Different lighting applications will impose different conditions on the selection of optics in LED lighting for those applications. Indoor LED horticultural grow lights will rely on optics that direct as much of the light source’s photosynthetically active radiation (PAR) as is possible onto the canopies and the lower growing surfaces of the plants that are being cultivated in a horticultural facility. A sports arena will want to concentrate light onto playing surfaces to give athletes the best opportunity to see the fast action and fine details of the play that is progressing around them, without stray beams blinding spectators in the stands. Large outdoor parking lots will prefer lighting that illuminates the entire lot uniformly, with no dark areas or shadows that might make motorists uncomfortable. The specific application will therefore define the optics that will go into the application’s lighting system.
Choosing the right optics for an application will reduce wasted energy and maximize the application’s lighting efficiency. An analysis of optics in LED lighting will generally begin with the light source’s spatial distribution. The light from an LED fixture will be at its most intense directly in front of the face and will decrease as you move away from the center in any direction. Almost all of an LED source’s intensity will fade as you move more than 100 degrees away from the center of the source.