Quantifying Noise in Optical Tweezers by Allan Variance

Much effort is put into minimizing noise in optical tweezers experiments because noise and drift can mask fundamental behaviours of, e. g., single molecule assays. Various initiatives have been taken to reduce or eliminate noise but it has been difficult to quantify their effect. We propose to use Allan variance as a simple and efficient method to quantify noise in optical tweezers setups. We apply the method to determine the optimal measurement time, frequency, and detection scheme, and quantify the effect of acoustic noise in the lab. The method can also be used on-the-fly for determining optimal parameters of running experiments. (C) 2009 Optical Society of America