Köhler integration optics improve illumination homogeneity

Köhler integration on 3-D surfaces The SMS three-dimensional (3-D) designs can, when two freeform surfaces are designed, ensure almost perfect imaging of the boundaries of an extended source onto a target.5' 6 A freeform RXI can be designed as a single dielectric solid in which light emitted by an LED undergoes a refraction at the input cavity surface, followed by a total internal reflection on the inside of the front surface, a reflection on the back mirror, and finally a refraction on the front surface, which therefore acts twice on the light (see Fig. 4). The RXI can be designed to be a very efficient collimator that can create radiation patterns of different vertical and horizontal spread as needed for automotive low-beam lights, for example.7 The low-beam light distribution is defined by very demanding legal photometric test specifications like a horizontal cut-off line (or grathent) at which the intensity must drop from the hotspot of 20 to 50 kcd to almost 0 within one to two vertical degrees.