Canon Kabushiki Kaisha

Kentaro Doguchi

Kohei Nakata

Michio Endo

Shigeru Fujino

An optical element comprising a vacuum-sintered body comprising a plurality of particles each having a two-layer structure comprising a ceramic particle and a coating layer, wherein the ceramic particle comprises LnAlO, where Ln represents a rare-earth element, x represents 1&#x2266;x&#x2266;10, and y represents 1&#x2266;y&#x2266;5, and has an average particle diameter of 1 &#x3bc;m or more and 10 &#x3bc;m or less, and wherein the coating layer comprises a ceramic having a lower sintering temperature than a sintering temperature of the ceramic particle.

Optical material and optical element

An optical element is formed by vacuum-sintering a molded body of ceramic particles having an average particle diameter of 1 &#x3bc;m or more and 10 &#x3bc;m or less and including LnAlO(Ln represents a rare-earth element, 1&#x2266;x&#x2266;10, and 1&#x2266;y&#x2266;5). Ln preferably includes at least one kind selected from La, Gd, Yb, and Lu. The optical element preferably has a refractive index of 1.85 or more and 2.06 or less, and an Abbe number of 48 or more and 65 or less. The obtained optical element has optical properties of high refractive index and low dispersibility.

A method for manufacturing fluoride crystal includes the steps of adding scavenger and a material to a crucible, melting the scavenger and material at a temperature higher than a melting point so that a ratio of a thickness of the fluoride crystal that has been melted to an inner diameter of the crucible may be 0.2 or higher, and gradually crystallizing and purifying the material.

Growing community of inventors

Utsunomiya, Japan

Kentaro Doguchi