Jun AMAKO and Tomio SONEHARA

R&D Division, Seiko Epson Corp., 3-3-5 Owa, Suwa, Nagano, 392 Japan

(Received May 12, 1995; Accepted August 1, 1995)

A binary phase grating capable of shaping an incident Gaussian beam to a flattop beam in a Fourier domain is designed iteratively. It is essential in grating design to consider the phases of diffracted waves by the grating, in addition to their amplitude uniformity and diffraction efficiency. The optimized grating phase produces the in-phase diffracted waves that interfere constructively to form a uniform amplitude and phase profile. The dependence of the shaped profile on the illuminating amplitude distribution, the grating misalignment, and the lens focusing error is investigated by computer simulation and optical experiment.

Key words : flattop, Fourier spectrum, phase grating, interference, phase jump, simulated-annealing