Rotational Doppler velocimetry to probe the angular velocity of spinning microparticles
Rotational Doppler velocimetry to probe the angular velocity of spinning microparticles
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DOI：
10.1103/physreva.90.011801
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发表时间：
2014-07-01
影响因子：
2.9
通讯作者：
Gibson, G. M.
中科院分区：
文献类型：
--
作者：
Phillips, D. B.;Lee, M. P.;Gibson, G. M.
激光多普勒测速是一种用于测量线速度的技术，范围从废气到血流。激光多普勒测速仪的旋转模拟最近被证明，使用旋转对称干涉图案探测旋转物体的角速度。在这项工作中，我们演示了使用衍射限制的结构化照明图案来测量被捕获的微米级颗粒的角速度，并在几十赫兹的旋转在光阱。该技术不需要粒子形状的详细知识，也不需要粒子内散射体的分布，并且与粒子的手性、透明度和双折射无关。粒子也受到布朗运动的影响，这通过影响旋转速率和旋转轴而使信号复杂化。通过仔细考虑这些影响，我们展示了如何测量是强大的，代表一种技术，探测微尺度粒子的旋转运动。
Laser Doppler velocimetry is a technique used to measure linear velocity, ranging from that of exhaust gases to blood flow. A rotational analog of laser Doppler velocimetry was recently demonstrated, using a rotationally symmetric interference pattern to probe the angular velocity of a spinning object. In this work, we demonstrate the use of a diffraction-limited structured illumination pattern to measure the angular velocity of a micron-sized particle trapped and spinning at tens of Hz in an optical trap. The technique requires no detailed knowledge of the shape of the particle, or the distribution of scatterers within it, and is independent of the particle's chirality, transparency, and birefringence. The particle is also subjected to Brownian motion, which complicates the signal by affecting the rotation rate and the rotation axis. By careful consideration of these influences, we show how the measurement is robust to both, representing a technique with which to probe the rotational motion of microscale particles.