Physics Department;
Faculty of Science;
Helwan University;
Cairo;
Egypt;
Teachers Colleges of Makkah;
Umm-Alqura University;
Umm-Alqura;
Saudi Arabia;
Physics Department;
Faculty of Science;
Cairo University;
Giza;
Egypt;
Speckle Photgraphy; Photo-Refractive Materials; Two-Beam Coupling; Measurement Uncertainty; Tilt Measurement;