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Browse Prior Art Database

New Defect-Analysis Method in Optical Disk

IP.com Disclosure Number: IPCOM000115847D
Original Publication Date: 1995-Jun-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Hayashi, R: AUTHOR [+2]

Abstract

This article describes a New Defect Analysis method for Optical Media, which is consisted of Laser Scanning System, Optical Microscope system and Low magnificent and small (Numerical Aperture) (N.A) objective lens. Media defect caused by small non-uniformity of protective layer on top surface of the optical media is detected with the interference fringe observation.

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New Defect-Analysis Method in Optical Disk

      This article describes a New Defect Analysis method for Optical
Media, which is consisted of Laser Scanning System, Optical
Microscope system and Low magnificent and small (Numerical Aperture)
(N.A) objective lens.  Media defect caused by small non-uniformity of
protective layer on top surface of the optical media is detected with
the interference fringe observation.

      Fig. 1 shows one example of this method.  (A) is He-Ne Laser,
(B)Scanning element, (C) Beam Splitter, (D)CCD, (E) Optical
Microscope unit, (F) small N.A.(N.A=0.045) object lens, (G) Optical
Media.  One example of dotted line is Laser Microscope.  The
interference fringe is observed on the CRT.  Fig. 2(a) shows the
interference fringe pattern of normal area.  Non-ununiform protective
layer generates a regular interval pattern.  Fig. 2(b) shows defect
area which is ununiform area of the protective layer.  Special
pattern is observed on the interference fringe.  This kind of defect
is not found with Optical microscope nor normal Laser microscope.

This method is not limited for optical media.  It is possible to use
for LCD, glass media etc.