Investigation of Electronic Fringe Detector for a Stellar Interferometer

摘要

A fringe detector was constructed to detect fringes from a Michelson stellar interferometer and to relate these measurements to the characteristics of the source of illumination. A rotating reflector, a single slit, and a phototube were combined to transform the spatially-varying intensity pattern of the fringe field into a time-varying voltage signal displayed on an oscilloscope face. The oscilloscope trace was photographed and analyzed to determine fringe contrast. The maximum sensitivity of the detector was determined to be equivalent to a source providing 10 to the -10th power W/sq. cm at a fringe contrast of 1 and a signal-to-noise ratio of 1. Modifications can provide a factor of 500 to 1000 improvement in detector sensitivity. The interferometer was determined to have potentially better resolution than a single-mirror telescope because it can electrically filter the effects of ambient background illumination and turbulence. The use of an interferometer to measure the angular size of a pie-shaped source was studied and found to be not particularly suited to this purpose. The action of apodized and unapodized lens systems on the field due to an extended background and a small source was analyzed. (Author)