TY - JOUR T1 - Thickness measurement using the extrema of the intensity profile in Fresnel diffraction from a phase step TT - اندازه گیری ضخامت لایه نازک با استفاده از فاصله فرینه های توزیع شدت از هم در نقش پراش فرنل از پله فازی JF - opsi JO - opsi VL - 21 IS - 0 UR - http://opsi.ir/article-1-711-en.html Y1 - 2015 SP - 777 EP - 780 KW - Extrema KW - Fresnel diffraction KW - Thickness KW - Thin film N2 - In Fresnel diffraction from a phase step, the intensity profile and spacing between its extremum points have a universal dependence on step height and light's incident angle. Therefore, plotting variations of the distances of these extrema versus the phase, provides the phase due to the step and the height of the step with remarkable accuracy. We've applied these plots on experimentally obtained data of diffraction patterns from steps with different heights to measure their thickness, using two wavelengths, 532nm and 632.8nm.The uncertainty of the results is less than few nanometers. M3 ER -