Influence of Area Focal Plane Arrays on the Deterioration of Interference Modulation for Fourier Transform Spectral Imaging

摘要

The Imaging Fourier Transform Spectrometer (IFTS) is the temporal modulated Michelson interferometer in which a single-element detector is replaced by an area focal plane arrays. Each pixel of detector arrays records observed area radiation and then yield the corresponding spectrum by Fourier transforms. While, area focal plane arrays improve spatial resolution and expand area coverage. However, this innovation technology has many technical challenges to be overcome. In this paper, the challenges caused by area focal plane arrays are discussed. The simulations of interference modulation (IM) of Fourier transform spectral imaging are presented. The IM changes as the extensions of pixel are simulated and analyzed. And a phenomenon that interference modulation deteriorates with spectral resolution improvement is discussed. The results show that, the off-axis pixels are sampled at slightly shorter OPDs, compared with the pixel in the center. The decrease of interference modulation caused by area focal plane arrays is related to both the position of each pixel and maximum optical path difference. Interference modulation decline in the format of a quadratic function as the pixel position extends. And this decrease in short waveband is more significant than that in long waveband. It is noticed that there is a key spectral resolution for IFTS interference modulation. When the spectral resolution is set below the key point, the IM decrease smoothly and slowly at the high level. However, if the spectral resolution keeps improving over the key point, the modulation will decline abruptly.