Browse Prior Art Database

Optical Head

IP.com Disclosure Number: IPCOM000114388D
Original Publication Date: 1994-Dec-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Hirasaka, Y: AUTHOR [+3]

Abstract

Disclosed is a scheme for realizing a low cost and compact optical head for the Magneto-Optical (MO) disk drive without the half-wave plate by mounting the laser diode at 45 degrees with respect to the polarized beam splitter. This scheme is widely applicable to any magneto-optical disk drives.

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This is the abbreviated version, containing approximately 90% of the total text.

Optical Head

      Disclosed is a scheme for realizing a low cost and compact
optical head for the Magneto-Optical (MO) disk drive without the
half-wave plate by mounting the laser diode at 45 degrees with
respect to the polarized beam splitter.  This scheme is widely
applicable to any magneto-optical disk drives.

      The Figure shows an example of this opical head for a MO disk
drive.  The disclosed scheme will be best understood with reference
to the Figure of a sample layout of the optical head.  Laser diode 1
is mounted at 45 degrees with respect to the X-axis and Y-axis.  The
laser beam out of Laser diode is collimated by Collimator lens 2,
goes through Beam splitter 3, turned by Mirror 4, and focused on the
Disk 5 by Objective lens 6.  The reflected light is recollimated by
the Objective lens 6, turned by mirror 4, and reflected into the
polarized beam splitter 7 by the beam splitter 3.  Polarized beam
splitter 7 splits the incident beam into the S component beam and P
component beam.  Each component beam is converged onto detector 8 by
condenser lenses 9.  As the polarization of the light reflected at
Disk is slightly rotated according to the data pattern due to the
Kerr effect, the outputs of two detectors become imbalanced and a
differential signal is observed between them.

      The polarization of the incident beam onto the polarized beam
splitter is rotated by 45 degrees because the laser diode is mounted
at 45 degrees.  Therefore the ha...