JP2004335080A5 - - Google Patents

Claims (14)

In a method for producing an optical information recording / reproducing objective lens, comprising press-molding a molding material preformed into a predetermined shape and heat-softened using a pair of upper and lower molds having opposed molding surfaces ,
The objective lens has a convex aspheric surface on the first surface and a numerical aperture NA.
NA ≧ 0.8
A lens that satisfies
including a step of transferring a molding surface shape by pressing a spherical molding material having a radius r and pressing the molding material between a pair of upper and lower molds;
The paraxial radius of curvature R of the convex aspheric surface is:
r / R ≦ 1.35
An objective lens manufacturing method characterized by satisfying the following conditions: The paraxial radius of curvature R of the r and the convex aspheric surface is
1.0 ≦ r / R ≦ 1.3
The objective lens manufacturing method according to claim 1, wherein: When the maximum height of the space generated between the molding surface and the molding material is h, the pressing speed while the upper and lower molds approach the distance corresponding to h is set to 1 mm / sec or less. The method for manufacturing an objective lens according to claim 1, wherein: The temperature of the molding material is 10 at the glass viscosity at least on the glass surface. ^6.5 -10 ^8.5 The method of manufacturing an objective lens according to any one of claims 1 to 3, wherein the molding material is pressed when it is equivalent to Poise. The objective lens manufacturing method according to any one of claims 1 to 4, wherein the objective lens has an optical magnification of zero with respect to a reference wavelength. When the focal length of the objective lens is f (mm),
0.5 ≦ f ≦ 2.1
The objective lens manufacturing method according to any one of claims 1 to 5 , wherein: The objective lens is at the reference wavelength lambda, the manufacturing method of the objective lens according to any one of claims 1 to claim 6, axis wavefront aberration is equal to or less than 0.04Ramudarms. The objective lens has a refractive index n is 1.65 or more and an Abbe's number νd of 40 or more, and any of the claims 1 to 7, sag TS is characterized in that it consists of 650 ° C. or less of the optical glass A method for manufacturing the objective lens according to claim 1. The first surface has a convex aspheric surface and the numerical aperture NA is NA ≧ 0.8
An objective lens for recording / reproducing optical information satisfying
When the volume of the objective lens is V,
(4/3) πr ³ = V
Between r and the paraxial radius of curvature R of the convex aspheric surface,
1.0 ≦ r / R ≦ 1.35
An objective lens, which is a mold press lens that satisfies the following relationship. Specific gravity is 2.20 to 4.70 g / cm ³ The objective lens according to claim 9, wherein the objective lens is made of the following optical glass. Volume is 0.3-25mm ³ The objective lens according to claim 9 or 10, wherein: The objective lens according to any one of claims 9 to 11, wherein the objective lens is formed by press-molding optical glass having a yield point Ts of 650 ° C or lower. Any one of claims 9 to 12, wherein when the reference wavelength λ is 400 to 450 nm, the refractive index n at the reference wavelength λ is 1.65 or more and the Abbe number νd is 40 or more. The objective lens according to claim 1. The off-axis wavefront aberration at an angle of view of 0.5 ° at the reference wavelength λ when the reference wavelength λ is 400 to 450 nm is 0.05λrms or less. The objective lens according to claim 1.