RIGOROUS CONCEPT FOR THE DESIGN OF DIFFRACTIVE MICROLENSES WITH HIGH NUMERICAL APERTURES

Cylindrical dielectric diffractive microlenses are designed by the use of rigorous electromagnetic diffraction theory, and their performance s are compared with microlenses based on a conventional scalar design concept. Microlenses with a relief of four depth levels are considered as well as binary microlenses with subwavelength structures. We show that the density of energy in the focus of high-numerical-aperture mic rolenses can be significantly increased if the phase distribution of t he transmitted electrical field is optimized. (C) 1997 Optical Society of America.