Study On Design And Fabrication For The Optical Coherence Tomography

The optical coherence tomography is the advancing edge and hot field of the burgeoning subject branch, Biomedical Photonics which crosses the subjects of Optics, Electronics, and Computer Science, etc. It is also the landmark to achieve the noninvasive and high resolution biomedical tomography. In order to overcome the difficulties of OCT and meet the requirements of native development of OCT, the theory, design, fabrication, alignment and data process of OCT were studied to finally improve the performance of OCT and generate our own intellectual property rights.Firstly, based on the various structure of OCT and the theory of signal interference, we analyzed the problems about axial resolution and the signal contrast generated from Doppler shift, etc. In order to conveniently design the transverse scanning system, the idea dividing the transverse scanning system into two different scanning methods, pointwise scanning and continuous scanning, was proposed. And the parameters for designing the transverse scanning system were discussed, which is important to meet the requirement of the various application of OCT. We also simulated the complicated relations about rotational speed, distance of acceleration or deceleration, screw pitch and scanning speed, etc, which supplied the results for developing a new kind of OCT.The long focal depth generalized zone plate was proposed for in place of ordinary lens in the sample arm of OCT, which can simultaneously achieve the long focal depth and high transverse resolution. It can not only maintain the transverse resolution at 24.9um within the 4mm axial range but also improve the uniformity of intensity distribution along the focal segment.We also researched for the theory of various axial scanning methods. By comparison of the merits and drawbacks of these various axial scanning methods, we proposed a new kind of axial scanning method and detailedly described its principle and error calculation. The results show that the method has the features of high speed, low nonlinear scanning and free of dispersion, which provides a useful method for axial scanning of OCT.Finally, we designed and fabricated an OCT system. The implementation of optical part and electronic part of OCT system was researched. The diffuse scattering method was proposed to decrease the difficulty of alignment. Then, we measured the axial resolution and experimented on tomographic image for some samples. The results show that the axial resolution of our fabricated OCT has reached the 17um which approaches the parameter of American product (10~20um).