Preparation of lens having refractive index distribution in axial direction

Abstract

Abstract PURPOSE:To prepare the titled lens having a small axial aberration, by bringing a medium containing a specific cation into contact with a glass plate, giving a refractive index distribution varying in the thickness direction by using the ion exchange, and working the resultant glass plate. CONSTITUTION:A glass plate 10 consisting of a glass containing an alkyli metal is brought into contact with a medium 11, e.g. a molten salt of thallium sulfate, containing one or more metallic cations, e.g., Tl, Li or Cs, to replace the alkali metallic ions in the glass with the above-mentioned cations and form a glass plate 10 having the refractive index n (2) (i) maximum at both plate surfaces (10A) and (10A), reducing to the interior and minimum at the center and (ii) uniform in the cross section parallel to the plate surfaces (10A) and (10A). A region having a desired refractive index distribution is cut from the above-mentioned glass plate 10 to give a lens material 12, which is then ground and finished to afford the aimed lens having the spherical surface as the high-refractive index surface and a plane perpendicular to the optical axis as the low-refractive index surface.

Inventors

• 👤 Akitaka Momokita
• 👤 百北　昭宝
• 👤 Eiji Okuda
• 👤 奥田　栄次

Bibliographic Details