Disk File Optical Servo System Using Doppler Shifting or Frequency Broadening of Scattered Laser Light
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
In a disk file having rotating data recording disks, the radial position of the transducer for reading or writing data onto the disk is controlled with an optical technique that determines either or both the Doppler shift or frequency broadening of a laser source whose light is reflected off the rotating disk. As shown in the figure, the rotating data recording disk 10 is illuminated by a laser 12. The laser 12 is mounted to the actuator (not shown) which moves the read/write transducer radially relative to the disk. Alternatively, the laser 12 is mounted separate from the actuator and the light is reflected through a set of focusing and reflecting optics mounted on the actuator. The laser beam passes through a beam splitter 14 and a focusing lens 16 before reaching the rotating disk 10.