In the measurement of the infrared imager, noise is the primary parameter in evaluating the quality of the infrared imager. In the engineering application of the infrared imager, three-dimensional noise pattern is not applied widely in the hard technology of the infrared imager due to its pattern is complex, physical significance is not definite and visualized. Noise parameters include the temporal noise and the spatial noise. The temporal noise can be divided into high frequency temporal noise and low frequency temporal noise (namely 1/f noise), and the spatial noise can be divided into high frequency spatial noise (namely fixed pattern noise, FPN) and low frequency spatial noise (un-uniform noise). The strict definition about high frequency temporal noise and low frequency temporal noise is given in this paper. The algorithm and measuring methods for low frequency temporal noise equivalent temperature difference are proposed. The algorithms and measuring methods of high frequency noise equivalent temperature difference are given, ignoring low frequency temporal noise in short-time during measuring high frequency noise equivalent temperature difference or not. Moreover, the uncertainty of measurement results for high frequency temporal noise equivalent temperature difference is analyzed in the paper.
