We extend the theory of photoresistive heterodyne detectors to include the cases where two electromagnetic fields propagate in different directions and detector dimensions include many wavelengths of the heterodyned signal. Our theory shows that the amplitude of the time-varying component of photoconductivity has a [(sinA)/A (sinB)/B] dependence. The argument of each sampling function depends upon the difference in propagation constants of the two waves in the transverse and longitudinal directions, respectively. The significance of these results to the experimenter is discussed.
O. Zucker, "Derivation of the General Expression for the Heterodyne Output Voltage of a Photoresistive Detector," Appl. Opt. 10, 1012-1015 (1971)