Emissivity Study Of The Array Shaped Rectangular Cavity

In the test method provided by the measurement system used to evaluate the performance of the infrared imaging system,the minimum resolution temperature difference is one of the main parameters for testing and evaluating the performance of the infrared imaging system,which quantitatively reflects the sensitivity and resolution of the infrared imaging system.In the classical MRTD test method,the heat transfer between the target and the environment,and between the target and the blackbody,significantly affects the flexibility and accuracy of the temperature regulation.Besides,the combination of the target and the blackbody could not make a continuously adjustable temperature difference,which further limits the testing capability for infrared imaging equipment to a large extent.This paper is aiming at the problems in the current infrared imaging system performance test,a temperature-adjustable unit combined cavity array is designed.Based on the structural model of the array,the ratio of the groove depth to width is found to be the key factor of the unit surface emissivity.With the principle of contact measurement,the corresponding measurement system was built,and the emissivity stability experiment and temperature difference function test were carried out respectively.It shows that the unit combination cavity array can adjust the temperature difference through changing the heating temperature,which can be used for infrared imaging system performance test.In the temperature measurement process,a common method is to use a sample with given emissivity as a reference to determine the surface emissivity of another one.But the current reference object has two shortcomings,one is that temperature range is not wide enough;the second is that in the working temperature range,the emissivity of reference object is a fixed value,which cannot be adjusted.This paper designs a deep gradient continuous cavity array on the basis of unit combined cavity array.The thermal images are photographed using an infrared thermal imager with different apparent temperature of each unit,which depends on the unit surface emissivity.The surface emissivity values at the three regions of the sample were measured at different temperatures.The result shows that the surface of the deep gradient continuous cavity array has a stable emissivity distribution innormal direction,which can provide different emissivity.