Apparatus and method for measuring eccentricity of aspherical surface
First Claim
1. An apparatus for measuring eccentricity of an aspherical surface in which an amount of eccentricity of an aspherical lens is measured, the apparatus comprising:
- a first light source unit;
a first condenser lens for condensing light rays emitted from the first light source unit in a proximity of a center of paraxial curvature of a first surface to be examined, of the aspherical lens;
a first angle changing means for entering the light rays on the first surface, at angles θ
1i (i =1, 2, . . . , N) with an optical axis;
a holding tool for holding the aspherical lens;
a first light-splitting element interposed between the first angle changing means and the holding tool;
a first imaging lens for collecting light reflected by the first light-splitting element;
a first light-detecting element for detecting a situation of light collected by the first imaging lens; and
an arithmetical unit, the arithmetical unit including the processes of;
storing spot positions P1mi(i=1, 2, . . . , N) derived from the first light-detecting element with respect to light rays Q1i(i=1, 2, . . . , N) produced by the first angle changing means;
calculating spot positions P1i(i=1, 2, . . . , N) relative to the light rays Q1i(i=1, 2, . . . , N) on the basis of design data of the first surface; and
calculating the amount of eccentricity of the first surface from amounts of shift Δ
P1i(i=1, 2, . . . , N) between the spot positions P1i(i=1, 2, . . . , N) and the spot positions P1mi(i=1, 2, . . . , N).
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Accused Products
Abstract
An apparatus for measuring the eccentricity of the aspherical surface has a light source unit; a condenser lens condensing light rays in the proximity of the center of paraxial curvature of a surface to be examined, of an aspherical lens; an angle changing means for entering the rays on the surface to be examined, at angles θ1i (i=1, 2, . . . , N) with an optical axis; a holding tool of the aspherical lens; a light-splitting element; an imaging lens; a light-detecting element detecting the situation of light collected by the imaging lens; and an arithmetical unit. The arithmetical unit is such as to calculate the amount of eccentricity of the surface to be examined, from amounts of shift ΔP1i (i=1, 2, . . . , N) between spot positions P1i (i=1, 2, . . . , N) based on the design data of the surface to be examined and spot positions P1mi (i=1, 2, . . . , N) derived from the light-detecting element, with respect to light rays Q1i (i=1, 2, . . . , N) produced by the angle changing means.
13 Citations
16 Claims
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1. An apparatus for measuring eccentricity of an aspherical surface in which an amount of eccentricity of an aspherical lens is measured, the apparatus comprising:
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a first light source unit; a first condenser lens for condensing light rays emitted from the first light source unit in a proximity of a center of paraxial curvature of a first surface to be examined, of the aspherical lens; a first angle changing means for entering the light rays on the first surface, at angles θ
1i (i =1, 2, . . . , N) with an optical axis;a holding tool for holding the aspherical lens; a first light-splitting element interposed between the first angle changing means and the holding tool; a first imaging lens for collecting light reflected by the first light-splitting element; a first light-detecting element for detecting a situation of light collected by the first imaging lens; and an arithmetical unit, the arithmetical unit including the processes of; storing spot positions P1mi(i=1, 2, . . . , N) derived from the first light-detecting element with respect to light rays Q1i(i=1, 2, . . . , N) produced by the first angle changing means; calculating spot positions P1i(i=1, 2, . . . , N) relative to the light rays Q1i(i=1, 2, . . . , N) on the basis of design data of the first surface; and calculating the amount of eccentricity of the first surface from amounts of shift Δ
P1i(i=1, 2, . . . , N) between the spot positions P1i(i=1, 2, . . . , N) and the spot positions P1mi(i=1, 2, . . . , N). - View Dependent Claims (2, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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3. A method for measuring eccentricity of an aspherical surface in which an amount of eccentricity of an aspherical lens is measured, the method comprising the steps of:
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setting a unit shift δ
A0 and a unit tilt ε
A0 for expressing an amount of eccentricity of a first surface to be examined of the aspherical lens with a shift component and a tilt component, considering design data of the first surface;calculating an inclination angle shift change function gA shift(y) of the first surface, on the basis of the design data of the first surface; calculating an inclination angle tilt change function gA shift(y) of the first surface, on the basis of the design data of the first surface; actually measuring an inclination angle distribution of tangents to the first surface; performing fitting of the inclination angle distribution of tangents to the first surface, which has been actually measured, to a function expressed by α
gA shift(y)+β
gA tilt(y); andcalculating an amount of shift δ
A and an amount of tilt ε
A, which compose the amount of eccentricity of the first surface, from α and
β
, values of which have been determined by the previous step of fitting, and the unit shift α
A0 and the unit tilt ε
A0, on a basis of a relationship (δ
A, ε
A)=(α
δ
A0, β
ε
A0),where the inclination angle shift change function gA shift(y) is a function introduced from a difference in inclination angle distribution of tangents to the first surface, between a supposed state where the first surface is displaced in parallel from an ideal noneccentric position by an amount of the unit shift δ
A0 and a supposed state where the first surface is in the ideal noneccentric position, the inclination angle tilt change function gA tilt(y) is a function introduced from a difference in inclination angle distribution of tangents to the first surface, between a supposed state where the first surface is rotationally displaced from the ideal noneccentric position by an amount of the unit tilt ε
A0 and the supposed state where the first surface is in the ideal noneccentric position. - View Dependent Claims (4)
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Specification