We are building a Fourier Transform Spectrometer (FTS) of the Martin-Puplett type (which makes use of a wire grid polarizer rather than a half-silvered mirror or other type of beam splitter to split the beam). The entire FTS will be encased in a plexiglass box which will be kept slightly over pressure with nitrogen gas. This nitrogenpurge system will remove the majority of the oxygen and water vapor in the air to preventabsorption lines in our spectra. We plan to use the FTS in a variety of
projects, including ACT (Atacama Cosmology Telescope), to test telescope optics such as lenses and filters. The source will be a 77 K blackbody (container of liquid nitrogen)at one input port and the detector will be a bolometer. At present the FTS is assembled and aligned to first order and nice fringes have been obtained using a strong monochromatic source and diode detector. We are in the process of designing a bolometer and cryostat for use as our permanent detector.
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