Study On Optical Coherence Tomograghy At Time Domain And Fourier Domain Systems

Optical coherence tomography (OCT) combines the advantages of confocalmicroscopy and low-coherence interferometry to produce noninvasive high-resolutioncross-sectional images of internal microstructure of living tissue. OCT demonstratesits great potential in clinic biopsy and microsurgical, where OCT images are severelyimportant. But still there are many limitations of OCT, such as limitation inpenetration, resolution, acquisition rate, image contrast, 2D digital images infacultative angle and stratum. Only when these parameters are extraordinarilysatisfactory for biopsy can it prevent catastrophic consequences and reduce iatrogenicinjury.This paper manages to set up a more completed OCT system that can satisfy theneed of clinic biopsy and microsurgical.This dissertation introduces the basic technology and the evolution of opticalcoherence tomography (OCT), analyses OCT advantages and disadvantages,investigates the effects of numerical aperture of imaging lens (NA) and time gate onthe OCT imaging.We analyse and investigate the basis theory about OCT-Huygens-Fresnelprinciple and the speckle of photons. The concepts of signal-carrying andsignal-degrading speckle are defined in terms of the phase and amplitude disturbancesof the sample beam. Four speckle-reduction methods—polarization diversity, spatialcompounding, frequency compounding and digital signal processing-are discussed .This system and principle for time domain optical coherence tomography arestudied in this paper. The structure,the characteristic of light source,the improvementof the Michelson interferometer and imaging of the theory have been adequatelydiscussed. Subsequently we studied the experiment about the TDOCT system andacquired a better result.The last part in the paper, fourier domain optical coherence tomography has beenadequately analysed. We analyse and studied The structure,imaging of the theory,thesystemic hardware about FDOCT. And tell how to pick-up information of bio-tissuefrom CCD signal. At the same time the experiment about the FDOCT has beencompleted, the result tell us that FDOCT have better effect than TDOCT.