Theoretical Performance of a Novel Wide-Slit Infrared Spectrometer.
Martin O. Harwit · The Astronomical Journal · 1966
A new type of grating instrument is described. Radiation enters this spectrometer through a wide slit where a rotating disk pattern labels the location at which any given photon passes through the slit. The same pattern is also used to sort out photons at the exit slit. Phase-sensitive domodulation at different frequencies can then be used to recover spectral information about the incident radiation. The method allows the simultaneous use of large slits and wide acceptance angles without loss of resolving power. We derive the relation between resolving power, slit size, acceptance angle, and wavelength. The over-all performance of the instrument is compared to the Fabri-Perot and Michelson interferometers. In fact, the wide slit spectrometer can be made to simulate the properties of either of these instruments if proper demodulation techniques are devised. We point out some of the advantages and disadvantages of the spectrometer and compare preliminary performance figures with theory.