High Precision Infra-Red Stellar Interferometry

This dissertation describes work performed at the Palomar Testbed Interferometer (PTI) during 1998-2002. Using PTI, we developed a method to measure stellar angular diameters in the 1-3 milli-arcsecond range with a precision of better than 5%. Such diameter measurements were used to measure the mass-radius relations of several lower main sequence stars and hence verify model predictions for these stars. In addition, by measuring the changes in Cepheid angular diameters during the pulsationa...