Molded lens

Abstract

A laser beam output from a semiconductor laser light source 1 is transmitted through a cover glass 2 in the optical axis Z direction, is incident on a molded lens 4 in a state of divergent rays, is converted into convergent rays by the molded lens 4 , and is applied onto a recording face 5 of the optical recording medium. A diaphragm 3 is arranged. An area of each lens surface onto which a luminous flux of the laser beam restricted by the diaphragm 3 is applied corresponds to an effective area. The following expression (1) is satisfied: d 1 −d 0 ≧0.04 mm  (1) where d 0 denotes an effective aperture of one of the lens surfaces, and d 1 denotes an outer diameter of the one of the lens surfaces.

1 . A molded lens manufactured by a compression molding process comprising the steps of:
 transferring a shape of a mold so that said lens comprises a first lens surface and a second lens surface, wherein the first lens surface satisfies the following conditional expression (1):
   0.04 mm≦ d   1   −d   0   (1)
 
   where d 0  denotes a usable aperture of the first, lens surface, and d 1  denotes an outer diameter of the first lens surface, wherein the first lens surface is larger in usable aperture than the second lens surface; and   controlling transferability of said shape of said mold by controlling a molding pressure at a high temperature and a molding pressure at a time of cooling.   
     
     
         2 . A molded lens manufactured by a compression molding process comprising the steps of:
 transferring a shape of a mold so that said lens comprises a first lens surface and a second lens surface, wherein the first lens surface satisfies the following conditional expression (1):
   0.04 mm≦ d   1   −d   0   (1)
 
   where d 0  denotes a usable aperture of the first lens surface, and d 1  denotes an outer diameter of the first lens surface, and the second lens surface satisfies the following conditional expression (1)′:
   0.04 mm≦ d   1   ′−d   0 ′  (1)′
 
   where d 0 ′ denotes a usable aperture of the second lens surface, and d 1 ′ denotes an outer diameter of the second lens surface, wherein the first lens surface is larger in usable aperture than the second lens surface; and   controlling transferability of said shape of said mold by controlling a molding pressure at a high temperature and a molding pressure at a time of cooling.   
     
     
         3 . A molded lens manufactured by a compression molding process comprising the steps of
 transferring a shape of a mold so that said lens comprises a first lens surface and a second lens surface, wherein the second lens surface satisfies the following conditional expression (1)′:
   0.04 mm≦ d   1   ′−d   0 ′  (1)′
 
   where d 0 ′ denotes a usable aperture of the second lens surface, and d 1 ′ denotes an outer diameter of the second lens surface, wherein the first lens surface is larger in usable aperture than the second lens surface; and   controlling transferability of said shape of said mold by controlling a molding pressure at a high temperature and a molding pressure at a time of cooling.