Based on the theory of dispersion characteristics of double-ring photoelectric oscillator and chirped grating, a broadband ultra-low phase noise spectral frequency shift system is constructed. Firstly, the mathematical model is discussed. Secondly, according to the frequency response of the photonic filter formed by the chirped grating interfering with the optoelectronic oscillation circuit, the simulation of the effect of grating dispersion on oscillation frequency is performed. The simulation results show that the oscillation frequency decreases with the increase of grating dispersion value. In the range of 350—4 000 ps/nm, the oscillation frequency varies from 5 GHz to 16.9 GHz, and the phase noise can reach-140.5 dBc/Hz at 10 kHz, which realizes the generation of ultra-low phase noise spectral shift with broadband tuning.
提出一种基于扫频光学相干层析术(SSOCT)的重建人体皮下微血管三维结构的新算法。该方法利用搭建的手持式人体皮肤微血管扫频光学相干层析系统,采用多帧B扫描对数强度血流图像微分标准偏差计算,获取人体皮肤在体截面图像和微血管正面图(en face image)。实验结果证明,与现有的对数强度微分标准偏差算法(DSDLI)相比,本文算法能够更好地恢复出血流图像信息,在重建图像中可以明显看到原算法的处理结果中看不出的血流细节,更有利于光学相干层析术(OCT)系统在癌症、糖尿病、酒色斑等疾病在医学诊断方面的现实应用。
