Fiber Optic Object Sensor
Original Publication Date: 1980-Sep-01
Included in the Prior Art Database: 2005-Feb-13
In a light-emitting diode (LED)/fiber-optic sensor, an LED emits a short pulse of light into a single fiber and then switches into a receive mode to detect the returning pulse. The necessary delay in signal return to permit the LED to switch can be achieved, for example, by recourse to the fact that signal velocity in a fiber is finite. Thus appropriate selection of fiber length will afford any desired delay time. Light emitting diodes capable of detecting as well as emitting light are known, but in current LED/fiber-optic sensors, LEDs are used solely for emitting light, and this requires the provision of fiber-optic bundles in order to carry light from the LED to an object and then back to a separate detector.