Abstract
We constructed an optical tweezer system capable of trapping and manipulating micron size dielectric microspheres. Optical traps are instruments that have been used to study the mechanical properties of biological components, such as molecular motors and biopolymer networks. A trapping laser is focused on a dielectric sphere, then following Newton’s third law, an equal and opposite momentum change is imparted. The force on sphere is proportional to the light intensity. Forces involved in this interaction are the Scattering and Gradient restoring forces, and in small displacements, they show Hookean spring characteristics. Starting from basic optical components, such as lenses and mirrors, we constructed a system capable of trapping and manipulating particles with nanometer precision. We also added imaging and force measurement capabilities to our system. This setup can be used in any application involving non-invasive precision manipulation.