Ahlawat Sunita, Verma Ravi Shanker, Dasgupta Raktim, Gupta Pradeep Kumar
Laser Biomedical Applications and Instrumentation Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, India.
Appl Opt. 2011 May 1;50(13):1933-40. doi: 10.1364/AO.50.001933.
We report the use of an aspheric holographic optical element (axilens) that essentially combines the properties of the long focal depth of an axicon and the high energy concentration of a conventional spherical lens for long-distance guiding of microscopic objects. With the use of the axilens, polystyrene spheres (~6 μm diameter) could be transported over a distance of ~16 mm that was ~3 times longer compared with that obtained using a spherical lens of focal length identical to the mean focal length of the axilens. Further, due to the availability of good on-axis power density, even objects having very marginally higher refractive index than the medium (differing only at third decimal place) could be guided with a guiding speed of ~5 μm/s.
我们报告了一种非球面全息光学元件（轴透镜）的应用，它本质上结合了轴棱锥的长焦深特性和传统球面透镜的高能量集中度，用于微观物体的远距离引导。使用轴透镜时，直径约6μm的聚苯乙烯球体能够被传输约16mm的距离，这比使用焦距与轴透镜平均焦距相同的球面透镜所获得的传输距离长约3倍。此外，由于具有良好的轴上功率密度，即使是折射率仅比介质略高（仅在千分位上有差异）的物体也能够以约5μm/s的引导速度被引导。
