Novel method for parameter estimation of Newton's rings based on CFRFT and ER-WCA

Newton's rings is one of the important optical signals, it can be used to measure the curvature radius of optical lens. Owing to the photoelectronic digitized realization and newly established mathematical model of Newton's rings, the measuring of curvature radius can be changed to parameter estimation of Newton's rings. Therefore, some modern signal processing tools have been successfully applied to parameter estimation of Newton's rings, such as Fourier transform (FT), chirp-Fourier transform (CFT) and fractional Fourier transform (FRFT). Nowadays, it has been one of the latest developments in optical signal processing field. In this paper, a novel method for parameter estimation of Newton's rings is proposed based on concise fractional Fourier transform (CFRFT) and evaporation rate based water cycle algorithm (ER-WCA). A pretreatment technology is further proposed to solve uneven illumination of actual Newton's rings. The experimental results show that the efficiency of proposed method is much higher than that of FRFT-based method. It can also be seen from the experimental results that the proposed pretreatment technology can increase the accuracy.