Method for measuring eccentricity quantity

Abstract

The invention discloses a measuring method of eccentricity. A detected lens (S3) is set at a preset rotating angle, and transversal line (P1,P2)(S4) crosses with image ordinate of reticule, and ordinate (Q1,Q2)(S5) crosses with image transversal line of reticule, and the peak position A, B of light intensity on the transversal line (P1,P2) and the peak position C, D of light intensity on the ordinate (Q1,Q2) is specified. The cross ordinate for connecting A and B is determined and the cross transversal line (S8,S9) for connecting C and D is also determined. Then, the crossing point of the cross ordinate and cross transversal line is specified to be as center R(S11) of reticule image. Each center R is based on multi rotating positions, the image center tracking circle (S14) is calculated and the radius of the image center tracking circle is used as eccentricity Ec(S15) of the detected surface. Therefore, in the measuring method of eccentricity using autocollimation method, the measurement precision is greatly raised in simple structure.

Description

technical field [0001] The invention relates to a method for measuring the eccentricity of an inspected surface of an optical element such as a lens. Background technique [0002] As an important item in the evaluation and inspection of lenses, there is the measurement of the decentering amount of the lens surface. [0003] The amount of eccentricity of the lens surface is represented by the amount of misalignment between the center of curvature of the lens surface and their central axes. [0004] As a method of measuring such an amount of eccentricity, a method called "autocollimation" disclosed in Patent Document 1 below is known. For example, the eccentricity measuring device shown in FIG. 8 is a device provided for a reflection-type eccentricity measuring method for automatic alignment, and it is provided with: the lens to be inspected (spherical lens) 110 is rotatably centered on its central axis. A base 122 provided; a light source 111; an index plate (pinhole: pinho...

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Problems solved by technology

[0010] However, in order to calculate the eccentricity of the inspected lens 110 by the method described above, the radius of the circle formed by the locus of the image of the pinhole must be specified, but since the image of the pinhole has a certain area, it is difficult to specify correct circle radius

For example, FIG. 9 shows that the image of the pinhole on the imaging surface is formed in a circle based on the reflected light from the above-mentioned upper inspection surface or the above-mentioned lower inspection surface, but it is difficult to specify which of the pinhole images Since the position is its center, it is difficult to improve the measurement accuracy of eccentricity

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