High-Resolution Luminescent Screens for Image Intensifier Tubes

Publisher Summary This chapter discusses the high-resolution luminescent screens for image-intensifier tubes. In image intensifier tubes, the picture quality can be characterized by the modulation transfer function (MTF), the output contrast versus spatial frequency for 100% input contrast. This function depends on several parameters such as the photoelectron energies, tube voltages, distance between electrodes, channel diameters (for MCP intensifiers), screen granularity, and fiber optic pitch. The chapter discusses the improvement of the modulation transfer function of the screen when it is settled on a fiber-optic output window. Luminescent screens are often settled on fiber optics to reduce the light spread from the emitting phosphor particles and to minimize the veiling glare of the tube. Twisted fiber optics allows the image to be inverted with low-light losses. To increase the contrast, Piedmont and Pollehn proposed the intagliation of the phosphor particles in holes scooped out at the input of each elementary fiber.