Anti-reflective lens makes brighter and cheaper LED lenses

Researchers have recently created a LED light that closely mimics the internal structure of a firefly's lantern cuticle. Like the lantern cuticle, the surface of the LED is curved. On this curved surface different nanostructures have been etched; these nanostructures provide space that creates different reflective patterns. Different reflective patterns ensure that light is being directed in a variety of directions rather than forming one straight pattern in multiple directions. This helps to reduce the amount of light being internally reflected because the light is not reflected in a straight pattern between the reflector and lens. In addition, the curved surface of the reflector helps to once again reflect light that has been redirected from the surface back out of the lens.

Key Differentiators

Many existing products use a smooth surface lens, which inefficiently transmits light due to loss of energy in the form of heat. Technology has overcome this inefficiency of energy transmission through the invention of light-emitting diodes (LEDs). While LED lights prove much more efficient at transmitting light than regular bulbs containing filaments, there is still room for improvement. The problem with existing LED technology is that there is a large amount of light reflected internally due to an optical mismatch between the air and lens. The team of researchers from the Korea Advanced Institute of Science and Technology reduce the amount of light reflected internally "by preparing polydimethylsiloxane lens nano-templates etched with different nanostructures and then recast these with a UV-curable optical resin to produce several lenses" (Urquhart 2012). This one-step process is cheaper than the two-step molding and anti-reflective coating process used by existing LED lights.James Urquhart. 2012. Fireflies inspire low-cost LED lighting. Chemistry World: Royal Society of Chemistry 2012.

Biomimicry Story

Fireflies produce chemicals inside a lantern cuticle that efficiently reflect light outward. The cuticle is filled with different nanostructures that minimize space between the cuticle and the reflective surface. The different surface patterns created by each nanostructure also cause the light to form patterns in different directions, which helps to reduce the amount of light that is reflected internally (as opposed to externally, which is the visible light observers can see). By mimicking the structure of the lantern in an LED, researchers have minimized the amount of light being lost due to internal reflection and maximized the amount of light being transmitted in the visible spectrum.

Challenges Solved

This product substantially increases the efficiency of high-power lighting in LED packages. By reducing the amount of light reflected internally (i.e., the light reflected inside the lens), more light is available for transmission across the visible spectrum.

References


Fireflies inspire low-cost LED lighting


Biologically inspired LED lens from cuticular nanostructures of firefly lanternProceedings of the National Academy of SciencesOctober 30, 2012
J.-J. Kim, Y. Lee, H. G. Kim, K.-J. Choi, H.-S. Kweon, S. Park, K.-H. Jeong