Infrared antenna measurement of the spatial coherence function.

The degree of coherence of a partially coherent monochromatic optical field is measured with a dual-dipole phased-array antenna coupled to a metal-oxide-metal tunnel diode detector. For a two-element phased-array, the degree of coherence is a measure of the correlation of electric fields received by the antennas as a function of the element separation. To extract the coherence function from the measured antenna response, a calibration method is developed to remove propagation loss and device nonuniformity. Measurements at 10.6 µm are substantiated by electromagnetic simulations and compared to the result derived from the Van Cittert-Zernike theorem.