory. The CPU connects to the signal acquisition card via a serial peripheral interface bus and is connected to multiple drive circuits via general purpose input / output ports.

[0075] The signal acquisition card is designed based on the EP4CE10 field-programmable gate array (FPGA) chip, which contains 10,000 logic cells. The card integrates six synchronous sampling analog-to-digital converters (ADCs), each with a 16-bit resolution and a maximum sampling rate of 200 kHz. The inputs of the ADCs are connected to the six output channels of the reference detector and the sample detector, respectively. The FPGA includes an internal digital filter module that uses a moving average filtering algorithm to perform an arithmetic average of eight consecutively acquired data points from each channel before outputting the result. The card also integrates a temperature sensor interface, which connects to a platinum resistance temperature sensor in the multi-condition dynamic environment simulation unit via a four-wire connection, converting the resistance signal into a temperature value. The FPGA packages the six optical signal data streams and one temperature data stream into seven-byte data packets per frame and transmits them to the central processing unit (CPU) via the serial peripheral interface at a rate of 1,000 frames per second.

[0076] The drive circuit comprises three independent power drive boards. The first drive board connects to the semiconductor cooling chip and resistance heating wire of the wide-temperature-range temperature control module, providing ±15V DC voltage for cooling and 220V AC voltage for heating at its output terminals. The second drive board connects to the laser trigger port of the high-power laser loading module, outputting a 5V transistor-to-transistor logic level pulse with a pulse width of 10 microseconds to trigger a single emission from the external pulsed laser. The third drive board connects to the motorized turntable, adjustable aperture, motorized filter wheel, and grating drive controller in the full-parameter synchronous optical test unit, outputting phase drive signals for the stepper motor and speed control signals for the DC motor. All three drive boards are connected to the general-purpose input / output ports of the central processing unit via optocoupler isolation devices to prevent electromagnetic interference from the power circuit from being transmitted back to the central processing unit.

[0077] The closed-loop iterative control algorithm running on the central processing unit executes the following steps in sequence:

[0078] In the first step, the central processing unit sets the temperature control module to 25 degrees Celsius through the drive circuit. After waiting for 30 seconds, it reads the first full-spectrum data through the signal acquisition card and stores it as a baseline dataset.

[0079] The second step involves the central processing unit reading the pre-stored temperature-laser composite loading curve, which is stored in an array in flash memory. Each element of the array contains three fields: target temperature value, heating rate, and laser energy density value.

[0080] In the third step, the central processing unit (CPU) starts the temperature control module through the drive circuit and begins to heat up according to the target temperature value and heating rate in the curve. At the same time, it reads the real-time temperature value once every second through the signal acquisition card. When the difference between the real-time temperature value and the target temperature value is less than plus or minus 0.5 degrees Celsius, it is considered that the temperature node has been reached. The CPU sends an instruction to the drive circuit to pause the heating and collects the spectral data at that temperature node through the signal acquisition card.

[0081] In the fourth step, the central processing unit (CPU) calculates the center wavelength offset in real time based on the acquired spectral data, and calculates the difference between it and the previous node data stored in memory to obtain the offset rate. If the offset rate exceeds the preset rate threshold register value of 0.005 nanometers per degree Celsius, the CPU sends an instruction to the drive circuit to adjust the wavelength scanning step size of the full-parameter synchronous optical test unit from one point per nanometer to one point per 0.1 nanometers, and adjusts the integration time from 100 milliseconds to 500 milliseconds. If the offset rate falls back below the threshold and remains below 0.004 nanometers per degree Celsius for three consecutive judgments, the original scanning step size and integration time are restored.

[0082] In the fifth step, after the temperature node sequence is completed, the central processing unit reads the energy density value in the laser loading curve and sends a 10-microsecond pulse to the laser trigger port through the drive circuit to trigger the laser to output a single pulse. After the laser pulse is output, there is a 100-millisecond delay. The central processing unit collects the spectral data after the pulse through the signal acquisition card, calculates the relative decrease in transmittance, and stores the magnitude value in association with the pulse energy density value.

[0083] In the sixth step, after the central processing unit completes all curve nodes, it calculates the center wavelength temperature coefficient, laser damage threshold, and comprehensive performance attenuation factor, and compares them with the preset thresholds in memory.

[0084] In the seventh step, if any indicator does not meet the threshold, the central processing unit retrieves the sensitive sub-interval from the historical data, shrinks the temperature scanning range to that interval, reduces the temperature step size and laser energy step size to half of the original value, and repeats steps three through six. If the threshold is still not met after two iterations, the central processing unit outputs the maximum tolerable temperature and critical laser energy density.

[0085] The specific configurations of the aforementioned central processing unit, signal acquisition card, drive circuit, and closed-loop iterative control algorithm constitute the complete hardware and software implementation of the cross-coupled collaborative control unit.

[0086] The data output module consists of an embedded display panel, a universal serial bus interface circuit, and a micro printer driver circuit. The embedded display panel is a color LCD touchscreen with a resolution of 800 x 480 pixels, mounted on the front panel of the test system. The universal serial bus interface circuit uses a CH340 chip to convert serial data from the central processing unit in the cross-coupled cooperative control unit into universal serial bus protocol data, which is then led out via a standard Type A connector for connecting to an external computer or mobile storage device. The micro printer driver circuit uses a thermal printhead control chip and connects to an embedded thermal printer via a four-wire serial interface. The printer paper width is 58 mm.

[0087] The connection between the data output module and the cross-coupled collaborative control unit is as follows: the embedded display panel is directly connected to the LCD controller interface of the central processing unit via a 16-bit parallel bus; the universal serial bus interface circuit is connected to the universal serial bus data pin of the central processing unit via universal serial bus signal lines; the micro printer driver circuit is connected to two output pins of the central processing unit via universal input / output ports, which are used for data transmission and print triggering, respectively.

[0088] The test report output by the data output module contains two main parts: multi-parameter dynamic evolution curves and failure boundary conditions.

[0089] The multi-parameter dynamic evolution curve is generated as follows: Throughout the test, the cross-coupled collaborative control unit stores the spectral data acquired after each temperature node and each laser pulse in real time in a circular buffer within the central processing unit's random access memory. The circular buffer can store up to two thousand data points, each containing seven fields: timestamp, real-time temperature value, laser energy density value, center wavelength value, spectral bandwidth value, peak transmittance value, and cutoff depth value. After the test, the central processing unit transmits all data points from the buffer to the data output module at once. The graphics processor in the embedded display panel plots these data points into four curves: center wavelength versus temperature, peak transmittance versus laser energy density, spectral bandwidth versus temperature, and cutoff depth versus temperature. The horizontal axis of each curve represents the temperature or laser energy density value, and the vertical axis represents the corresponding spectral parameter value. The curves are plotted as line graphs, with data points connected by straight line segments. Users can touch any point on the curve via the touchscreen to display the specific value of that point.

[0090] The failure boundary condition is output as follows: When the test result is deemed unqualified, the cross-coupled collaborative control unit transmits the extracted maximum withstand temperature and critical laser energy density values ​​in text format to the data output module. The embedded display panel displays these two values ​​in a table below the curve display area. The table contains two rows and two columns: the first row contains the parameter name, and the second row contains the measured value. Simultaneously, the universal serial bus interface circuit generates a comma-separated text file named with the current test time and filter number. The file content includes four parts: basic test information (test time, filter number, operator), a list of raw data points for the multi-parameter dynamic evolution curve (seven fields per row), failure boundary conditions (maximum withstand temperature and critical laser energy density), and a pass / fail judgment conclusion (qualified or unqualified).

[0091] Upon receiving a print command, the micro printer driver circuit drives the thermal printer to output a paper report. The content of the paper report is consistent with the content displayed on the touchscreen, including graphs and a failure boundary condition table. The graphs are printed in grayscale, with each curve distinguished by a different line type, including solid lines, dashed lines, and dotted lines. Line type legends are indicated at the bottom of the paper. The failure boundary condition table is printed below the graphs, with a solid line border and a monospaced font.

[0092] Data interaction between the data output module and the cross-coupled collaborative control unit is interrupt-driven. After the central processing unit (CPU) of the cross-coupled collaborative control unit completes all test calculations, it sends a ready interrupt signal to the data output module. Upon receiving the interrupt signal, the data output module reads a data packet from a designated memory address of the CPU. The data packet is fixed at 32 kilobytes in length and contains all curve point data and failure boundary condition values. After reading, the data output module returns an acknowledgment signal to the CPU, which then releases the circular buffer memory, preparing for the next test.

[0093] A performance testing method for a wide bandgap filter, applied to a performance testing system for wide bandgap filters, specifically includes the following steps performed in sequence:

[0094] The first step is to install the filter under test onto the sample mounting base of the multi-condition dynamic environment simulation unit, close the cavity sealing door, and start the cross-coupling collaborative control unit. The cross-coupling collaborative control unit first performs a system self-test to confirm that the temperature control module, laser loading module, full-parameter synchronous optical testing unit, and all detectors are in normal working order. After the self-test passes, the system enters standby mode.

[0095] The second step involves the cross-coupled collaborative control unit controlling the full-parameter synchronous optical testing unit to perform the first full-parameter baseline scan. The cross-coupled collaborative control unit first switches the broadband composite light source to deuterium lamp mode, drives the motorized turntable to position the deuterium lamp in the output optical path, and simultaneously switches the motorized filter wheel to the 220 nm cutoff position. Then, it controls the grating drive controller to scan from 190 nm to 400 nm in steps of one point per nanometer, with an integration time of 100 milliseconds at each wavelength, simultaneously acquiring the output signals of the reference detector and the sample detector. After completing the deuterium lamp scan, it automatically switches to halogen tungsten lamp mode, switches the filter wheel to the 850 nm cutoff position, and scans from 350 nm to 2500 nm in the same phase length. The deep ultraviolet light-emitting diode array is only lit simultaneously with the deuterium lamp in the 190 nm to 250 nm band to enhance the energy in this band. After the scan is completed, the cross-coupled collaborative control unit stores the initial center wavelength value, initial spectral bandwidth value, initial peak transmittance value, and initial cutoff depth value.

[0096] The third step involves applying temperature changes and laser irradiation in stages according to a preset temperature-laser composite loading curve. Simultaneously, a full-parameter synchronous optical testing unit acquires the dynamic spectral response in real time at each environmental state point. The specific parameters of the composite loading curve are as follows: the temperature starts at 25 degrees Celsius, increasing to 120 degrees Celsius at a rate of 10 degrees Celsius per minute. Every 10 degrees Celsius increase is followed by an automatic 30-second pause as a data acquisition node, with a total of ten temperature nodes set. During each temperature node pause, the cross-coupled collaborative control unit triggers the full-parameter synchronous optical testing unit to repeatedly perform wavelength scanning. The scanning range is centered at the current estimated center wavelength, ±20 nanometers, with a step size of one point per nanometer and an integration time of 100 milliseconds. After acquisition, the temperature increase resumes. After the heating phase, the temperature control platform maintains a constant 120 degrees Celsius. Then, the laser irradiation phase begins: the laser loading module starts at 5 joules per square centimeter, increasing by 2 joules per square centimeter each time, sequentially outputting single-pulse lasers up to a maximum of 100 joules per square centimeter. After each pulse output, there is a 100-millisecond delay. The cross-coupled collaborative control unit triggers the full-parameter synchronous optical test unit to collect transmittance and reflectance at a fixed wavelength point, i.e., the initial center wavelength value. The collection time is 500 milliseconds, and the average value is taken as the measurement value after that pulse.

[0097] The fourth step involves dynamically adjusting the wavelength scan step size and integration time of the full-parameter synchronous optical test unit based on the real-time calculated center wavelength offset, thus completing the dynamic compensation test. The trigger condition for the dynamic compensation test is as follows: at each temperature node in the heating phase, the cross-coupled collaborative control unit calculates the difference between the current node's center wavelength value and the previous node's center wavelength value, divides it by ten degrees Celsius to obtain the offset rate. When this rate exceeds 0.005 nanometers per degree Celsius, in subsequent temperature node scans, the wavelength scan step size is adjusted from one point per nanometer to one point per 0.1 nanometers, and the integration time is extended from one hundred milliseconds to five hundred milliseconds. When the offset rate is below 0.004 nanometers per degree Celsius for three consecutive nodes, the original step size and integration time are restored.

[0098] The fifth step involves completing all temperature node and laser pulse tests. The cross-coupled collaborative control unit calculates multiple parameters and compares them with preset thresholds. These parameters include the center wavelength temperature coefficient, laser damage threshold, and overall performance attenuation factor. The center wavelength temperature coefficient is the maximum value of the center wavelength offset rate across all temperature intervals. The laser damage threshold is the laser energy density value corresponding to the first permanent decrease in transmittance exceeding 0.5%. The overall performance attenuation factor is equal to the sum of the maximum decrease in peak transmittance divided by the initial peak transmittance, the maximum degradation in cutoff depth divided by the initial cutoff depth, and the maximum broadening of the spectral bandwidth divided by the initial spectral bandwidth. The preset thresholds are: center wavelength temperature coefficient less than or equal to 0.01 nanometers per degree Celsius, laser damage threshold greater than or equal to 10 joules per square centimeter, and overall performance attenuation factor less than or equal to 0.15.

[0099] If all indicators meet the threshold requirements, the cross-coupled collaborative control unit determines that the filter passes the qualification test and outputs a qualification assessment result. If any indicator fails to meet the threshold, the second iteration test process is automatically initiated: the cross-coupled collaborative control unit identifies the sensitive sub-range corresponding to the failed indicator, narrows the temperature scan range from the original -40°C to 120°C to the sensitive sub-range, reduces the temperature step size from 10°C to 5°C, and reduces the laser energy step size from 2 joules per square centimeter to 1 joule per square centimeter. Then, steps three through five are repeated within the narrowed range. After the second iteration test, the threshold is compared again. If all indicators meet the threshold after the second iteration, a qualification assessment result is output with the note "qualified after iterative test". If any indicator still fails to meet the threshold after the second iteration, the failure boundary conditions, including the maximum withstand temperature and critical laser energy density, are output, and a third iteration is not performed.

[0100] Throughout the entire testing process, the filter under test remains in its original clamped state without requiring disassembly or movement. The cross-coupled collaborative control unit automatically records all intermediate data and generates a complete test report upon completion of the test.

[0101] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A performance testing system for a wide bandgap filter, characterized in that, include: The multi-condition dynamic environment simulation unit is used to generate temperature change sequences and laser irradiation sequences within the cavity where the filter under test is located. The full-parameter synchronous optical testing unit is used to acquire light signals transmitted through the filter and reflected by the filter in real time during the operation of the multi-condition dynamic environment simulation unit, and to calculate spectral performance parameters including center wavelength, spectral bandwidth, cutoff depth, transmittance, and reflectance. A cross-coupled collaborative control unit is electrically connected to the multi-condition dynamic environment simulation unit and the full-parameter synchronous optical test unit, respectively. It is used to use the temperature value and laser energy value monitored in real time by the multi-condition dynamic environment simulation unit as trigger signals to control the full-parameter synchronous optical test unit to perform optical signal acquisition at a specific environmental state point. At the same time, it uses the center wavelength offset calculated in real time by the full-parameter synchronous optical test unit as a feedback parameter to dynamically adjust the wavelength scanning step size and integration time of the full-parameter synchronous optical test unit, forming an adaptive compensation closed loop for optical detection. The cross-coupled collaborative control unit also integrates a closed-loop iterative test module, which is configured to perform the following progressive test process: first, perform a full-parameter baseline scan; second, excite stepwise according to the preset temperature-laser composite loading curve and collect dynamic responses in real time; third, dynamically adjust the acquisition parameters of the full-parameter synchronous optical test unit according to the center wavelength offset to perform dynamic compensation test; fourth, calculate multi-parameter indicators and compare them with preset thresholds; fifth, when the thresholds are not met, automatically shrink the operating range and refine the step amplitude to perform a second iterative test.

2. The performance testing system for a wide bandgap filter according to claim 1, characterized in that: The dynamic compensation test specifically involves the following steps: when the cross-coupled collaborative control unit determines that the rate of change of the center wavelength offset exceeds the preset rate threshold, it controls the full-parameter synchronous optical test unit to reduce the wavelength scanning step size from the normal step size to the fine step size, and at the same time, extends the integration time from the normal integration time to the long integration time. The standard step size is one wavelength point per nanometer, the fine step size is one wavelength point per 0.1 nanometers, the standard integration time is one hundred milliseconds, and the long integration time is five hundred milliseconds.

3. The performance testing system for a wide bandgap filter according to claim 2, characterized in that: The multi-parameter indicators include the center wavelength temperature coefficient, laser damage threshold, and comprehensive performance degradation factor. The comprehensive performance degradation factor is equal to the sum of the ratio of the maximum decrease in peak transmittance to the initial peak transmittance, the ratio of the maximum degradation in cutoff depth to the initial cutoff depth, and the ratio of the maximum broadening of spectral bandwidth to the initial spectral bandwidth.

4. The performance testing system for a wide bandgap filter according to claim 3, characterized in that: The multi-condition dynamic environment simulation unit includes a wide-temperature-range temperature control module and a high-power laser loading module. The temperature control module has a temperature control range of -40 degrees Celsius to 120 degrees Celsius, and the laser loading module outputs pulsed laser energy density ranging from 0.1 joules per square centimeter to 100 joules per square centimeter.

5. The performance testing system for a wide bandgap filter according to claim 4, characterized in that: The full-parameter synchronous optical testing unit includes a broadband composite light source, a dual-path differential detection optical path, and a multi-channel synchronous detector group. The dual-path differential detection optical path splits the incident light into two paths: a reference light and a sample light, which are synchronously received by the reference detector and the sample detector, respectively.

6. The performance testing system for a wide bandgap filter according to claim 5, characterized in that: The preset thresholds in the closed-loop iterative test module include the center wavelength temperature coefficient threshold, the laser damage threshold, and the comprehensive performance attenuation factor threshold. When any index fails to meet the corresponding threshold, the cross-coupled collaborative control unit automatically shrinks the temperature scanning range to the sensitive sub-interval corresponding to the index, and reduces the temperature step amplitude and laser energy step amplitude in the sub-interval to half of the original value.

7. The performance testing system for a wide bandgap filter according to claim 6, characterized in that: If the threshold is still not met after two iterations of testing, the cross-coupled collaborative control unit outputs the failure boundary conditions of the filter, which include the maximum tolerance temperature and the critical laser energy density.

8. The performance testing system for a wide bandgap filter according to claim 7, characterized in that: The cross-coupled collaborative control unit includes a central processing unit, a signal acquisition card, and a drive circuit. The central processing unit runs a closed-loop iterative control algorithm.

9. The performance testing system for a wide bandgap filter according to claim 8, characterized in that: It also includes a data output module, which is connected to the cross-coupled collaborative control unit and is used to output a test report containing multi-parameter dynamic evolution curves and failure boundary conditions.

10. A performance testing method for a wide bandgap filter, applied to the system according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Install the filter to be tested into the multi-condition dynamic environment simulation unit; S2: The cross-coupled collaborative control unit controls the full-parameter synchronous optical test unit to perform the first full-parameter baseline scan to obtain the initial spectral parameters; S3: According to the preset temperature-laser composite loading curve, the multi-condition dynamic environment simulation unit applies temperature changes and laser irradiation step by step, while the full-parameter synchronous optical test unit collects dynamic spectral responses in real time at each environmental state point; and during the test, the wavelength scanning step size and integration time of the full-parameter synchronous optical test unit are dynamically adjusted according to the center wavelength offset calculated in real time to complete the dynamic compensation test. S4: The cross-coupled collaborative control unit calculates multiple parameter indicators and compares them with preset thresholds. If all indicators meet the thresholds, a qualified evaluation result is output. If they do not meet the thresholds, the operating condition range is automatically narrowed and the step size is refined to perform a second iteration test until the final evaluation result or failure boundary condition is output.

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