Object lens producing device and producing method

Abstract

An objective lens unit manufacturing apparatus for manufacturing an objective lens unit, with a numerical aperture not less than 0.7, made up by a plurality of lenses, includes a positioning mechanism ( 31 ) for positioning one lens ( 2 ) in a cylindrically-shaped lens holder ( 3 ) of a synthetic resin material, using another lens ( 1 ), already mounted and secured to the lens holder, as a reference, and for securing the one lens to the lens holder, for setting relative positions of the one and the other lenses.

1 - 2 . (canceled)  
   
   
       3 . An objective lens unit manufacturing apparatus for manufacturing an objective lens unit with a numerical aperture not less than 0.7, made up by a plurality of lenses, comprising: 
 a positioning mechanism for positioning one lens in a cylindrically-shaped lens holder of a synthetic resin material, using another lens, already mounted and secured to said lens holder, as a reference, and for securing said one lens to said lens holder, for setting relative positions of said one and the other lens:    a mechanism for measuring the state of offset between the lenses using the laser light;    a light source for causing a light beam to fall on the respective lenses in the lens holder;    a reflecting member or reflecting said light beam converged by said respective lenses; and    a focusing error signal detecting mechanism for receiving the light beam reflected by said reflecting member to fall again on said respective lenses to detect the focusing error signals with respect to said reflecting member; wherein    the amount of spherical aberration in the light beam transmitted through said respective lenses is measured, based on changes in said focusing error signals when said reflecting member is moved along the optical axes of the respective lenses, to adjust the distance between the respective lenses based on said amount of spherical aberration.    
   
   
       4 . The objective lens unit manufacturing apparatus according to  claim 3  wherein said reflecting member is vibrated along the optical axes of the respective lenses.  
   
   
       5 . The objective lens unit manufacturing apparatus according to  claim 3  wherein the lens holder includes lens inserting sections into which the outer rims of the respective lenses are inserted to control the offset of said respective lenses; said respective lenses being inserted into said lens inserting sections to control the offset of the respective lenses; said respective lenses being secured to said lens holder with an adhesive as the offset of the respective lenses is controlled by said lens inserting sections.  
   
   
       6 . The objective lens unit manufacturing apparatus according to  claim 5  further comprising: 
 a light source for causing a light beam to fall on the respective lenses in the lens holder;    a reflecting member for reflecting said light beam converged by said respective lenses; and    a focusing error signal detecting mechanism for receiving the light beam reflected by said reflecting member to fall again on said respective lenses to detect the focusing error signals with respect to said reflecting member; wherein    the amount of spherical aberration in the light beam transmitted through said respective lenses is measured, based on changes in said focusing error signals when said reflecting member is moved along the optical axes of the respective lenses, to adjust the distance between the respective lenses based on said amount of spherical aberration.    
   
   
       7 . The objective lens unit manufacturing apparatus for manufacturing an objective lens unit used as an objective lens unit of an optical pickup device for writing or reading out information signals on or from an optical recording medium, according to  claim 5 , further comprising: 
 a mechanism for determining the distance between the lens surface closest to the optical recording medium and an end face of a lens holder lying around said lens surface along the optical axis.    
   
   
       8 . The objective lens unit manufacturing apparatus for manufacturing an objective lens unit used as an objective lens unit of an optical pickup device for writing or reading out information signals on or from an optical recording medium, according to  claim 3 , wherein 
 the other lens used as a positioning reference for said one lens is the lens remotest from the optical recording medium, with a surface of the outer rim of said one lens remote from the optical recording medium being used as a reference surface for positioning said one lens;    the surface of the outer rim of said other lens close to said optical recording medium being used as said positioning reference for said one lens.    
   
   
       9 . The object lens unit manufacturing apparatus for manufacturing an objective lens unit as claimed in  claim 8  wherein, in securing said one lens to said lens holder, said one lens is held, the distance of said one lens to said other lens is determined in a state not position-controlled by said lens holder, insofar as the direction of the optical axis is concerned, said one lens being secured to said lens holder by an adhesive.  
   
   
       10 . The objective lens unit manufacturing apparatus for manufacturing an objective lens unit as claimed in  claim 8  wherein, in securing said one lens to said lens holder, said one lens is held, the parallelism of said one lens to said other lens is determined in a state not position-controlled by said lens holder, insofar as the tilt with respect to the optical axis is concerned, said one lens being secured to said lens holder by an adhesive.  
   
   
       11 . The objective lens unit manufacturing apparatus for manufacturing an objective lens unit as claimed in  claim 8  further comprising: 
 a positioning member for positioning a reference surface of a lens; and    a mechanism for measuring the parallelism between said reference surface and said positioning member, using a laser light beam.    
   
   
       12 . The objective lens unit manufacturing apparatus for manufacturing an objective lens unit as claimed in  claim 8  further comprising: 
 a positioning member for positioning a reference surface of a lens; and    a mechanism for measuring the parallelism between said reference surface and said positioning member in a state in which said reference surface is abutted against said positioning member.    
   
   
       13 . The objective lens unit manufacturing apparatus for manufacturing an objective lens unit as claimed in  claim 8  further comprising: 
 a positioning member for positioning a reference surface of a lens; and    a mechanism for abutting said reference surface against said positioning member by attracting said lens by a pneumatic pressure differential.    
   
   
       14 . The objective lens unit manufacturing apparatus for manufacturing an objective lens unit as claimed in  claim 8  wherein 
 the parallelism between the surface of the outer rim of said other lens remote from the optical recording medium and the surface of the outer rim of said one lens close to said optical recording medium is measured by detecting only the reflected light from the surface of said outer rim of said other lens remote from the optical recording medium, using a photodetector, in a state in which the light is incident on the outer rim of said other lens and in which the light transmitted through said outer rim and reflected by the surface of said outer rim close to said optical recording medium is not referred to said photodetector.    
   
   
       15 - 22 . (canceled)