IRCF filter dual optical path contrast detection method and related equipment

Abstract

The application provides an IRCF filter double optical path contrast detection method and related equipment, the method comprises the following steps: dividing an incident light beam into a test light path that transmits through a to-be-detected IRCF filter and a reference light path that transmits through an uncoated substrate; collecting dark noise data, and collecting spectral intensity of the test light path and the reference light path in a visible light to infrared wave band to obtain test spectral data and reference spectral data; at each wavelength point, dividing the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data to generate a transmittance spectral curve; extracting a transmittance characteristic parameter in a visible light wave band and a cutoff characteristic parameter in an infrared wave band from the transmittance spectral curve; and comparing the transmittance characteristic parameter and the cutoff characteristic parameter with a preset judgment threshold to determine whether the to-be-detected IRCF filter is qualified. The method eliminates system errors such as light source fluctuation and environmental interference, and improves the repeatability and stability of IRCF filter detection.

Description

Technical Field

[0001] This invention relates to the field of optical inspection technology, and in particular to a dual-optical-path contrast inspection method and related equipment for IRCF filters. Background Technology

[0002] Infrared Cut-off Filters (IRCFs) are crucial filtering elements in imaging optical systems. Their function is to allow visible light to pass through while blocking infrared light, thus ensuring that image sensors achieve color reproduction consistent with human vision. In applications such as smartphone cameras, automotive cameras, security monitoring, and machine vision, the performance of IRCF filters directly affects image quality and color accuracy. The core performance indicators of IRCF filters include visible light transmittance, infrared cut-off wavelength, and infrared cut-off depth. During the manufacturing process, factors such as coating uniformity, film thickness control, and material properties all affect these performance indicators. Therefore, rigorous optical performance testing is required for each IRCF filter to ensure that product quality meets design requirements.

[0003] Existing IRCF filter testing methods typically employ spectral transmittance measurement technology. This involves illuminating the filter with a light beam emitted from a light source and measuring the spectral intensity distribution of the transmitted light to evaluate the filter's optical properties. However, these methods are susceptible to systematic errors such as fluctuations in light source intensity and changes in ambient temperature during actual testing, leading to insufficient repeatability and stability of the measurement results. Particularly in batch testing scenarios, light source aging and changes in environmental conditions can accumulate significant measurement errors, making it difficult to meet the quality control requirements of high-end optical components. Summary of the Invention

[0004] The main objective of this invention is to solve the technical problem that existing IRCF filter detection methods are susceptible to systematic errors such as fluctuations in light source intensity and changes in environmental conditions, resulting in insufficient repeatability and stability of measurement results.

[0005] The first aspect of this invention provides a dual-path comparison detection method for IRCF filters. The method includes: acquiring an incident light beam; dividing the incident light beam into a test light path that passes through the IRCF filter under test and a reference light path that passes through an uncoated substrate; acquiring dark noise spectral intensity under no illumination to obtain dark noise data; and acquiring the spectral intensities of the test light path and the reference light path at multiple wavelength points covering the visible light to infrared bands to obtain test spectral data and reference spectral data; at each wavelength point, dividing the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data to generate a transmittance spectral curve; extracting transmittance characteristic parameters for the visible light band and cutoff characteristic parameters for the infrared band from the transmittance spectral curve; comparing the transmittance characteristic parameters and the cutoff characteristic parameters with preset judgment thresholds, and determining whether the IRCF filter under test is qualified based on the comparison results.

[0006] A second aspect of the present invention provides a dual-optical-path comparison and detection device for IRCF filters. The device includes: an optical path splitting module for acquiring an incident light beam and splitting it into a test optical path that transmits through the IRCF filter under test and a reference optical path that transmits through an uncoated substrate; a data acquisition module for acquiring dark noise spectral intensity under no light to obtain dark noise data, and acquiring the spectral intensity of the test optical path and the reference optical path at multiple wavelength points covering the visible light to infrared bands to obtain test spectral data and reference spectral data; a transmittance calculation module for dividing the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data at each wavelength point to generate a transmittance spectral curve; a parameter extraction module for extracting transmittance characteristic parameters in the visible light band and cutoff characteristic parameters in the infrared band from the transmittance spectral curve; and a pass / fail determination module for comparing the transmittance characteristic parameters and the cutoff characteristic parameters with preset determination thresholds and determining whether the IRCF filter under test is pass / fail based on the comparison results.

[0007] The aforementioned dual-optical-path comparative detection method and related equipment for IRCF filters achieve a dual-optical-path comparative detection architecture by acquiring an incident beam and dividing it into a test optical path that transmits through the IRCF filter under test and a reference optical path that transmits through an uncoated substrate. Dark noise data is obtained by acquiring the dark noise spectral intensity under no-light conditions. Simultaneously, the spectral intensities of the test and reference optical paths at multiple wavelengths covering the visible to infrared bands are acquired to obtain test spectral data and reference spectral data. At each wavelength point, the difference between the test spectral data and the dark noise data is divided by the difference between the reference spectral data and the dark noise data. A differential algorithm is used to eliminate systematic errors such as light source fluctuations and environmental interference, and a transmittance spectral curve is generated. Transmission characteristic parameters in the visible band and cutoff characteristic parameters in the infrared band are extracted from the transmittance spectral curve to comprehensively characterize the optical performance of the IRCF filter. The transmission characteristic parameters and cutoff characteristic parameters are compared with preset judgment thresholds, and the pass / fail status of the IRCF filter under test is determined based on the comparison results. This solution achieves real-time elimination of common-mode noise such as light source intensity fluctuations and environmental condition changes through dual-optical-path differential measurement. It solves the technical problems of existing single-optical-path detection methods being susceptible to systematic errors and having insufficient measurement repeatability and stability. It significantly improves the accuracy and reliability of IRCF filter optical performance testing and meets the stringent requirements of batch quality inspection of high-end optical components.

[0008] Beneficial Effects: This invention's technical solution, through a dual-optical-path comparison detection architecture, achieves real-time elimination of systematic errors such as fluctuations in light source intensity and changes in ambient temperature, significantly improving the repeatability and stability of IRCF filter optical performance testing. Compared to traditional single-optical-path detection methods, this solution uses a differential algorithm to automatically cancel common-mode noise interference, ensuring that measurement results are unaffected by light source aging and changes in environmental conditions. By extracting visible light transmittance and infrared cutoff parameters, this solution can comprehensively evaluate the key performance indicators of IRCF filters, providing reliable quality assurance for visual inspection applications such as smartphone cameras, automotive cameras, and security monitoring. High-precision optical performance testing ensures the accuracy of color reproduction and infrared cutoff effect of each IRCF filter, meeting the stringent quality requirements of high-end imaging systems for optical components, and significantly improving the quality control level and product consistency in the mass production process of IRCF filters.

[0009] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0010] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the first embodiment of the dual-optical-path contrast detection method for IRCF filters in this invention. Figure 2 This is a schematic diagram of the test optical path structure in an embodiment of the present invention; Figure 3 This is a schematic diagram of the transmittance spectrum curve of the IRCF filter in an embodiment of the present invention; Figure 4 This is a schematic diagram of the second embodiment of the dual-optical-path contrast detection method for IRCF filters in this invention. Figure 5 This is a schematic diagram of one embodiment of the dual-optical-path contrast detection device for IRCF filters in this invention. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions 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, 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.

[0013] The terms "comprising" and "having," and any variations thereof, used in the embodiments of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include other steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0014] To facilitate understanding of this embodiment, a detailed description of the dual-optical-path contrast detection method for IRCF filters disclosed in this embodiment of the invention will be provided first. For example... Figure 1 As shown, this method includes the following steps: 101. Obtain the incident beam and divide the incident beam into a test optical path that passes through the IRCF filter under test and a reference optical path that passes through the uncoated substrate; In this embodiment, acquiring the incident beam and splitting it into a test optical path through the IRCF filter under test and a reference optical path through the uncoated substrate includes: acquiring an incident beam covering the visible to infrared band from a light source and splitting the incident beam to obtain a first beam and a second beam; guiding the first beam to the IRCF filter under test, wherein the first beam passes through the IRCF filter under test at a near-vertical angle to form a test optical path; and guiding the second beam to an uncoated substrate of the same substrate material as the IRCF filter under test, wherein the second beam passes through the uncoated substrate at a near-vertical angle to form a reference optical path.

[0015] Specifically, such as Figure 2 The test optical path structure diagram shown includes a light source 1, a beam splitter 2, an IRCF filter under test 3, an uncoated substrate 4, and a detector 5. First, an incident beam is obtained from a broadband LED light source or halogen lamp (i.e., light source 1). The spectral range of this incident beam covers the visible light band (400-700nm) to the near-infrared band (700-1100nm). The incident beam is focused into a parallel beam column with a diameter of approximately 5-10 mm by a collimating lens and then perpendicularly illuminates the beam splitter (i.e., beam splitter 2) on its beam-splitting surface. The beam splitter is a planar optical glass with a special dielectric film coated on its surface. The coating design allows a portion (approximately 50%) of the incident beam to directly pass through the glass substrate and continue propagating in its original direction to form the first beam, while another portion (approximately 50%) is reflected at the coated surface and changes its propagation direction by 90 degrees to form the second beam. The beam splitting ratio (the intensity ratio of transmitted light to reflected light) remains essentially constant throughout the visible to infrared band, with a deviation not exceeding ±5%. This optical beam splitting method ensures that the intensity ratio of the first beam and the second beam is consistent at each wavelength point, providing a reliable reference for the differential calculation in the subsequent transmittance calculation and avoiding systematic errors caused by the difference in the splitting ratio of different wavelengths.

[0016] Then, after the first beam is transmitted from the beam splitter, it propagates in a straight line to the position of the IRCF filter under test (i.e., IRCF filter 3 under test). The IRCF filter under test is fixed on an adjustable sample stage, and the sample stage is adjusted by an angle adjustment mechanism to make the surface of the filter perpendicularly aligned with the propagation direction of the first beam. The specific alignment method is as follows: adjust the pitch angle and yaw angle of the sample stage so that the reflected light after the first beam hits the surface of the filter returns to the direction of the light source. At this time, the angle between the incident direction of the beam and the normal of the filter surface is less than 2 degrees, which satisfies the near-perpendicular incident condition. Near-perpendicular incident means that the propagation direction of the beam is basically coincident with the normal direction of the filter surface, and the deviation angle is controlled within 2 degrees. After the first beam is incident on the IRCF filter under test, most of the light energy in the visible light band penetrates the filter and continues to propagate, while most of the light energy in the infrared band is reflected or absorbed by the multilayer dielectric film on the surface of the filter, with only a small amount passing through. The light beam passing through the filter continues to propagate in its original direction. After traveling a spatial distance of 10-20 cm, it enters the light inlet of the spectral detector (i.e., detector 5), completing the construction of the test optical path. The near-perpendicular incident design is based on the fact that when the light beam is obliquely incident on the filter, the effective optical path of light of different wavelengths is different in the film layer, which leads to changes in interference conditions and the measurement results will deviate from the actual performance of the filter in actual camera applications.

[0017] Finally, after the second beam is reflected from the beam splitter, its propagation direction forms a 90-degree angle with the first beam. An uncoated substrate (i.e., uncoated substrate 4) is placed along the propagation path of the second beam. The material of this substrate is identical to that of the substrate of the IRCF filter under test. For example, if the substrate of the IRCF filter under test is BK7 optical glass, then the uncoated substrate is also made of the same grade of BK7 optical glass, and the thickness is also consistent (usually 0.3-0.5 mm). The uncoated substrate is fixed on another sample stage, and its surface is adjusted to be perpendicularly aligned with the propagation direction of the second beam to ensure near-perpendicular incidence. After passing through the uncoated substrate, the second beam travels the same spatial propagation distance as the first beam and enters another entrance of the spectrometer (if a dual-channel detector is used), or switches to the same detector entrance after the first beam measurement is completed (if a single-channel detector with mechanical shutter switching is used). The reason for using an uncoated substrate of the same material is that optical glass substrates inherently have absorption and reflection losses for different wavelengths of light. By allowing the reference light path to pass through a substrate of the same material and thickness, the substrate losses of the two light paths cancel each other out when calculating transmittance. The final transmittance value only reflects the filtering effect of the coating layer on the IRCF surface, without including the influence of the substrate material. The essence of dual-path comparative testing is to use the reference light path as a real-time benchmark to eliminate common-mode interference on the test light path caused by fluctuations in light source intensity, detector response drift, and changes in ambient temperature. This ensures that the measurement results only reflect the optical performance differences between the IRCF filter under test and the uncoated substrate.

[0018] 102. Obtain dark noise data by collecting the dark noise spectral intensity under no light, and obtain test spectral data and reference spectral data by collecting the spectral intensity of the test optical path and the reference optical path at multiple wavelength points covering the visible light band to the infrared band. In this embodiment, the process of acquiring dark noise spectral intensity under no light conditions to obtain dark noise data, and acquiring the spectral intensity of the test optical path and the reference optical path at multiple wavelength points covering the visible light to infrared bands to obtain test spectral data and reference spectral data, includes: turning off the light source, repeatedly acquiring the signal intensity values ​​output at each wavelength point, and averaging the acquired signal intensity values ​​at each wavelength point to obtain dark noise data; turning on the light source, adjusting and acquiring the spectral intensity of the reference optical path at each wavelength point, and when the spectral intensity at each wavelength point is less than a preset saturation threshold and greater than a preset multiple of the dark noise data, recording the current spectral acquisition parameters, which include the light source intensity and exposure time; and based on the spectral acquisition parameters, acquiring the spectral intensity of the test optical path at each wavelength point to obtain test spectral data, and acquiring the spectral intensity of the reference optical path at each wavelength point to obtain reference spectral data.

[0019] Specifically, first, turn off the power switch of the light source, so that both the test and reference optical paths are in a completely dark state. At this time, the spectrometer will still generate a weak background signal output due to its own thermal noise and circuit noise; this signal is called dark noise. Dark noise will be superimposed on subsequent optical signal measurements, causing systematic errors, and needs to be measured beforehand and subtracted during data processing. Start the data acquisition program of the spectrometer, set the exposure time, and begin acquisition. The sensor array inside the spectrometer converts the light intensity signal at each wavelength point into a digital output; the value output under no-light conditions is the dark noise signal intensity value. Collect complete spectral data multiple times, setting the number of acquisitions to 8-15 times (10 times in this embodiment), each acquisition covering all wavelength points in the 400-1100 nanometer band. Calculate the arithmetic mean of the 10 acquired data points at each wavelength point: for any wavelength point, add the signal intensity values ​​of that point in the 10 measurements, then divide by 10 to obtain the average dark noise value for that wavelength point. Repeat the above calculation for each wavelength point within the spectral range, finally obtaining a complete set of dark noise data. Averaging multiple measurements effectively reduces random fluctuations in dark noise because random noise statistically exhibits positive and negative fluctuations. Multiple averagings cancel each other out, making the dark noise data more stable and reliable. This set of dark noise data is then subtracted from both the test and reference spectral data during subsequent transmittance calculations, eliminating the impact of detector background noise on the accuracy of transmittance measurements.

[0020] Next, the light source power is turned on, and the spectral detector begins to collect the spectral intensity of the reference light path at each wavelength. Spectral intensity refers to the signal intensity value output by the sensor array at each wavelength after the light beam from the reference light path enters the detector. The detector's signal output range has an upper limit. When the input light intensity is too high, causing the output to reach the upper limit, the detector enters a saturation state, at which point the measurement data becomes distorted and invalid. A certain percentage of the detector's output upper limit is set as a preset saturation threshold, with this percentage ranging from 85% to 95% (90% is used in this embodiment). The preset multiple for dark noise data is set to 5-15 times (10 times is used in this embodiment), meaning that the light signal intensity must be at least a preset multiple of the dark noise to ensure that the effective signal is significantly higher than the noise level, meeting the signal-to-noise ratio requirements for subsequent transmittance calculations. It is then checked whether the spectral intensity of each wavelength point collected by the reference light path simultaneously meets two conditions: the spectral intensity of all wavelength points is less than the preset saturation threshold, and the spectral intensity of all wavelength points is greater than 10 times the dark noise value at that wavelength point. If the spectral intensity at certain wavelengths exceeds a preset saturation threshold, the light source output power is reduced or the detector exposure time is shortened. If the spectral intensity at certain wavelengths is less than 10 times the dark noise, the light source output power is increased or the detector exposure time is extended. The light source intensity is adjusted by changing the light source drive current, and the exposure time is adjusted by modifying the detector's integration time parameter. After repeated adjustments and checks, when the spectral intensity of the reference optical path at each wavelength simultaneously meets both conditions, the current light source drive current value and detector exposure time value are recorded. These two parameters constitute the spectral acquisition parameters. Adaptive calibration ensures that the spectral intensity of the reference optical path fully utilizes the detector's measurement range: avoiding saturation distortion in strong signal bands while ensuring sufficient signal-to-noise ratio in weak signal bands, thus optimizing the measurement data quality across the entire spectral range. If the above two conditions are not met after more than 15 adjustments, the system outputs a warning message, prompting a check of the light source status or replacement of the sample to be tested, and continues measurement using the closest parameter combination to the requirements, ensuring the robustness of the detection process.

[0021] Finally, the light source drive current and detector exposure time are fixed at the spectral acquisition parameter values ​​recorded in the previous step to ensure completely consistent measurement conditions. First, the spectral intensity of the test optical path is acquired. The beam of the test optical path passes through the IRCF filter under test and enters the detector. The detector outputs the corresponding signal intensity value at each wavelength point, and this set of values ​​is saved as test spectral data. Because the IRCF filter has a cutoff effect on infrared light, the spectral intensity of the test optical path is high in the visible light band (400-700 nm) and significantly reduced in the infrared band (850-1100 nm). This is because the IRCF filter has a cutoff effect on infrared light. Then, the spectral intensity of the reference optical path is acquired. The beam of the reference optical path passes through the uncoated substrate and enters the detector. The detector outputs the corresponding signal intensity value at each wavelength point, and this set of values ​​is saved as reference spectral data. The transmittance of the uncoated substrate is basically consistent across all wavelength bands, and the reference spectral data reflects the combined effect of the light source spectral distribution and the detector response characteristics. The same spectral acquisition parameters are used for measurements of the test optical path and the reference optical path to ensure the comparability of the two sets of data. When the light source intensity fluctuates, the test spectral data and the reference spectral data will increase or decrease synchronously. In the subsequent calculation of the transmittance ratio, the light source fluctuation is canceled out in the numerator and denominator as a common factor, and the measurement result is unaffected. This method of simultaneous measurement with differential calculation effectively suppresses the interference of systematic errors such as light source instability and ambient temperature changes on the measurement results, and significantly improves the accuracy and repeatability of IRCF filter transmittance measurement.

[0022] 103. At each wavelength point, divide the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data, and combine them to generate a transmittance spectral curve. In this embodiment, the step of dividing the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data at each wavelength point to generate a transmittance spectral curve includes: calculating the difference between the test spectral data and the dark noise data at each wavelength point to obtain the test net intensity, and calculating the difference between the reference spectral data and the dark noise data to obtain the reference net intensity; determining the effective wavelength points corresponding to the reference net intensity being greater than a preset noise threshold, and calculating the ratio of the test net intensity to the reference net intensity at each effective wavelength point to obtain a transmittance value; smoothing the transmittance values ​​at each effective wavelength point to obtain smoothed transmittance values, and combining the smoothed transmittance values ​​in wavelength order to form a transmittance spectral curve.

[0023] Specifically, three sets of raw data were obtained based on the above: test spectral data, reference spectral data, and dark noise data. Each of these three sets of data contains signal intensity values ​​corresponding to various wavelengths covering the 400-1100 nm band. For each wavelength point within the spectral range, a difference calculation was performed. The formula for calculating the net test intensity is: Is net = Is - Id, where Is net The values ​​represent the net intensity, Is represents the spectral data at that wavelength, and Id represents the dark noise data at that wavelength. The formula for calculating the reference net intensity is: Ir net = Ir - Id, where Ir net Here, Ir represents the reference net intensity, Id represents the reference spectral data at that wavelength, and Ir represents the dark noise data at that wavelength. The above calculation is repeated for all wavelengths within the spectral range to obtain the test net intensity and reference net intensity for each wavelength, forming a complete test net intensity data sequence and reference net intensity data sequence. Subtracting dark noise eliminates the influence of the detector's own background noise on the optical signal measurement, ensuring that the net intensity data only reflects the true light intensity after the beam passes through the filter or substrate. This is a prerequisite for accurate subsequent transmittance calculations.

[0024] Then, based on a preset noise threshold, which represents the lowest effective signal level of the reference net intensity, the reference net intensity data for all wavelengths is traversed, and wavelengths with a reference net intensity greater than the preset noise threshold are selected; these wavelengths are called effective wavelengths. Wavelengths with a reference net intensity less than or equal to the preset noise threshold are excluded because the light signal intensity at these wavelengths is too low, close to the detector noise level; using these data to calculate transmittance would lead to large errors or even outliers. For each effective wavelength, the transmittance value is calculated using the formula: T = Is net / Ir net Where T represents the transmittance value, Is net Ir represents the net intensity of the test at that wavelength point. net This represents the reference net intensity at that wavelength. This calculation process ratios the net intensities of the test and reference optical paths at the same wavelength to obtain the transmittance of the IRCF filter under test relative to the uncoated substrate at that wavelength. Performing the above calculation on all effective wavelengths yields a set of discrete transmittance values. The purpose of selecting effective wavelengths is to filter out weak signal regions with excessively low signal-to-noise ratios, preventing these low-quality data from interfering with the accuracy of the transmittance curve and ensuring that the final generated transmittance spectrum has reliable measurement accuracy across the entire effective wavelength range.

[0025] Finally, the transmittance values ​​of the effective wavelength points are smoothed to eliminate high-frequency noise fluctuations in the original data. The smoothing process uses a moving average algorithm. Specifically, a window containing several adjacent wavelength points is selected, with the window size set to 5-11 wavelength points (7 wavelength points in this embodiment). The arithmetic mean of the transmittance values ​​of each wavelength point within the window is calculated, and this average is used as the smoothed transmittance value of the center wavelength point of the window. The window is moved sequentially along the wavelength direction, and the same averaging calculation is performed for each effective wavelength point. The window size is adjusted for wavelength points at boundary positions based on the actual number of adjacent points. After smoothing, the smoothed transmittance values ​​of all effective wavelength points are arranged in ascending order of wavelength to form a continuous transmittance spectrum curve. The horizontal axis of this curve represents wavelength, and the vertical axis represents the smoothed transmittance value. Figure 3 As shown, the generated transmittance spectrum curve exhibits typical IRCF spectral characteristics: it maintains a high transmittance level in the visible light band (the 400-700 nm range marked in region L1 of the figure), with a relatively flat curve in this band; in the transition region of 700-850 nm, the curve drops rapidly; and in the infrared band (the 850-1100 nm range marked in region L2), the curve drops to a very low transmittance level and remains relatively stable. Smoothing makes the transmittance spectrum curve more continuous and smooth, eliminating random fluctuations and spikes in the original data, facilitating accurate identification and extraction of characteristic parameters from the curve, and enhancing the curve's intuitive representation of the optical properties of the IRCF filter.

[0026] 104. Extract the transmittance characteristic parameters of the visible light band and the cutoff characteristic parameters of the infrared band from the transmittance spectrum curve, respectively. In this embodiment, the transmittance characteristic parameters include the average transmittance of visible light, and the cutoff characteristic parameters include the infrared cutoff wavelength and the minimum infrared transmittance. Extracting the transmittance characteristic parameters for the visible light band and the cutoff characteristic parameters for the infrared band from the transmittance spectrum curve includes: calculating the average transmittance at each wavelength point of the transmittance spectrum curve within a preset wavelength range in the visible light band to obtain the average transmittance of visible light; determining the wavelength corresponding to a transmittance value equal to a preset cutoff threshold from the transmittance spectrum curve between the end wavelength of the visible light band and the beginning wavelength of the infrared band to obtain the infrared cutoff wavelength; and extracting the minimum transmittance value on the transmittance spectrum curve within a preset wavelength range in the infrared band as the minimum infrared transmittance.

[0027] Specifically, a preset wavelength range in the visible light band is determined on the transmittance spectrum curve. For example... Figure 3As shown in region L1, the preset wavelength range for the visible light band is set to 400-700 nm, covering the main spectral region perceptible to the human eye. The transmittance values ​​at all wavelength points on the transmittance spectrum curve within this range are extracted, and these values ​​are arithmetically averaged to obtain the average visible light transmittance. The average visible light transmittance refers to the average light transmission capability of the IRCF filter under test across the entire visible light band. (Refer to...) Figure 3 The transmittance spectrum curve maintains a high level in the visible light band. The figure shows that the average transmittance P1 in the visible light band is 91%. This parameter comprehensively reflects the light transmission capability of the IRCF filter within the visible light spectrum. Using the band-average evaluation method can comprehensively reflect the light transmission performance of the IRCF filter in the entire visible light range, avoiding evaluation deviations caused by measurement fluctuations at individual wavelength points.

[0028] Furthermore, the infrared cutoff wavelength is extracted from the transition region of the transmittance spectrum curve. The transition region refers to the area where transmittance decreases rapidly between the visible light band's ending wavelength and the infrared band's starting wavelength. For example... Figure 3 As shown, the visible light band termination wavelength is 700 nm, and the infrared band start wavelength is 850 nm. A preset cutoff threshold is set as the transmittance benchmark value defining the infrared cutoff performance. The position where the transmittance value equals the preset cutoff threshold is determined on the transmittance spectrum curve of the transition region; the wavelength corresponding to this position is the infrared cutoff wavelength. The infrared cutoff wavelength marks the transition point from a high visible light transmittance state to an infrared cutoff state for the IRCF filter. (Refer to...) Figure 3 The horizontal dashed line indicates that the preset cutoff threshold is set to 50%, and the vertical dashed line marks the intersection of the transmittance curve and the 50% threshold line, corresponding to an infrared cutoff wavelength P2 of approximately 800 nanometers. A smaller infrared cutoff wavelength indicates a faster response of the IRCF filter to infrared light, and a more effective ability to prevent infrared light from entering the image sensor.

[0029] Finally, the minimum infrared transmittance is extracted from the infrared band of the transmittance spectrum curve. For example... Figure 3 As shown in region L2, the preset wavelength range for the infrared band is set to 850-1100 nm, covering the main wavelength band for which image sensors are sensitive to infrared light. The minimum transmittance value is found on the transmittance spectrum curve within this wavelength range and taken as the minimum infrared transmittance. The minimum infrared transmittance reflects the strongest cutoff capability of the IRCF filter for infrared light. (Refer to...) Figure 3The circled area in the figure marks the lowest point of the transmittance curve in the infrared band, corresponding to a minimum infrared transmittance P3 of 2%. This parameter characterizes the IRCF filter's strongest suppression capability for infrared light. Using the minimum value, rather than the average value, as the evaluation metric allows for the identification of any possible points of abnormal transmittance increase in the infrared band, ensuring that the IRCF filter maintains sufficient cutoff depth throughout the entire infrared spectrum.

[0030] 105. Compare the transmission characteristic parameter and the cutoff characteristic parameter with a preset judgment threshold, and determine whether the IRCF filter under test is qualified based on the comparison result.

[0031] In this embodiment, the determination threshold includes a first determination threshold, a second determination threshold, and a third determination threshold. The step of comparing the transmittance characteristic parameter and the cutoff characteristic parameter with the preset determination thresholds and determining whether the IRCF filter under test is qualified based on the comparison results includes: comparing the average visible light transmittance with the first determination threshold, comparing the infrared cutoff wavelength with the second determination threshold, and comparing the minimum infrared transmittance with the third determination threshold; when the average visible light transmittance is greater than or equal to the first determination threshold, the infrared cutoff wavelength is less than or equal to the second determination threshold, and the minimum infrared transmittance is less than or equal to the third determination threshold, the IRCF filter under test is determined to be qualified; otherwise, the IRCF filter under test is determined to be unqualified.

[0032] Specifically, the three performance parameters extracted based on the above steps are compared with their corresponding judgment thresholds. The first, second, and third judgment thresholds are performance standard values ​​preset according to the design specifications and application requirements of the IRCF filter. The first judgment threshold is set for the average visible light transmittance, representing the minimum transmittance that the IRCF filter must achieve in the visible light band; the second judgment threshold is set for the infrared cutoff wavelength, representing the latest permissible wavelength position of the transition from visible to infrared light; and the third judgment threshold is set for the minimum infrared transmittance, representing the maximum permissible transmittance in the infrared band. Three independent numerical comparison operations are performed: the average visible light transmittance is compared with the first judgment threshold to determine whether the average visible light transmittance is greater than or equal to the first judgment threshold; the infrared cutoff wavelength is compared with the second judgment threshold to determine whether the infrared cutoff wavelength is less than or equal to the second judgment threshold; and the minimum infrared transmittance is compared with the third judgment threshold to determine whether the minimum infrared transmittance is less than or equal to the third judgment threshold. Each comparison yields a conclusion of satisfaction or dissatisfaction, and the three comparisons produce three independent comparison conclusions. Three different threshold values ​​are set to evaluate visible light transmittance and infrared cutoff performance respectively, enabling comprehensive testing of the optical characteristics of IRCF filters across different wavelengths. This ensures that the product simultaneously meets imaging brightness and infrared interference suppression requirements. The specific values ​​of the threshold values ​​are determined based on the IRCF filter's design specifications and application scenario. For example, for IRCF filters used in smartphone cameras, typical criteria are: first threshold (average visible light transmittance) ≥ 92%, second threshold (infrared cutoff wavelength) ≤ 650 nm, and third threshold (minimum infrared transmittance) ≤ 0.5%. For IRCF filters used in automotive cameras, which need to operate in low-light environments at night, the first threshold can be relaxed to ≥ 88%, but the second and third thresholds should be more stringent, set to ≤ 630 nm and ≤ 0.3% respectively, to ensure that the infrared supplementary light does not interfere with imaging. For IRCF filters used in security monitoring, which require day / night switching functionality, the criteria can be flexibly adjusted according to specific product requirements.

[0033] Then, a pass / fail determination is performed based on the comparison results of the three performance parameters. The determination rule is as follows: when the average visible light transmittance is greater than or equal to the first determination threshold, the infrared cutoff wavelength is less than or equal to the second determination threshold, and the minimum infrared transmittance is less than or equal to the third determination threshold, all three conditions are met, and the IRCF filter under test is determined to be qualified; when any one of the three conditions is not met, the IRCF filter under test is determined to be unqualified. (Refer to...) Figure 3The measurement results show that the average visible light transmittance P1 is 91%, the infrared cutoff wavelength P2 is 800 nm, and the minimum infrared transmittance P3 is 2%. These three parameters meet the corresponding performance requirements: sufficient transmittance in the visible light band, an infrared cutoff wavelength within a reasonable range, and sufficient cutoff depth in the infrared band. Therefore, the tested IRCF filter is deemed qualified. The judgment result is output as either qualified or unqualified. Qualified IRCF filters continue to the subsequent production process, while unqualified IRCF filters are rejected or reworked. The judgment rule that all three conditions must be met simultaneously reflects the strict control over the quality of IRCF filters. In practical imaging applications, insufficient visible light transmittance will lead to a darker image, affecting image quality; an excessively large infrared cutoff wavelength will cause infrared light leakage, resulting in color shift; and insufficient infrared cutoff depth will produce severe color distortion in strong infrared light source environments. Failure to meet any of these performance standards will affect image quality. By setting clear judgment thresholds and a well-defined judgment logic, an objective quantitative evaluation of the optical performance of IRCF filters is achieved. Compared with traditional manual visual inspection or single-point wavelength measurement, dual-optical-path comparative detection combined with multi-parameter comprehensive judgment can more accurately and comprehensively screen out qualified products that meet application requirements. Compared with single-optical-path detection methods, the measurement repeatability of the dual-optical-path comparative detection method is improved by 5-10 times, effectively solving the measurement instability problem caused by light source fluctuations and environmental interference. The complete detection cycle of a single IRCF filter is approximately 30-60 seconds, including dark noise acquisition, adaptive calibration, dual-optical-path data acquisition, and data processing, meeting the cycle time requirements of mass production lines.

[0034] In this embodiment of the invention, a dual-optical-path contrast detection architecture is used to achieve real-time elimination of common-mode noise such as fluctuations in light source intensity and changes in environmental conditions, solving the technical problems of existing single-optical-path detection methods being susceptible to systematic errors and lacking measurement repeatability and stability. Systematic errors are eliminated through a differential algorithm to generate high-quality transmittance spectrum curves; the optical performance of the IRCF filter is comprehensively characterized by extracting three characteristic parameters: average visible light transmittance, infrared cutoff wavelength, and minimum infrared transmittance; and automated qualification judgment is performed by setting clear judgment thresholds, significantly improving the accuracy, reliability, and efficiency of IRCF filter optical performance testing, meeting the stringent requirements of batch quality inspection of high-end optical components.

[0035] Please see Figure 4 Another embodiment of the dual-path contrast detection method for IRCF filters in this application includes: 201. Obtain the incident beam and divide the incident beam into a test optical path that passes through the IRCF filter under test and a reference optical path that passes through the uncoated substrate; 202. Obtain dark noise data by collecting the dark noise spectral intensity under no light, and obtain test spectral data and reference spectral data by collecting the spectral intensity of the test optical path and the reference optical path at multiple wavelength points covering the visible light band to the infrared band. 203. At each wavelength point, divide the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data, and combine them to generate a transmittance spectral curve. In this embodiment, steps 201-203 are similar to steps 101-103 in the first embodiment, and will not be described again here.

[0036] 204. Within a preset wavelength range in the visible light band, calculate the average transmittance at each wavelength point of the transmittance spectrum curve to obtain the average transmittance of visible light; In this embodiment, firstly, within a preset wavelength range in the visible light band, the average transmittance at each wavelength point of the transmittance spectrum curve is calculated to obtain the average transmittance of visible light. The specific extraction method is the same as step 104 in the first embodiment, and will not be repeated here. Then, in the transition region between the end wavelength of the visible light band and the start wavelength of the infrared band, the transmittance values ​​at each wavelength point are checked sequentially along the transmittance spectrum curve from short wavelength to long wavelength. (Refer to...) Figure 3 The visible light band terminates at 700 nm, the infrared band begins at 850 nm, and the transition region covers the 700-850 nm range. A preset cutoff threshold of 50% is set; this threshold defines the boundary between the visible light transmission state and the infrared cutoff state of the IRCF filter. Figure 3 The horizontal dashed line indicates the location of the threshold line. Within the transition region, the transmittance values ​​at each wavelength are compared with the preset cutoff threshold. When the transmittance of a wavelength point is found to be higher than the preset cutoff threshold, while the transmittance of its adjacent next wavelength point is lower than the preset cutoff threshold, the former is designated as the first wavelength point, and the latter as the second wavelength point. The first and second wavelength points refer to two adjacent measurement data points on the transmittance spectrum curve located on either side of the preset cutoff threshold and preceding and following each other in the wavelength sequence. Figure 3 It can be observed that the transmittance curve drops rapidly in the transition region and crosses the 50% threshold line. There are two adjacent wavelength points on either side of the crossing point, with one point having a transmittance slightly higher than 50% and the other point having a transmittance slightly lower than 50%. These two adjacent wavelength points define the position range of the preset cutoff threshold on the transmittance curve, providing necessary boundary data for subsequent interpolation calculations.

[0037] 205. Between the visible light band termination wavelength and the infrared band start wavelength, determine the wavelength corresponding to the transmittance value being equal to the preset cutoff threshold from the transmittance spectrum curve to obtain the infrared cutoff wavelength. In this embodiment, determining the wavelength corresponding to a transmittance value equal to a preset cutoff threshold from the transmittance spectrum curve between the visible light band termination wavelength and the infrared band start wavelength to obtain the infrared cutoff wavelength includes: finding a first wavelength point with transmittance higher than the preset cutoff threshold and a second wavelength point with transmittance lower than the preset cutoff threshold from the transmittance spectrum curve between the visible light band termination wavelength and the infrared band start wavelength, wherein the first wavelength point and the second wavelength point are adjacent; calculating the wavelength value corresponding to the preset cutoff threshold based on the wavelength difference between the first wavelength point and the second wavelength point, the difference between the transmittance of the first wavelength point and the preset cutoff threshold, and the transmittance difference between the first wavelength point and the second wavelength point, and using the wavelength value as the infrared cutoff wavelength.

[0038] Specifically, linear interpolation is performed based on the measurement data from the first and second wavelength points to determine the precise wavelength position corresponding to the preset cutoff threshold. The principle of linear interpolation is to assume a linear change in the transmittance curve between the first and second wavelength points, and to calculate the wavelength value corresponding to the preset cutoff threshold based on the wavelength-transmittance coordinate relationship between the two points. The calculation formula is: λ c = λ1+ (T c - T1) × (λ2- λ1) / (T2- T1), where λ c Indicates the infrared cutoff wavelength, λ1 represents the wavelength value at the first wavelength point, λ2 represents the wavelength value at the second wavelength point, and T c This represents the preset cutoff threshold, T1 represents the transmittance at the first wavelength point, and T2 represents the transmittance at the second wavelength point. In the formula, (λ2 - λ1) is the wavelength difference between the first and second wavelength points, reflecting the wavelength interval between two adjacent measurement points; (T... c - T1) is the difference between the transmittance at the first wavelength point and the preset cutoff threshold, reflecting the degree to which the first wavelength point deviates from the threshold; (T2 - T1) is the difference between the transmittance at the first wavelength point and the transmittance at the second wavelength point, reflecting the magnitude of the transmittance change between the two points. Substituting these differences into the formula for calculation, the resulting λc is the infrared cutoff wavelength. (Refer to...) Figure 3The vertical dashed line marks the intersection of the transmittance curve and the 50% threshold line. The marking indicates that the infrared cutoff wavelength P2 is approximately 800 nm, calculated using the linear interpolation method described above. Linear interpolation interpolates between two discrete measurement points, resulting in a more accurate infrared cutoff wavelength than methods that directly select a discrete wavelength point. Spectroscopic detectors have limited wavelength resolution, and there is a certain wavelength interval between adjacent wavelength points. If a discrete point is directly selected as the cutoff wavelength, the measurement accuracy will be limited by the detector's wavelength resolution. Linear interpolation can calculate a more precise cutoff wavelength position between adjacent wavelength points, allowing the measurement results to more accurately reflect the cutoff characteristic boundary of the IRCF filter. Linear interpolation is suitable for situations where the interval between adjacent wavelength points is small (less than 10 nm) and the transmittance change is relatively gentle. When the cutoff edge is extremely steep, cubic spline interpolation or other higher-order interpolation methods can be used to further improve the calculation accuracy.

[0039] 206. Within a preset wavelength range in the infrared band, extract the minimum transmittance value on the transmittance spectrum curve as the minimum infrared transmittance; In this embodiment, the minimum infrared transmittance is extracted within a preset wavelength range in the infrared band of the transmittance spectrum curve. The preset wavelength range for the infrared band is set to 850-1100 nanometers, such as... Figure 3 The L2 region is marked in the image. This wavelength range covers the near-infrared spectral region, a band where image sensors have a strong response to infrared light, and is also a band that IRCF filters need to specifically cut off. Within this wavelength range, transmittance values ​​are sequentially read at each wavelength point on the transmittance spectrum curve. All read transmittance values ​​are compared, and the transmittance value with the lowest value is identified as the minimum infrared transmittance. (Refer to...) Figure 3 The transmittance curve shows a low transmittance level in the infrared band, with a trough at which the curve reaches its lowest point. The circled area in the graph marks this trough, and the extracted minimum infrared transmittance P3 is 2%. The minimum infrared transmittance reflects the location of the strongest cutoff effect of the IRCF filter across the entire infrared band; the smaller the value, the stronger the filter's maximum suppression of infrared light. Using the minimum value as the evaluation metric, rather than the average transmittance of the infrared band, allows for the identification of wavelengths with abnormally high transmittance. In actual testing, even if the transmittance is low across most of the infrared band, a significant increase in transmittance at a local wavelength will create an infrared light leakage channel at that wavelength, causing infrared light to enter the image sensor and resulting in color distortion. Extracting the minimum transmittance as the evaluation metric ensures that quality inspection can detect any potential weaknesses in the infrared band's cutoff performance, reflecting the stringent requirements for the infrared cutoff depth of the IRCF filter and guaranteeing that qualified products have sufficient cutoff capability across the entire infrared band.

[0040] 207. Compare the transmission characteristic parameter and the cutoff characteristic parameter with a preset judgment threshold, and determine whether the IRCF filter under test is qualified based on the comparison result.

[0041] In this embodiment, step 207 is similar to step 105 in the first embodiment, and will not be described again here.

[0042] In this embodiment, a dual-optical-path contrast detection architecture is used to achieve real-time elimination of common-mode noise such as fluctuations in light source intensity and changes in environmental conditions, solving the technical problems of existing single-optical-path detection methods being susceptible to systematic errors and lacking measurement repeatability and stability. Systematic errors are eliminated through a differential algorithm to generate high-quality transmittance spectrum curves; the optical performance of the IRCF filter is comprehensively characterized by extracting three characteristic parameters: average visible light transmittance, infrared cutoff wavelength, and minimum infrared transmittance; and automated pass / fail determination is performed by setting clear judgment thresholds, significantly improving the accuracy, reliability, and efficiency of IRCF filter optical performance testing, meeting the stringent requirements of batch quality inspection of high-end optical components.

[0043] The dual-path contrast detection method for IRCF filters in embodiments of the present invention has been described above. The dual-path contrast detection device for IRCF filters in embodiments of the present invention will be described below. Please refer to [link to relevant documentation]. Figure 5 One embodiment of the dual-optical-path contrast detection device for IRCF filters in this invention includes: The optical path beam splitting module 301 is used to acquire the incident beam and split the incident beam into a test optical path that passes through the IRCF filter under test and a reference optical path that passes through the uncoated substrate. The data acquisition module 302 is used to acquire the dark noise spectral intensity when there is no light to obtain dark noise data, and to acquire the spectral intensity of the test optical path and the reference optical path at multiple wavelength points covering the visible light band to the infrared band to obtain test spectral data and reference spectral data. The transmittance calculation module 303 is used to divide the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data at each wavelength point, and combine them to generate a transmittance spectral curve. The parameter extraction module 304 is used to extract the transmission characteristic parameters of the visible light band and the cutoff characteristic parameters of the infrared band from the transmittance spectrum curve, respectively. The pass / fail determination module 305 is used to compare the transmission characteristic parameter and the cutoff characteristic parameter with a preset determination threshold, and determine whether the IRCF filter under test is qualified based on the comparison result.

[0044] In this embodiment of the invention, an incident light beam is acquired and divided into a test light path that transmits through the IRCF filter under test and a reference light path that transmits through the uncoated substrate, thereby realizing a dual-path comparison detection architecture. Dark noise data is obtained by acquiring the dark noise spectral intensity under no-light conditions. Simultaneously, the spectral intensities of the test and reference light paths at multiple wavelengths covering the visible to infrared bands are acquired to obtain test spectral data and reference spectral data. At each wavelength point, the difference between the test spectral data and the dark noise data is divided by the difference between the reference spectral data and the dark noise data. A differential algorithm is used to eliminate systematic errors such as light source fluctuations and environmental interference, and a transmittance spectral curve is generated. Transmission characteristic parameters in the visible light band and cutoff characteristic parameters in the infrared band are extracted from the transmittance spectral curve to comprehensively characterize the optical performance of the IRCF filter. The transmission characteristic parameters and cutoff characteristic parameters are compared with preset judgment thresholds, and the IRCF filter under test is determined to be qualified based on the comparison results. This solution achieves real-time elimination of common-mode noise such as light source intensity fluctuations and environmental condition changes through dual-optical-path differential measurement. It solves the technical problems of existing single-optical-path detection methods being susceptible to systematic errors and having insufficient measurement repeatability and stability. It significantly improves the accuracy and reliability of IRCF filter optical performance testing and meets the stringent requirements of batch quality inspection of high-end optical components.

[0045] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system or system / unit described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0046] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-optical-path contrast detection method for IRCF filters, characterized in that, The dual-path contrast detection method for IRCF filters includes: Acquire the incident beam and divide the incident beam into a test optical path that passes through the IRCF filter under test and a reference optical path that passes through the uncoated substrate; The process involves acquiring dark noise data by collecting the dark noise spectral intensity under no light conditions, and acquiring the spectral intensity of the test optical path and the reference optical path at multiple wavelength points covering the visible to infrared bands to obtain test spectral data and reference spectral data. Specifically, this includes: turning off the light source, repeatedly acquiring the signal intensity values ​​output at each wavelength point, and averaging the acquired signal intensity values ​​at each wavelength point to obtain dark noise data; turning on the light source, adjusting and acquiring the spectral intensity of the reference optical path at each wavelength point, and when the spectral intensity at each wavelength point is less than a preset saturation threshold and greater than a preset multiple of the dark noise data, recording the current spectral acquisition parameters, including the light source intensity and exposure time; based on the spectral acquisition parameters, acquiring the spectral intensity of the test optical path at each wavelength point to obtain test spectral data, and acquiring the spectral intensity of the reference optical path at each wavelength point to obtain reference spectral data. At each wavelength point, the difference between the test spectral data and the dark noise data is divided by the difference between the reference spectral data and the dark noise data, and the transmittance spectral curve is generated by combining the results. The transmittance characteristic parameters of the visible light band and the cutoff characteristic parameters of the infrared band are extracted from the transmittance spectrum curves, respectively. The transmittance characteristic parameter and the cutoff characteristic parameter are compared with a preset judgment threshold, and the test IRCF filter is judged to be qualified based on the comparison result.

2. The dual-optical-path comparison detection method for IRCF filters according to claim 1, characterized in that, The acquisition of the incident beam, which involves splitting the incident beam into a test optical path passing through the IRCF filter under test and a reference optical path passing through the uncoated substrate, includes: An incident beam covering the visible to infrared band is obtained from a light source, and the incident beam is split into a first beam and a second beam. The first beam is guided to the IRCF filter under test, and the first beam passes through the IRCF filter under test at a near-vertical angle to form a test optical path; The second beam is guided to an uncoated substrate with the same material as the IRCF filter substrate under test, and the second beam passes through the uncoated substrate at a near-vertical angle to form a reference optical path.

3. The dual-optical-path comparison detection method for IRCF filters according to claim 1, characterized in that, The step of dividing the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data at each wavelength point to generate a transmittance spectral curve includes: For each wavelength point, the difference between the test spectral data and the dark noise data is calculated to obtain the test net intensity, and the difference between the reference spectral data and the dark noise data is calculated to obtain the reference net intensity; Determine the effective wavelength points corresponding to the reference net intensity being greater than the preset noise threshold, and for each effective wavelength point, calculate the ratio of the test net intensity to the reference net intensity to obtain the transmittance value; The transmittance values ​​at each effective wavelength point are smoothed to obtain smoothed transmittance values, and the smoothed transmittance values ​​are combined in wavelength order to form a transmittance spectrum curve.

4. The dual-optical-path comparison detection method for IRCF filters according to claim 1, characterized in that, The transmittance characteristic parameters include the average transmittance of visible light, and the cutoff characteristic parameters include the infrared cutoff wavelength and the minimum infrared transmittance. Extracting the transmittance characteristic parameters for the visible light band and the cutoff characteristic parameters for the infrared band from the transmittance spectrum curve includes: Within a preset wavelength range in the visible light band, the average transmittance at each wavelength point of the transmittance spectral curve is calculated to obtain the average transmittance of visible light. Between the visible light band termination wavelength and the infrared band start wavelength, the wavelength corresponding to the transmittance value being equal to the preset cutoff threshold is determined from the transmittance spectrum curve to obtain the infrared cutoff wavelength. Within a preset wavelength range in the infrared band, the minimum transmittance value on the transmittance spectral curve is extracted as the minimum infrared transmittance.

5. The dual-optical-path comparison detection method for IRCF filters according to claim 4, characterized in that, The process of determining the infrared cutoff wavelength by selecting the wavelength corresponding to a transmittance value equal to a preset cutoff threshold from the transmittance spectral curve, between the visible light band termination wavelength and the infrared band start wavelength, includes: Between the visible light band termination wavelength and the infrared band start wavelength, find a first wavelength point with transmittance higher than a preset cutoff threshold and a second wavelength point with transmittance lower than a preset cutoff threshold from the transmittance spectrum curve, wherein the first wavelength point and the second wavelength point are adjacent. Based on the wavelength difference between the first wavelength point and the second wavelength point, the difference between the transmittance of the first wavelength point and the preset cutoff threshold, and the transmittance difference between the first wavelength point and the second wavelength point, the wavelength value corresponding to the preset cutoff threshold is calculated, and the wavelength value is used as the infrared cutoff wavelength.

6. The dual-optical-path comparison detection method for IRCF filters according to claim 1, characterized in that, The determination thresholds include a first determination threshold, a second determination threshold, and a third determination threshold. The step of comparing the transmittance characteristic parameter and the cutoff characteristic parameter with the preset determination thresholds, and determining whether the IRCF filter under test is qualified based on the comparison result, includes: The average transmittance of visible light is compared with a first determination threshold, the infrared cutoff wavelength is compared with a second determination threshold, and the minimum infrared transmittance is compared with a third determination threshold. When the average visible light transmittance is greater than or equal to the first determination threshold, the infrared cutoff wavelength is less than or equal to the second determination threshold, and the minimum infrared transmittance is less than or equal to the third determination threshold, the IRCF filter under test is determined to be qualified; otherwise, the IRCF filter under test is determined to be unqualified.

7. A dual-optical-path contrast detection device for IRCF filters, characterized in that, The IRCF filter dual-optical-path contrast detection device includes: The optical path beam splitting module is used to acquire the incident beam and split the incident beam into a test optical path that passes through the IRCF filter under test and a reference optical path that passes through the uncoated substrate. The data acquisition module is used to acquire dark noise spectral intensity at no light to obtain dark noise data, and to acquire the spectral intensity of the test optical path and the reference optical path at multiple wavelength points covering the visible light to infrared bands to obtain test spectral data and reference spectral data. Specifically, it includes: turning off the light source, repeatedly acquiring the signal intensity values ​​output at each wavelength point, and averaging the acquired signal intensity values ​​at each wavelength point to obtain dark noise data; turning on the light source, adjusting and acquiring the spectral intensity of the reference optical path at each wavelength point; when the spectral intensity at each wavelength point is less than a preset saturation threshold and greater than a preset multiple of the dark noise data, recording the current spectral acquisition parameters, including the light source intensity and exposure time; based on the spectral acquisition parameters, acquiring the spectral intensity of the test optical path at each wavelength point to obtain test spectral data, and acquiring the spectral intensity of the reference optical path at each wavelength point to obtain reference spectral data. The transmittance calculation module is used to divide the difference between the test spectral data and the dark noise data by the difference between the reference spectral data and the dark noise data at each wavelength point, and combine them to generate a transmittance spectral curve. The parameter extraction module is used to extract the transmission characteristic parameters of the visible light band and the cutoff characteristic parameters of the infrared band from the transmittance spectrum curve, respectively. The pass / fail determination module is used to compare the transmission characteristic parameters and the cutoff characteristic parameters with preset determination thresholds, and determine whether the IRCF filter under test is qualified based on the comparison results.

8. A dual-optical-path comparison and detection device for IRCF filters, characterized in that, The IRCF filter dual-path contrast detection device includes: a memory and at least one processor, wherein the memory stores instructions; The at least one processor invokes the instructions in the memory to cause the IRCF filter dual-path contrast detection device to perform each step of the IRCF filter dual-path contrast detection method as described in any one of claims 1-6.

9. A computer-readable storage medium storing instructions thereon, characterized in that, When the instructions are executed by the processor, they implement the various steps of the dual-path contrast detection method for IRCF filters as described in any one of claims 1-6.

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