photoelectric cell
51smoke detector — an electronic fire alarm that is activated by the presence of smoke. Also called smoke alarm. [1925 30] * * * device used to warn occupants of a building of the presence of a fire before it reaches a rapidly spreading stage and inhibits… …
52History of the single-lens reflex camera — The history of the single lens reflex camera predates the invention of photography in 1826/27 by one and a half centuries with the use of a reflex mirror in a camera obscura first described in 1676. Such SLR devices were popular as drawing aids… …
53printing — /prin ting/, n. 1. the art, process, or business of producing books, newspapers, etc., by impression from movable types, plates, etc. 2. the act of a person or thing that prints. 3. words, symbols, etc., in printed form. 4. printed material. 5.… …
54motion-picture technology — Introduction the means for the production and showing of motion pictures. It includes not only the motion picture camera and projector but also such technologies as those involved in recording sound, in editing both picture and sound, in… …
55Video camera tube — In older video cameras, before the mid to late 1980s, a video camera tube or pickup tube was used instead of a charge coupled device (CCD) for converting an optical image into an electrical signal. Several types were in use from the 1930s to the… …
56photocell — /foh toh sel /, n. Electronics. a solid state device that converts light into electrical energy by producing a voltage, as in a photovoltaic cell, or uses light to regulate the flow of current, as in a photoconductive cell: used in automatic… …
57cesium — /see zee euhm/, n. a rare, highly reactive, soft, metallic element of the alkali metal group, used chiefly in photoelectric cells. Symbol: Cs; at. wt.: 132.905; at. no.: 55; sp. gr.: 1.9 at 20°C; melts at 28.5°C. Also, caesium. [1930 35; < NL,… …
58Mechanical television — This schematic shows the circular paths traced by the holes in a Nipkow disk. Mechanical television (also called televisor) was a broadcast television system that used mechanical or electromechanical devices to capture and display video images.… …
59photography, technology of — Introduction equipment, techniques, and processes used in the production of photographs. The most widely used photographic process is the black and white negative–positive system (Figure 1 >). In the camera the lens projects an image of… …
60Optigan — Keyboard overview of a model 35002 Optigan. The coded strip above the main keyboard corresponded to numbers in the music books for those unable to read music. The Optigan (a portmanteau of Optical Organ) was an electronic keyboard instrument… …
