Wavefront reconstruction optics for use in a disk drive position measurement system

摘要

An optical measurement system for use in a data recording disk drive includes wavefront reconstruction optics which correct and compensate for aberrations in laser beams reflected from radial and linear diffraction gratings. The reconstruction optics include two spherical lenses and two reflectors, one of each positioned on each side of a diffraction grating. Light directed from a laser beam toward the grating diffracts into a +1 order component directed at the first set of reconstruction optics and into a -1 order component directed at the second set of reconstruction optics. The reconstruction optics compensate for the variable yaw angle caused by a linear grating and for the optical wavefront aberrations caused by a radial grating. Use of the reconstruction optics permits an optical measurement system in a data recording disk drive to accurately measure the position of either a linear or rotary actuator and to generate a precise reference clock for use in timing the recording of servo information to the data recording disk.