KINOFORMS DESIGNED TO PRODUCE DIFFERENT FAN-OUT PATTERNS FOR 2 WAVELENGTHS

Kinoforms (diffractive optical elements) were designed to produce diff erent fan-out (i.e., spot) patterns when illuminated with green (543-n m wavelength) and red (633-nm) light. Three design examples are presen ted, each using one of three different techniques for this wavelength discrimination. If the fan-out pattern is to be produced in the near f ield (Fresnel region) of the kinoform, focusing-defocusing distinguish es between the two colors. For a far-field pattern the color distincti on can be obtained either by active suppression of unwanted spots, whi ch also decreases the diffraction efficiency, or, preferably, by an in crease in the maximum phase modulation of the kinoform (to more than 2 pi rad). AU three examples were designed with. a method based on the full scalar wave equation and optimal-rotation-angle optimization. The designed binoforms were manufactured and performed, at least qualitat ively, as predicted by the design. (C) 1998 Optical Society of America .