Infrared radiation measuring device response slope calibration apparatus and method

Abstract

The present application belongs to the technical field of equipment calibration, and particularly relates to an infrared radiation measuring equipment response slope calibration device and method. The infrared radiation measuring equipment comprises a telescope barrel, and the calibration device comprises a cylinder, a lens cover, a diffuse reflection plate and a black body. The cylinder is sleeved on the outer edge of the front end of the telescope barrel, the lens cover covers the aperture of the cylinder, the diffuse reflection plate is attached to the inside of the lens cover and is synchronously turned with the lens cover, and the black body is arranged outside the lens cover and can be connected and detached. The aperture of the opening on the lens cover is smaller than the aperture of the black body. The calibration range of the method meets the requirements of low-end and high-end ranges, the cost is relatively low, and obvious economic benefits are achieved.

Description

Technical Field

[0001] This invention belongs to the field of equipment calibration technology, and particularly relates to a method for calibrating the response slope of infrared radiation measurement equipment. Background Technology

[0002] In some applications of infrared radiation response data from infrared radiation measurement equipment, only the slope of the linear segment of the equipment's response needs to be obtained, which simplifies the equipment's infrared radiation response calibration system. Currently, methods for calibrating the response slope include large-aperture blackbody (aperture larger than the optical aperture of the calibration equipment) and the small blackbody + collimator method. However, both methods are costly and bulky for calibrating large-aperture equipment, making them unsuitable for field use. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a method for calibrating the response slope of infrared radiation measurement equipment.

[0004] To achieve the above objectives, this invention proposes a calibration device for the response slope of an infrared radiation measurement equipment. The calibration device includes a cylinder, a lens cap, a diffuse reflector, and a blackbody; wherein...

[0005] The cylinder is fitted onto the outer edge of the front end of the telescope tube, the lens cap covers the cylinder opening, and the diffuse reflector is attached to the inside of the lens cap and rotates synchronously with the lens cap.

[0006] The blackbody is located on the outside of the lens cover and can be docked and detached. The lens cover has an opening with a diameter smaller than that of the blackbody.

[0007] As an improvement to the above-mentioned device, the diameter of the cylinder is larger than the entrance pupil of the telescope, so that the emission or reflection of light from the cylinder has no effect on the pixel grayscale of the infrared radiation measuring equipment under test.

[0008] As an improvement to the above-mentioned device, the lens cover is electrically flipped. During the entire flipping process, the edge of the lens cover is outside the effective aperture of the telescope, so that the light emitted or reflected by the lens cover has no effect on the pixel grayscale of the infrared radiation measuring equipment under test.

[0009] As an improvement to the above-mentioned device, the device also includes a thermal insulation layer for shielding and insulating the exposed aperture of the blackbody.

[0010] As an improvement to the above-mentioned device, the diffuse reflector is made of polytetrafluoroethylene.

[0011] A method for calibrating the response slope of an infrared radiation measuring device, implemented using the aforementioned calibration apparatus, the method comprising:

[0012] Close the lens cap;

[0013] Set the blackbody temperature to T1, push the blackbody into the opening or leave the blackbody open, and record the corresponding grayscale D at the blackbody temperature T1. Ns1 and normalized brightness L of the radiation spectrum Ts1 ;

[0014] Remove or block the blackbody, set the blackbody temperature to T2, then push the blackbody into the opening, and record the grayscale response D corresponding to the blackbody temperature T2. Ns2 and normalized brightness L of the radiation spectrum Ts2 ;

[0015] Based on the predetermined ratio of the lens cap opening area S t The slope K of the linear response model of the infrared radiation measurement equipment is obtained from the following formula. T Thus, calibration is achieved:

[0016]

[0017] Compared with the prior art, the advantages of the present invention are:

[0018] 1. Construct an easy-to-use infrared radiation response slope calibration system for equipment by utilizing a small blackbody, thermal insulation material, diffuse reflector, lens cap, electric servo motor, and angle measuring mechanism;

[0019] 2. This method meets the calibration requirements of full-aperture, full-process, and full-field infrared radiation measurement equipment; the calibration range meets the requirements of both low-end and high-end ranges; the number of calibration points is sufficient to obtain the response curve of the radiation measurement equipment with relatively accurate results; the requirement for the detector to operate in the linear segment is not high; the calibration equipment and installation are relatively simple, and the operation is easy, which can effectively reduce the workload and operation time, improve work efficiency, reduce work difficulty, and has relatively low cost, resulting in significant economic benefits. Attached Figure Description

[0020] Figure 1 is a schematic diagram of the infrared radiation measuring device of the present invention, wherein Figure 1(a) is a full-aperture front view and Figure 1(b) is a full-aperture left view;

[0021] Figure 2 This is a flowchart of the infrared radiation measurement equipment response slope calibration method of the present invention.

[0022] Figure Labels

[0023] 1. Lens cap 2. Diffuse reflector 3. Cylindrical tube

[0024] 4. Opening 5. Blackbody Detailed Implementation

[0025] 1. Calibrate the basic model

[0026] Currently, most infrared radiation calibration of equipment mainly uses linear models, which have the following characteristics for the response of a pixel's spectrum in the radiation measurement camera of the equipment:

[0027] D n (λ)=K(λ)L(λ)+c (1)

[0028] Equation (1) is a radiation calibration formula based on the linear response assumption, that is, assuming that K(λ) and c are constant values. Where, D n (λ) is the digital response (grayscale value) of a certain pixel in the camera, K(λ) is the radiance response coefficient of that pixel, c is the response value corresponding to the dark current (bias, including the fixed radiation of the reflector itself), and L(λ) is the target radiance.

[0029] Considering that the radiation response of detectors usually exhibits a certain degree of nonlinearity, with one input corresponding to one response, i.e., representing only one mapping relationship, to avoid confusion, the nonlinear response calibration model is written in the following form:

[0030] D N (λ)=F DN (λ)L(λ)orD N (λ)=F L (λ)L(λ) (2)

[0031] Among them, D N (λ) represents the digital response (grayscale value) of a camera pixel when the target brightness is L(λ), F DN (λ) represents the response grayscale value as D. N (λ) and the response coefficient identified by it, F L (λ) is the response coefficient identified by the input radiance L(λ).

[0032] The diffuse reflector is placed in front of the infrared radiation measurement camera of the infrared radiation measurement device (hereinafter referred to as the device). The sunlight is corrected using data from the atmospheric correction subsystem. The diffuse reflector reflects the sunlight to the device camera. Based on the measurement results of the diffuse reflector, the device camera can calculate the response coefficient of the device's radiation measurement camera using equation (1), thereby achieving the calibration of the device's infrared radiation measurement.

[0033] By rotating the ground-based infrared radiation measurement equipment, the combined ratio of the diffuse reflector and the infrared radiation area of ​​the sky background is changed, thereby altering the infrared radiation energy input to the equipment's camera and expanding the calibration dynamic range.

[0034] D N (λ)=F DN (λ)[L K (λ)S K +L S (λ)(1-S K (3)

[0035] Among them, L k For the brightness of the diffuse reflector, L S For sky brightness, S k This represents the percentage of the aperture area occupied by the diffuse reflector. When processing target radiation data after nonlinear response calibration, the grayscale of each pixel must first be converted to luminance before other calculations can be performed, such as pixel summation and background subtraction of target luminance.

[0036] 2. Calibration device

[0037] The aim is to construct an easy-to-use infrared radiation response slope calibration system for equipment using a small blackbody, shielding and insulation materials, a diffuse reflector, a lens cap, an electric servo motor, and an angle measuring mechanism.

[0038] In the atmospheric correction factor process, only the slope of the linear response model is used for the equipment response characteristics. It is only necessary to calibrate the response slope in the linear segment of the equipment response during the calibration phase. A partial-aperture blackbody is used here; that is, a hole slightly smaller than the blackbody's aperture is made in the lens cap, and an insulation layer is added. A baffle device is used to shield and insulate the exposed aperture of the blackbody. Outside the exposed aperture, the blackbody's influence on other parts is negligible. A quick-connect / remove device for the blackbody is added to avoid prolonged radiative heating effects. See Figures 1(a) and 1(b). Only the portion including the diffuse reflector is shown in the figures.

[0039] The diffuse reflector panel is made of polytetrafluoroethylene (PTFE), a material known for its relatively flat spectral characteristics and strong thermal insulation. Its surface is treated with a roughening or microporous process to enhance its infrared diffuse reflectance properties. There is significant industrial demand for this panel, and customized panels can be produced to meet specific requirements. Taking into account factors such as flatness, thermal uniformity, and inherent non-uniformity, the infrared radiation and reflection deviation of a 1m x 1m diffuse reflector panel can be controlled within 3.0%.

[0040] 3. Method for Measuring Blackbody Parameters of Integrated Lens Cap

[0041] In the same calibration, a portion of the aperture was used for blackbody calibration, and its response linear segment included the full-aperture lens cap.

[0042]

[0043] Where S t D represents the percentage of the aperture area exposed by the blackbody. Ns1 and D Ns1 To correspond to two temperatures T of the same blackbody source s1 and T s2 The response grayscale, L Ts1 and L Ts2L represents the normalized luminance of the radiation spectrum at two temperatures of the same blackbody. g For several energy hood radiation, K T Let be the slope of the linear response model for the full-aperture calibration results, and c be the output grayscale value without input. Partial-aperture lens caps have...

[0044]

[0045] The slope of the linear model of the device response can be obtained from equation (7) or (8).

[0046]

[0047] This method does not depend on atmospheric transmittance and has high accuracy.

[0048] 4. Calibration Method and Steps

[0049] With the lens cap closed, after the blackbody temperature T1 stabilizes, push it into the opening, perform measurements, and record the data; remove the blackbody, change the temperature T2 until it stabilizes, then push it into the window, perform measurements, and record the data.

[0050] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0051] Example 1

[0052] Embodiment 1 of the present invention proposes a response slope calibration device for an infrared radiation measurement device. The infrared radiation measurement device includes a telescope tube, and the calibration device includes a cylinder 3, a lens cap 1, a diffuse reflector 2, and a blackbody 5. The cylinder 3 is fitted around the outer edge of the front end of the telescope tube, the lens cap 1 covers the diameter of the cylinder 3, the diffuse reflector 2 is attached to the inside of the lens cap 1 and rotates synchronously with the lens cap 1, and the blackbody 5 is disposed on the outside of the lens cap 1, allowing for docking and disassembly. The lens cap 1 has an opening 4 with a diameter smaller than that of the blackbody 5. Figure 1(a) is a front view, and Figure 1(b) is a left view. It should be noted that the shape of the opening in the figures is only schematic and is not limited to a circle; the diameter only needs to be smaller than that of the blackbody.

[0053] The diameter of cylinder 3 is larger than the entrance pupil of the telescope, so that the emission or reflection of cylinder 3 does not affect the pixel grayscale of the infrared radiation measuring equipment under test.

[0054] The lens cap 1 is electrically flipped. During the entire flipping process, the edge of the lens cap 1 is outside the effective aperture of the telescope, so that the light emitted or reflected by the lens cap 1 has no effect on the pixel grayscale of the infrared radiation measuring equipment under test.

[0055] The exposed aperture of the blackbody 5 is shielded and insulated by an insulation layer.

[0056] The diffuse reflector 2 is made of polytetrafluoroethylene.

[0057] Example 2

[0058] like Figure 2 As shown, Embodiment 2 of the present invention proposes a method for calibrating the response slope of an infrared radiation measurement device, which is implemented based on the above-mentioned calibration device. The method includes:

[0059] Close the lens cap;

[0060] Set the blackbody temperature to T1, push the blackbody into the opening or leave the blackbody open, and record the corresponding grayscale D at the blackbody temperature T1. Ns1 and normalized brightness L of the radiation spectrum Ts1 ;

[0061] Remove or block the blackbody, set the blackbody temperature to T2, then push the blackbody into the opening, and record the grayscale response D corresponding to the blackbody temperature T2. Ns2 and normalized brightness L of the radiation spectrum Ts2 ;

[0062] Based on the predetermined ratio of the lens cap opening area S t The slope K of the linear response model of the infrared radiation measurement equipment is obtained from the following formula. T Thus, calibration is achieved:

[0063]

[0064] Finally, it should be noted that the above 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 embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for calibrating the response slope of an infrared radiation measuring device, based on an infrared radiation measuring device response slope calibration device, wherein the infrared radiation measuring device includes a telescope tube, and the calibration device includes a cylinder, a lens cap, a diffuse reflector, and a blackbody; wherein, The cylinder is fitted onto the outer edge of the front end of the telescope tube, the lens cap covers the cylinder opening, and the diffuse reflector is attached to the inside of the lens cap and rotates synchronously with the lens cap. The blackbody is located on the outside of the lens cover and can be docked and disassembled. The lens cover has an opening with a diameter smaller than that of the blackbody. The method includes: Close the lens cap; Set the blackbody temperature to T1, push the blackbody into the aperture or open the blackbody, and record the corresponding grayscale response at the blackbody temperature T1. and normalized brightness of the radiation spectrum ; Remove or block the blackbody, set the blackbody temperature to T2, then push the blackbody into the opening and record the response grayscale at the corresponding blackbody temperature T2. and normalized brightness of the radiation spectrum ; Based on the predetermined ratio of the lens cap opening area The slope of the linear response model of the infrared radiation measuring device is obtained from the following formula. Thus, calibration is achieved: 。 2. The method for calibrating the response slope of an infrared radiation measuring device according to claim 1, characterized in that, The diameter of the cylinder is larger than the entrance pupil of the telescope, so that the emission or reflection of light from the cylinder has no effect on the pixel grayscale of the infrared radiation measuring device under test.

3. The method for calibrating the response slope of an infrared radiation measuring device according to claim 1, characterized in that, The lens cap is electrically flipped, and during the entire flipping process, the edge of the lens cap remains outside the effective aperture of the telescope, so that the light emitted or reflected by the lens cap has no effect on the pixel grayscale of the infrared radiation measuring equipment under test.

4. The method for calibrating the response slope of an infrared radiation measuring device according to claim 1, characterized in that, The calibration device also includes a thermal insulation layer for shielding and insulating the exposed aperture of the blackbody.

5. The method for calibrating the response slope of an infrared radiation measuring device according to claim 1, characterized in that, The diffuse reflector is made of polytetrafluoroethylene.

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