Abstract
Photoelasticity is applied to measure the shear strain of the plastic lenses of glasses. The lenses of CR-39 are fixed to two kinds of glasses frames, the old frames and the new ones whose rim lock mechanism is improved to reduce the strain of the lenses. The measurement results show that the strain of the lenses attached to the new rim lock mechanism decreases by about 33% on the average of whole area of the lenses, compared with the old mechanism. At the center of the lenses, however, the strain of the lens attached to the new rim lock mechanism is roughly the same as that of the lenses fixed with the old rim lock mechanism. The shear strain is of the order of 10-4, which brings to the change of lens' refractive index of 10-5 . The measured data can be the basis to investigate how much the strain of glasses' lenses deteriorates the quality of vision.
