Photo-sensitive Tubes

Photo-sensitive Tubes

Photo-sensitive tubes, also known as photoelectric tubes, are vacuum tubes that convert light into an electrical signal. These tubes were widely used in early television cameras and image scanners before being replaced by solid-state detectors. The basic design of a photo-sensitive tube consists of a cathode, an anode, and a photosensitive material placed between them. When light falls on the photosensitive material, it emits electrons, which are then attracted to the anode. The resulting current is proportional to the intensity of the light falling on the photosensitive material. There are several types of photo-sensitive tubes, each with different materials and operating principles. The most common types are the photomultiplier tube (PMT), the phototube, and the image orthicon. PMTs are highly sensitive and can detect very low levels of light, making them useful in scientific instruments such as spectrometers and telescopes. Phototubes are simpler and less sensitive than PMTs, but are still used in some applications such as radiation detectors. Image orthicons were used in early television cameras and worked by converting an image into an electrical signal that could be transmitted and displayed on a screen. Despite their advantages, photo-sensitive tubes have several drawbacks. They are bulky, fragile, and require high voltages to operate. They also suffer from noise and distortion, which can limit their accuracy and resolution. As a result, they have largely been replaced by solid-state detectors such as charge-coupled devices (CCDs) and complementary metal-oxide-semiconductor (CMOS) sensors, which are smaller, more reliable, and offer better performance.

vacuum tubes, electrical signal, photosensitive material, photomultiplier tube, phototube, image orthicon, sensitivity, noise, distortion, solid-state detectors

— Eric Walker

CITATION : "Eric Walker. 'Photo-sensitive Tubes.' Design+Encyclopedia. https://design-encyclopedia.com/define/photo-sensitive-tubes?E=382213 (Accessed on October 14, 2026)"