Comparison of a high-speed camera and a quadrant detector for measuring displacements in optical tweezers

We compare the performance of a high-speed camera and a quadrant detector for measuring the displacement of micron-sized particles in optical tweezers. For trapping powers up to 100 mW, the standard deviation of the particle displacements measured by the two techniques shows excellent agreement. This comparison also provides a method for calibrating one technique against the other.