Micro-Optics: A Novel Approach for Unique Styling 2007-01-1390
Customers and OEM are increasingly asking for a more homogeneous appearance of lighting surfaces, to give new styling opportunities and allow for volume appearance of rear lamps and front lamps. Since LEDs are by nature point like, efforts have to be made to achieve homogeneous appearance. Mostly, this is done by using Fresnel like optics, eventually combined with some pillow optics, or with pillow reflectors and indirect illumination. While this approach typically gives quite good photometric values, the homogeneity is acceptable only for flat two-dimensional lamps like CHMSLs (Center High Mounted Stop Lamps). A micro-optics approach has been developed to offer a very stylish means for achieving completely homogeneous and lambertian appearance over a large lamp area (or even of the complete lamp). It is based on a distribution of very tiny, nearly invisible scattering elements on a two-dimensional light guide. LEDs are feeding light into the light guide sheet, where the scattering elements are responsible for the very even light distribution. To realize these optical elements, a laser etching process is applied to the mold.