Patent ID: 8699010
Filing Date: 2014-04-15
Classification: G01M

Abstract:
1. A method of measuring the axis of direction and magnitude of stress of a polarized lens, the method having the steps of: a) placing a first polarized film and a second polarized film upon a lighted and transparent working surface such that the vectors of light transmission of the first and second polarized films are placed at a 30 to 60 degree angle from a guideline, the guideline being an expected direction of polarization of a tested lens; b) rotating the first and second polarized films until two areas of darkness of equal proportions are observed and then stopping the rotation and using the area between the two areas of equal darkness as a measured axis of polarization of the tested lens; c) using a dial gauge with a first notch and a second notch and using a first centerline intersecting the first notch and the second notch as the expected axis of polarization, comparing the measured axis of polarization with the first and second notches as a standard of product quality such that a measured axis of polarization falling outside of the first and second notches falls below accepted lens quality for a correct axis of polarization; and d) measuring the magnitude of lens stress by observing an area of brightest light upon the polarized lens to be tested and then rotating the lens until the area of brightest light is observed to become a predetermined color and then multiplying the rotation of the lens by the lens thickness found at the area of brightest light.