Optical characteristic of an infrared focal plane array (FPA) based on thermo-optic effect is analyzed using film optics
method. Then, an optimizing film assembly of thermo-optic infrared focal plane array (TOFPA) described as
air|<HL><sup>2</sup>30.1H<LH><sup>2</sup>16L|substrate is obtained with its temperature sensitivity 6.23% K<sup>-1</sup>. Furthermore, the influence of
substrate material, device package and absorption is discussed. The results show that the temperature sensitivity of the
film assembly of TOFPA is modulated by 16.4%, 8.99%, -11.3 %, and -0.6% with the influence of glass substrate,
silicon substrate, glass package and optical absorption of film material, respectively.