Heterodyne measurement of Wigner distributions for classical optical fields

We demonstrate a two-window heterodyne method for measuring the x-p cross c orrelation, (E*(x)E(p)), of an optical field E for transverse position x an d transverse momentum p. This scheme permits independent control of the x a nd p resolution. A simple linear transform of the x-p correlation function yields the Wigner phase-space distribution. This technique is useful for bo th coherent and low-coherence light sources and may permit new biological i maging techniques based on transverse coherence measurement with time gatin g. We point out an interesting analogy between x-p correlation measurements for classical-wave and quantum fields. (C) 1999 Optical Society of America OCIS codes: 000.1600, 030.1640, 270.6570, 170.3880.