Understanding the Role of Optics in LED Lighting

With the recent introduction of our high end OpticPAR^TM LED grow lights to the horitculture market, there’s been plenty of discussion on the role of optics in LED lighting. The optics in any LED lighting system are crucial elements of that system’s performance, as they alter the directionality and intensity of light from the LED source. Optics in LED lighting can include the spatial distribution of light from the diode itself, and the reflectors, lenses, and holders that cut off or limit output light with mechanical blocking devices. Facilities that install LED lighting systems will use different optics in LED lighting, for example, to control the beam angle of the output light, to create either crisp-edged or diffused light, or to concentrate light in certain areas while limiting it in others.

Custom Optics for LED Lighting Applications

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. Secondary optics are employed in SpecGrade products both to vary this spatial distribution and to alter the characteristics of the LED light to suit a desired end goal.

Methods of Modifying LED Lighting Optics

Lenses can be used to diffuse the light more evenly over a larger surface area. More advanced “TIR” lenses can be used to achieve even greater uniformity with how LED lighting is diffused over a particular surface.  Further, some lenses will filter out different light wavelengths in order to create patterns or colors over different surfaces.

Reflectors that sit over an LED light come in different shapes and sizes, and either with or without a sub-lens that allows even greater diffusion of the light. Reflectors can have smooth or variegated interior surfaces to create different lighting optical effects or to concentrate or diffuse lighting in conjunction with an integrated lens. Holders are the simplest form of optics in LED lighting, as they do little more than sit on top of an LED fixture to mechanically block portions of the fixture’s light.     

The multiple options for optics in LED lighting have created new ways to generate and focus light onto specific areas and to optimize the benefits of that lighting for the underlying application. The OpticPAR™ technology found inside SpecGrade LED grow lights aims every micromole (µmol) of PAR produced by the luminaire onto the plants. The increased intensity of PAR delivered to the plant canopy penetrates the canopy and reaches the lower levels of the cannabis plants, resulting in higher yields and a higher return on your LED investment.