Fiber optic image couplers are essential components in many types of image intensifier tubes. The paper described the various forms of couplers for such applications and some of the steps leading to their development. The properties and capabilities of image couplers were discussed along with test methods and specifications, also examples of intensifier tubes and systems employing their components.
Walter P. Siegmund,
"Fiber Optic Image Couplers", Proc. SPIE 0042, Image Intensifiers: Technology, Performance, Requirements, and Applications, (1 March 1974); doi: 10.1117/12.953868; https://doi.org/10.1117/12.953868