Manipulation of objects on a microscopic scale can be done conveniently with a device known as a laser or optical tweezers. While laser trapping was originally devised for trapping Rayleigh particles (i.e. particles much less than the wavelength of the incident light) it's ability to manipulate biological particles such as macromolecules, viruses, microtubules and chromosomes offers great practical potential. In addition a laser tweezers can be used to fabricate small-scale devices such as microscale motors, pumps and switches. Many systems of interest require multiple optical traps and several methods have been developed to achieve multiple trap configurations. However currently available trapping systems can produce at most only a few independent traps. Recently, Grier and Dufresne conceived of a new solution for achieving a multi-trap system. In their method a hologram is used to alter a single laser beam's wave front. The wave front is altered so that the downstream laser beam forms a large number of individual laser beams with relative positions and directions of travel fixed by the exact nature of the hologram. The hologram can be calculated from a user specified pattern of desired trap positions. During the Phase I work we have successfully developed a commercial prototype of a holographic optical tweezers, which is capable of deploying up to 200 independent laser traps. As part of this work we have designed an easy to use laser tweezers with an imaging system, computer interface, sample chamber, and optical system. Field-testing at the Whitehead Institute and the University of Maryland has resulted in those institutions initiating purchase negotiations (the University of Maryland has purchased an instrument). In addition field-testing programs at the University of Chicago, Albert Einstein College of Medicine, and Drexel University are being negotiated. We now propose to make the holographic optical tweezers a commercial product by developing manufacturing standards for components and incorporating a greater variety of imaging modalities. We will also develop methodology to facilitate use of existing applications of laser trapping in a user friendly way.
