Research On Spectral Domain Optical Coherence Tomography System Based On Linear Wavenumber Spectrometer

Optical coherence tomography(OCT)is a non-invasive,high-resolution,radiation-free biomedical imaging technique.As the second generation of OCT technology,Spectral domain OCT(SDOCT)is superior to the first generation of time-domain OCT technology in imaging speed and sensitivity.Firstly,the basic principles of SDOCT technology and some important performance parameters is introduced.Compared to traditional spectrometer,spectral domain optical coherence tomography based on a linear wavenumber(k)spectrometer does not need resampling or interpolation of the nonlinear k interference spectral data,which greatly reduces the cost of computation and improves the imaging sensitivity.The SDOCT system based on linear wavenumber spectrometer was built.Then a novel optimization method of linear wavenumber spectrometer based on numerical simulation is proposed.We take the reciprocal of the full width half maximum of the simulated point spread function as the evaluating criteria to optimize the structure parameters of the linear wavenumber spectrometer,including the refractive index and the vertex angle of the dispersive prism and the rotation angle between the diffraction grating and the dispersive prism.According to the optimization,an F2 equilateral dispersive prism is used to construct the optimized linear wavenumber spectrometer with the rotation angle of 21.8 degree.The constructed linear wavenumber spectrometer is employed in a developed SDOCT system as the detection unit.The experimentally measured axial resolution of the SDOCT system based on the linear wavenumber spectrometer is 8.52 ?m,and the sensitivity is measured to be 91 dB with-6 dB roll-off within the depth range of 1.2 mm.Utilizing the general parallel computing capability of a GPU card,the high quality OCT images of the human finger skin can be reconstructed in real time without any process of resampling or interpolation.Finally,functional imaging studies is performed using a high-resolution SDOCT system based on a linear wavenumber spectrometer.The OCT-based angiography technique is introduced.A complex variance algorithm is proposed for angiography.