Scientific research of microscale objects could advance significantly thanks to a combination of optical tweezers and holograms developed by University of Chicago physicist David Grier. Optical tweezers invented by Bell Laboratories researchers 17 years ago can trap and move tiny particles in defiance of gravity through the manipulation of a laser beam's optical intensity, but only one or two tweezers can be created at a time within a given microenvironment. Grier sought a solution to this dilemma, which was holding up his research into colloidal behavior; then in 1997 his student Eric Dufresne discovered a commercially available hologram that refracted a single laser into16 smaller beams, which could theoretically snare 16 particles at once by focusing them through the lens of a microscope. Grier and Dufresne employed such a hologram, even though it was designed to work with red light, whereas the optical tweezers were generated with green light to prevent heat damage to the cell samples. A key element of the methodology the researchers arrived at is a spatial light modulator (SLM), which responds to an electric field by thickening its pixels rather than changing their color; laser light undergoes a subtle phase shift as it passes through the beefed-up pixel, and this effect enabled Grier and Dufresne to create the required interference to produce multiple tweezers, which are easy to manipulate because the holograms are computer-generated. The computer algorithms used to create the holograms were the product of several years' work, and the ultimate technique, which combines a computer, an SLM, and some optics, can yield as many as 200 tweezers at once. A microscope-compatible device containing all the optics is made by Arryx, a company Grier started. Holographic optical tweezers are being looked into as a control mechanism for micromachines, and Grier believes his method will help expedite the sculpting of micromachines as well.