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Browse Prior Art Database

Integrated Head for Optical Storage

IP.com Disclosure Number: IPCOM000107600D
Original Publication Date: 1992-Mar-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Lean, EG: AUTHOR

Abstract

In a conventional optical storage head, the collimated incident polarized beam (with a diameter D) is bent 45 degrees by a 90-degree mirror and is focused onto the MO medium by a high NA objective lens. A partially polarized beam splitter (PPBS) is used to couple out from the MO disk the reflected MO signals and servo signals. The optical beam is coupled through the air and the beam diameter must be large enough for alignment and vibration tolerances. This makes the conventional optical head bulky, tall in profile (> 2D in height), and critical in alignment for all the optical elements. In an ideal integrated optical head all optical elements would have plane surfaces for easy alignment.

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Integrated Head for Optical Storage

       In a conventional optical storage head, the collimated
incident polarized beam (with a diameter D) is bent 45 degrees by a
90-degree mirror and is focused onto the MO medium by a high NA
objective lens.  A partially polarized beam splitter (PPBS) is used
to couple out from the MO disk the reflected MO signals and servo
signals.  The optical beam is coupled through the air and the beam
diameter must be large enough for alignment and vibration tolerances.
This makes the conventional optical head bulky, tall in profile (> 2D
in height), and critical in alignment for all the optical elements.
In an ideal integrated optical head all optical elements would have
plane surfaces for easy alignment.  Further, if the integrated
elements of the integrated head can be mounted together without
coupling  through the air, the head can be made rugged, small, and
low cost.

      Disclosed is an arrangement for combining paraboloidal
reflectors to form an integrated head for optical storage. As shown
in the figure, the integrated head consists of a partial polarization
beam splitter sandwiched between a paraboloidal reflector focusing
element and a paraboloidal collimator and circularizer.  The
paraboloidal collimator is rotated 90 degrees with respect to the
paraboloidal reflector (the base of the collimator is in the xz plane
while the base of the focusing reflector is in the xy plane).  The
partial polarizing splitter is also rotated 90 degrees with respect
to the interface surface parallel to the z-axis.  The incident light
is polarized along the x-axis.  The incident light can be from a GaAs
laser or a single-mode fiber butted against the base of the
c...