Micro-fresnel lens

Abstract

Abstract PURPOSE:To facilitate the manufacture and to decrease the chromatic aberration by specifying the height of an uneven pattern in each Fresnel zone. CONSTITUTION:Height of an uneven pattern of each zone is set to a value for giving a phase shift of 2npi (n is a positive integer of >=2). Accordingly, a period of each zone becomes two times, comparing with a conventional Fresnel lens having a value for giving a phase shift whose height is 2pi. That is, even in case of the same numerical aperture NA, the period of each zone becomes (n) times by setting the height of the lens to (n) times. In such a way, the manufacture accuracy is improved, the lens efficiency is raised, and also, the period of the Fresnel zone is lengthened, by which a light beam is curved by a refraction rather than a diffraction effect, and a chromatic aberration caused by a use wavelength variation is decreased.

Inventors

• 👤 Shigeru Aoyama
• 👤 茂 青山
• 👤 Maki Yamashita
• 👤 山下　牧
• 👤 Shiro Ogata
• 👤 司郎 緒方

Bibliographic Details