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
  • G02B6/4298—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
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—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 planar or of plate-like form
  • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
  • G02B6/0023—Means for improving the coupling-in of light from the light source into the light guide provided by one optical element, or plurality thereof, placed between the light guide and the light source, or around the light source
  • G02B6/003—Lens or lenticular sheet or layer
• • 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
  • G02B6/0011—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 planar or of plate-like form
  • G02B6/0013—Means for improving the coupling-in of light from the light source into the light guide
  • G02B6/0015—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/002—Means for improving the coupling-in of light from the light source into the light guide provided on the surface of the light guide or in the bulk of it by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces

Definitions

• the invention relates to the technical field of injecting light into a waveguide.
• the invention finds its application in particular in:
• spectroscopic sensors such as fluid sensors (e.g. a gas), particle sensors and biological sensors.
• An optical system known from the prior art, in particular from document WO 2013/139721, comprises:
• - a light source adapted to emit electromagnetic radiation
• - a waveguide adapted to guide the electromagnetic radiation in a guiding direction, and having an inlet
• an injection device suitable for injecting the electromagnetic radiation emitted by the light source at the entrance of the waveguide.
• the injection device comprises:
• the light source being disposed at the focal point of the parabolic mirror or at the focal point of the optical lens so as to obtain electromagnetic radiation parallel to the guide direction;
• Such an optical system of the prior art makes it possible to significantly improve the injection of light when the waveguide is slightly thick (ie a thickness less than or equal to 1 mm) and when the light source has a beam of very open emission (eg a light emitting diode).
• the invention aims to remedy all or part of the aforementioned drawbacks.
• the invention relates to an optical system, comprising:
• - a light source adapted to emit electromagnetic radiation
• - a waveguide adapted to guide the electromagnetic radiation in a guiding direction, and having an inlet
• an injection device suitable for injecting the electromagnetic radiation emitted by the light source at the entrance of the waveguide
• the injection device consists of a single diopter designed to focus the electromagnetic radiation emitted by the light source at the entrance of the waveguide.
• such an optical system according to the invention makes it possible to obtain a satisfactory injection of light when the waveguide is slightly thick (ie a thickness less than or equal to 1 mm) and when the light source has an emission beam. very open (eg a light emitting diode), and this while significantly simplifying the injection device compared to the prior art, the injection device consisting of a single diopter.
• diopter a surface separating two media with different refractive indices.
• focusing is meant the fact of concentrating light rays emitted by the light source at a point in the waveguide.
• the optical system according to the invention may include one or more of the following characteristics.
• the electromagnetic radiation emitted by the light source has a wavelength, denoted l
• the single diopter has a portion extending in a direction perpendicular to the guide direction, said portion having a dimension greater than or equal to 10 l.
• the single diopter extends at the entrance to the waveguide.
• an advantage provided is to allow continuity of refractive index between the diopter and the waveguide, in the absence of a gel, glue or other additive.
• the single diopter is fixed to the entry of the waveguide by gluing or welding.
• an advantage provided is to facilitate the mounting of the single diopter on the waveguide.
• the single diopter and the waveguide are in one piece.
• an advantage provided is to ensure excellent continuity of refractive index between the diopter and the waveguide.
• the single diopter is made of a material chosen from polymethyl methacrylate, polycarbonate, a glass.
• an advantage provided by such materials is to be transparent in the visible range.
• polymethyl methacrylate and polycarbonate make it possible to manufacture the single diopter by molding.
• the light source is Lambertian.
• the waveguide is chosen from a planar guide and a cylindrical guide.
• the single diopter has a geometric shape defined by the following equations:
• n 2 denote the refractive indices of the two media separated by the single diopter, nor being the refractive index of the medium containing the light source, n 2 being the refractive index of the medium containing the waveguide ;
• an advantage provided by such a geometric shape of the diopter is to allow the focusing of the light rays emitted by a point source Lambertian at the entrance of the waveguide, and this without the presence of additional optical elements.
• the focus is checked by varying the position of the light source on the optical axis (between -50% and 40% relative to the initial position, located at the distance d from the origin of the Cartesian coordinate system),
• the focus is also checked for an extended Lambertian source, when the extension is less than 20% of the distance d,
• the ratio d / fo is less than or equal to 0.5.
• an advantage provided is to significantly increase the solid angle intercepted by the diopter.
• the ratio n 2 / ni is greater than or equal to 1.5.
• Figure 1 is a schematic longitudinal sectional view of an optical system according to the invention, illustrating an embodiment of the single diopter.
• Figure 2 is a graph illustrating the parameters of an optical system according to the invention in a Cartesian coordinate system.
• Figure 3 is a graph illustrating, using a ray tracing, an optical system according to the invention with a single diopter focusing the electromagnetic radiation emitted by the light source at the entrance of the waveguide.
• Figure 4 is a graph representing on the abscissa the ratio between d (distance separating the light source from the origin of the Cartesian coordinate system illustrated in Figure 2) and fo (distance separating the entry of the waveguide from the origin of the coordinate system Cartesian illustrated in Figure 2), and on the ordinate the maximum angle (6 ma , illustrated in Figure 2) intercepted by the diopter, and this for different ratio m / ni corresponding to the indices of refraction of the two media separated by the single diopter.
• Figure 5 is a graph representing the relative position of the light source on the abscissa (“1” being the initial position of the light source, located at the distance d from the origin of the Cartesian coordinate system), and on the ordinate the percentage of the light flux emitted by the light source which is focused at the input of the waveguide.
• the data in Figure 5 are from digital simulations.
• Figure 6 is a graph showing on the abscissa the relative position of the light source ("1" being the initial position of the light source, located at the distance d from the origin of the Cartesian coordinate system), and on the ordinate the diameter (in mm ) from the focal spot of electromagnetic radiation at the input of the waveguide.
• the data in Figure 6 are from digital simulations.
• an object of the invention is an optical system 1, comprising:
• - a light source S adapted to emit electromagnetic radiation
• - A waveguide 2 adapted to guide the electromagnetic radiation in a guiding direction, and having an input E;
• An injection device 3 adapted to inject the electromagnetic radiation emitted by the light source S at the input E of the waveguide 2;
• the injection device 3 consists of a single diopter 30 designed to focus the electromagnetic radiation emitted by the light source S at the input E of the waveguide 2.
• the light source S is preferably Lambertian, that is to say that the luminance of the light source S is preferably identical in all the directions of emission.
• the light source S can be a point source or an extended source.
• the electromagnetic radiation emitted by the light source S has a wavelength, denoted l, preferably between 380 nm and 780 nm (visible range).
• l preferably between 380 nm and 780 nm (visible range).
• other wavelengths can be envisaged, for example in the near infrared (780 nm - 3 gm) or in the near ultra-violet (315 nm - 380 nm).
• the wavelength of the light source S is preferably in the infrared range (1 gm - 10 gm).
• the light source S can be a light-emitting diode.
• the light source S can have an emission surface greater than or equal to 1 mm 2 .
• the light source S can have a very open emission beam (greater than ⁇ 30 ° from the optical axis, for example ⁇ 60 ° from the optical axis).
• the waveguide 2 is advantageously chosen from a planar guide and a cylindrical guide.
• the waveguide 2 can be produced in the form of a thin film.
• the waveguide 2 can also be produced in the form of an optical fiber.
• the waveguide 2 advantageously has a thickness less than or equal to 5 mm.
• the waveguide 2 is advantageously made of a transparent material in the visible range, the material being preferably chosen from polymethyl methacrylate, polycarbonate, a glass.
• the glass is preferably a borosilicate glass.
• the waveguide 2 is advantageously made of a material transparent to the wavelength of the electromagnetic radiation emitted by the light source S. diopter
• the electromagnetic radiation emitted by the light source S has a wavelength, noted l.
• the single diopter 30 advantageously has a portion 300 extending in a direction perpendicular to the guide direction, said portion 300 having a dimension D greater than or equal to 10 l.
• the single diopter 30 advantageously extends at the entrance E of the waveguide 2.
• the single diopter 30 can be fixed to the input E of the waveguide 2 by gluing or welding. According to an alternative, the single diopter 30 and the waveguide 2 are in one piece, for example by molding.
• the single diopter 30 is advantageously made of a transparent material in the visible range, the material preferably being chosen from polymethyl methacrylate, polycarbonate, a glass.
• the glass is preferably a borosilicate glass.
• the single diopter 3 is advantageously made of a material transparent to the wavelength of the electromagnetic radiation emitted by the light source S.
• the single diopter 30 advantageously has a geometric shape defined by the following equations:
• - x and y respectively designate the abscissa and the ordinate of the single diopter 30 in a plane provided with a Cartesian coordinate system;
• - ni and m denote the refractive indices of the two media separated by the single diopter 30, nor being the refractive index of the medium containing the light source S, m being the refractive index of the medium containing the waveguide 2;
• Equation (1.1) comes from trigonometric relationships in combination with the Snell-Descartes law, the parameters of equation (1.1) being illustrated in Figure 2.
• Equation (1.2) establishes a boundary condition, the single diopter 30 extending from the origin O of the Cartesian coordinate system.
• Equation (1.3) establishes a new boundary condition, and comes from a development limited to order 2 of the function y (x) - Taylor theorem-
• Numerical simulations with ray tracing show that it is possible to define a geometric shape of the diopter 30 making it possible to focus the electromagnetic radiation emitted by the light source S Lambertian at the input E of the waveguide 2.
• the focus is verified by varying the position of the light source S on the optical axis (between -50% and 40% relative to the initial position, located at the distance d from the origin of the Cartesian coordinate system) ,
• Property (ii) is illustrated in FIGS. 5 and 6.
• numerical simulations show that the focal spot of the electromagnetic radiation at the entry of the waveguide 2 has a diameter of 0.04 mm for the initial position of the light source S, located at the distance d from the origin of the Cartesian coordinate system. The diameter of the focal spot remains less than 0.26 mm when the position of the light source S on the optical axis is varied, between -50% and 40% relative to the initial position.
• numerical simulations show that the percentage of the light flux emitted by the light source S which is focused at the input of the waveguide 2 is of the order of 22% for the initial position of the light source S, located at the distance d from the origin of the Cartesian coordinate system. The percentage of the luminous flux remains greater than 16% when the position of the light source S on the optical axis is varied, between -50% and 40% relative to the initial position.
• a geometric shape of the diopter 30, defined by equations (1.1), (1.2) and (1.3) can also be defined with negative refraction indices ni, n 2 , and also makes it possible to focus the electromagnetic radiation emitted by the light source S Lambertian to input E of the waveguide 2.
• Such negative refractive indices can have a physical reality if one chooses materials, separated by the diopter 30, which are metamaterials, for example metamaterials known as the left hand. Metamaterials are advantageously used when the electromagnetic radiation emitted by the light source S has a frequency range between 3 MHz and 50 THz. Indeed, metamaterials are easier to manufacture at this frequency range. This frequency range thus covers:
• Metamaterials can be made in photonic structures - or photonic crystals - with magnetic resonators formed by coupled metal rings.
• the refractive index of a metamaterial is understood as an effective (negative) index of an effective environment.
• the photonic structures forming the metamaterials are considered to be an effective medium.
• the effective medium approach requires that the photonic structures have a characteristic dimension smaller than the wavelength of the light source S.
• the ratio d / fi is advantageously less than or equal to 0.5 so as to significantly increase the solid angle intercepted by the diopter 30.
• the ratio m / is advantageously greater than or equal to 1.5 so as to significantly increase the solid angle intercepted by the diopter 30.
• the optical system 1 can be connected to a coupler or to a multiplexer (eg of the AWG type “Arrayed Waveguide Gratings” in English) for the manufacture of a gas sensor.
• the measurement can be carried out by photo-acoustic techniques.
• the waveguide 2 of the optical system 1 can be provided with an orifice adapted to receive the particles.
• the waveguide 2 of the optical system 1 (preferably made of silicon nitride) can be oriented towards areas of tissue to be analyzed.
• the invention is not limited to the embodiments described. Those skilled in the art are able to consider their technically effective combinations, and to substitute equivalents for them.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Couplings Of Light Guides (AREA)
• Radiation-Therapy Devices (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=65201159

Family Applications (1)

Country Status (4)

Family Cites Families (4)

• 2018
  • 2018-08-24 FR FR1857655A patent/FR3085213B1/fr not_active Expired - Fee Related
• 2019
  • 2019-08-20 WO PCT/FR2019/051940 patent/WO2020039144A1/fr unknown
  • 2019-08-20 US US17/270,314 patent/US11294130B2/en active Active
  • 2019-08-20 EP EP19782655.5A patent/EP3841325A1/de not_active Withdrawn

Also Published As

Similar Documents

Legal Events