  Dynamical instrument limitations, such as finite detection bandwidth, do not
simply add statistical errors to fluctuation measurements, but can create
significant systematic biases that affect the measurement of steady-state
properties. Such effects must be considered when calibrating ultra-sensitive
force probes by analyzing the observed Brownian fluctuations. In this article,
we present a novel method for extracting the true spring constant and diffusion
coefficient of a harmonically confined Brownian particle that extends the
standard equipartition and power spectrum techniques to account for video-image
motion blur. These results are confirmed both numerically with a Brownian
dynamics simulation, and experimentally with laser optical tweezers.
