Abstract
The reflection type laser photoelasticity that possesses high detection sensitivity of the birefringence measurement was developed to detect the stress of the film. A He-Ne laser was used as a light source. The magnitudes of principal stress difference and the direction of the principal stress were obtained simultaneously and quantitatively using this equipment. This type of the photoelasticity has a problem that the reflected light from the surface give rise to the error of measurement. We had adopted the confocal lens set and pin hall in order to reduce the influence the reflected light from film surface on the measurement.
