Demonstration of Thermo-optical Infrared Image Defocus and Correction

In the paper, we report the experimental demonstration of thermo-optic impact on imaging performance. To create the temperature-controlled environment, we built the optic heater which can heat the IR window over 700°C. For imaging experiment, we placed a long-wave infrared camera in front of a heater and located the blackbody unit behind the heater used as a target element. The temperature of a blackbody target was set at 1000°C and fixed. The window was heated from the room temperature to 600°C and the camera collected a series of images looking at a blackbody through the heated window. The optical degradation was seen at a heating temperature of 400°C or above. As a result, blurred images were captured showing gradient change. To re-focus impacted images, the blur pattern was estimated by the Gaussian-based spread function. By applying designed spread functions to the image deconvolution process with, blurred images were refocused.