An improved real-time optical image subtraction method based on the work of Zhao and Liu ["Real-time optical interferometric image subtraction by wave polarization," Appl. Opt. 21, 3864 (1982)] is proposed. A hologram of the beams from a Wollaston prism is recorded and used as an optical element in the system. It is shown that a dark field over a larger area for image subtraction can be obtained with such a system.
V. Venkateswara Rao,
Rajpal S. Sirohi,
"Improved Real-Time Optical Image Subtraction Based On Wave Polarization," Optical Engineering 25(12), 251320 (1 December 1986). https://doi.org/10.1117/12.7974007