Calibration of Optical Tweezers

A highly-focused laser beam can provide an attractive force (on the order of piconewtons) capable of trapping small, dielectric objects. Optical tweezers make use of this phenomenon to manipulate and study microscopic objects, especially in biology. Much like a spring, the approximate force that the laser beam applies to an object is proportional to the object’s displacement from the center of the beam. A known trap stiffness is often required to make reliable force measurements. The purpose of the report is to test different methods that experimentally measure the trap stiffness for our optical tweezers set-up