Laser interferometry positions disk drive heads

Increasing the storage capacity of computer disk drives means increasing the density of data tracks, which requires more accurate positioning of the drive`s read/write heads. Because heads are positioned with voice-coil-motor (VCM) actuators, specialized techniques are required to place reference positioning information on the disk surface to allow the heads to follow each track. These techniques include closed-loop feedback systems to keep the recording head centered on the data track.

ARPA-sponsored team to develo¥uncooled focal-plane-array silicon detectors