OPTICAL ELEMENT AND METHOD FOR MANUFACTURING THE SAME

1 . A method for manufacturing an optical element, wherein

a mold-press molding is performed by use of a material body having a prismatic shape to form a light transmission part and a flange of the optical element, the material body comprising a chalcogenide material and/or a chalcohalide material, the flange extending outward from the light transmission part; and

the mold-press molding plastically deforms the material body by making the material body receive a press force from a heated metal mold, and causes only a corner of the material body to be subjected to a mold transfer to provide an edge face of the flange.

2 . The method according to claim 1 , wherein, prior to the mold-press molding, the corner of the material body is locally heated and plastically deformed such that the corner of the material body is chamfered.

3 . The method according to claim 1 , wherein, when the material body comprises the chalcogenide material, the mold-press molding is performed for 10 seconds to 5 minutes under a condition that a temperature of the metal mold is 250 to 350° C. and an application of pressure is 5 to 100 kgf.

4 . The method according to claim 1 , wherein, when the material body comprises the chalcohalide material, the mold-press molding is performed for 30 seconds to 30 minutes under a condition that a temperature of the metal mold is 350 to 450° C. and an application of pressure is 5 to 100 kgf.

5 . The method according to claim 1 , wherein the mold-press molding deforms the single material body under pressure to provide an integrated form of the light transmission part and the flange from the single material body.

6 . The method according to claim 1 , wherein a metal mold is used in the mold-press molding, the metal mold being composed at least of a mold main part and a mold sleeve part, and

the mold transfer causes only the corner of the material body to be pressed against the mold sleeve part.

7 . The method according to claim 1 , wherein an applying of the press force to the material body is stopped after the corner of the material body is pressed against the metal mold, and thereby providing the edge face of the flange.

8 . The method according to claim 1 , wherein the material body has an approximately quadrangle shape in a plan view, and the mold-press molding causes the four corners of the main body to be subjected to the mold transfer.

9 . The method according to claim 1 , wherein a lens is manufactured as the optical element, the lens being one for allowing at least an infrared-region light ray to be transmitted through the lens.

10 . An optical element comprising a light transmission part and a flange extending outward from the light transmission part,

wherein the optical element comprises a chalcogenide material and/or a chalcohalide material,

wherein the flange has a plurality of furthest edge portions at an edge face of the flange, the furthest edge portions being located furthest from a center of the light transmission part, and

only the plurality of furthest edge portions have a mold-transferred form to serve as a positioning face for placing the optical element.

11 . The optical element according to claim 10 , wherein an outer contour of the flange has an approximately quadrangle shape in a plan view of the optical element, and

the four furthest edge portions are respectively at corners of the approximately quadrangle shape of the flange.

12 . The optical element according to claim 10 , wherein the furthest edge portions are in a symmetrical arrangement with respect to the center of the light transmission part in a plan view of the optical element.

13 . The optical element according to claim 10 , wherein the furthest edge portions each have an arc-like periphery in a plan view of the optical element.

14 . The optical element according to claim 10 , wherein the light transmission part and the flange are made of the same material as each other, and the light transmission part and the flange have an integrated form with each other.

15 . The optical element according to claim 10 , wherein the optical element is a lens for allowing at least an infrared-region light ray to be transmitted through the lens.