Design of a simple, low-cost, computer-controlled, dual-beam optical tweezer system

We present the design of a simple optical tweezer system. Our system modifies a simple compound microscope to provide one stationary and one steerable trap. Vertical integration of the optical components results in a device with a small footprint that is both compact and portable. Motorized mounting systems are constructed to achieve precise trap motion in three dimensions. Control and image acquisition are performed via an intuitive computer interface. Common and readily obtainable components were incorporated into the apparatus to reduce cost and complexity. The system was used to successfully trap and manipulate yeast cells, and by tuning the laser power, trapping can easily be extended to a wide range of biological and dielectric samples.