Photoemissive Detectors: Principles and Applications

This lecture covers the principles and applications of photoemissive detectors, focusing on micro-channel photomultiplier tubes (PMTs) and image intensifiers. The instructor explains how a micro-channel PMT operates under vacuum, where photons strike a photocathode to generate primary electrons. These electrons enter micro-channels, leading to an avalanche effect that amplifies the signal. The lecture details the construction of image intensifiers, which amplify weak visible light for night vision applications. The spectral response characteristics of image intensifiers are discussed, highlighting their efficiency in various light conditions, including visible, ultraviolet, and near-infrared. The instructor also describes the integration of image intensifiers with cameras, emphasizing the importance of high voltage power supplies and the use of optical fibers to transfer the amplified signal to CCD arrays. The lecture concludes with practical applications of these technologies in night vision systems, illustrating how they enhance visibility in low-light environments.