基于数字全息技术的变形测量

Deformation measurement via digital holography

全息技术在测量、防伪中有大量应用。数字全息技术采用数字记录和计算机处理,实现测量的方法上有其特点。本文重点对数字全息技术实现变形测量的方法和具体算法开展了研究。论文首先总结了数字全息技术应用中的基本问题,包括数字全息算法问题和噪声抑制问题等。叙述了基于数字全息技术的变形测量基本思想,及相位恢复算法,同时分析了几种变形测量的实现方法,并提出了“2+2”步变形测量方法。该方法相对于“1+1”步变形测量方法,提高了测量精度,同时比“4+4”步变形测量法提高了动态性。本文建立了实验系统,获得了硬币的数字全息图,实现了常用的“1+1”步变形测量方法、相移算法的变形测量方法以及“2+2"步变形测量方法,给出了“2+2”变形测量的实验结果。实验结果表明在数字全息技术中结合相移技术进行测量,可以提高物波再现精度,进而提高变形等的测量精度。

Holography is applied in measurement and anti-counterfeit.Contrary to some others measurement techniques,the digital holography directly investigates the microinterference patterns produced by reference and object wave,which are recorded on the CCD-target.The emphasis of this paper is to develop research about some deformation measurement ways and its corresponding algorithms of digital holography.This paper first summarizes some basic problems on the application of digital holography,including the algorithms and noise suppressing of digital holography,etc.It describes the basic idea for deformation measurement and phase reconstruction algorithms by digital holography.Meanwhile,it analyzes several ways for deformation measurement and puts forward '2+2' algorithm.Comparing to '1+1' algorithm,this algorithm improves measurement precision,and at the same time,it improves dynamic speciality with comparing to '4+4' deformation measurement algorithm.This paper sets up the experimental system that gets the digital holograms of RMB coin and realizes deformation measurement,by using '1+1' digital holography phase-shifting digital holography and '2+2' digital holography.The typical processing results of '2+2' technique are presented.The results indicate that if we combine phase-shifting technical into digital holography,the reconstruction precision of object wave can be improved,thus to improve the measurement precision of deformation.