Abstract: A system for adjusting the spot size of an optical recording system includes a variable magnification lens assembly for adjusting the beam size while obtaining feedback of the actual beam size through an image device. The variable magnification lens assembly includes a beam expander with manual or motor-driven actuators for positioning a beam sizing lens while viewing an image of the spot. An acousto-optic modulator may be combined with the spot sizing function to reduce the number of lenses. The image device may include a charge coupled device camera connected to an image viewer or to a computer having image processing software. An operator may adjust the spot size while viewing an image of the spot, or the computer may control the beam size motors according to the measurement of the spot size.

Abstract: An improved method and apparatus for maintaining a recording head in an optical recording system at a constant linear velocity relative to a rotatable disk support. A rotation controller uses a cumulative measure of rotation to determine an angular velocity of the rotating disk support necessary to maintain a constant linear velocity.