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WO1999066355A2 - Dispositif d'eclairage pour fibres optiques et procede correspondant - Google Patents

Dispositif d'eclairage pour fibres optiques et procede correspondant Download PDF

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Publication number
WO1999066355A2
WO1999066355A2 PCT/US1999/013901 US9913901W WO9966355A2 WO 1999066355 A2 WO1999066355 A2 WO 1999066355A2 US 9913901 W US9913901 W US 9913901W WO 9966355 A2 WO9966355 A2 WO 9966355A2
Authority
WO
WIPO (PCT)
Prior art keywords
luminous flux
optical
targets
optical targets
area
Prior art date
Application number
PCT/US1999/013901
Other languages
English (en)
Other versions
WO1999066355A3 (fr
Inventor
Christopher F. Bragg
Original Assignee
Fiberstars, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fiberstars, Inc. filed Critical Fiberstars, Inc.
Publication of WO1999066355A2 publication Critical patent/WO1999066355A2/fr
Publication of WO1999066355A3 publication Critical patent/WO1999066355A3/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0005—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type
    • G02B6/001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being of the fibre type the light being emitted along at least a portion of the lateral surface of the fibre
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/241—Light guide terminations

Definitions

  • This invention relates to optical fiber lighting apparatus, and more particularly to apparatus and method for substantially uniformly laterally distributing illuminating light flux from a linear fixture coupled to a cable of optical fibers.
  • Numerous lighting applications require high-intensity illumination without infrared or ultraviolet radiation commonly associated with conventional filament or gas-discharge types of electrical light sources.
  • Conventional fiber optic lighting apparatus usually obviates the undesirable infrared and ultraviolet radiation and is commonly employed to direct illumination from an end of an illuminated cable of optical fibers toward an object to be illuminated.
  • such lighting apparatus also typically requires a lens system to distribute luminous flux from an end of an illuminated cable of optical fibers.
  • other known lighting apparatus relies upon lateral emission of luminous flux from the optical fibers of an optical cable. Apparatus of this type is described in the literature (see, for example, U.S. Patent No. 4,763,948).
  • Certain other lighting applications rely upon optical fibers to deliver luminous flux without infrared or ultraviolet radiation at a location that is remote from the light source.
  • an optical channel of optical material having an index of refraction greater than the index of refraction of air is illuminated from one or both ends and includes polished surfaces to inhibit lateral emission of luminous flux from within the channel into the surrounding air, except at selected distributed locations along the length thereof between the ends.
  • Specific diffusively reflective targets are disposed in spaced relationships along a surface of the optical channel opposite locations therealong from which substantially uniform surface illumination per unit length is desired.
  • Various patterns of targets that exhibit diffusive and reflective properties i.e., DR targets
  • a computer-implemented program computes the spatial positioning of the DR targets on a rear surface of the optical channel or light guide at locations opposite a front surface thereof from which substantially uniform luminous flux per unit length is desired.
  • Figure 1 is a sectional view illustrating representative luminous ray traces within an optical channel
  • Figure 2 is a sectional view illustrating representative luminous ray traces within an optical channel that includes discrete DR targets at spaced locations;
  • Figure 3 is a graph illustrating a theoretical distribution of output illumination from an elongated optical channel according to the present invention
  • Figure 4 is a chart illustrating the calculations of areas and positions and relative brightness of DR targets according to the method of the present invention
  • Figure 5 is a graph illustrating actual output illumination from an elongated optical channel having DR targets disposed thereon at locations and with areas as illustrated in the chart of Figure 4;
  • Figure 6 is a flow chart illustrating the process according to the present invention.
  • Figure 7 is a graph illustrating output illumination about the axis of an optical channel prepared according to the present invention. Detailed Description of the Invention:
  • an optical channel is commonly formed of optical fibers that are arranged to emit luminous flux in lateral directions from illumination supplied at one or both ends of the optical fibers.
  • Optional backside reflectors or diffusers and front side lenses may be employed to enhance the lateral emission of luminous flux from within the optical fibers.
  • scattering particles may be distributed uniformly along the lengths of each optical fiber to promote lateral diffuse emission of luminous flux through the sidewalls of the fibers.
  • Lighting apparatus of these types commonly emit luminous flux laterally from each optical fiber and then require equipment external to the optical fibers such as back side reflectors to control the directionality of the laterally-emitted luminous flux.
  • an optical channel or light guide 5 of optical material such as glass or acrylic resin that extends linearly from an inlet port 6 that is optically coupled to an end of a fiber optic cable 7.
  • Each unit length 8 of the surface of the optical channel subtends a decreasingly smaller angle, ⁇ , of luminous flux from the inlet port 6 at an end of the channel. Accordingly, the intensity of luminous flux emitted from the optical channel 5 per unit length 8 decreases non-uniformly with distance from the inlet port 6.
  • discrete diffusively reflective (DR) targets are disposed in spaced relationships at the interface of the optical channel 5 and surrounding air to provide aperiodic locations along the channel 5 at which luminous flux from within the channel is substantially laterally emitted through and along the channel to promote emission of luminous flux primarily perpendicularly from the surface of the channel.
  • DR targets 15-18 in contrast to continuous diffusive surface treatments, the uniformity of laterally- emitted luminous flux per unit length may be more readily controlled.
  • DR targets 15-18 ideally promote diffused rays that exhibit a cosine pattern of ray intensities measured with respect to the perpendicular to the diffusing surface, and not to the direction of an incident ray. This provides the advantage of altering the direction or angular orientation of incident light to an orientation for emission obliquely from the optical channel or light guide 5.
  • ray traces 1, 2, and 3 are shown emanating from inlet port 6 at an illuminated end of the optical channel 5 within an angle 11 of illumination that is attributable to the numerical aperture of the illuminating optical fiber cable 7.
  • Discrete DR targets 15-18 are shown distributed aperiodically along the length of the channel 5 and in contact with the optical surface at the interface of the material of the optical channel 5 with the surrounding air.
  • optical material such as methyl methacrylate or lead-doped glass
  • ray traces 1, 2, and 3 of luminous flux within the angle 11 of incident illumination may internally reflect from smooth interfacing walls one or more times along the length of the channel 5, and may also reflect from a DR target 15, 16, 18 for lateral emission through an opposite surface.
  • Other ray traces may traverse the channel 5 via multiple internal reflections at interfaces 9, 12 in combination with reflections at selected DR targets.
  • Diffused luminous flux 19 from a discrete target is shown incident upon the interface ⁇ , surface at an angle greater than an angle for total internal reflection thereat, and some of such diffusively reflected luminous flux emerges from the wall of the channel 5 at locations within diffusion angles from the discrete DR targets 15, 16, 18.
  • Discrete DR targets 16, 18 spaced at greater distances from the inlet port 6 receive incident luminous flux in combinations of flux that is internally reflected from interfaces, and that is diffusively reflected from discrete DR targets, and that is directly projected from the inlet port 6.
  • the contributions to diffused luminous flux 19 from a given DR target is due to such total internal reflections, diffuse reflections, and projections of flux within the channel 5 and may be calculated according to the process embodiment of the present invention for each discrete target 15-18 as a function of position or distance from the inlet port 6.
  • Each discrete target 15-18 may be varied in spacing relative to the inlet port in aperiodic array (with closer spacings at greater distances), or the diffusive targets 15-18 may vary in diffusively reflective properly (as, for example, by color variations, area of the target, or the like) as a function of distance from the inlet port 6, with greater ratio of disfuse-to-internally reflective areas or increased diffuse reflection at greater distances.
  • variable parameters may also be used.
  • the intensity of laterally-emitted luminous flux 19 per unit length may be rendered substantially uniform over the length of the optical channel 5.
  • calculations of luminous flux intensity per unit length may be performed for illuminating flux supplied to the channel 5 from opposite ends thereof, with the results of the separate calculations for each end of illumination substantially superposed to yield more uniform intensity of laterally-emitted luminous flux per unit length of the channel 5 between illuminated ends thereof.
  • Intermediate discrete DR target 20-22 may be spaced away from other discrete DR targets at aperiodic positions along the length of the channel as may be desired to further enhance uniformity of laterally-emitted luminous flux per unit length along the channel 5.
  • the pattern of DR targets can thus be distributed to uniformly illuminate or to produce many non-uniform patterns of illumination, as desired.
  • An optical channel 5 disposed to receive illuminating flux at only one end may include a DR target substantially covering the opposite other end.
  • Discrete DR targets 15- 18 are spaced from each other to expose regions of surface walls of the channel 5 that interface with surrounding air to form refractive interfaces attributable to the difference of indices of refraction of the surrounding air and of the material forming optical channel 5.
  • a spectral or diffusive reflector 23 is disposed out of contact with a back surface of the channel 5 (on which the discrete DR targets 15- 18 are formed) in order to re-direct the light lost out the back of the channel to the back surface of channel 5 for passage therethrough and lateral emission from an opposite, or front surface of the channel 5.
  • the discrete DR targets 15-18 may be formed as spots or strips on a smooth surface of an optical channel 5 using highly diffusively reflective material such as white paint or ink containing particles of barium sulfate or titanium dioxide in a binder.
  • highly diffusively reflective material such as white paint or ink containing particles of barium sulfate or titanium dioxide in a binder.
  • Such discrete DR targets 15-18 are illustrated and described as positioned in one dimension along the length of an optical channel (such as an acrylic rod of about V -inch square dimension), but it should also be understood that such targets may also be positioned at discrete 2-dimensional coordinate locations relative to an inlet port 6 of an optical channel 5 having substantial width relative to length.
  • the process according to the present invention calculates 2-dimensional coordinates of diffusive targets based upon internal reflections from side walls and angular dependence of the transverse direction that are involved.
  • FIG. 3 there is shown a graph 31 of theoretical luminous intensity derived from a lighting apparatus of Figure 2 for which a body 5 of selected length, say one meter is mathematically segregated 41 into arbitrary units or divisions of resolution, say 500 or 1000 divisions, between the ends thereof.
  • One facet (surface) of the body 5 receives a pattern of highly diffusively-reflective surface treatments 15-18, as previously described, that are capable of directing out of the body luminous flux from within the body.
  • DRs diffusive-reflective regions or targets
  • the position of elements along the body are designated 43 by an array XN (n) , where n has integer values from 1 to the total number of elements of selected resolution, and each element may be considered as ON or OFF, depending upon whether such element(s) constitute a DR is, or not.
  • each element of area is assigned an identifier which designates 45 the element as a DR or as an unobstructed portion of the facet surface.
  • each element identified as a DR is next calculated 47 with respect to its position relative to location of the input aperture 6 of the body 5, and to other DR's.
  • This calculation assumes that luminous flux is well mixed or 'homogenized' within the body at each location of an element. In practice, this assumption can be enhanced in accuracy by including an entry or lead-in portion 4 of the body 5 adjacent the entry port 6, as shown in Figure 2. That is devoid of DR's to ensure more uniform luminous flux intensity within the body.
  • "Well-mixed" luminous flux thus means that the intensity and angular distribution of luminous flux at all points in a cross-sectional plane of the body are substantially constant.
  • a DR at this plane will be illuminated by a portion of luminous flux passing through the plane with a radiance determined by the area of the DR, and the numerical aperture (NA) of the optical fiber(s) that couple luminous flux to the entry port 6 of the body 5 (essentially, establishing the skew angle from the longitudinal axis of the body at which luminous flux is launched within the body).
  • the total luminous flux passing through each such cross-sectional plane diminishes at each DR with distance away from the entry port and can be computed and stored for calculations of radiance 49 at each successive DR.
  • the areas (in increments of 1 mm, all 1 cm wide, for the example set forth above) and locations along the length of the body can be computed 51, as illustrated in the graph of Figure 4.
  • This graph illustrates the computational results of the process according to the present invention by which the DR areas and locations along the length of the body are determined.
  • the DR's are represented by top segments 33 of the chart that are spaced approximately equally along the length of the body, but with different areas that generally increase with distance from the input end (near the origin).
  • a desired far-field distribution of light flux can be selected and the pattern of luminous regions and the radiance of each region along the optical channel can be determined (on a scale of arbitrary units of radiance) according to the present invention.
  • This graph illustrates the illuminance on a planar surface disposed at a constant selected distance away from the body 5 of the optical channel along the length thereof, and such surface may be mathematically divided into discrete regions for determining contributions of luminous flux thereto from each DR, assuming diffusely reflective luminous flux intensity from each DR.
  • the intensity of illumination of the surface regions may thus be calculated, and may be subjected to a least squares fit to a desired output 55 in conventional manner, for example, as described in Numerical Recipes.
  • FIG. 5 there is shown a graph 35 of actual data on illuminance in units of foot-candles on a planar surface disposed about 20 cm away from the body 5 of lighting apparatus.
  • the body 5 is approximately 1/2" square and about 2 feet long, containing a pattern of DR's on one facet surface thereof, in an array as illustrated in Figure 4, and illuminated at one end by luminous flux supplied from a bundle or cable of optical fibers having a numerical aperture of about 0.51.
  • the curve 35 of actual data in Figure 5 resulting from lighting apparatus fabricated according to the present invention closely resembles the theoretical luminous output illustrated by curve 31 of Figure 3.
  • FIG. 7 there is shown a pattern of illumination from lighting apparatus fabricated according to the present invention, in a plane normal to the elongated axis of the body 5, showing a confined pattern of illumination centered substantially about the angular orientation directly in front of the body. Similar patterns are obtained in other lateral planes at varying distances from the entry port 6, with some variations in the maximum luminous output indicated in such planes at locations along the axis of the body 5 between the ends thereof, with rear reflector 23 in place. From this graph, it should be noted that forward-directed lighting is achieved without the aid of lenses or focusing schemes disposed along the length of the elongated body 5.
  • the process of the present invention operates on a desired illumination pattern that is generally non-uniform with a decrease in luminous output as a function of increasing distance from an illuminated end.
  • the luminous intensity at each DR is selectively decreased more with distance from the illuminated end than for a single-ended channel, and over essentially one half the total length of the channel.
  • the pattern of DR's is copied and inverted or assembled on the remaining one half length from the opposite end.
  • the original pattern of DR's and its copy are thus connected co-linearly to form a complete pattern that is twice as long as the original pattern, but that extends between the ends and that is substantially symmetrical about the center of the channel between the ends thereof.
  • Luminous flux that might have migrated to the end of each half-length pattern now adds to the luminous flux in the other half-length beyond the center for added intensity of luminous output over the entire length of the channel, substantially in excess of the luminous intensity attainable from two single- ended channels placed in close proximity.
  • the method and apparatus of the present invention provide an illuminating fixture with intense luminous output and enhanced directionality from a source of luminous flux supplied to one or both ends of a linear optical channel.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Light Guides In General And Applications Therefor (AREA)

Abstract

L'invention concerne un appareil d'éclairage comprenant un corps de forme allongé en matériau optique formant un canal optique à indice de réfraction élevé. Ledit appareil est conçu pour recevoir le flux lumineux par l'une ou les deux extrémités dudit corps de façon qu'une émission latérale de flux lumineux se fasse à une intensité superficielle sensiblement uniforme par unité de longueur du canal. Des cibles diffusantes discrètes sont espacées par des distances apériodiques sur une interface lisse du canal, l'air ambiant venant parfaire l'uniformité de la lumière diffusée par unité de longueur du canal à émission latérale. C'est un calcul réalisé par ordinateur qui déterminera les orientations optimales des cibles discrètes sur la surface d'interface de façon à répartir de manière sensiblement uniforme les intensités des flux lumineux à émission latérale par unité de longueur à partir du canal optique.
PCT/US1999/013901 1998-06-19 1999-06-18 Dispositif d'eclairage pour fibres optiques et procede correspondant WO1999066355A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10044798A 1998-06-19 1998-06-19
US09/100,447 1998-06-19

Publications (2)

Publication Number Publication Date
WO1999066355A2 true WO1999066355A2 (fr) 1999-12-23
WO1999066355A3 WO1999066355A3 (fr) 2000-02-24

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003077004A3 (fr) * 2002-03-12 2003-12-24 Tyco Electronics Canada Appareil, procedes et articles de fabrication d'un conduit de lumiere coextrude

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69217177T2 (de) * 1991-11-28 1997-05-15 Enplas Corp Flächenartige Lichtquelle
US5438484A (en) * 1991-12-06 1995-08-01 Canon Kabushiki Kaisha Surface lighting device and a display having such a lighting device
AU4409496A (en) * 1994-11-29 1996-06-19 Precision Lamp, Inc. Edge light for panel display
EP0961901A1 (fr) * 1996-01-19 1999-12-08 Lumenyte International Corporation Canal optique a eclairage lateral

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003077004A3 (fr) * 2002-03-12 2003-12-24 Tyco Electronics Canada Appareil, procedes et articles de fabrication d'un conduit de lumiere coextrude
US6769799B2 (en) 2002-03-12 2004-08-03 Tyco Electronics Canada Apparatus, methods and articles of manufacture for a co-extruded light pipe

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