Abstract: Integrated circuit mask patterns are laser machined by mounting substrates on a support that is periodically stepped in a y direction after each scan by a laser writing beam in an x direction. X-direction scanning is accomplished by mounting a mirror on a carriage that reciprocates by rebounding between two displaced coil springs. A coding laser beam is reflected from the carriage through a stationary code plate, comprising alternate transparent and opaque stripes, to monitor the position of the carriage and to control the modulation of the writing beam.

Abstract: A table is reciprocated along a straight line by a force that does not precisely control movement direction. Accurate motion constraint is provided by two separated air bearings arranged along a common axis. A third air bearing, displaced from the common axis, supports the table on a sleeve that is free to rotate on its axis.