Abstract

The classical reflection, shadow, and in-plane moire methods for slope, deflection, and in-plane displacement measurement, respectively, employ an incoherent light source for illumination. Diffraction effect on the grating is either ignored or blamed for the lack of fringe clarity. In this paper we use a laser as the light source and take advantage of the Talbot effect to construct various forms of Talbot interferometers to increase the sensitivity and fringe quality of these methods. In the Talbot reflection moire we reach a sensitivity of 4 × 10⁻⁵ rad per fringe for slope measurement; in the Talbot shadow moire we obtain a sensitivity of 0.0116 mm per fringe with increased range of measurable depth; and in the in-plane Talbot moire high quality fringes are observed even when the specimen and reference gratings (spatial frequency up to 40 lines/mm) are separated at a distance half a meter apart.

© 1985 Optical Society of America