Conoscopy

The part to be measured is illuminated by a beam of light through the measuring lens, and the scattered light is collected by the lens (figure 11 ). A birefringent crystal, which can be placed before or after the objective, creates a different phase delay between two orthogonally polarized waves. This delay increases with the inclination of the light wave with respect to the measurement axis, as the thickness of the crystal traversed increases. Two sets of polarizers and quarter-wave blades are placed on either side of this crystal, so that the orthogonally polarized waves passing through the birefringent crystal can interfere (as is done...