Исследование влияния дифракционного поля на интерференционную картину в зоне Фраунгофера

The paper is devoted to consideration of phase characteristics of wave fields of interferential pattern, occurring while moving narrow coherent light beam on the surface of cylindrical string placed into one of the branches of countering light beams interferometer. The objectives of interferential pattern analysis in this case are: obtaining of phase values of wave front and estimation of the influence of light intensity distribution in the diffracted beam on the interferential pattern visibility. The task is to synthesize noise-stable treatment operators using reverse trigonometric functions. Different algorithms for determination of phase difference using interferential patterns can be divided into two groups: the analysis of one interferogram for detecting of strip centers or separating of frequency components; the analysis of several interferograms, obtained at different positions of laser beam on the string. Complex amplitude of unknown field is determined by varying of base wave while object wave field remains constant. Interferential methods of measurement have phase ambiguity. Besides that, the corruption of interferential pattern by diffraction effects takes place, especially in distant zone. In this case mathematical and experimental simulation is necessary. Forming of the diffraction pattern is considered using Huygens-Fresnel principle. Having definite signal/noise value, one can determine the quantity of effective extreme points for obtaining of demanded accuracy of registration.