Xie Zhixing, Wang Lihong V, Zhang Hao F
Department of Electrical Engineering and Computer Science, The University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA.
Appl Opt. 2009 Jun 10;48(17):3204-11. doi: 10.1364/ao.48.003204.
We have modified the existing convolution method of the Monte Carlo simulation for finite photon beams with both translational and rotational invariance. The modified convolution method was applied to simulate the optical fluence distribution in tissue in dark-field confocal photoacoustic microscopy. We studied the influence of the size of the dark field and the illumination incident angle on the depth position of the effective optical focus (the region with the highest fluence) and the fluence ratio (the ratio of the optical fluence at the effective optical focus inside the tissue to the optical fluence on the tissue surface along the ultrasonic axis). Within the reach of diffuse photons, the depth position of the effective optical focus increases with the size of the dark field and is much less sensitive to the incident angle. The findings show that, while the fluence at the effective optical focus decreases, the fluence ratio increases with the size of the dark field. The incident angle has a weaker influence on the fluence ratio than the size of the dark field does. An incident angle between 30 and 50 degrees gives the highest fluence at the effective optical focus.
我们对现有的蒙特卡罗模拟卷积方法进行了改进，使其适用于具有平移和旋转不变性的有限光子束。改进后的卷积方法被用于模拟暗场共焦光声显微镜中组织内的光通量分布。我们研究了暗场大小和照明入射角对有效光学焦点（光通量最高的区域）的深度位置以及光通量比（组织内有效光学焦点处的光通量与沿超声轴的组织表面光通量之比）的影响。在漫射光子可达的范围内，有效光学焦点的深度位置随暗场大小增加，且对入射角的敏感度低得多。研究结果表明，虽然有效光学焦点处的光通量降低，但光通量比随暗场大小增加。入射角对光通量比的影响比对暗场大小的影响弱。30至50度之间的入射角在有效光学焦点处产生的光通量最高。
