Diffractive Optical Elements (DOEs): potential and limitations

Diffractive optical elements become more important for the design of optical systems due to several reasons: New production methods make them available for a larger number of applications, and cheaper IR sensors open a new spectral window, where the longer wavelength relieve the manufacturing and testing of these elements. This presentation shows, how classical lens designers can approach DOEs, and how they can be integrated into the design of complex optical systems. Several methods of different commercial design programs to model, analyse and optimize DOEs are presented. The large dispersion of DOEs allows an easy colour correction of hybrid lenses, where the optical power consists of refractive and diffractive components. But the relative partial dispersions far away from that of normal glasses and the increasing intensity of unwanted diffraction orders for larger wavelength ranges complicates the design of broadband optical systems. The transfer of design results to the production process is more complex than for conventional optical systems: The amount of data is much larger, and until now there exists no standard format. Examples of several optical systems with DOEs for VIS/NIR and LWIR are shown, where the DOEs help to reduce the number of optical elements, or they introduce functions, that cannot be achieved with conventional optical elements.