Phase Imaging With Long Dynamic Range And High Sensitivity Based On Optical Coherence Tomography

Optical Coherence Tomography(OCT)is a new optical imaging technique that has been developed for nearly two decades.It has advantages of high resolution,fast acquisition speed,non-contact imaging,depth-resolved,and has huge promise in clinical trial,industrial detection and scientific research.By analyzing the complex phase information of the interference fringe,OCT is able to achieve nano-scale resolution imaging.However,the detecting range is limited by the phase ambiguity.This article brings up a novel phase unwrapping method based on OCT with high resolution and large dynamic range,and it overcomes the phase wrapping ambiguity involved in traditional OCT phase imaging.The main content of this thesis contains follows:Firstly,the theory of OCT imaging and its performance are discussed,and a functional OCT imaging system is built based on that.Its functional modules,parameters and hardware coordination process are introduced,as well as its adjustments.The axial sensitivity,lateral resolution and working distance are testified.Secondly,by combining the spectral-domain OCT technique and phase imaging,a new phase unwrapping method is proposed.This method solves the ambiguous wrapping period by analyzing information in spectral domain,which is achieved by calculating the phase deviation between the simulated fringes and the acquired fringe.It enables long dynamic range and high sensitivity of sub-nanometer.Finally,PZT movements and optical plane surface detections were performed to testify the stability,accuracy and the sensitivity of the system;and biomedical cells imaging and material surface topography were demonstrated to show its implementation in biomedical inspection and surface imaging;finally six volunteers' central corneal thicknesses in vivo were detected to demonstrate its promising future in research and clinical application.