Development Of Complex Master Slave Algorithm In Spectral-domain OCT

Spectral-domain Optical Coherence Tomography(SD-OCT)systems often have problems such as nonlinear sampling and dual-arm dispersion mismatch in the acquisition of interferometric spectra,which affect the axial resolution and sensitivity of the system and increase the complexity of data processing.Complex Master Slave Algorithm(CMS)based on spectral domain Phase solves the Complex Phase Mask for recording the nonlinear sampling characteristics and dispersion information in advance.After data collection,matrix operation is carried out to obtain the sample reflection coefficient distribution within the local depth of interest,which not only improves the axial resolution and simplifies the data processing steps,but also has a significant advantage of fast local imaging.This paper focuses on the depth-domain Phase detection method based on complex master-slave algorithm.The main work includes the wavenumber calibration of grating spectrometer,the reconstruction of complex phase template and the optical path measurement with Phase information in Depth domain.The specific research contents and innovations of this paper are as follows:1.Spectral-domain OCT technology and theory has been studied.The existing spatial SD-OCT system has been rebuilt and the light source module of the system has been improved.The actual transverse resolution of the system is about 3.9μm,the axial resolution is about 1.7μm,and the imaging depth is about 689.8μm.2.In order to realize the accurate construction of complex phase template,a wavenumber calibration method based on the saturated absorption characteristic spectrum lines of neodymium glass and a wavenumber calibration method based on the phase fitting of characteristic spectrum line under precise optical path difference and window constraint are proposed.Based on the above method,the absolute wavenumber distribution of each sampling point of the grating spectrometer can be calibrated accurately,and then the interference position can be accurately located and the image can be reconstructed with high quality under the conventional fast Fourier transform algorithm.3.In order to realize the rapid and accurate positioning of discrete interface,a phase detection technology in depth domain based on complex master-slave algorithm is proposed.The complex master-slave algorithm was used to reconstruct the local depth domain information rapidly,and then the subpixel offset between the depth domain sampling position and the ideal optical path difference was accurately solved by using the phase information of the depth domain peak sampling point.In the experiments,the standard deviation of optical path measurement for cover glass is about 4nm,which indicates that the proposed method has outstanding advantages in fast and accurate positioning of discrete interfaces and high local sensitivity imaging of precise surface structures.