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Browse Prior Art Database

Fiber Optics Scanner

IP.com Disclosure Number: IPCOM000086971D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 38K

Publishing Venue

IBM

Related People

Cocke, J: AUTHOR [+3]

Abstract

The rotating fiber-optics scanner (Fig. 1) has n fibers (e.g., 18) cast in a plastic disk with the ends of the fibers held on the circumference with equal spacing between fibers, and the other end closely packed in a ring near the center shaft of the disk with fibers pointing normal to the disk. A light beam (or an array of light beams) is coupled through a lens to one of the fibers. As the fiber disk rotates, the output from the fiber scans over a section of the circumference, which can be imaged to form a scanning line by an optical system. The n-fibers disk operates similarly to the n-facets rotating mirrors and increases the scanning speed.

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Fiber Optics Scanner

The rotating fiber-optics scanner (Fig. 1) has n fibers (e.g., 18) cast in a plastic disk with the ends of the fibers held on the circumference with equal spacing between fibers, and the other end closely packed in a ring near the center shaft of the disk with fibers pointing normal to the disk. A light beam (or an array of light beams) is coupled through a lens to one of the fibers. As the fiber disk rotates, the output from the fiber scans over a section of the circumference, which can be imaged to form a scanning line by an optical system. The n-fibers disk operates similarly to the n-facets rotating mirrors and increases the scanning speed.

The resolution of the fiber-optics scanner is determined by the following relation, N = F 2 Pi R over nd where F is the fraction of the on time for the light coupling to one fiber as it rotates. In principle F can be designed to be close to one. R is the radius of the disk; d is the diameter of the fiber core; and n is the number of fibers. To increase N, d has to be small and R large. For example, if N = 2400, F = 1, n = 18 and d = 1 mil. We have R = 6,875" for 2400 perfectly resolved spots. For other criteria, the radius can be reduced proportionally.

The NA and d of the output ends of the fibers are limited by the complexity of the output lens to image the output spots on the medium (a photoconductor film, ribbon or a liquid crystal cell). In the foregoing example, the field of the image lens is 2.4". This will limit the output fibers to be low NA fibers.

The NA and diameter of the input fiber ends and the nature of light source determine the coupling efficiency, the fraction of on-time F, the tolerance of the alignment, and the stability required in the rotating disk.

If the input beam is collimated (as from a He-Ne laser), one possib...