Low-Profile Prism for Optical Disk File
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-29
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 round beam to the objective lens. Using an elliptical beam to travel in the radial direction, and performing circularization just before the objective lens, allows a lower profile system. Circularizing of the elliptical beam and beam bending can be combined in one lens element. As shown in the Figure, the prism requires only three polished surfaces and the beam experiences only one internal reflection.