非相干相关数字全息术:原理、发展及应用

Incoherent Correlation Digital Holography:Principle,Development,and Applications

全息术最初被设定为一种相干成像技术,通过物光和参考光干涉形成全息图,对全息图进行重建可以实现三维成像和物信息的获取。全息图记录过程要求物体上任意两点的光场具有空间互相干性,这一特性限制了全息术在非相干光领域的应用。空间非相干光的普遍存在和易获取等优点,使得非相干全息术的提出和发展具有重要意义。非相干全息术源于20世纪60年代Mertz和Young提出的菲涅耳波带片编码成像理论,是指在空间非相干光照明情形下利用某种编码孔径对图像进行变换,实现全息图记录和再现的技术。Lohmann把这一技术进一步发展为基于分波技巧的干涉成像技术(源于同一物点的物光和参考光相干涉),实现了非相干物体的波前再现,从而明确了非相干全息记录时物光场中任意两点之间的互相干不再是全息图记录的必要条件。经过几十年的发展,科研人员对非相干全息图的记录机制、重建算法、非相干全息术成像性能的提升和应用等方面的研究都取得了显著成果。本文聚焦于阐明空间非相干光情形下基于编码相位掩模波前调制的自干涉或无干涉数字全息术的成像原理及其演化技术的发展和应用,并在此基础上探讨该技术下一步的发展和有潜力的研究方向。

According to D.Gabor’s proposal,holography is a coherent imaging technique where the object’s three-dimensional information is first recorded and then reconstructed from the hologram that obtained through the interference of object and reference beams.The coherence of light originating from any two points on the object is required for holographic techniques.However,this requirement on spatial coherence prevents holography from being used in incoherent light applications.Indeed,the development of incoherent holography is important because the incoherent light sources widely exist and are easy to obtain in nature compared with the laser source.Merz and Young first proposed Fresnel-zone-plate coded imaging technique with incoherent illumination and explained their methodology according to holographic theory.Lohmann further presented wavefront retrieval of incoherent objects based on the skills of beam split and self-interference of an object beam and a same originated reference beam,thereby forming the academic idea of incoherent holography.The spatial coherence is no longer necessary in incoherent holography since using specific beam splitting skills to form the hologram of incoherent illuminated or self-luminous objects by the interference of two beams that originated from the same point.In the past few decades,enormous efforts have been addressed to develop the basic principle and reconstruction algorithms and improve imaging performances and applications of incoherent holography.This review focuses on demonstrating the basic concept and applications of various incoherent coded aperture correlation digital holography techniques,with or without a two-beam interference,to provide a clear picture of recent progress in incoherent holography.We also discussed the main challenges and limitations of existing methods and potential directions in which efforts can be made to advance incoherent research holography.