The proposed multilayer technology makes it possible to approximate a continuous phase distribution by discrete phase steps. Compared with binary techniques, a higher diffraction efficiency can be achieved. In most known processes a bulk substrate is used and etched directly; therefore it is difficult to control the height of the phase steps. We propose applying layers of a well-known thickness and structuring them with a selective etching process. In this new multilayer process for reflecting elements a system of metal and dielectric layers is used that can easily be produced by standard methods.
© 1996 Optical Society of America
B. Goebel, L. L. Wang, and T. Tschudi, "Multilayer technology for diffractive optical elements," Appl. Opt. 35, 4490-4493 (1996)