Browse Prior Art Database

Magneto Optical Read Out System

IP.com Disclosure Number: IPCOM000075983D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Albert, PA: AUTHOR [+3]

Abstract

The read-out system for a recorded magnetic medium 10, such as a disk or tape, includes a magnetic thin film 12 having an AC or DC bias magnetic field, indicated at 14, directed perpendicular to the film's easy axis, for increasing the speed of magnetic flux reversal in film 12. In Fig. 1, only an edge view of medium 10 and film 12 is shown, the major flat surfaces of medium 10 and film 12 are perpendicular to the sheet of the drawing and parallel to each other.

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Magneto Optical Read Out System

The read-out system for a recorded magnetic medium 10, such as a disk or tape, includes a magnetic thin film 12 having an AC or DC bias magnetic field, indicated at 14, directed perpendicular to the film's easy axis, for increasing the speed of magnetic flux reversal in film 12. In Fig. 1, only an edge view of medium 10 and film 12 is shown, the major flat surfaces of medium 10 and film 12 are perpendicular to the sheet of the drawing and parallel to each other.

In operation, polarized light, created by light source 16 and polarizer 18 and passed through condensing lens 20 and prism 22, is focused on and deflected by film 12 which is located in the proximity of medium 10. The deflected light is passed through prism 22, objective lens 24 and analyzer 26 before it is intercepted by photodetector 28. The intensity of the light received by detector 28 is determined by the state of magnetization of film 12, as influenced by the stored information in magnetic medium 10.

By applying the hard axis bias field 14, e. g., of magnitude F, to film 12, the switching of film 12 is accomplished by fast rotation of magnetization whether the easy axis signal is of magnitude Hs1 or Hs2, as indicated at points A and B, respectively, lying outside of the switching asteroid shown in Fig. 2. Without this bias field, the magnetization in film 12 would be switched either by slow domain wall motion or incompletely.

Bias field 14 may be applied to film 12 by...