Algorithm for near-field reconstruction based on radial-shearing interferometry

Abstract

A new iterative algorithm to be used to precisely reconstruct near-field distribution from an interferogram of a laser output generated by a cyclic radial-shearing interferometer is proposed. First, by use of a window function around the zero-frequency part of the Fourier transform of the interferogram and calculation of the inverse Fourier transform of the zero-frequency part, we obtain the background intensity distribution of the interferogram. Then, according to the iterative algorithm, the near-field distribution of the laser output is precisely reconstructed from the background intensity distribution obtained in the first step. A numerical simulation and an actual experiment of the near-field reconstruction of the laser output with arbitrary amplitude distribution are implemented successfully.

4D measurements of biological and synthetic structures using a dynamic interferometer

“…Figures 7(b) and 7(c) show the slope, the average diameter is 0.2 mm. In Figure 8, we show a thin film to test lenses and spherical surfaces (38)(39)(40)(41)(42)(43)(44)(45)(46)(47). In Figure 10, representative frame of the temporal variation of the slope calculated for this case is displayed, in the Video 3, can observe the phase variations induced by the evaporation of alcohol.…”

Radial Shearing Interferometer

“…The interferogram generated by the proposed RSI is calculated from Eqs. (12), (15) and (16), as shown in Figure 12(a). The matrix K, L and R are calculated by Eqs.…”

“…Radial shearing interferometer (RSI) was proposed firstly in 1961 [1]. After development of many years, the RSI has been used widely in optical testing [2][3][4], corneal topographic inspection [5][6][7], wavefront sensing [8][9][10][11] and laser beam characterization [12][13][14]. Radial shear can be introduced by some classical optical components [15,16] and the other different ways [17][18][19][20][21] including optical gratings [17,18], zone plate [19], speckle interference [20,21] and the other applications.…”