Study on the Performance of Spatial Heterodyne Spectrometer Influenced by the Field Widened Prism

Abstract

Spatial heterodyne spectrometer(SHS) is based on Fourier transform spectroscopy, and field widening techniques of conventional FTS interferometers can also be applied to Spatial heterodyne Spectrometer(SHS) system. The field widened prism and spacers of SHS system should be adjusted so the reduction in the fringe contrast resulting from the fringe frequency on off-axis angle is less than 0.36, and it is one of the most important advantages to use field widened prism to increase the throughput for SHS system with high spectral resolution. Unlike the original method for the prism and spacer, the new method combines original field widened method and offers fabrication flexibility. Using this new method, we evaluate the theoretical modulation efficiency of the field widened interferometer for an experimental set up, including effect of the field view on the fringe frequency and subsequently on the spectral calibration accurate. To minimize the influence of the fringe frequency errors, the dispersion effects introduced by the prism are considered in the analysis. Finally, the new method and analysis are validated through a serial of simulations and experiments, and it gives a theoretical explanation of the spectrum shift and stretch in previous processing to recover the spectrum.