In order to evaluate methods of enhancing the response of state-of-the-art photocathodes, such as the S-20, we have used a mathematical absorption-diffusion model to study the effects of skewed incidence of light on the quantum efficiency. The phenomenon of increased optical absorption due to multiple reflections of light within the emitting layer-glass substrate combination is treated as a function of the angle of incidence. When the quantum efficiency generated for skewed incidence is compared with the quantum yield generated for normal incidence, a gain of 3.5 is predicted. The gain is greatest for the smallest absorption coefficient-photocathode thickness product.
John R. Sizelove and John A. Love, III, "Analysis of a Multiple Reflective Translucent Photocathode," Appl. Opt. 6, 443-446 (1967)