41. Such materials are required for anti-reflective coating and photonic devices such as light emitting diodes ( LEDs ) and image sensors. 42. Because of its perylene-type optical emission in the visible spectrum, it has also been used in organic light emitting diodes . 43. Light emitting diodes were relatively new at the time and were much dimmer than high efficiency diodes developed in subsequent decades.44. Light emitting diodes , or LED's have been around for a long time, used mainly as indicators rather than sources of illumination.45. An array of light emitting diodes ( LEDs ) is used to provide white light illumination as well as infrared observation. 46. When a finger rests on a transparent or gel-like platen, a light emitting diode sends light at an angle off its surface. 47. The park has two large light emitting diode ( LED ) video displays and one ribbon display in the outfield from Daktronics. 48. Recent advances in lighting technology have also made available a completely new technology for aquarium lighting : light emitting diodes ( LEDs ). 49. The first displays to use light emitting diodes ( LEDs ) instead of light bulbs came off of the assembly line in 1996. 50. A transmitter is often a light emitting diode ( LED ) which is built into the pointing end of the remote control handset.
