Research On Key Technologies In 850nm Spectral Domain Optical Coherence Tomography System

Optical coherence tomography(OCT)is a high-resolution and non-destructive optical imaging technology that developed in the early 1990 s.Because of the advantanges of non-invasive,non-radiative damage,optical information diversity,the compact structure and easy combination with endoscopic techniques,OCT technology has become a research hotspot for biological tissue imaging.Due to the slow imaging speed and low signal-to-noise ratio of the first-generation OCT technology system which named the time domain OCT(TD-OCT),the spectral domain OCT(SD-OCT),which can achieve high-speed imaging based on high signal-to-noise ratio,has developed rapidly as the second-generation OCT technology,and it has played an important role in the fields of ophthalmology and biology.This paper focuses on the SD-OCT imaging system and its key technologies.The main research contents are as follows:1.The SD-OCT system which based on fiber-optic Michelson interferometer was designed and constructed in the 850 nm band.The data processing algorithm of SD-OCT system was studied,and the two-dimensional imaging of scattered samples was successfully realized.In order to improve the data processing speed,the experiment uses a Graphics Processing Unit(GPU)programming method which based on the Compute Unified Device Architecture(CUDA)to perform parallel computing on the data processing process of the SD-OCT system.The imaging speed has increased nearly20 times,laying the foundation for real-time in vivo imaging.2.A new wavelength calibration technique which based on the source spectrum of SD-OCT system has been proposed.This method need not the additionally calibration source,and it directly uses the peaks and troughs of the system light source as the characteristic wavelength to replace the characteristic line in the mercury argon lamp wavelength calibration method.Then,the one-to-one mapping of wavelengths to pixels can be done by a third-order polynomial fitting method.The calibration results were compared with those based on conventional mercury argon lamp wavelength calibration methods.The new method is applied to the actual imaging of SD-OCT system,and the system point spread function(PSF)map and rubber tube imaging map are obtained,which further validates the effectiveness of the new calibration method.3.Based on the SD-OCT system,a spectral domain phase microscopy(SDPM)system was designed and built.A spectral phase-based SDPM method is used to solve the problem of the influence of 2? ambiguity on the phase unwrapping in the image,and the phase diagram of the surface defects of the glass sample is obtained.