MEASUREMENT OF SMALL FORCES USING AN OPTICAL TRAP
MEASUREMENT OF SMALL FORCES USING AN OPTICAL TRAP
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DOI：
10.1063/1.1144613
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发表时间：
1994-09-01
影响因子：
1.6
通讯作者：
WEBB, WW
中科院分区：
文献类型：
--
作者：
GHISLAIN, LP;SWITZ, NA;WEBB, WW
一种用于检测施加到光学捕获的微球体上的小的力的简单且灵敏的方法利用捕获激光器的透射光束来监测阱的势阱内的微球体偏转。在1 Hz至10 kHz的频率范围内测得的rms动态位移检测灵敏度在径向方向上类似于1 nm，在z（光学）轴上类似于沿着10 nm。在瑞利（r < 0.2 λ）和米氏（r远大于λ）尺寸范围之间的范围内，针对微球上的粘性阻力校准辐射捕获力常数。对于一个1 μ m直径的聚苯乙烯球，用60 mW的光束捕获，均方根自发热运动限制力的灵敏度优于10（-12）N和横向空间分辨率为10 nm的频率范围内，从1 Hz到粘性滚降频率类似于1 kHz。测量的最大捕获效率进行比较的射线光学近似的理论预测。
A simple and sensitive method for detecting small forces applied to an optically trapped microsphere utilizes the transmitted beam of the trapping laser to monitor microsphere deflections within the potential well of the trap. The rms dynamic displacement detection sensitivity measured in the frequency range from 1 Hz to 10 kHz is similar to 1 nm in the radial direction and similar to 10 nm along the z (optic) axis. Radiation trapping force constants were calibrated against viscous drag on microspheres in the range between the Rayleigh (r < 0.2 lambda) and Mie (r much greater than lambda) size regimes. For a 1-mu m-diam polystyrene sphere trapped with a 60 mW beam the rms spontaneous thermal motion limits the force sensitivity to better than 10(-12) N and lateral spatial resolution to similar to 10 nm in a frequency range from 1 Hz to the viscous rolloff frequency similar to 1 kHz. The measured maximum trapping efficiencies are compared with the theoretical predictions of the ray-optics approximation.