电子英语证书考试(PEC)-光电子学术语.docVIP

电子英语证书考试(PEC)-光电子学术语 A ABSORPTION - Losses in an optical fiber caused by the presence of some impurities - iron, copper, cobalt, vanadium, and chromium. For optical fibers, even one or two parts per billion of these impurities are considered unacceptable. ACCEPTANCE PATTERN - Curve of total transmitted light plotted against the incident angle ALPHANUMERIC DISPLAY - Readout of numbers and letters ANALOG DISPLAY - Readout that provides a continuous, illuminated movement along a predetermined calibrated path to provide an indication of a desired measurement ANALOG METER - Readout that provides a continuous numbered scale along which a pointer moves C CLADDING - A thin glass or plastic material applied to the surface of a fiber optic strand core, having less density than the core. If a light strikes the boundary between the two materials at a suitable angle, the light is reflected back into the denser core. CONNECTOR INSERTION LOSS - Light loss, expressed in decibels (dB), caused by the insertion of a mating connector between two sections of a fiber optic transmission system CONTRAST - The difference in light output between the areas of a display that are illuminated and non-illuminated CORE - The inner section of a fiber optic strand made of either pure glass (silica) or plastic through which light is guided. Typically, it is approximately .01 to .05 inches in diameter. CURRENT TRANSFER RATIO (CTR) - Ratio of an opto-couplers output current to its input current D DARK CURRENT - The output current of a photodetector with no light at its input. DECODER/DRIVER - A circuit that converts digital information into analog voltages, then amplifies the voltages to an adequate level to energize the elements of a display DIGITAL DISPLAY - A readout of alphanumerics (letters and numbers) as opposed to analog or linear meter indications DOMINANT WAVELENGTH - The wavelength that is a quantitative measure of the color of light as perceived by the human eye. DOT-MATRIX D