Characterization and evaluation of spatial jitter's influence on the intrinsic geometric calibration of an infrared camera for gas visualization

Infrared cameras for gas visualization, also known as gas cameras, offer a practical and safe way for spotting gas leakages in different industrial sectors such as chemical and oil industries by sensing the intensity of the infrared radiation emitted by a gas and its surroundings within a defined spectral range at which gases of interest (i. e. volatile organic compounds) absorb infrared radiation. If the temperature of the gas differs from the temperature of its surroundings, then the gas appears as a texture in the images of the camera. In order to be able to detect small temperature changes, the camera uses a cooling engine, which is in most of the cases based on the Stirling motor principle. Due to its working principle, the cooler generates vibrations in the housing of the camera and in the detector matrix. These vibrations lead to a spatial jitter in the images. The spatial jitter can affect the performance of image processing techniques or computer vision applications, since it introduces disturbances in the considered scenes. In this work a characterization of the jitter of such gas cameras by means of a single-point vibrometer and image processing techniques is carried out. Furthermore, the influence of the jitter on the geometric calibration of the camera is analyzed. The results show that the vibrations in the camera are periodic and generate detector shifts of about 3 μm in vertical and horizontal direction. In addition, after calibrating the gas camera geometrically, no considerable effects of the jitter on the calculation of the calibration parameters were observed.