Light-emitting diode of their major uses until their price drops low enough to make signaling and illumination uses more economically feasible. Barcode scanners are the most common example of machine vision applications, and many of those scanners use low-cost products red LEDs instead of laser-based LEDs. Optical computer mice are an example of LEDs in machine vision, as it is used to provide an even light source on the surface for the miniature camera within the mouse. LEDs constitute a nearly ideal light source for machine vision systems for several reasons: The light from LEDs can be modulated very quickly so they
Light-emitting diode quantum dot layer and recombine forming an exciton that excites a QD. This scheme is commonly studied for quantum dot display. The tunability of emission wavelengths and narrow bandwidth is also beneficial as excitation sources for fluorescence imaging. Fluorescence near-field scanning optical microscopy (NSOM) utilizing an integrated QD-LED has been demonstrated. In February 2008, a luminous efficacy of 300 lumens of visible light per watt of radiation (not per electrical watt) and warm-light emission was achieved by using nanocrystals. The main types of LEDs are miniature, high-power devices, and custom designs such as alphanumeric or multicolor. These are mostly single-die