This site describes a force-measuring optical trap called "miniTweezers". It provides a complete mechanical design for the instrument, suitable for construction in a university shop by machinists and electronic technicians.
Optical traps (also called “laser tweezers”) use focused laser beams to capture and move microscopic refracting objects. Optical tweezers can be used as quantitative tools to exert calibrated forces on systems of interest and to measure the forces and displacements generated by these systems.
The miniTweezers is a compact and cost-effective analytical optical trap capable of picoNewton, sub-nanometer, millisecond resolution. It is designed to be built in a university shop using the information given in this web site.