عنوان مقاله [English]
نویسندگان [English]چکیده [English]
When a plane wavefront of a monochromatic and semi coherent is incident on a step, the reflected beam of light diffracted from the step because of the abrupt changes in the amplitude and phase of wave at the boundary of the step therefore fringes pattern is formed in perpendicular of propagation of light that can be described by Fresnel- Kirchhoff integrals. Recently numerous applications of this kind of Fresnel diffraction has been investigated involving measurement of thickness of thin films by accuracy of nanometers, accurate measurement of refractive index of solids and liquids, determination of dispersion relation of materials, measurement of nanometer displacement and measurement of wavelength by angstrom accuracy. In this report we will be shown that when two sides of a phase step which its boundary is perpendicular to the plane of incidence are two different materials, the intensity distribution in the fringes pattern of diffraction from a step is a function of optical constants of materials and height of the step. Numerical simulations of this case indicates that by having the intensity distribution of fringes pattern in several incident angels for polarized beam of light parallel or normal to the plane of incident we can determine optical constants of materials of both sides of step and its height. These simulations are performed for cases of one side dielectric and other side conductor, both side’s conductor and both side dielectric. Primary experimental results are in good agreement with theoretical and numerical results.