Study On Optical Coherence Tomography System

Optical coherence tomography(OCT) is a new technology distinguished from the other tomographic imaging techniques,and possesses features of fast,real-time, non-destructive and high-resolution,etc.By means of low-coherence interferometry,OCT filters,amplifies and demodulates the interference light signals which carries the information of biological samples,and then makes the reconstructed tomographic images, and has a wide range of applications and development in the biomedicine and materials sciences.A study on a fiber-based optical coherence tomography system is carried out comprehensively and thoroughly in this thesis.Based on the basic principles of OCT,the system configuration technology was analyzed in detail,and the corresponding experimental research and numerical calculation were conducted.In particular,by introducing the relevant micro-lenses in the proper places of the reference arm and the signal arm of the system respectively,the abilities for gathering the signal light were enhanced significantly,the system signal to noise ratios and the lateral resolution were improved.Secondly,on the basis of the above-mentioned study,the relevant optical components and the matched parameters were selected,the reference and signal arm of the OCT system were constructed and debugged,and the complete OCT system,thereafter,was assembled. The OCT system was debugged roundly and systematically,the experimental skills for seeking out the optimal match point between the reference and signal arm were obtained, the experiments for the standard and biological sample scanning were conducted.The scan depth of the OCT system has been calibrated primarily with the standard samples,the axial and lateral resolutions of the system were determined experimentally.The longitudinal resolution reaches 77μm,while the lateral resolution can be adjusted flexibly according to the examination requirements of the samples to be tested.Finally,the influence factors on the axial resolution of OCT system were analyzed, then the pupil filter has been suggested to be used to improve the longitudnal resolution based on the concept of the super-resolution.A pupil filter has been designed for removing the impact of sidelobe in the coherent signals,and then the axial resolution of the system has been improved considerably in theory.