Optical waveguides – With optical coupler – Input/output coupler
Reexamination Certificate
1999-01-29
2001-03-27
Phan, James (Department: 2872)
Optical waveguides
With optical coupler
Input/output coupler
C385S047000, C385S901000, C362S554000
Reexamination Certificate
active
06208782
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to optical lightguide illumination systems, and more particularly to optical lightguide illumination systems employing improved and more efficient technology for capturing light from an extended source and coupling that light into a plurality of lightguides.
BACKGROUND OF THE INVENTION
In optical lightguide illumination systems, such as fiber optic lighting applications, it is often desirable to couple light from an illumination source (typically a single lamp) into a plurality of lightguides, such as optical fibers. This generally increases the coupling efficiency, and prevents damage to the optical fiber by reducing the optical power coupled into any one fiber.
Lamps, particularly high intensity white light sources, are considered to be extended sources (as opposed to point sources), because they have a finite illuminating element, e.g. 1×4 mm. In addition, lamps radiate in all directions (although generally not uniformly). Energy cannot be efficiently coupled into any individual fiber because fiber cross-sectional areas and fiber numerical apertures are generally small than those of a lamp.
SUMMARY OF THE INVENTION
The present invention resolves the difficulties discussed supra, by providing a segmented reflector that efficiently couples energy from a lamp into a plurality of optical fibers. A segmented reflector offers the ability to improve the coupling efficiency by utilizing the cross-sectional area and numerical aperture of more than one optical fiber at the output of a reflector. Also this reduces the energy collected by a single fiber, and can be useful in preventing damage created by the source intensity.
More particularly, in one embodiment of the invention a source lamp is placed along a reflector axis. The reflector is specifically designed for a particular style and type of lamp, and is designed to collect as many rays from that lamp as possible. In a preferred embodiment, the reflector comprises four segments. Each of the four segments forms a distinct focus. In this embodiment, a plurality of lightguides, preferably optical fibers, are placed at the output of the reflector, one each at each focus of the respective reflector segments, with the longitudinal axis of each optical fiber substantially parallel to the axes of the reflector and the lamp. Assuming radial symmetry, each of the four fibers will collect substantially the same amount of light energy, and will transmit this light energy to an end device or user.
In one aspect of the invention, there is provided an illumination system comprising an illumination source, a reflector disposed adjacent to the illumination source, wherein the reflector is comprised of a plurality of segments, and a plurality of lightguides having receiving ends for receiving light distributed from different corresponding ones of the plurality of reflector segments. Preferably, the lightguides comprise optical fibers, and there is a one-to-one correspondence of reflector segments to lightguides. In the preferred embodiment, the reflector is divided into pie-shaped segments.
In another aspect of the invention, there is provided an illumination system comprising an extended illumination source having a length, a reflector disposed adjacent to the extended illumination source, wherein the reflector is comprised of a plurality of segments and has an axis, and a plurality of lightguides having receiving ends for receiving light distributed from different corresponding ones of the plurality of reflector segments, wherein the length of the extended illumination source lies substantially along the reflector axis.
In still another aspect of the invention, there is provided a method of fabricating a segmented illumination reflector of an illumination system having an extended illumination source, wherein the segmented reflector comprises a plurality of reflector segments and the illumination system includes a plurality of lightguides having receiving ends for receiving light distributed from different corresponding ones of the plurality of reflector segments. This method comprises an initial step of mapping the radiation patterns of the extended illumination source. Then, a database of the radiation patterns emitted by the extended illumination source is created. Once the database has been created, it is used to generate a configuration for the segmented reflector which provides an optimal distribution and intensity of illumination at the receiving end of each of the lightguides.
The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawing.
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European Search Report for related application no. 99905557.7 -2317 -US9902002, Sep. 22, 2000.
Riddick Kathryn
Riser Andrew P.
Phan James
Stout Donald E
Stout, Uxa Buyan & Mullins, LLP
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