Abstract
When an object produces a small phase variation not less than the minimum phase variation detectable by the used system and more than the system's noise, the object is considered as a tiny (or small) object. The measurement of interferometric phase differences evolved from a tiny optical phase object has gained attention in recent years due to its usefulness in accurate detection of nanometric dimensions. In the current work, a Fizeau wedge interferometer is used as an aberrationless method to amplify phase variations of a tiny object. The phase object is inserted between the two semi-reflecting/partially transmitting plates making a smallwedge angle in between. The fast Fourier transformation (FFT) spectrum of the obtained interferograms is characterized by some frequency equidistant peaks. The number of these peaks is related to the number of the interfered rays and each peak represents a set of two-beam interferences. We applied a mask to select one of these peaks and reproduced its corresponding optical phase map via employing inverse fast Fourier transformation. The produced map contains the magnified phase variation with a magnification factor equal to 2 times the selected peak's order. Experimental verification of two different phase object samples to amplify their phase variations with different amplification factors is performed. An integrated magnified phase by the object is calculated to test the validity of the proposed method. It is found that the magnification according to the selection of different FFT peaks is a little bit deviated from the expected magnification factors which is referred to ignoring refraction of the optical rays by the object. In spite of these deviations, good results are obtained. (C) 2020 Optical Society of America