针对光学相干层析(OCT)系统中迈克尔逊干涉仪两臂色散不匹配导致纵向分辨率的降低,提出了一种基于频域干涉及非线性曲线拟合的方法对干涉仪两臂色散差进行在线测量,根据测量结果在干涉仪一臂中加入非零色散位移光纤(NZDSF)对色散差进行补偿。实验结果表明,经过色散补偿后系统的纵向分辨率与理论值相符合,离体牙齿OCT图像的质量得到了明显改善。
It is known that if the dispersion of one channel of the Michelson interferometer in the optical coherence tomography(OCT) system does not match the other,the interferogram envelope will be broadened so that the axial resolution will be decreased.The influence of unbalanced dispersion between the two channels of michelson interferometer,on the axial resolution in the OCT system is analyzed and an on-line method based on the spectral interference pattern and nonlinear curve fitting is presented to measure the dispersion difference between two channels of the interferometer.According to the measured results,a non zero dispersion shifted fiber(NZDSF) is used in one channel to compensate the dispersion of the interferometer.The experimental results indicate that the axial resolution after the dispersion compensation agrees with the theoretical value,and the quality of the OCT image of an extracted human tooth is improved significantly.