Science and Education Publishing American Journal of Mechanical Engineering 2 7 2014 10 30 Characteristic Entities in PhotoStress Method 239 243 EN Peter Frankovsky Department of Mechatronics, Faculty of Mechanical Engineering, Technical University of Košice, Košice, Slovakia František Trebuňa Ján Kostka František Šimčák Oskar Ostertag Władysław Papacz AJME20142713 10.12691/ajme-2-7-13 2014 09 15 2014 10 01 2014 10 30 The presented paper describes characteristic entities in PhotoStress method - isoclinic fringes, singular points, isostatic lines, and isochromatic fringes. These entities are used in PhotoStress method to visualise and quantify deformation and stress fields of various photoelastically coated structural elements.