Simultaneous detection of rotational and translational motion in optical tweezers by measurement of backscattered intensity.We describe a simple yet powerful technique of simultaneously measuring both translational and rotational motion of mesoscopic particles in optical tweezers by measuring the backscattered intensity on a quadrant photodiode (QPD). 
optical tweezers
Simultaneous detection of rotational and translational motion in optical tweezers by measurement of backscattered intensity.We describe a simple yet powerful technique of simultaneously measuring both translational and rotational motion of mesoscopic particles in optical tweezers by measuring the backscattered intensity on a quadrant photodiode (QPD). 
quadrant photodiode (QPD)
Simultaneous detection of rotational and translational motion in optical tweezers by measurement of backscattered intensity.We describe a simple yet powerful technique of simultaneously measuring both translational and rotational motion of mesoscopic particles in optical tweezers by measuring the backscattered intensity on a quadrant photodiode (QPD). 
optical tweezers