The method for evaluating schlieren in glassy or crystalline optical materials
includes irradiating a test sample of the optical material with light and producing
a shadow image of the test sample on a projection screen. The shadow image of the
test sample is received in an electronic image receiving device, such as a digital
camera, and is compared with another shadow image of schlieren obtained with a
comparison sample by means of interferometry. Then the optical material of the
test sample is evaluated with the help of the comparison results.
