  The Hanbury Brown Twiss (HBT) interferometer was proposed to observe
intensity correlations of starlight to measure a star's angular diameter. As
the intensity of light that reaches the detector from a star is very weak, one
cannot usually get a workable signal-to-noise ratio. We propose an improved HBT
interferometric scheme introducing optical parametric amplifiers into the
system, to amplify the correlation signal, which is used to calculate the
angular diameter. With the use of optical parametric amplifiers, the
signal-to-noise ratio can be increased up to 400 percent.
