The research about radiometric technology of two

According to specific dynamic target infrared radiation measurement requirements, the above measurement model is improved. The calibration and data processing system involved in the model is composed of calibration equipment, atmospheric correction equipment, and target characteristics data processing equipment. The system mainly completes the radiation calibration of the infrared measurement equipment and the inversion processing of the target measurement data, and finally obtains the infrared radiation characteristics of the target.

Indirect-type infrared radiation calibration equipment including high-temperature chamber gray body, low-temperature diffuse gray body, parallel light tube, infrared radiometer, and calibration data processing equipment such as computer, used in the infrared measurement equipment in the laboratory radiation calibration, determine the infrared radiation of input and output signal of the measuring device, the radiation response of the relationship between the radiation response. Atmospheric correction equipment includes micro-pulse lidar, temperature-humidity instrument, and atmospheric radiation transmission calculation software, which are used to measure atmospheric parameters and calculate the atmospheric transmittance and range radiation between the target and the infrared measurement equipment according to atmospheric parameters and target position information. The calibration equipment mainly includes the surface source gray body and the infrared paint reference plate, which is used to calibrate the atmospheric transmittance between the target and the infrared measurement equipment in real time. The target characteristics data processing equipment USES the radiation response of the infrared measurement equipment, atmospheric transmittance between the target and the infrared measurement equipment and other data to calculate the infrared radiation characteristics of the target from the target measurement data, such as the target radiance and radiation intensity.

The most important function of the infrared characteristics measurement system based on image grayscale is to measure the infrared radiation characteristics of the target [2, 3, 12,13,14,15,16,17,18,19,20]. The operating principle of the system is shown in Fig. 1.

Schematic diagram of the model

In Fig. 1, the symbols in the data processing block diagram of the target characteristics are as follows:

α—infrared radiation response measuring equipment;

DN0—calibration deviation of dn0-infrared measuring equipment;

τR′—target aircraft and the atmospheric transmittance between infrared measuring equipment;

LR′— target aircraft and infrared measuring equipment between atmospheric path radiation;

Lsky—Lsky-measured sky background brightness;

DNt—infrared measurement equipment to the target;

DNbb—measured value of the standard calibration gray body (or the infrared paint pod) of the dnbb-infrared measuring equipment;

IT—infrared measuring equipment integral time;

WB—infrared measuring equipment working band.

The measurement of infrared characteristics based on image grayscale includes two tasks: first, acquisition of target information and acquisition of target infrared digital image information. The second is the data processing of the target characteristics.

The process of target information acquisition is as follows:

Step 1: get the infrared image of the surface source gray body. The two-dimensional infrared measurement rotary table equipment can capture the target according to the guidance information, and then the servo tracking equipment can achieve precise tracking and measurement of the target through reasonable tracking means, and obtain the gray level of the surface source gray body (or the infrared image gray level) and transmit it to the data acquisition and transmission equipment.

Step 2: acquire the target infrared image. The image grayscale is transmitted to the data acquisition and transmission equipment.

Step 3: import the gray image index of the two into the calculation model, get the relationship curve between the gray value and infrared radiation value under specific target and specific condition, and invert the required target radiation value according to the curve.

The data processing process of the target features is as follows:

First, calibration equipment of infrared measuring equipment is used to calibrate the radiation and determine the degree of infrared radiation response of the measuring equipment offset DN0 α and calibration. By the target information acquisition process, infrared measuring equipment first obtain H0 height, horizontal distance R0 of non-point source gray body infrared image, thus calculate the distance measured atmospheric transmittance of R0 LR0, R0, and Cheng radiation. At the same time, a laser radar, the temperature and humidity meter atmospheric measurement equipment, was used so as to obtain highly H0 Ta aerosol extinction coefficient, temperature, and relative humidity RH, parameters, such as the provided MODTRAN software calculation theory of atmospheric transmittance R0 and theoretical path radiation LR0. As a result, get the atmospheric transmittance correction coefficient C = R0, routine radiation correction coefficient Cp = LR0/LR0.

Then, the infrared characteristic of the target of distance R is measured, and the infrared image of the target aircraft is obtained. Ta, RH, and according to the atmospheric parameters, by using MODTRAN software to calculate the distance R theory of atmospheric transmittance R routine radiation LR and theory, and then multiplied by the transmittance correction coefficient C respectively and routine radiation correction coefficient Cp, after correction of atmospheric transmittance LR * R * and radiation.

Finally, using the infrared radiation response of measurement equipment, calibration after atmospheric transmittance LR*R and Cheng radiation, the gray value is measured by the target infrared radiation characteristics of inverse calculation target aircraft, such as radial brightness and radiant intensity.

Based on the calibration theory of infrared coating radiation measurement model, the model based on infrared target image is improved:

From the above equation, Lt measurement accuracy depends on DNt, DN0, α, τR0, LR0, \( \frac{{\tau_R}^{\hbox{'}}}{{\tau_{R0}}^{\hbox{'}}} \), \( \frac{{L_R}^{\hbox{'}}}{{L_{R0}}^{\hbox{'}}} \), τ1, and L1. The above uncertainty parameters are analyzed as follows: target measurement output value DNt is better than 1%. The radiance response of infrared equipment DN0 is better than 4.7%. Measured atmospheric transmittance based on infrared targets τR0 uncertainty is 10.5%. The uncertainty of measured atmospheric path radiation based on infrared target is set at 12%., uncertainty is about 4.1%. The uncertainty of transmittance ratio and radiation ratio is 3.5%. According to the above analysis, the accuracy of the infrared target inversion method is 49%. Compared with the traditional measurement model, the accuracy of the model is improved by 50%.