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Magneto-Optic Beam Splitter

IP.com Disclosure Number: IPCOM000036439D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Budd, RA: AUTHOR

Abstract

A new prism geometry allows the use of a single detector unit to detect the reflected, data-containing beam received from a magneto-optic storage medium.

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Magneto-Optic Beam Splitter

A new prism geometry allows the use of a single detector unit to detect the reflected, data-containing beam received from a magneto-optic storage medium.

Fig. 1 illustrates a first embodiment. One-half of a polarizing beam-splitting cube 10 is mated with a wedged-shape piece of glass 11. The outer surface of this wedge may be coated with a reflector or left uncoated. Playback beam 12 passes through an optional phase plate 13 and enters the beam splitter. The S polarized light is reflected from surface 1 of the beam splitter, the P polarized light is transmitted through this surface. The P polarized light then reflects from surface 2, passes again through surface 1, and exits the prism. Since surface 2 is at an angle (theta) with respect to surface 1, the two exiting beams 14 and 15 are at an angle of 2x theta to each other; therefore, the S and P polarizations are angularly separated.

(Image Omitted)

These two beams are now focussed through lens 16 toward detector 17. This detector has two active areas 18 and 19 separated by a gap 20. A preamp and a difference circuit is packaged inside this detector package. Therefore, the playback signal is obtained directly from the single detector.

Fig. 2 illustrates a second embodiment. Beam splitter 30 consists of two pieces 31 and 32 of bi-refringent quartz. Their optical axes are oriented as shown. Playback beam 33 passes through optional phase plate 34 and enters the beam splitter. The S polar...