JPS5459163A - Inspector of aspherical lens - Google Patents

Abstract

PURPOSE: To perform highly accurate automatic inspection of aspherical quantity over the entire part of the lens by correcting the displacement detection quantity owing to the roundness at the tip of a stylus when the lens is turned with the turning optical axis as an axis.

CONSTITUTION: A lens 61 is turned together with the optical axis 61 running the center 62 of a reference spherical face 73 in the direction perpendicular to the optical axis 61 and turns about the optical axis 61 as an axis. Turning angles α, θ are applied to a microcomputer 68 via encoders 66, 67 mounted to a DC servo motor. At the same time, the contact displacement quantity of a stylus 63 with the lens 60 is optically tetected by a laser light source 69, direction discrimination part 71, arithmetic part 72, etc. and is applied to the computer 68, by which apparent aspherical quantity δ' is calculated. From the contact point coordinates of the stylus 63 and lens 60 based on the aspherical quantities δ'... subsequently calculated along with the change in the angles α, θ, the computer 68 corrects the error quantity Δ owing to the roundness of the tip of the stylus 63 and calculates the true aspherical quantity. Thereby, the highly accurate aspherical quantity over the entire face of the lens is automatically measured

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