Dissertation
Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Photonics technology,laser technology > Laser technology, the maser > Laser

Study on Optical Source and System of Optical Coherence Tomography

Author GuoYiPing
Tutor WangZhaoYing
School Tianjin University
Course Physical Electronics
Keywords Nonlinear polarization rotation Passively mode-locked Fiber laser Ultrashort pulse Supercontinuum Optical coherence tomography
CLC TN248
Type Master's thesis
Year 2009
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Optical coherence tomography (OCT) technology enables real-time, high-resolution tomographic imaging of living tissue, internal organs of living tissue physiological, pathological changes in the process for accurate analysis and diagnosis, its research and development for the biomedical field provide a new important diagnostic tool. This thesis focuses on the core components of the OCT hardware systems OCT light source and system itself, combined with the existing conditions of the following work: First, the nonlinear polarization rotation (NPR) passively mode-locked fiber laser (PMLFL) numerical simulation and experimental study The theoretical analysis of passively mode-locked fiber laser cavity parameters of the output pulse characteristics. On NPR passively mode-locked fiber laser numerical simulation analysis, an effective method to avoid the multi-pulse phenomenon is proposed and analyzed. 3, in annular chamber PMLFL, utilization sideband spectral measurement method of total dispersion of the cavity length to achieve dispersion matching by changing the cavity ordinary single-mode fiber (SMF), the repeat frequency of 25MHz the pulse width 520.5fs, center wavelength 1558.4nm 3dB bandwidth of 29.5nm ultrashort pulse, the output power 1.81mW. Achieve in σ-shaped PMLFL, pulse width 670.5fs, repetition frequency of 6,2 MHz, the center wavelength 1562.3nm stable mode-locked output, the output power of 1.5mW, and packaged into a laboratory prototype. Second, the optical fiber generated supercontinuum numerical simulation and experimental study of by numerical analysis of the factors affecting the continuous spectrum characteristics from various nonlinear effects of the fiber fiber parameters and pump pulse parameters. The different fiber as a nonlinear medium supercontinuum generation, the experimental results were analyzed and compared. 3 different kinds of fiber matching connection supercontinuum generation, the comparison spectral characteristics obtained the maximum extent of the first paragraph is pumped fiber dispersion and nonlinear characteristics affect the spectral quality of the conclusions in a highly nonlinear fiber ( HNLF) access dispersion-shifted fiber (DSF) or SMF to balance the average power of the spectrum, spectral width and flatness performance indicators, in order to be applied to the related fields. Organisms detection window in the pump 120m HNLF 4.57km DSF 2.04km SMF 1300nm 3dB spectral width of the broadband spectrum of 140.6nm. The light source as the light source of the optical coherence tomography system, in theory, can be lt; vertical resolution of 4.1μm. Third, the experimental study of the frequency-domain OCT system. Discussed the first-order Born approximation Fourier diffraction tomography theorem and frequency domain OCT measurement principle. 2 according to the basic principle of the frequency-domain OCT, build from the set of frequency domain OCT system. The coverslip stacked on a plane mirror and three detection, thereby obtaining the depth information of the detection point on the detected interference signal processing, the discovery system vertical resolution of 16.4μm or higher can be achieved.

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