Abstract: A method of and apparatus for reading out information disposed as a surface deformation such as a thermoplastic deformation pattern is disclosed in accordance with the teachings of the present invention. A coherent light beam is projected to the surface deformation pattern and one of the first order components of the diffraction pattern received from the deformation pattern is imaged onto a surface. At the surface, the first order component is mixed with a further coherent light beam to form an interference pattern comprised of image modulated sinusoidal interference fringes. The interference pattern has an intensity that varies as a linear function of the amplitude of the deformation pattern. In a preferred embodiment thereof, the first order component of the diffraction pattern is imaged to the surface by an imaging lens optically positioned out of optical communication with the zero order component of the diffraction pattern.