Isopachic method with unpolarized light

An isopachic method with unpolarized light using a Mach-Zehnder interferometer is proposed. In the case of light, isopachics are observed not only due to change in thickness model but also induced birefringence. contrast existing methods, proposed allows you study sections three-dimensional models or flat stressed samples no variation. A brief theoretical consideration based on formalism coherence matrix given, as well experimentally obtained field for made from high-modulus material. The convenient and simple technical implementation. Keywords: photoelasticity, interferometry, stresses, isopachic, isochrome, isocline.