Browse Prior Art Database

Circularizing/Low Profile Prism

IP.com Disclosure Number: IPCOM000036270D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Cohen, DK: AUTHOR [+3]

Abstract

In a digital optical disk file, the minimum spacing between disks, or the minimum height of a single-disk drive, is limited by, among other things, the diameter of a circularized round beam to the objective lens. A typical optical path is depicted in Fig. 1.

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Circularizing/Low Profile Prism

In a digital optical disk file, the minimum spacing between disks, or the minimum height of a single-disk drive, is limited by, among other things, the diameter of a circularized round beam to the objective lens. A typical optical path is depicted in Fig. 1.

Once passing through the circularizer, the beam (diameter of about 5 mm) is directed to the disk by a beam bender. It is desirable to keep the dimension of the device perpendicular to the disk as small as possible. The invention described here eliminates the additional component for circularization by providing this function at the beam bender. By combining the beam bender with the circularizer, the elliptical beam diameter, perpendicular to the disk surface, is reduced to about 1.5 mm. Using an elliptical beam to travel in the radial direction, and performing circularization just before the objective lens, allows a lower profile system, combining circularizing and beam bending in one element.

Fig. 2 shows the circularizing prism design, which requires only 3 polished surfaces and in which the beam experiences only one internal reflection. With this design, the overall height of the prism and thus the optical package may be reduced. This invention provides for the elimination of a separate circularizer optical component from a typical optical storage device path and a lower profile to allow higher volumetric packing density.

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