Introduction to Nonimaging Optics, 2nd Edition

12

Köhler Optics and Color-Mixing

12.1 Introduction

Nonimaging optics transfer light from an emitter to a receiver. However, in many situations, the emitter is not uniform (may have hot spots, for example) and those nonuniformities are transferred by the optic from emitter to receiver, resulting in an undesirable irradiance pattern. In other situations, the emitter changes over time. This is the case, for example, of sunlight, as the sun moves across the sky; it is also the case of LED light sources composed of several emitters that may be on or off separately, and at different times. There are still other situations in which the position of the emitter (say an LED) may vary, for example, due to position tolerances in the assembly process, ...