Research On High-resolution Spectral Domain Optical Coherence Tomography System

Optical Coherence Tomography(OCT)is a technique that uses the principle of optical low-coherence interference to image the internal structure of tissues.OCT technology has been successfully applied in the fields of biology and medicine by virtue of its high resolution,in-vivo,non-destructive and high-sensitivity characteristics.It is still a research focus in these fields.Depth resolution and imaging speed are two important indicators of the OCT imaging system and have an important impact on the application of OCT.The improvement of depth resolution means that more information can be obtained from the image,and the improvement of imaging speed can further expand the application range of OCT.The depth resolution mainly depends on the optical system design,and the imaging speed is not only limited by the hardware speed,but also by the image reconstruction speed.The work of this thesis mainly includes the design and construction of high-resolution spectral domain OCT(SD-OCT)imaging system and GPU acceleration research of image reconstruction.The main research contents are as follows:1.A fiber-optic high-resolution SD-OCT imaging system based on Michelson interferometer was designed and built.The specific work includes the selection and design of the light source module,interferometer module and spectrometer module in the system.At the same time,real-time display software for system control,signal acquisition and image reconstruction was developed based on LabVIEW platform and Visual Studio platform.The SD-OCT system developed in this thesis has a center wavelength of 850 nm,a bandwidth of 165nm,an axial resolution of the system of 2.8?m,and a maximum imaging depth of about 1.7mm in air.2.Design and build the core module of the SD-OCT system--spectrometer.In this thesis,a broadband spectrometer is designed based on the transmission holographic grating,and the mechanical structure design and processing of the spectrometer are completed to make the spectrometer structure more compact and stable.After the calibration of the mercury argon lamp light source,the detection spectrum width of the spectrometer is about 211nm,which matches the selected light source,and the spectral resolution is about 0.1nm.3.Research on GPU(Graphics Processing Unit)acceleration of OCT image reconstruction.In order to improve the data processing speed,the GPU parallel computing technology based on the Compute Unified Device Architecture(CUDA)is applied to the system data processing module,and the CPU(Central Processing Unit)and GPU are used in parallel processing instead of the CPU's serial processing.In order to verify the accuracy and operation speed of the developed software system,this thesis will conduct multiple sets of experiments on the collected interference data on MATLAB,CPU and GPU.The experimental results show that when the data size is 2048×4096,the spectral domain OCT software system developed in this thesis can achieve 23.1 times acceleration,which provides the possibility of real-time 3D imaging.