Photoelastic stress analysis is an important experimental method.The key of this method is to determine isoclinic line parameters and isochromatic line parameters.Commonly used six-step phase shifting method can automatically determine the isoclinic and isochromatic parameters.However in solving the isoclinic angle,this method will cause errors due to unavoidable effect of isochromatic line coupling with isoclinic lines in phase diagram.An optimized program-multiple loads-six-step phase shifting method was ...