LENS MIDDLE-THICKNESS MEASURING INSTRUMENT AND LENS MIDDLE-THICKNESS MEASURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a lens middle-thickness measuring instruments of high accuracy, capable of measuring the middle thickness of a lens being tested the middle of machining, on a lens working machine.;SOLUTION: This measuring instrument has a low-coherence light source 21, a polarization beam splitter 24 for dividing light flux emitted from the low-coherence light source 21, and a reference mirror 33 for varying an optical path length of one divided light flux. The beam splitter 24 leads the other divided light flux to the lens 4 on the lens working machine via a collimator lens 28 and superimposes one light flux on light flux reflected by the front face and the rear face of the test lens 4. The measuring instrument also has an image sensor 32 for imaging the pattern of the superimposed interference light; and a measurement processing unit 8 for extracting the signals of respective intensities of the interference light of a portion where the measuring light coincides with the lens to be tested optical axis, from the pattern of the interference light corresponding to the respective reflected light flux of the front and rear faces of the test lens 4, on the basis of an imaged signal of the image sensor 32, and measuring the middle thickness of the test lens 4 by both the intensity signals.;COPYRIGHT: (C)2002,JPO