A novel evaluating method for the MEMS-based uncooled IR system

An experiment using 4f system model is designed to test the consistency of the units on the FPA , which is made based on MEMS technology. An optical stop as a filter is set at the back focal plane of the first lens. We get each image where the light source locates when it is rotated round FPA. The size of the stop and the rotating angle can be deduced according to the parameters of two lens. Meanwhile reflectance spectrum of each unit on the FPA can be drawn with the gray level of the image presented by CCD. Contourgraph is used to test the displacement deflection value caused by thermal deformation of FPA. According to the displacement deflection value and the unit size of FPA, we get the average deflection angle of FPA's units when temperature changes per centigrade degree. We can define a gray level difference of two adjacent images at the same position as M. When we let the value of M larger than a number N, we can say that the system has met the requirement of temperature sensitivity-T. With the help of M, light rotating angle and FPA's deflection angle, we can get the temperature sensitivity of the IR system. The actual value of temperature sensitivity approximates the NETD of the system. The calculating process proves that it can estimate the NETD, if we don't want to get the accurate value of NETD. The expression of T is much easier and more feasible than that of NETD.