Research On Key Technologies Of Spectral Optical Coherence Tomography Imaging System

Optical coherence tomography(Optical Coherence Tomography,OCT)is based on the principle of low coherence interference,which can detect the backscattered light of the internal structure of the sample for tomography.It has the characteristics of noninvasive,high-resolution,fast imaging speed and easy to combine with other technologies such as endoscope.It is suitable for non-destructive testing of biological tissue,ancient Chinese calligraphy and painting,industry and other fields.The main research object of this paper is spectral domain OCT.Aiming at the problems of phase instability and imaging speed limitation caused by mechanical scanning in traditional spectral domain OCT system,a set of spectral domain OCT system using cylindrical mirror to generate line focused illumination is designed and developed.The two-dimensional cross-section of the sample can be quickly imaged without any mechanical scanning The work is as follows:1.By comparing and analyzing the existing OCT system structure,the imaging principle of the line focusing spectral domain OCT system is deeply studied.Several main performance parameters of the line focusing spectral domain OCT system are analyzed,as well as the factors affecting the system performance and imaging quality.2.The spectral OCT system of line-focused lighting is designed and built,and the optical path structure of the system is modeled and simulated.Using the sequence mode of ZEMAX to simulate and analyze the lateral parallel detection range of the system and the imaging quality of the sample imaging through the optical path of the system.Using the non-sequence of ZEMAX mode to simulate the whole system.Through the simulation and analysis of the interference performance of the system and the detection of the interference spectrum,the feasibility of the designed system is illustrated,and the basis for the experiment is provided.Finally,we build the system through the plane mirror.3.The interference signal model of imaging spectrum is established,and the data processing process of the optimized system is analyzed.The methods of data optimization are described in detail from three aspects: noise removal,spectral resampling and spectral shaping.The data images before and after processing are compared and analyzed.Based on the GUI interface design of MATLAB software,the software modules of the system are developed,including camera control,interference image acquisition,data processing and image reconstruction.4.Based on the built-up line focused spectral OCT imaging system,the mirror surface is imaged and optimized.Through the peak value and half height width analysis of point spread function(PSF),the axial resolution of the system is 11.72 μ m,the imaging depth of line illumination center is 1 mm,the parallel transverse detection range is 8 mm.Finally,a tomogram of the sample of the coin is obtained.