As an important parameter of IRFPA imaging system - the integration time must be considered in the system design process.
Integration time refers to the time for IRFPA imaging system detector pixel that accumulate radiation signals to generate charges. For the infrared focal plane detectors, there are many performance parameters related to the integration time, such as the output voltage, response rate, noise and specific detection rate of the system, etc.
The selection of an appropriate integration time has a great impact on the overall performance of the system.
Ideally, when the infrared focal plane array is subjected to uniform radiation, the output amplitude should be exactly the same. However, due to the inhomogeneity of semiconductor materials (impurity concentration, crystal defects, inhomogeneity of internal structure, etc.), mask errors, defects, process conditions, etc., the output amplitude of the device is not the same, which is the so-called non-uniformity of the infrared focal plane array response, also known as stationary pattern noise.
This noise cannot be eliminated by averaging multiple measurements like transient noise, and must be corrected to reduce it. However, no matter which method is used for non-uniformity correction, changing the integration time of the detector after the correction is completed will significantly reduce the uniformity of the image.
By choosing different integration times for the same target, different output effects will result in. When the integration time is too small, it is almost impossible to observe the target. When the integration time continues to increase, the output will also increase continuously, making the target gradually clear. When it is too large, saturation occurs. It is very important to choose the appropriate integration time according to the radiation intensity of different targets, otherwise it will seriously affect the effect of thermal images.
Therefore, the selection of integration time is very important in the design process of infrared systems. By choosing appropriate integration time, the system can achieve best performance. In addition, considering the influence of integration time on the system performance, the working mode of changing integration time can be adopted. In this way, when the target has different irradiance brightness, according to the gray value of the obtained image, different integration time can be chosen to improve the detection ability of the system for the target with too high or too low irradiance brightness, thereby improving the overall performance of the system