Browse Prior Art Database

Reflectivity And Domain Size Mapping of Optical Storage Disks

IP.com Disclosure Number: IPCOM000121188D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 1 page(s) / 39K

Publishing Venue

IBM

Related People

Marinero, E: AUTHOR [+6]

Abstract

A method is disclosed to directly measure the absolute energy absorbed by the multilayer structure which can be incorporated into the fabrication process to produce MO disk for high performance applications.

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Reflectivity And Domain Size Mapping of Optical Storage Disks

      A method is disclosed to directly measure the absolute energy
absorbed by the multilayer structure which can be incorporated into
the fabrication process to produce MO disk for high performance
applications.

      To rapidly monitor the absolute absorption across the entire
surface of the disk, an apparatus consisting of a GaAs laser, a 0.55
NA focussing lens and an integrating sphere equipped with a
photodiode as the detection channel has been constructed.  The sphere
allows all outgoing radiation to be detected even from grooved disks
which diffract light at large angles.  The focussing optics are
chosen such that the angles of incidence simulate those present in an
actual optical storage drive head.  The current spatial resolution of
1 mm can be readily extended by altering the focussing optics, and
reflectivity variations as small as 0.05% can be reliably measured.

      This capability can be applied to investigate the source of
domain size variations across optical storage disk surfaces.  The
apparatus can be used to measure, for example, reflectivity
variations originating from thickness variations in the dielectric
layer which, in turn, impact the amount of laser power absorbed.  A
linear correlation was established between the power absorbed by the
media and the domain size distribution.

      Disclosed anonymously.