Precision table control system using friction drive for optical disk mastering machine

The purpose of this paper is to present a design outline and describe the characteristics of the table control system of a high density optical disk mastering machine. The table control system consists of a friction drive, a double guide air-pressurized slider, a laser interferometer and a controller. Friction drive makes it possible to position the table with 10 nm accuracy over 200 mm travel. The laser interferometer system is designed to measure the position of an optical head, exposure point, using the special laser optics configuration with two reflectors, between which the optical head is located. The table is positioned with a standard deviation of 2.9 nm (a) in a ramp command of 10 μm/s and the steady-state error and the settling time are better than 10 nm and 0.15 second, respectively, in 1 μm step response. The mastering machine has made pits and grooves with a track pitch of 0.65 μm and a pit width of 0.3 μm.