Planar surface scanning system

A scanner system comprising

• structure defining a radiation beam path,
• deflector means in the beam path for deflecting a radiation beam to effect major scanning on a surface to be scanned,
• an image forming optical system in said beam path including a focusing component and a compensating optical component, said compensating optical component being mounted for movement along said beam path,
• and support means allowing sinusoidal reciprocating movement of said compensating optical component in synchronism with the motion of said deflector means to shift the focal point of the beam along said surface to be scanned while maintaining the substantial focus of the beam on that surface.

A method of scanning a planar surface comprising

• deflecting a portion of an optical path by angular motion of a scanning element,
• aligning an optical element with stationary portions of said optical path,
• driving said optical element in rectilinear sinusoidal motion, and
• causing the sinusoidal motion and the motion of the scanner to be interdependent in frequency and phase.

A surface-scanning system defining an optical path for scanning a planar surface, and comprising

• an angularly moving scanner for deflecting a portion of said path back and forth through a central location on said planar surface,
• an optical element aligned with stationary portions of said optical path and driven in rectilinear sinusoidal motion for providing focus correction as said surface is scanned,
• means for causing said sinusoidal motion and motion of said scanner to be interdependent, with the maximum positive excursion of said optical element in one direction occurring at a time when said scanner is deflecting said path to said central location, and
• means for reading or writing on said surface only at times during which said optical element is not at its maximum negative excursion.