Applying phase retrieval techniques to infrared spectrometer alignment

We have developed a test method using parametric phase retrieval to estimate the wavefront of a cryogenic infrared spectrometer. The phase retrieval algorithm accounts for optical system obscurations, apodization, noisy detector pixels, polychromatic sources, and spectrometer dispersion. This tool was used in establishing the optimal alignment and focus for a two channel infrared spectrometer operating in a cryogenic environment. This paper provides an overview of the technique and test implementation.