Shortly after the invention of the laser, Bell Labs physicist Arthur Ashkin began exploring the range of the new devices. Could the force of light in the beam move an object, much as a finger pushes a ball, he wondered? If they did, it would confirm an old theory that had intrigued him since his college days during WWII.1 "It was known a laser could push [a particle], the question was, could you observe it," Ashkin recalls. But he discovered something else, as well: "I discovered when I did that, that there were forces that were pulling the particles into the high-intensity regions of the beam."
Thus was born the concept of "optical trapping," or "optical tweezers" – systems of lasers and optics that can hold micrometer-scale objects steady against Brownian motion. Experiments done with such systems would win several physicists the Nobel Prize, but they were of little use ...
