WO2005001535A1 - Light source with a number of light-emitting diodes - Google Patents

Light source with a number of light-emitting diodes Download PDF

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Publication number
WO2005001535A1
WO2005001535A1 PCT/EP2004/051221 EP2004051221W WO2005001535A1 WO 2005001535 A1 WO2005001535 A1 WO 2005001535A1 EP 2004051221 W EP2004051221 W EP 2004051221W WO 2005001535 A1 WO2005001535 A1 WO 2005001535A1
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WO
WIPO (PCT)
Prior art keywords
light source
optical
light
source according
optical fibers
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Application number
PCT/EP2004/051221
Other languages
French (fr)
Inventor
Yves Agnet
Original Assignee
Yves Agnet
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Publication date
Application filed by Yves Agnet filed Critical Yves Agnet
Publication of WO2005001535A1 publication Critical patent/WO2005001535A1/en

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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
    • 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
    • G02B6/0006—Coupling light into 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
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4249—Packages, e.g. shape, construction, internal or external details comprising arrays of active devices and fibres
    • 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
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4298—Coupling light guides with opto-electronic elements coupling with non-coherent light sources and/or radiation detectors, e.g. lamps, incandescent bulbs, scintillation chambers
    • 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
    • G02B6/42—Coupling light guides with opto-electronic elements
    • G02B6/4201—Packages, e.g. shape, construction, internal or external details
    • G02B6/4249—Packages, e.g. shape, construction, internal or external details comprising arrays of active devices and fibres
    • G02B6/425—Optical features

Definitions

  • the present invention relates to a light source. It applies, in particular, to optical measurement systems by transmission, reflection, diffraction, microscopy and data transmission. Many techniques applied in the laboratory or in industry require the use of a light source whose characteristics must be adapted to the intended use. The design of a light source for a precise application therefore requires that at least the following three characteristics be defined: - should the emission of the source be directional or not? - should the light emitted be coherent or not? and - should the source emit a continuous spectrum (white light), a discrete series of wavebands (polychromatic source) or a single waveband (monochromatic source)?
  • a directional source which can emit: - either monochromatic and coherent light for interference applications, for example in interferometry or holography, - or white light for directional lighting applications, for example for microscopic observation in transmitted or reflected light, - either monochromatic light for spectrometry applications, for example in molecular absorption spectrometry, microscopy applications, for example in microscopy by fluorescence or for data transmission applications, for example data transmission by optical fibers, - or a polychromatic light for the same types of applications, when it is necessary to carry out the same observations at several different wavelengths.
  • an incandescent or halogen type bulb To constitute a directional source, it is known to use an incandescent or halogen type bulb and to add to it an optical system (mirror and / or lens) making it possible to orient the light beam in a preferred direction.
  • This system has many drawbacks.
  • a bulb gives off a large amount of heat and the light source must therefore be cooled.
  • this type of source consumes a lot of energy and occupies a large volume.
  • the bulbs age quickly, which is detrimental to any spectral and / or quantitative analysis.
  • Light sources with laser components emit a coherent monochromatic light beam.
  • LED and, in English, LED for light emitting diode have the main drawback that their light power is very low, of the order of one milliwatt. It is known to associate LEDs in panels but the power per unit of emitting area, called emittance, remains very low.
  • the present invention aims to remedy these drawbacks.
  • the length of the optical fibers between two repeaters, which amplify the signal, is directly linked to the light power emitted at the input of these optical fibers.
  • the present invention aims to provide a large light power and at a lower cost at the input of these optical fibers and thus to increase their range.
  • the present invention relates to a light source comprising: - a plurality of light emitting diodes the optical axes of which intersect at one point, - a cylindrical or spherical optical component centered on the point of convergence of the optical axes of the emitting diodes of light and concentrating the light flux of each light emitting diode at an image point of said light emitting diode, and - A plurality of optical fibers, each optical fiber having an input face near one of the image points, in the axis of the light emitting diode corresponding to this image point.
  • a single optical component allows the concentration of the light flux emitted by all the LEDs towards the input faces of optical fibers which are respectively associated with them and the light power per unit area at the output of the optical fibers is increased by relative to the light power per unit area at the output of the LEDs.
  • the light source object of the present invention is thus very compact, inexpensive, dissipates very little heat and is very stable over time.
  • the exit faces of the optical fibers are gathered close to one another in one or more groups. Thanks to these provisions, the invention makes it possible to exploit the advantages of LEDs while reducing the effect of their main drawbacks, relating to the light power emitted and the emittance of this light power.
  • a light source of high power and of small output range has therefore been constituted, comparable to a point source of high emittance and at the lowest cost.
  • the meeting of the exit faces of the optical fibers of a group is inscribed in a rectangular surface such that the length of the rectangle is at least equal to twice the width of said rectangle. Thanks to these arrangements, the light source constitutes an optical brush.
  • the union of the exit faces of the optical fibers of at least one group has a symmetry of revolution of angle multiple of 60 degrees. Thanks to these arrangements, the light source is practically point-like and has a high emittance.
  • the exit faces of the optical fibers of at least one group are staggered.
  • the emittance of the light source object of the present invention is high.
  • the output faces of the optical fibers of the same group are associated with a collimator or an optical condenser in such a way that their optical beams are concentrated.
  • the light power concentrated at one point can be similar to that of a powerful laser source, for example one to three tens of milliwatts, for a cost price ten times lower and a much smaller footprint.
  • the light source as succinctly explained above comprises an optical fiber placed in the axis of the collimator or of the condenser, said optical fiber receiving said concentrated optical beams. Thanks to these provisions, the light power carried by said optical fiber is high.
  • the cylindrical or spherical optical component is a sphere. Thanks to these arrangements, the light source which is the subject of the present invention can be very small (because the spheres concentrate the light flux which they receive near their surface) and the LEDs and the optical fibers can be arranged all around the spherical optical component and close to its surface in such a way that most of the light flux that they emit reaches the spherical optical component. According to particular characteristics, the cylindrical or spherical optical component allows the passage, inside, of a liquid. Thanks to these arrangements, the optical characteristics of the liquid influence the transmission of light and can therefore be analyzed. According to particular features, at least two light emitting diodes have identical wavelengths.
  • the light power of the light source object of the present invention can be concentrated on one or more spectral bands.
  • at least two light emitting diodes have different wavelengths.
  • the light source object of the present invention is polychromatic, even in white light.
  • the light source as succinctly explained above comprises at least three light emitting diodes and at least three optical fibers arranged around the optical component.
  • the light source as succinctly explained above comprises at least seven light emitting diodes and at least seven optical fibers arranged around the optical component.
  • the light source as succinctly explained above comprises at least twelve light emitting diodes and at least twelve optical fibers arranged around the optical component.
  • the exit faces of the optical fibers can be staggered and inscribed in a circle in such a way that the emittance of the light source, on this circle, is maximum.
  • the light source comprises a power modulator adapted to vary the electric current passing through all of the light emitting diodes. Thanks to these provisions, the power emitted by the light source can be modulated. It is observed that in order to control the electric current passing through all of the light-emitting diodes, we can either adjust the electric current passing through each of the light-emitting diodes, or supply only part of the light-emitting diodes.
  • the light source as succinctly described above comprises a signal modulator adapted to modulate the electric current passing through the light emitting diodes with a signal to be transmitted remotely and in that the optical fibers have the same length. Thanks to these provisions, an optical signal representing the signal to be transmitted remotely is conveyed, in phase, on all the output faces of the optical fibers.
  • FIG. 4 shows, in elevation, a mechanical support of optical components of the light source illustrated in Figure 2
  • - Figures 5A, 5B and 5C show, schematically, an organization of three, seven and twelve optical fibers for modes of particular embodiment, with three, seven and twelve LEDs, of the light source object of the present invention
  • - Figure 6 shows, in elevation, a mechanical support of optical components of a particular embodiment of the source object of the present invention, in which circulates a liquid to be analyzed.
  • a spherical optical component has been represented in the form of a sphere.
  • the present invention is not limited to this type of spherical optical component but also relates to spherical optical components delimited by two spherical surfaces which do not have the same center and / or the same radius.
  • a spherical optical component 100 we observe a spherical optical component 100, two LEDs 110 and 120 and two optical fibers 130 and 140. The optical axes of the LEDs 110 and 120 converge at a point 150.
  • the spherical optical component 100 here a sphere, is centered on the point
  • the spherical optical component has a diameter of 5 mm.
  • the optical fibers 130 and 140 respectively have input faces
  • the diameters of the optical fibers 160 and 170 are smaller than the diameters of the light beams emitted by the LEDs 110 and 120, in output of these LEDs.
  • the diameters of the optical fibers are 1 mm. and the LED diameters are 5mm.
  • the choice of a larger fiber diameter, for example 2 mm, will make it possible to collect more light on the entry face of the fiber but will increase the exit area of the group of fibers.
  • the spherical optical component 100 is treated with anti-reflection treatment in the range of wavelengths concerned.
  • the anti-reflection treatment can vary on the surface of the spherical optical component 100 and concern, opposite each LED and / or each optical fiber, ranges of different wavelengths.
  • spherical optical component 200 there is a spherical optical component 200, a source frame 205, four LEDs 210, 215, 220 and 225 and four optical fibers 230, 235, 240 and 245 each surrounded by a sleeve 232.
  • the Diameter of the spherical optical component 200 (or cylindrical) is given by way of example as having a value of 5 mm. Other diameters can be used depending on their adaptation to the geometry of the assembly, with reference to FIG.
  • the optical axes of LEDs 210, 215, 220 and 225 converge at a point 250.
  • the spherical optical component 200 here a sphere, is centered on point 250 and concentrates the light fluxes coming from LEDs 210, 215, 220 and 225 in image points 260, 265, 270 and 275.
  • the optical fibers 230, 235, 240 and 245 have input faces placed near the image points 260, 265, 270 and 275, respectively, perpendicular to the optical axes of the LEDs 210 , 215, 220 and 225.
  • the diameters of the optical fibers 260, 265, 270 and 275 are smaller than the diameters of the light beams emitted by the LEDs 210, 215, 220 and 225, at the output of these LEDs.
  • the diameters of the optical fibers are 1 mm. and the LED diameters are 5mm.
  • the emittance at the output of each of the optical fibers 260, 265, 270 and 275 is greater than the emittance at the output of the LEDs 210, 215, 220 and 225.
  • the source frame 205 carries and maintains all the other components illustrated in FIG. 2.
  • the optical fibers 260, 265, 270 and 275 are joined together and their outlet faces 280, 285, 290 and 295 are assembled on a plane, here in square.
  • the outlet faces can also be assembled in a row or in two rows, in staggered rows, to increase the emittance of the light source according to the embodiment illustrated in FIGS. 2 and 3.
  • the assembly shapes of the outlet faces include assemblies in circles of minimum diameter (see Figure 5) and in rectangular surfaces such that the length of the rectangle is at least twice the width of said rectangle and causes the formation of a light brush.
  • FIG. 3 there is shown, associated with the output faces of the optical fibers 280 to 295, a collimator or an optical condenser 405 placed in such a way that their optical beams are concentrated at the input of an optical fiber 410 placed in the collimator or condenser axis. This optical fiber 410 thus receives the concentrated optical beams.
  • the optical fiber 410 receives the concentrated optical beams.
  • a power modulator 420 of known type, adapted to vary the electric current passing through l set of light emitting diodes. The light power emitted by the light source is thus controlled.
  • the power modulator 420 is connected to an input of a signal modulator 430 adapted to modulate the electric current passing through the light-emitting diodes with a signal to be transmitted remotely.
  • the signal carried by the optical fiber 410 is thus representative of a signal to be transmitted remotely, for example a signal representative of information.
  • all the light emitting diodes of the light source emit in the same wavelength range and the optical fibers 230, 235, 240 and 245 have the same length between their input faces and their output faces. .
  • the frame 205 before installation of the LEDs 210, 215, 220 and 225 and the optical fibers 260, 265, 270 and 275.
  • the spherical optical component 200 is held in position by two threaded pins 300 and 305 screwed into threaded openings 310 and 315 of the frame 205, which are, in FIG. 4, perpendicular to the plane of the LEDs and the optical fibers, when the LEDs and the optical fibers are arranged, as here, in a plane.
  • the position of the spherical optical component 200 is adjusted so that its center is placed at the intersection of the optical axes of the LEDs 210, 215, 220 and 225.
  • the spherical optical component 200 is replaced by a cylindrical optical component (not shown) whose axis passes through the point of intersection of the optical axes of the LEDs, perpendicular to these optical axes. The efficiency of the light source is then reduced.
  • FIG. 5A that we can reproduce the planar organization illustrated in FIGS. 2 to 4, in the space surrounding the spherical optical component
  • FIGS. 5A, 5B, 5C represent groups of fibers formed by juxtaposition of fibers leaving between them substantially triangular spaces into which light does not penetrate due to the sheathing of the fibers.
  • the fibers can be deformed so that their contours become contiguous, which eliminates the dark triangular spaces and improves the homogeneity of the emittance of the exit surface of the group of fibers.
  • the frame 205 in which the spherical optical component 200 illustrated in FIG. 2 to 4 is replaced by a transparent pipe 605, of circular section, provided with a spherical reservoir 600, the center of which is placed at the intersection of the optical axes of the LEDs.
  • the transparent pipe 605 By circulating a liquid to be analyzed, for example wine, water, milk, in the pipe 605, we collect, with the optical fibers, a light modulated by the transparency of the liquid, which allows its analysis and the determination of some of its components.
  • the transparent pipe 605 does not include a spherical reservoir, the optical efficiency of the light source then being more reduced.
  • at least two LEDs, or even all LEDs can have identical wavelengths in order to increase the light power emitted in these wavelengths.
  • at least two LEDs, or even all of the LEDs can have different wavelengths, for example distributed over an entire spectral band, at equidistance, so as to uniformly cover all of said spectral band.
  • the exit faces of the optical fibers are associated with a collimator or an optical condenser in such a way that their optical beams are concentrated, as is known in optical systems.
  • the power supply of the LEDs comprises a power modulator adapted to control the electric current passing through all the light-emitting diodes, for example by controlling the electric current passing through each of the LEDs or by supplying power that part of the LEDs
  • the outputs of the optical fibers are bevelled, so that their output faces are polygonal, for example squares (in particular for the arrangement of the exit faces in one or more lines) or hexagons (in particular for the arrangement of the exit faces in staggered rows).
  • the exit faces of the optical fibers are gathered close to one another in several groups, in which, the union of the exit faces is preferably inscribed in a rectangular surface or have a symmetry of revolution of angle multiple of 60 degrees or are staggered.
  • Each group can emit white, polychromatic or monochromatic light, as explained above, and be oriented in a different direction from the other groups, for example for lighting applications.
  • the space between the optical fibers of the same group, close to their outlet end is filled with a liquid of optical index approximately equal to that of the optical fibers, for example a liquid adhesive with adaptation to index so that the light emission is more uniform.
  • the present invention allows the production of a directional, non-coherent light source capable of emitting white, polychromatic or monochromatic light, in the spectral range visible and near infrared, for laboratory or industrial applications, in particular in the fields of spectrometry and microscopy.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Couplings Of Light Guides (AREA)
  • Led Device Packages (AREA)

Abstract

The invention relates to a light source comprising: a number of light-emitting diodes (210, 215, 220, 225) of which the optical axes intersect at a point (250, 600); a cylindrical or spherical optical component (200) that is centered on the crosspoint of the optical axes of the light-emitting diodes and concentrates the luminous flux of each light-emitting diode into an image point of said light-emitting diode, and; a number of optical fibers (230, 235, 240, 245), each optical fiber having an entry face (260, 265, 270, 275) located close to one of the image points, in the axis of the light-emitting diode corresponding to this image point, and the exit faces (280, 285, 290, 295) of the optical fibers are closely bunched together. The cylindrical or spherical optical component is preferably provided with a spherical shape.

Description

SOURCE LUMINEUSE AVEC UNE PLURALITÉ DE DIODES ÉMETTRICES DE LUMIÈRE LIGHT SOURCE WITH A PLURALITY OF LIGHT EMITTING DIODES
La présente invention concerne une source lumineuse. Elle s'applique, en particulier, aux systèmes de mesure optique par transmission, réflexion, diffraction, à la microscopie et à la transmission de données. De nombreuses techniques appliquées au laboratoire ou à l'industrie requièrent l'usage d'une source lumineuse dont les caractéristiques doivent être adaptées à l'utilisation envisagée. La conception d'une source lumineuse en vue d'une application précise nécessite donc que soient au moins définies les trois caractéristiques suivantes : - l'émission de la source doit-elle être directionnelle ou non ? - la lumière émise doit-elle être cohérente ou non ? et - la source doit-elle émettre un spectre continu (lumière blanche), une série discrète de bandes d'ondes (source polychromatique) ou une seule bande d'ondes (source monochromatique) ? Quatre critères complémentaires conditionnent la bonne adaptation de la source lumineuse à son application et à sa facilité de mise en oeuvre : - quelle est la puissance lumineuse requise par l'application en terme de flux lumineux ? - la source doit-elle être étendue ou ponctuelle en terme d'émittance ? - quelle est l'efficacité lumineuse de la source ? - quelle est sa stabilité dans le temps ? La plupart des techniques de laboratoire mettant en oeuvre une source lumineuse ont besoin d'une source directionnelle qui puisse émettre : - soit une lumière monochromatique et cohérente pour des applications interférentielles, par exemple en interférométrie ou en holographie, - soit de la lumière blanche pour des applications d'éclairage directionnel, par exemple pour .'observation microscopique en lumière transmise ou réfléchie, - soit une lumière monochromatique pour des applications de spectrometrie, par exemple en spectrometrie d'absorption moléculaire, des applications de microscopie, par exemple en microscopie par fluorescence ou pour des applications en transmission de données, par exemple en transmission de données par fibres optiques, - soit une lumière polychromatique pour les mêmes types d'applications, lorsqu'on a besoin d'effectuer les mêmes observations à plusieurs longueurs d'onde différentes. Pour constituer une source directionnelle, il est connu d'utiliser une ampoule à incandescence ou de type halogène et de lui adjoindre un système optique (miroir et/ou lentille) permettant d'orienter le faisceau lumineux dans une direction préférentielle. Ce système présente de nombreux inconvénients. En particulier, une ampoule dégage une grande quantité de chaleur et la source lumineuse doit donc être refroidie. De plus, ce type de source consomme beaucoup d'énergie et occupe un volume important. De plus, les ampoules vieillissent rapidement, ce qui est nuisible à toute analyse spectrale et/ou quantitative. Les sources lumineuses à composant laser émettent un faisceau lumineux monochromatique cohérent. Ces sources lumineuses assez puissantes pour certaines applications sont très coûteuses et leur très faible dispersion chromatique peut être un inconvénient pour des applications particulières, comme la spectrometrie d'absorption moléculaire. Les sources lumineuses à diodes émettrices de lumières (DEL et, en anglais, LED pour light emitting diode) de type connu présentent comme principal inconvénient que leur puissance lumineuse est très faible, de l'ordre de un milliwatt. Il est connu d'associer des DEL en panneaux mais la puissance par unité de surface émettrice, appelée émittance, reste très faible. La présente invention vise à remédier à ces inconvénients. Dans le domaine des communications à distance basées sur l'usage des fibres optiques, la longueur des fibres optiques entre deux répéteurs, qui amplifient le signal, est directement liée à la puissance lumineuse émise en entrée de ces fibres optiques. La présente invention vise à fournir une puissance lumineuse importante et à moindre coût en entrée de ces fibres optiques et à augmenter ainsi leur portée. A cet effet, la présente invention vise une source lumineuse comportant : - une pluralité de diodes émettrices de lumière dont les axes optiques se coupent en un point, - un composant optique cylindrique ou sphérique centré sur le point de convergence des axes optiques des diodes émettrices de lumière et concentrant le flux lumineux de chaque diode émettrice de lumière en un point image de ladite diode émettrice de lumière, et - une pluralité de fibres optiques, chaque fibre optique présentant une face d'entrée à proximité de l'un des points images, dans l'axe de la diode émettrice de lumière correspondant à ce point image. Grâce à ces dispositions, un seul composant optique permet la concentration des flux lumineux émis par toutes les DEL vers des faces d'entrée de fibres optiques qui leur sont respectivement associées et la puissance lumineuse par unité de surface en sortie des fibres optiques est augmentée par rapport à la puissance lumineuse par unité de surface en sortie des DEL. La source lumineuse objet de la présente invention est ainsi très compacte, de moindre coût, dissipe très peu de chaleur et est très stable dans le temps. Selon des caractéristiques particulières, les faces de sortie des fibres optiques sont rassemblées à proximité l'une de l'autre en un ou plusieurs groupes. Grâce à ces dispositions, l'invention permet d'exploiter les avantages des DEL tout en réduisant l'effet de leurs principaux inconvénients, relatifs à la puissance lumineuse émise et à l'émittance de cette puissance lumineuse. On a donc constitué une source lumineuse de forte puissance et de faible étendue de sortie, assimilable à une source ponctuelle de forte émittance et au moindre coût. Selon des caractéristiques particulières, la réunion des faces de sortie des fibres optiques d'un groupe est inscrite dans une surface rectangulaire telle que la longueur du rectangle est au moins égale à deux fois la largeur dudit rectangle. Grâce à ces dispositions, la source lumineuse constitue un pinceau optique. Selon des caractéristiques particulières, la réunion des faces de sortie des fibres optiques d'au moins un groupe possède une symétrie de révolution d'angle multiple de 60 degrés. Grâce à ces dispositions, la source lumineuse est pratiquement ponctuelle et présente une émittance élevée. Selon des caractéristiques particulières, les faces de sortie des fibres optiques d'au moins un groupe sont réunies en quinconce. Grâce à ces dispositions, l'émittance de la source lumineuse objet de la présente invention est élevée. Selon des caractéristiques particulières, les faces de sortie des fibres optiques d'un même groupe sont associées à un collimateur ou à un condenseur optique de telle manière que leurs faisceaux optiques soient concentrés. Grâce à ces dispositions, la puissance lumineuse concentrée en un point peut être similaire à celle d'une source laser puissante, par exemple une à trois dizaines de milliwatts, pour un coût de revient dix fois inférieur et un encombrement beaucoup plus réduit. Selon des caractéristiques particulières, la source lumineuse telle que succinctement exposée ci-dessus comporte une fibre optique placée dans l'axe du collimateur ou du condenseur, ladite fibre optique recevant lesdits faisceaux optiques concentrés. Grâce à ces dispositions, la puissance lumineuse véhiculée par ladite fibre optique est importante. Selon des caractéristiques particulières, le composant optique cylindrique ou sphérique est une sphère. Grâce à ces dispositions, la source lumineuse objet de la présente invention peut être de très petite dimension (car les sphères concentrent le flux lumineux qu'elles reçoivent à proximité de leurs surface) et les DEL et les fibres optiques peuvent être disposées tout autour du composant optique sphérique et à proximité de sa surface de telle manière que la majeure partie du flux lumineux qu'elles émettent atteint le composant optique sphérique. Selon des caractéristiques particulières, le composant optique cylindrique ou sphérique permet le passage, en son intérieur, d'un liquide. Grâce à ces dispositions, les caractéristiques optiques du liquide influencent la transmission de la lumière et peuvent donc être analysées. Selon des caractéristiques particulières, au moins deux diodes émettrices de lumière possèdent des longueurs d'onde identiques. Grâce à ces dispositions, la puissance lumineuse de la source lumineuse objet de la présente invention peut être concentrée sur une ou plusieurs bandes spectrales. Selon des caractéristiques particulières, au moins deux diodes émettrices de lumière possèdent des longueurs d'onde différentes. Grâce à ces dispositions, la source lumineuse objet de la présente invention est polychromatique, voire en lumière blanche. Selon des caractéristiques particulières, la source lumineuse telle que succinctement exposée ci-dessus comporte au moins trois diodes émettrices de lumière et au moins trois fibres optiques disposées autour du composant optique. Selon des caractéristiques particulières, la source lumineuse telle que succinctement exposée ci-dessus comporte au moins sept diodes émettrices de lumière et au moins sept fibres optiques disposées autour du composant optique. Selon des caractéristiques particulières, la source lumineuse telle que succinctement exposée ci-dessus comporte au moins douze diodes émettrices de lumière et au moins douze fibres optiques disposées autour du composant optique. Grâce à chacune de ces dispositions, les faces de sortie des fibres optiques peuvent être positionnées en quinconce et inscrites dans un cercle de telle manière que l'émittance de la source lumineuse, sur ce cercle, est maximale. Selon des caractéristiques particulières, la source lumineuse comporte un modulateur de puissance adapté à faire varier le courant électrique traversant l'ensemble des diodes émettrices de lumière. Grâce à ces dispositions, la puissance émise par la source lumineuse peut être modulée. On observe que pour commander le courant électrique traversant l'ensemble des diodes émettrices de lumière ont peut soit ajuster le courant électrique traversant chacune des diodes émettrices de lumière, soit n'alimenter qu'une partie des diodes émettrices de lumière. Selon des caractéristiques particulières, la source de lumière telle que succinctement exposé ci-dessus comporte un modulateur de signal adapté à moduler le courant électrique traversant les diodes émettrices de lumière avec un signal à transmettre à distance et en ce que les fibres optiques présentent la même longueur. Grâce à ces dispositions, un signal optique représentant le signal à transmettre à distance est véhiculé, en phase, sur toutes les faces de sortie des fibres optiques. D'autres avantages, buts et caractéristiques de la présente invention ressortiront de la description qui va suivre, faite en regard des dessins annexés dans lesquels : - la figure 1 représente, schématiquement, en coupe, un mode de réalisation particulier à deux DEL, de la source lumineuse objet de la présente invention, - la figure 2 représente, schématiquement et partiellement, en coupe, un mode de réalisation particulier à quatre DEL, de la source lumineuse objet de la présente invention, - la figure 3 représente, en perspective, la source lumineuse illustrée en fig. 2, - la figure 4 représente, en élévation, un support mécanique de composants optiques de la source lumineuse illustrée en figure 2, - les figures 5A, 5B et 5C représentent, schématiquement, une organisation de trois, sept et douze fibres optiques pour des modes de réalisation particuliers, à trois, sept et douze DEL, de la source lumineuse objet de la présente invention, et - la figure 6 représente, en élévation, un support mécanique de composants optiques d'un mode de réalisation particulier de la source objet de la présente invention, dans lequel circule un liquide à analyser. Dans toute la description, on a représenté un composant optique sphérique sous la forme d'une sphère. Cependant, la présente invention ne se limite pas à ce type de composant optique sphérique mais concerne aussi les composants optiques sphériques délimités par deux surfaces sphériques ne possédant pas le même centre et/ou le même rayon. On observe, en figure 1, un composant optique sphérique 100, deux DEL 110 et 120 et deux fibres optiques 130 et 140. Les axes optiques des DEL 110 et 120 convergent en un point 150. Le composant optique sphérique 100, ici une sphère, est centré sur le pointThe present invention relates to a light source. It applies, in particular, to optical measurement systems by transmission, reflection, diffraction, microscopy and data transmission. Many techniques applied in the laboratory or in industry require the use of a light source whose characteristics must be adapted to the intended use. The design of a light source for a precise application therefore requires that at least the following three characteristics be defined: - should the emission of the source be directional or not? - should the light emitted be coherent or not? and - should the source emit a continuous spectrum (white light), a discrete series of wavebands (polychromatic source) or a single waveband (monochromatic source)? Four complementary criteria condition the good adaptation of the light source to its application and its ease of implementation: - what is the light power required by the application in terms of light flux? - should the source be extended or punctual in terms of emittance? - what is the light efficiency of the source? - what is its stability over time? Most laboratory techniques using a light source require a directional source which can emit: - either monochromatic and coherent light for interference applications, for example in interferometry or holography, - or white light for directional lighting applications, for example for microscopic observation in transmitted or reflected light, - either monochromatic light for spectrometry applications, for example in molecular absorption spectrometry, microscopy applications, for example in microscopy by fluorescence or for data transmission applications, for example data transmission by optical fibers, - or a polychromatic light for the same types of applications, when it is necessary to carry out the same observations at several different wavelengths. To constitute a directional source, it is known to use an incandescent or halogen type bulb and to add to it an optical system (mirror and / or lens) making it possible to orient the light beam in a preferred direction. This system has many drawbacks. In particular, a bulb gives off a large amount of heat and the light source must therefore be cooled. In addition, this type of source consumes a lot of energy and occupies a large volume. In addition, the bulbs age quickly, which is detrimental to any spectral and / or quantitative analysis. Light sources with laser components emit a coherent monochromatic light beam. These light sources, which are fairly powerful for certain applications, are very expensive and their very low chromatic dispersion can be a drawback for particular applications, such as molecular absorption spectrometry. Light sources with light emitting diodes (LED and, in English, LED for light emitting diode) of known type have the main drawback that their light power is very low, of the order of one milliwatt. It is known to associate LEDs in panels but the power per unit of emitting area, called emittance, remains very low. The present invention aims to remedy these drawbacks. In the field of remote communications based on the use of optical fibers, the length of the optical fibers between two repeaters, which amplify the signal, is directly linked to the light power emitted at the input of these optical fibers. The present invention aims to provide a large light power and at a lower cost at the input of these optical fibers and thus to increase their range. To this end, the present invention relates to a light source comprising: - a plurality of light emitting diodes the optical axes of which intersect at one point, - a cylindrical or spherical optical component centered on the point of convergence of the optical axes of the emitting diodes of light and concentrating the light flux of each light emitting diode at an image point of said light emitting diode, and - A plurality of optical fibers, each optical fiber having an input face near one of the image points, in the axis of the light emitting diode corresponding to this image point. Thanks to these provisions, a single optical component allows the concentration of the light flux emitted by all the LEDs towards the input faces of optical fibers which are respectively associated with them and the light power per unit area at the output of the optical fibers is increased by relative to the light power per unit area at the output of the LEDs. The light source object of the present invention is thus very compact, inexpensive, dissipates very little heat and is very stable over time. According to particular characteristics, the exit faces of the optical fibers are gathered close to one another in one or more groups. Thanks to these provisions, the invention makes it possible to exploit the advantages of LEDs while reducing the effect of their main drawbacks, relating to the light power emitted and the emittance of this light power. A light source of high power and of small output range has therefore been constituted, comparable to a point source of high emittance and at the lowest cost. According to particular characteristics, the meeting of the exit faces of the optical fibers of a group is inscribed in a rectangular surface such that the length of the rectangle is at least equal to twice the width of said rectangle. Thanks to these arrangements, the light source constitutes an optical brush. According to particular characteristics, the union of the exit faces of the optical fibers of at least one group has a symmetry of revolution of angle multiple of 60 degrees. Thanks to these arrangements, the light source is practically point-like and has a high emittance. According to particular characteristics, the exit faces of the optical fibers of at least one group are staggered. Thanks to these provisions, the emittance of the light source object of the present invention is high. According to particular characteristics, the output faces of the optical fibers of the same group are associated with a collimator or an optical condenser in such a way that their optical beams are concentrated. Thanks to these provisions, the light power concentrated at one point can be similar to that of a powerful laser source, for example one to three tens of milliwatts, for a cost price ten times lower and a much smaller footprint. According to particular characteristics, the light source as succinctly explained above comprises an optical fiber placed in the axis of the collimator or of the condenser, said optical fiber receiving said concentrated optical beams. Thanks to these provisions, the light power carried by said optical fiber is high. According to particular characteristics, the cylindrical or spherical optical component is a sphere. Thanks to these arrangements, the light source which is the subject of the present invention can be very small (because the spheres concentrate the light flux which they receive near their surface) and the LEDs and the optical fibers can be arranged all around the spherical optical component and close to its surface in such a way that most of the light flux that they emit reaches the spherical optical component. According to particular characteristics, the cylindrical or spherical optical component allows the passage, inside, of a liquid. Thanks to these arrangements, the optical characteristics of the liquid influence the transmission of light and can therefore be analyzed. According to particular features, at least two light emitting diodes have identical wavelengths. Thanks to these provisions, the light power of the light source object of the present invention can be concentrated on one or more spectral bands. According to particular characteristics, at least two light emitting diodes have different wavelengths. Thanks to these provisions, the light source object of the present invention is polychromatic, even in white light. According to particular characteristics, the light source as succinctly explained above comprises at least three light emitting diodes and at least three optical fibers arranged around the optical component. According to particular characteristics, the light source as succinctly explained above comprises at least seven light emitting diodes and at least seven optical fibers arranged around the optical component. According to particular characteristics, the light source as succinctly explained above comprises at least twelve light emitting diodes and at least twelve optical fibers arranged around the optical component. Thanks to each of these arrangements, the exit faces of the optical fibers can be staggered and inscribed in a circle in such a way that the emittance of the light source, on this circle, is maximum. According to particular characteristics, the light source comprises a power modulator adapted to vary the electric current passing through all of the light emitting diodes. Thanks to these provisions, the power emitted by the light source can be modulated. It is observed that in order to control the electric current passing through all of the light-emitting diodes, we can either adjust the electric current passing through each of the light-emitting diodes, or supply only part of the light-emitting diodes. According to particular characteristics, the light source as succinctly described above comprises a signal modulator adapted to modulate the electric current passing through the light emitting diodes with a signal to be transmitted remotely and in that the optical fibers have the same length. Thanks to these provisions, an optical signal representing the signal to be transmitted remotely is conveyed, in phase, on all the output faces of the optical fibers. Other advantages, aims and characteristics of the present invention will emerge from the description which follows, given with reference to the appended drawings in which: - Figure 1 shows, diagrammatically, in section, a particular embodiment with two LEDs, of the light source object of the present invention, - Figure 2 shows, schematically and partially, in section, a particular embodiment with four LEDs, of the light source object of the present invention, - Figure 3 shows, in perspective, the light source illustrated in fig. 2 - Figure 4 shows, in elevation, a mechanical support of optical components of the light source illustrated in Figure 2, - Figures 5A, 5B and 5C show, schematically, an organization of three, seven and twelve optical fibers for modes of particular embodiment, with three, seven and twelve LEDs, of the light source object of the present invention, and - Figure 6 shows, in elevation, a mechanical support of optical components of a particular embodiment of the source object of the present invention, in which circulates a liquid to be analyzed. Throughout the description, a spherical optical component has been represented in the form of a sphere. However, the present invention is not limited to this type of spherical optical component but also relates to spherical optical components delimited by two spherical surfaces which do not have the same center and / or the same radius. In FIG. 1, we observe a spherical optical component 100, two LEDs 110 and 120 and two optical fibers 130 and 140. The optical axes of the LEDs 110 and 120 converge at a point 150. The spherical optical component 100, here a sphere, is centered on the point
150 et concentre les flux lumineux issus des DEL 110 et 120 en des points images150 and concentrates the light fluxes coming from the LEDs 110 and 120 at image points
160 et 170. Par exemple, le composant optique sphérique possède un diamètre de 5 mm. Les fibres optiques 130 et 140 possèdent respectivement des faces d'entrées160 and 170. For example, the spherical optical component has a diameter of 5 mm. The optical fibers 130 and 140 respectively have input faces
131 et 141 placées à proximité des points images 160 et 170, respectivement, et perpendiculaires aux axes optiques des DEL 110 et 120. Les diamètres des fibres optiques 160 et 170 sont inférieurs aux diamètres des faisceaux lumineux émis par les DEL 110 et 120, en sortie de ces DEL. Par exemple, les diamètres des fibres optiques sont de 1 mm. et les diamètres des DEL sont de 5 mm. Ces dimensions sont données à titre non limitatif et notamment tous autres types de diode émettrice de lumière peut être mise en œuvre sans sortir de l'invention de la géométrie de l'ensemble. D'autres diamètres de fibres sont utilisables et seront choisis en fonction de leur adaptation à géométrie de l'ensemble. Le choix d'un diamètre de fibre supérieur par exemple 2 mm permettra de collecter plus de lumière sur la face d'entrée de la fibre mais augmentera la surface de sortie du groupe de fibres. On comprend que, grâce au seul composant optique sphérique 100, l'émittance en sortie de chacune des fibres optiques 160 et 170 est supérieure à l'émittance en sortie des DEL 110 et 120. Dans des variantes, le composant optique sphérique 100 est traité avec un traitement anti reflet dans la plage de longueurs d'ondes concernées. En variante, le traitement anti reflet peut varier sur la surface du composant optique sphérique 100 et concerner, en regard de chaque DEL et/ou de chaque fibre optique, des plages de longueurs d'ondes différentes. On observe, en figure 2, un composant optique sphérique 200, un bâti de source 205, quatre DEL 210, 215, 220 et 225 et quatre fibres optiques 230, 235, 240 et 245 entourées, chacune, d'un manchon 232. Le diamètre du composant optique sphérique 200 (ou cylindrique) est donné à titre d'exemple comme ayant une valeur de 5 mm. D'autres diamètres sont utilisables en fonction de leur adaptation à la géométrie de l'ensemble, par référence à la figure 2, il est visible qu'une fois réalisée, la série de perçage du bâti (205) au diamètre 5 mm pour loger les DEL (210, 215, 220 et 225) et les manchons de fibres (232), l'espace dégagé autour du centre optique (250) permet de loger un composant sphérique ou cylindrique de diamètre supérieur à 5mm, par exemple de diamètre 8 mm. Les axes optiques des DEL 210, 215, 220 et 225 convergent en un point 250. Le composant optique sphérique 200, ici une sphère, est centré sur le point 250 et concentre les flux lumineux issus des DEL 210, 215, 220 et 225 en des points images 260, 265, 270 et 275. Les fibres optiques 230, 235, 240 et 245 possèdent des faces d'entrées placées à proximité des points images 260, 265, 270 et 275, respectivement, perpendiculaires aux axes optiques des DEL 210, 215, 220 et 225. Les diamètres des fibres optiques 260, 265, 270 et 275 sont inférieurs aux diamètres des faisceaux lumineux émis par les DEL 210, 215, 220 et 225, en sortie de ces DEL. Par exemple, les diamètres des fibres optiques sont de 1 mm. et les diamètres des DEL sont de 5 mm. A nouveau, grâce au seul composant optique sphérique 200, l'émittance en sortie de chacune des fibres optiques 260, 265, 270 et 275 est supérieure à l'émittance en sortie des DEL 210, 215, 220 et 225. Gomme illustré en figures 3 et 4, le bâti de source 205 porte et maintient tous les autres composants illustrés en figure 2. Les fibres optiques 260, 265, 270 et 275 sont réunies et leurs faces de sortie 280, 285, 290 et 295 sont assemblées sur un plan, ici en carré. Les faces de sorties peuvent aussi être assemblées en une ligne ou en deux lignes, en quinconce, pour augmenter l'émittance de la source lumineuse selon le mode de réalisation illustré en figures 2 et 3. Les formes d'assemblages des faces de sortie comportent des assemblages dans des cercles de diamètre minimal (voir figure 5) et dans des surfaces rectangulaires telle que la longueur du rectangle est au moins égale à deux fois la largeur dudit rectangle et provoque la formation d'un pinceau lumineux. En figure 3, on a représenté, associé aux faces de sortie des fibres optiques 280 à 295, un collimateur ou à un condenseur optique 405 placé de telle manière que leurs faisceaux optiques soient concentrés en entrée d'une fibre optique 410 placée dans l'axe du collimateur ou du condenseur. Cette fibre optique 410 reçoit ainsi les faisceaux optiques concentrés. Ainsi, pratiquement toute l'énergie lumineuse émise par les diodes émettrices de lumière est véhiculée par la fibre optique 410. On observe aussi, en figure 3, un modulateur de puissance 420, de type connu, adapté à faire varier le courant électrique traversant l'ensemble des diodes émettrices de lumière. On commande ainsi la puissance lumineuse émise par la source de lumière. Le modulateur de puissance 420 est relié à une entrée d'un modulateur de signal 430 adapté à moduler le courant électrique traversant les diodes émettrices de lumière avec un signal à transmettre à distance. Le signal véhiculé par la fibre optique 410 est ainsi représentatif d'un signal à transmettre à distance, par exemple un signal représentatif d'information. Dans ce cas, toutes les diodes émettrices de lumière de la source lumineuse émettent dans la même plage de longueur d'ondes et les fibres optiques 230, 235, 240 et 245 présentent la même longueur entre leurs faces d'entrées et leurs faces de sortie. Les signaux lumineux qui sont en phase lors de leur traversée du composant optique sphérique 200, du fait de la symétrie de rotation de la source lumineuse, restent en phase jusqu'à leur arrivée dans la fibre optique 410. On observe, en figure 4, le bâti 205 avant mise en place des DEL 210, 215, 220 et 225 et des fibres optiques 260, 265, 270 et 275. Le composant optique sphérique 200 est tenu en position par deux axes filetés 300 et 305 vissés dans des ouvertures filetées 310 et 315 du bâti 205, qui sont, en figure 4, perpendiculaires au plan des DEL et des fibres optiques, lorsque les DEL et les fibres optiques sont disposées, comme ici, dans un plan. Par vissage ou dévissage des axes filetés 300 et 305, on ajuste la position du composant optique sphérique 200 de telle manière que son centre soit placé à l'intersection des axes optiques des DEL 210, 215, 220 et 225. En variante du mode de réalisation illustré aux figures 2 à 4, le composant optique sphérique 200 est remplacé par un composant optique cylindrique (non représenté) dont l'axe passe par le point d'intersection des axes optiques des DEL, perpendiculairement à ces axes optiques. Le rendement de la source lumineuse est alors réduit. On observe, en figure 5A, que l'on peut reproduire l'organisation planaire illustrée en figures 2 à 4, dans l'espace entourant le composant optique sphérique131 and 141 placed near the image points 160 and 170, respectively, and perpendicular to the optical axes of the LEDs 110 and 120. The diameters of the optical fibers 160 and 170 are smaller than the diameters of the light beams emitted by the LEDs 110 and 120, in output of these LEDs. For example, the diameters of the optical fibers are 1 mm. and the LED diameters are 5mm. These dimensions are given without limitation and in particular all other types of light emitting diode can be implemented without departing from the invention of the geometry of the assembly. Other fiber diameters can be used and will be chosen according to their adaptation to the geometry of the assembly. The choice of a larger fiber diameter, for example 2 mm, will make it possible to collect more light on the entry face of the fiber but will increase the exit area of the group of fibers. We understand that, thanks to the only spherical optical component 100, the emittance at the output of each of the optical fibers 160 and 170 is greater than the emittance at the output of the LEDs 110 and 120. In variants, the spherical optical component 100 is treated with anti-reflection treatment in the range of wavelengths concerned. As a variant, the anti-reflection treatment can vary on the surface of the spherical optical component 100 and concern, opposite each LED and / or each optical fiber, ranges of different wavelengths. In FIG. 2, there is a spherical optical component 200, a source frame 205, four LEDs 210, 215, 220 and 225 and four optical fibers 230, 235, 240 and 245 each surrounded by a sleeve 232. The Diameter of the spherical optical component 200 (or cylindrical) is given by way of example as having a value of 5 mm. Other diameters can be used depending on their adaptation to the geometry of the assembly, with reference to FIG. 2, it is visible that once made, the series of drilling of the frame (205) with a diameter of 5 mm to accommodate the LEDs (210, 215, 220 and 225) and the fiber sleeves (232), the space cleared around the optical center (250) makes it possible to house a spherical or cylindrical component with a diameter greater than 5mm, for example of diameter 8 mm. The optical axes of LEDs 210, 215, 220 and 225 converge at a point 250. The spherical optical component 200, here a sphere, is centered on point 250 and concentrates the light fluxes coming from LEDs 210, 215, 220 and 225 in image points 260, 265, 270 and 275. The optical fibers 230, 235, 240 and 245 have input faces placed near the image points 260, 265, 270 and 275, respectively, perpendicular to the optical axes of the LEDs 210 , 215, 220 and 225. The diameters of the optical fibers 260, 265, 270 and 275 are smaller than the diameters of the light beams emitted by the LEDs 210, 215, 220 and 225, at the output of these LEDs. For example, the diameters of the optical fibers are 1 mm. and the LED diameters are 5mm. Again, thanks to the single spherical optical component 200, the emittance at the output of each of the optical fibers 260, 265, 270 and 275 is greater than the emittance at the output of the LEDs 210, 215, 220 and 225. Gum illustrated in figures 3 and 4, the source frame 205 carries and maintains all the other components illustrated in FIG. 2. The optical fibers 260, 265, 270 and 275 are joined together and their outlet faces 280, 285, 290 and 295 are assembled on a plane, here in square. The outlet faces can also be assembled in a row or in two rows, in staggered rows, to increase the emittance of the light source according to the embodiment illustrated in FIGS. 2 and 3. The assembly shapes of the outlet faces include assemblies in circles of minimum diameter (see Figure 5) and in rectangular surfaces such that the length of the rectangle is at least twice the width of said rectangle and causes the formation of a light brush. In FIG. 3, there is shown, associated with the output faces of the optical fibers 280 to 295, a collimator or an optical condenser 405 placed in such a way that their optical beams are concentrated at the input of an optical fiber 410 placed in the collimator or condenser axis. This optical fiber 410 thus receives the concentrated optical beams. Thus, practically all the light energy emitted by the light emitting diodes is conveyed by the optical fiber 410. We also observe, in FIG. 3, a power modulator 420, of known type, adapted to vary the electric current passing through l set of light emitting diodes. The light power emitted by the light source is thus controlled. The power modulator 420 is connected to an input of a signal modulator 430 adapted to modulate the electric current passing through the light-emitting diodes with a signal to be transmitted remotely. The signal carried by the optical fiber 410 is thus representative of a signal to be transmitted remotely, for example a signal representative of information. In this case, all the light emitting diodes of the light source emit in the same wavelength range and the optical fibers 230, 235, 240 and 245 have the same length between their input faces and their output faces. . The light signals which are in phase when they pass through the spherical optical component 200, due to the rotation symmetry of the light source, remain in phase until they arrive in the optical fiber 410. We observe, in FIG. 4, the frame 205 before installation of the LEDs 210, 215, 220 and 225 and the optical fibers 260, 265, 270 and 275. The spherical optical component 200 is held in position by two threaded pins 300 and 305 screwed into threaded openings 310 and 315 of the frame 205, which are, in FIG. 4, perpendicular to the plane of the LEDs and the optical fibers, when the LEDs and the optical fibers are arranged, as here, in a plane. By screwing or unscrewing the threaded axes 300 and 305, the position of the spherical optical component 200 is adjusted so that its center is placed at the intersection of the optical axes of the LEDs 210, 215, 220 and 225. As a variant of the mode of embodiment illustrated in FIGS. 2 to 4, the spherical optical component 200 is replaced by a cylindrical optical component (not shown) whose axis passes through the point of intersection of the optical axes of the LEDs, perpendicular to these optical axes. The efficiency of the light source is then reduced. We observe, in FIG. 5A, that we can reproduce the planar organization illustrated in FIGS. 2 to 4, in the space surrounding the spherical optical component
200 afin de positionner, à la même distance de ce composant optique sphérique 200, trois DEL et, à la même distance entre elles, trois fibres optiques et réunir les faces de sortie des fibres optiques en triangle équilatéral. Cette organisation des faces de sortie de trois fibres optiques maximise l'émittance de la source lumineuse sur une zone presque circulaire inscrite dans un cercle 505. On observe, en figure 5B, que l'on peut reproduire l'organisation planaire illustrée en figures 2 à 4, dans l'espace entourant le composant optique sphérique200 in order to position, at the same distance from this spherical optical component 200, three LEDs and, at the same distance between them, three optical fibers and join the exit faces of the optical fibers in an equilateral triangle. This organization of the output faces of three optical fibers maximizes the emittance of the light source over an almost circular area inscribed in a circle 505. It can be seen in FIG. 5B that it is possible to reproduce the planar organization illustrated in FIGS. 2 at 4, in the space surrounding the spherical optical component
200 afin de positionner, à la même distance de ce composant optique sphérique 200, sept DEL et, à la même distance entre elles, sept fibres optiques et réunir les faces de sortie des fibres optiques en hexagone régulier. Cette organisation des faces de sortie de sept fibres optiques maximise l'émittance de la source lumineuse sur une zone presque circulaire inscrite dans un cercle 510. On observe, en figure 5C, que l'on peut reproduire l'organisation planaire illustrée en figures 2 à 4, dans l'espace entourant le composant optique sphérique200 in order to position, at the same distance from this spherical optical component 200, seven LEDs and, at the same distance between them, seven optical fibers and join the exit faces of the optical fibers in regular hexagon. This organization of the output faces of seven optical fibers maximizes the emittance of the light source over an almost circular area inscribed in a circle 510. It can be seen in FIG. 5C that it is possible to reproduce the planar organization illustrated in FIGS. 2 at 4, in the space surrounding the spherical optical component
200 afin de positionner, à la même distance de ce composant optique sphérique 200, douze DEL et, à la même distance entre elles, douze fibres optiques et réunir les faces de sortie des fibres optiques en quinconce pour former un hexagone irrégulier. Cette organisation des faces de sortie de douze fibres optiques maximise l'émittance de la source lumineuse sur une zone presque circulaire inscrite dans un cercle 515. Les figures 5A, 5B, 5C représentent des groupes de fibres constitués par juxtaposition de fibres laissant entre elles subsister des espaces sensiblement triangulaires dans lesquels la lumière ne pénètre pas en raison du gainage des fibres. Par sertissage à chaud où tout autre procédé et moyen, les fibres peuvent être déformées afin que leurs contours deviennent jointifs, ce qui élimine les espaces triangulaires sombres et améliore l'homogénéité de l'émittance de la surface de sortie du groupe de fibres. On observe, en figure 6, le bâti 205, dans lequel le composant optique sphérique 200 illustré en figure 2 à 4 est replacé par un tuyau transparent 605, de section circulaire, muni d'un réservoir sphérique 600, dont le centre est placé à l'intersection des axes optiques des DEL. En faisant circuler un liquide à analyser, par exemple du vin, de l'eau, du lait, dans le tuyau 605, on recueille, avec les fibres optiques, une lumière modulée par la transparence du liquide, ce qui permet son analyse et la détermination de certains de ses composants. En variante, le tuyau transparent 605 ne comporte pas de réservoir sphérique, le rendement optique de la source lumineuse étant alors plus réduit. Selon les besoins en terme de spectre d'émission, au moins deux DEL, voire toutes les DEL, peuvent posséder des longueurs d'onde identiques afin d'augmenter la puissance lumineuse émise dans ces longueurs d'onde. Inversement, au moins deux DEL, voire toutes les DEL, peuvent posséder des longueurs d'onde différentes, par exemple réparties sur toute une bande spectrale, à équidistance, de manière à couvrir uniformément toute ladite bande spectrale. Dans des modes de réalisation non représentés, les faces de sortie des fibres optiques sont associées à un collimateur ou à un condenseur optique de telle manière que leurs faisceaux optiques soient concentrés, de manière connue dans les systèmes optiques. Dans des modes de réalisation non représentés, l'alimentation des DEL comporte un modulateur de puissance adapté à commander le courant électrique traversant l'ensemble des diodes émettrices de lumière, par exemple en commandant le courant électrique traversant chacune des DEL ou en n'alimentant qu'une partie des DEL Dans des modes de réalisation non représentés, les sorties des fibres optiques sont biseautées, de telle manière que leurs faces de sorties soient polygonales, par exemple des carrés (en particulier pour la disposition des faces de sortie en une ou plusieurs lignes) ou des hexagones (en particulier pour la disposition des faces de sortie en quinconce). Dans des variantes, les faces de sortie des fibres optiques sont rassemblées à proximité l'une de l'autre en plusieurs groupes, dans lesquels, la réunion des faces de sortie est préférentiellement inscrite dans une surface rectangulaire ou possèdent une symétrie de révolution d'angle multiple de 60 degrés ou sont réunies en quinconce. Chaque groupe peut émettre une lumière blanche, polychromatique ou monochromatique, comme exposé ci-dessus, et être orienté dans un direction différente des autres groupes, par exemple pour des applications d'éclairage. Dans des variantes, on remplit l'espace entre les fibres optiques d'un même groupe, à proximité de leur extrémité de sortie, par un liquide d'indice optique approximativement égal à celui des fibres optiques, par exemple une colle liquide à adaptation d'indice afin que l'émission de lumière soit plus uniforme. En variante, on fait se rejoindre toutes les fibres optiques d'un même groupe, par des coupleurs de fibre, des faces de sortie des fibres optiques étant reliées à des entrées d'un coupleur de fibre, en forme de "Y" afin que toute l'énergie lumineuse des fibres optiques soient concentrées dans une seule face de sortie d'un coupleur de fibres optiques. Comme on l'a vu en regard de la description qui vient d'être donnée, la présente invention permet la réalisation d'une source lumineuse directionnelle, non cohérente et capable d'émettre en lumière blanche, polychromatique ou monochromatique, dans le domaine spectral du visible et du proche infrarouge, pour des applications de laboratoire ou industrielles, en particulier dans les domaines de la spectrometrie et de la microscopie. 200 in order to position, at the same distance from this spherical optical component 200, twelve LEDs and, at the same distance between them, twelve optical fibers and join the output faces of the optical fibers in staggered rows to form an irregular hexagon. This organization of the output faces of twelve optical fibers maximizes the emittance of the light source over an almost circular area inscribed in a circle 515. FIGS. 5A, 5B, 5C represent groups of fibers formed by juxtaposition of fibers leaving between them substantially triangular spaces into which light does not penetrate due to the sheathing of the fibers. By hot crimping where any other method and means, the fibers can be deformed so that their contours become contiguous, which eliminates the dark triangular spaces and improves the homogeneity of the emittance of the exit surface of the group of fibers. We observe, in FIG. 6, the frame 205, in which the spherical optical component 200 illustrated in FIG. 2 to 4 is replaced by a transparent pipe 605, of circular section, provided with a spherical reservoir 600, the center of which is placed at the intersection of the optical axes of the LEDs. By circulating a liquid to be analyzed, for example wine, water, milk, in the pipe 605, we collect, with the optical fibers, a light modulated by the transparency of the liquid, which allows its analysis and the determination of some of its components. As a variant, the transparent pipe 605 does not include a spherical reservoir, the optical efficiency of the light source then being more reduced. According to the needs in terms of emission spectrum, at least two LEDs, or even all LEDs, can have identical wavelengths in order to increase the light power emitted in these wavelengths. Conversely, at least two LEDs, or even all of the LEDs, can have different wavelengths, for example distributed over an entire spectral band, at equidistance, so as to uniformly cover all of said spectral band. In embodiments not shown, the exit faces of the optical fibers are associated with a collimator or an optical condenser in such a way that their optical beams are concentrated, as is known in optical systems. In embodiments not shown, the power supply of the LEDs comprises a power modulator adapted to control the electric current passing through all the light-emitting diodes, for example by controlling the electric current passing through each of the LEDs or by supplying power that part of the LEDs In embodiments not shown, the outputs of the optical fibers are bevelled, so that their output faces are polygonal, for example squares (in particular for the arrangement of the exit faces in one or more lines) or hexagons (in particular for the arrangement of the exit faces in staggered rows). In variants, the exit faces of the optical fibers are gathered close to one another in several groups, in which, the union of the exit faces is preferably inscribed in a rectangular surface or have a symmetry of revolution of angle multiple of 60 degrees or are staggered. Each group can emit white, polychromatic or monochromatic light, as explained above, and be oriented in a different direction from the other groups, for example for lighting applications. In variants, the space between the optical fibers of the same group, close to their outlet end, is filled with a liquid of optical index approximately equal to that of the optical fibers, for example a liquid adhesive with adaptation to index so that the light emission is more uniform. As a variant, all the optical fibers of the same group are joined together by fiber couplers, the output faces of the optical fibers being connected to inputs of a fiber coupler, in the shape of a "Y" so that all the light energy of the optical fibers is concentrated in a single output face of an optical fiber coupler. As seen with reference to the description which has just been given, the present invention allows the production of a directional, non-coherent light source capable of emitting white, polychromatic or monochromatic light, in the spectral range visible and near infrared, for laboratory or industrial applications, in particular in the fields of spectrometry and microscopy.

Claims

REVENDICATIONS :CLAIMS:
1 - Source lumineuse, caractérisée en ce qu'elle comporte :1 - Light source, characterized in that it comprises:
- une pluralité de diodes émettrices de lumière (110, 120, 210, 215, 220, 225) dont les axes optiques se coupent en un point (150, 250, 600),- a plurality of light emitting diodes (110, 120, 210, 215, 220, 225) whose optical axes intersect at one point (150, 250, 600),
- un composant optique cylindrique ou sphérique (100, 200) centré sur le point de convergence des axes optiques des diodes émettrices de lumière et concentrant le flux lumineux de chaque diode émettrice de lumière en un point image (160, 170) de ladite diode émettrice de lumière, et - une pluralité de fibres optiques (130, 140, 230, 235, 240, 245), chaque fibre optique présentant une face d'entrée (131 , 141 , 260, 265, 270, 275) à proximité de l'un des points images, dans l'axe de la diode émettrice de lumière correspondant à ce point image. 2 - Source lumineuse selon la revendication 1 , caractérisée en ce que les faces de sortie (280, 285, 290, 295) des fibres optiques sont rassemblées à proximité l'une de l'autre en un ou plusieurs groupes.- a cylindrical or spherical optical component (100, 200) centered on the point of convergence of the optical axes of the light emitting diodes and concentrating the light flux of each light emitting diode at an image point (160, 170) of said emitting diode of light, and - a plurality of optical fibers (130, 140, 230, 235, 240, 245), each optical fiber having an entry face (131, 141, 260, 265, 270, 275) near the 'one of the image points, in the axis of the light emitting diode corresponding to this image point. 2 - Light source according to claim 1, characterized in that the outlet faces (280, 285, 290, 295) of the optical fibers are gathered close to one another in one or more groups.
3 - Source lumineuse selon la revendication 2, caractérisée en ce que la réunion des faces de sortie des fibres optiques d'un groupe est inscrite dans une surface rectangulaire telle que la longueur du rectangle est au moins égale à deux fois la largeur dudit rectangle.3 - Light source according to claim 2, characterized in that the meeting of the outlet faces of the optical fibers of a group is inscribed in a rectangular surface such that the length of the rectangle is at least equal to twice the width of said rectangle.
4 - Source lumineuse selon la revendication 2, caractérisée en ce que la réunion des faces de sortie des fibres optiques d'au moins un groupe possède une symétrie de révolution d'angle multiple de 60 degrés.4 - Light source according to claim 2, characterized in that the union of the output faces of the optical fibers of at least one group has a symmetry of revolution of angle multiple of 60 degrees.
5 - Source lumineuse selon l'une quelconque des revendications 2 à 4, caractérisée en ce que les faces de sortie des fibres optiques d'au moins un groupe sont réunies en quinconce.5 - Light source according to any one of claims 2 to 4, characterized in that the output faces of the optical fibers of at least one group are joined in staggered rows.
6 - Source lumineuse selon l'une quelconque des revendications 1 à 9, caractérisée en ce que les faces de sortie des fibres optiques d'un même groupe sont associées à un collimateur ou à un condenseur optique (405) de telle manière que leurs faisceaux optiques soient concentrés.6 - Light source according to any one of claims 1 to 9, characterized in that the exit faces of the optical fibers of the same group are associated with a collimator or an optical condenser (405) so that their optical beams are concentrated.
7 - Source lumineuse selon la revendication 6, caractérisée en ce qu'elle comporte une fibre optique (410) placée dans l'axe du collimateur ou du condenseur, ladite fibre optique recevant lesdits faisceaux optiques concentrés.7 - Light source according to claim 6, characterized in that it comprises an optical fiber (410) placed in the axis of the collimator or the condenser, said optical fiber receiving said concentrated optical beams.
8 - Source lumineuse selon l'une quelconque des revendications 1 à 7, caractérisée en ce que le composant optique cylindrique ou sphérique (150, 250) est une sphère.8 - Light source according to any one of claims 1 to 7, characterized in that the cylindrical or spherical optical component (150, 250) is a sphere.
9 - Source lumineuse selon l'une quelconque des revendications 1 à 8, caractérisée en ce que le composant optique cylindrique ou sphérique (600) permet le passage, en son intérieur, d'un liquide.9 - Light source according to any one of claims 1 to 8, characterized in that the cylindrical or spherical optical component (600) allows the passage, inside, of a liquid.
10 - Source lumineuse selon l'une quelconque des revendications 1 à 9, caractérisée en ce que au moins deux diodes émettrices de lumière (110, 120, 210, 215, 220, 225) possèdent des longueurs d'onde identiques. 11 - Source lumineuse selon l'une quelconque des revendications 1 à 10, caractérisée en ce que au moins deux diodes émettrices de lumière (110, 120, 210, 215, 220, 225) possèdent des longueurs d'onde différentes.10 - Light source according to any one of claims 1 to 9, characterized in that at least two light emitting diodes (110, 120, 210, 215, 220, 225) have identical wavelengths. 11 - Light source according to any one of claims 1 to 10, characterized in that at least two light emitting diodes (110, 120, 210, 215, 220, 225) have different wavelengths.
12 - Source lumineuse selon l'une quelconque des revendications 1 à 11 , caractérisée en ce qu'elle comporte au moins trois diodes émettrices de lumière12 - Light source according to any one of claims 1 to 11, characterized in that it comprises at least three light emitting diodes
(210, 215, 220, 225) et au moins trois fibres optiques (230, 235, 240, 245) disposées autour du composant optique (250).(210, 215, 220, 225) and at least three optical fibers (230, 235, 240, 245) arranged around the optical component (250).
13 - Source lumineuse selon la revendication 12, caractérisée en ce qu'elle comporte au moins sept diodes émettrices de lumière et au moins sept fibres optiques disposées autour du composant optique. 14 - Source lumineuse selon la revendication 13, caractérisée en ce qu'elle comporte au moins douze diodes émettrices de lumière et au moins douze fibres optiques disposées autour du composant optique. 15 - Source lumineuse selon l'une quelconque des revendications 1 à 14, caractérisée en ce qu'elle comporte un modulateur de puissance (420) adapté à faire varier le courant électrique traversant l'ensemble des diodes émettrices de lumière.13 - Light source according to claim 12, characterized in that it comprises at least seven light emitting diodes and at least seven optical fibers arranged around the optical component. 14 - Light source according to claim 13, characterized in that it comprises at least twelve light emitting diodes and at least twelve optical fibers arranged around the optical component. 15 - Light source according to any one of claims 1 to 14, characterized in that it comprises a power modulator (420) adapted to vary the electric current passing through all the light emitting diodes.
16 - Source lumineuse selon l'une quelconque des revendications 1 à 15, caractérisée en ce qu'elle comporte un modulateur de signal (430) adapté à moduler le courant électrique traversant les diodes émettrices de lumière avec un signal à transmettre à distance et en ce que les fibres optiques présentent la même longueur. 16 - Light source according to any one of claims 1 to 15, characterized in that it comprises a signal modulator (430) adapted to modulate the electric current passing through the light emitting diodes with a signal to be transmitted remotely and in that the optical fibers have the same length.
PCT/EP2004/051221 2003-06-30 2004-06-24 Light source with a number of light-emitting diodes WO2005001535A1 (en)

Applications Claiming Priority (2)

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FR0307891 2003-06-30
FR0307891A FR2856807B1 (en) 2003-06-30 2003-06-30 LIGHT SOURCE.

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WO1991018280A1 (en) * 1990-05-17 1991-11-28 Roger George Jackson Tomographic monitoring of fluid flows
WO1998001071A1 (en) * 1996-07-08 1998-01-15 Animas Corporation Implantable sensor and system for in vivo measurement and control of fluid constituent levels
US6324320B1 (en) * 1998-03-17 2001-11-27 Polaroid Corporation Optical apparatus for producing a high-brightness multi-laser radiation source
WO1999058955A1 (en) * 1998-05-14 1999-11-18 Luminex Corporation Multi-analyte diagnostic system and computer implemented process for same
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DE19936958A1 (en) * 1999-08-05 2001-03-15 Wolf Gmbh Richard Light source for endoscopy has LEDs arranged on concave surface of calotte shell, with separate focussing lenses for each LED

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FR2856807A1 (en) 2004-12-31

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