Production of micro-fresnel lens

Abstract

Abstract PURPOSE:To bring lens characteristic close to an ideal value by applying resist to the surface of a substrate for a micro-Fresnel lens, executing multiplex drawing on the resist and exposing the drawn surface so that the optimum exposure is obtained on the central layer and the exposure is reduced in the upper layer direction and increased in the lower layer direction. CONSTITUTION:A transparent electrode film 2 is formed on the surface of the glass substrate, a resist film 3 is applied to the surface of the film 2 and them multiplex drawing is executed by changing drawn pictures in stages in accordance with the phase shifting function of an ideal curve of the micro- Fresnel lens. The exposure of the drawn pictures is controlled so that the optimum exposure is obtained on the central layer and the exposure is reduced in the upper layer direction and increased in the lower layer direction and Fresnel rings with a sawtooth-shaped section is formed. Consequently, the sectional shape of the outer periphery of the lens can be put close to the ideal curve of the micro-Fresnel lens and lens characteristics such as the primary converging efficiency or the diameter of a beam spot can be improved.

Inventors

• 👤 Koji Takusagawa
• 👤 田草川　幸次

Bibliographic Details