Chester F. Carlson Center for Imaging Science M.S. Thesis Defense Cara Perkins Spatial Heterodyne Spectroscopy: Modeling and Interferogram Processing Monday, 29 July 2013, 10:00 am Carlson Bldg. 3215

Chester F. Carlson Center for Imaging Science

M.S. Thesis Defense

Cara Perkins

Spatial Heterodyne Spectroscopy: Modeling and Interferogram Processing

Advisor: Dr. John Kerekes

Monday, 29 July 2013, 10:00 am 

Carlson Bldg. 3215

Abstract

This work presents a model of a spatial heterodyne spectrometer (SHS) and a corresponding interferogram-processing algorithm for the calculation of calibrated spectral radiance measurements. The SHS relies on Fourier Transform Spectroscopy (FTS) principles, and shares design similarities with the Michelson Interferometer. The advantages of the SHS design, including the lack of moving parts, high throughput, and instantaneous spectral measurements, make it suitable as a field-deployable instrument. Operating in the long-wave infrared (LWIR), the imaging SHS design example included provides the capability of performing chemical detection based on reflectance and emissivity properties of surfaces of organic compounds. This LWIR SHS model takes into account the instrument's entrance optics, interferometer, exit optics, and detection scheme to output realistic, interferometric data. The model serves as a tool to choose the optimal SHS design parameters for the desired performance requirements and system application. It also assists in the data analysis and system characterization. The interferogram-processing algorithm performs flat-fielding and phase corrections as well as apodization before recovering the measured spectral radiance from the recorded interferogram via the Inverse Fourier Transform (IFT). The model and processing algorithm are tested with a variety of spectra and the results are comparable to those in the literature with a noise-equivalent change in temperature of 0.2 K. These results demonstrate the model's validity and the algorithm's accuracy. Additional experiments show the algorithm's real-time processing capability, indicating the LWIR SHS system presented is feasible.