摘要:
光学相干层析成像的轴向分辨率和横向分辨率是互为独立的,其轴向分辨率由系统光源带宽和探测光束的聚焦条件共同决定,而横向分辨率由系统样品臂的聚焦条件决定.提高光学相干层析成像的轴向分辨率的方法主要基于宽带光源技术以及变迹术与相干门相结合的方法,而这些方法对于横向分辨率并没有提高.提出了一种通过光程编码与相干合成的方法,可以同时提高其轴向分辨率和横向分辨率.通过在光学相干层析成像系统的样品臂中加入光程编码分束器形成多种对应不同光程延迟的有效响应函数,基于光学相干层析成像术固有的光程分辨能力可以得到同一样品对应于不同有效响应函数的多幅图像.通过数字控制不同有效响应函数的相对贡献对其进行相干合成,可以同时实现轴向和横向的超分辨效果.与以前的方法相比,光程编码与相干合成方法简单易行、成本低廉,不仅可以避免系统复杂和价格昂贵等不足,而且可以同时较大幅度地提高系统的轴向分辨率和横向分辨率.
Abstract:
Axial resolution and traverse resolution in optical coherence tomography （OCT） imaging are determined by different factors,while axial resolution is determined by both the coherence length of light source and the beam-focusing condition,and traverse resolution is determined by the beam-focusing condition of the sample arm.In the main approaches to axial resolution improvement in OCT,a light source with a broaden bandwidth is used and coherence gating is combined with apodization,which cannot improve the traverse resolution.A method is introduced to increase both the axial resolution and traverse resolution simultaneously in an OCT system by the path length code and coherent compounding method.Different effective functions are formed by adding a path length coding lens in to the proposed OCT system,which are corresponding to different path lengths.Owing to the intrinsic ability to differentiate path lengths,we can obtain several images of the same sample,corresponding to the different effective functions simultaneously.By adding these functions through numerically controlling their relative contributions,we can finally obtain a coherent compounding signal with three-dimensional superresolutions of axial resolution and traverse resolution.Compared with the previous approaches,the path length code and coherent compounding method is very easy to operate and its cost is very low,which can not only avoid the high cost and inconvenience in implantation,but also increase both axial and traverse resolutions simultaneously.
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