Patent ID: 6927853

Claim:
A method for optical stress analysis comprising the steps of: directing an incident beam of polarized light to a sample to be analyzed and analyzing a light bundle exiting the sample in two detection channels arranged perpendicular to one another with respect to the polarization direction; providing that the incident beam is elliptically polarized; carrying out the elliptical polarization with an elliptic shape having a comparatively large ratio of the large principal axis to the small principal axis; the direction of rotation of the elliptical polarization of the incident beam changing periodically and using two alternative states of the direction of rotation for each measurement process; adjusting the detection channels which extend perpendicular to one another corresponding to the position of the principal axes of the ellipse; and evaluating the difference between two measurements consecutively with the same beam intensity of the incident beam and the same ratio of principal axes, but with opposite directions of rotation of the elliptical polarization, being given by the two detection channels.