Measurement of coherence area in parametric downconversion luminescence

Abstract
The coherence area is measured in a simple Young’s experiment using parametric downconversion light produced in a nonlinear crystal (LiIO3) pumped by a continuous argon-ion laser. The normalized mutual intensity or degree of coherence is obtained from the intensity distribution interference patterns and compared with a standard theory in which the light source behaves as a surface with infinitesimal uncorrelated emitters.