A light beam usually has a nonuniform intensity: as we travel across the beam, it is brightest at the center and dimmer toward the edges. If our little glass bead is sitting off-center, then more light is deflected away from the center than is deflected toward the center. This gives the bead a tiny kick. Light carries momentum, so when the bead bends the light, it changes the lights momentum, and that requires a force. As a result, the bead moves to the center of the light beam, where the intensities are symmetrical about the bead and the forces balance. That is optical trapping
Posted on: Mon, 20 Jan 2014 00:43:30 +0000
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