WO1994025849A1 - Systeme permettant de mesurer ponctuellement la luminance de reflexion de surfaces - Google Patents

Systeme permettant de mesurer ponctuellement la luminance de reflexion de surfaces Download PDF

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Publication number
WO1994025849A1
WO1994025849A1 PCT/EP1994/001305 EP9401305W WO9425849A1 WO 1994025849 A1 WO1994025849 A1 WO 1994025849A1 EP 9401305 W EP9401305 W EP 9401305W WO 9425849 A1 WO9425849 A1 WO 9425849A1
Authority
WO
WIPO (PCT)
Prior art keywords
concentrator
arrangement according
light
surface normal
radiation sources
Prior art date
Application number
PCT/EP1994/001305
Other languages
German (de)
English (en)
Inventor
Thomas Morgenstern
Jost SCHÜLER
Lutz Papenkordt
Original Assignee
Jenoptik Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jenoptik Gmbh filed Critical Jenoptik Gmbh
Priority to EP94914419A priority Critical patent/EP0648327A1/fr
Priority to JP6523869A priority patent/JPH07508590A/ja
Publication of WO1994025849A1 publication Critical patent/WO1994025849A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/47—Scattering, i.e. diffuse reflection
    • G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
    • G01N21/474—Details of optical heads therefor, e.g. using optical 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

Definitions

  • the invention relates to an arrangement for measuring the reflectance of small areas of solid and liquid bodies in several spectral ranges (in the VTS, near and middle IR), whereby the areal distribution of the spectral reflectance and / or the body color is possible.
  • the invention can be used in a wide variety of sectors of industry and manufacturing, in order to ensure that the colors of products are the same, to detect color deviations or to match colors.
  • the latter plays e.g. also play a major role in the manufacture of dentures, where it is important to match the color of the denture as closely as possible to the natural tooth color.
  • a large number of arrangements for determining the spectral reflectance of bodies are known from the prior art, which generally work with a plurality of spectrally selective radiation sources which can be controlled sequentially and a receiver.
  • the optical part of these arrangements differs essentially in the supply of the emitted radiation to the surface to be tested.
  • the surface to be examined is directly irradiated, so that the size of the "punctiform" areas to be measured is determined by the radiation cone of the
  • LED and the necessary distance between the object to be measured and the radiation source is determined and therefore cannot be chosen to be sufficiently small. Due to the divergence of the radiation, very high light intensities are required to obtain accurate measurement results with strongly absorbing surfaces. In addition, the overexposure accuracy of the various LEDs on the surface to be measured is inadequate due to the angular scatter in the radiation characteristics of the LEDs.
  • DE-PS 36 26 373 describes a device in which the radiation from the individual radiation sources is guided via two filter units onto a lens arrangement which focuses the radiation onto the sample to be examined. This beam guidance requires a high adjustment effort and a high mechanical stability. The achievable area resolution is just as in the abovementioned writings the emission characteristics of the LEDs determine and limit. In addition, the radiation intensity is reduced by the filter units and limited by the opening of the imaging system.
  • Optical fiber bundle is directed to the area to be examined. With a small distance between the light exit surface and the surface to be examined and the additional lenticular grinding of this exit surface, it is possible to concentrate the light on a very small measurement spot. The problem with such an arrangement is the coupling of sufficient radiation energy into it
  • the object of the invention is to provide an arrangement for the punctiform measurement of the reflectance in different spectral ranges, in which the radiation of several radiation sources with different radiation characteristics is concentrated with as little means and little loss of radiation energy as possible on a small section of the area to be examined.
  • the object is achieved with an arrangement for the punctiform measurement of the remission of surfaces of solid or liquid bodies in different spectral ranges with at least two radiation sources of different spectral ranges and a receiver which is sensitive at least for the selected different spectral ranges, the angular position being different for incident and reflected light and on the one hand corresponds to the surface normal of the surface and on the other hand to an angle which is substantially different from the surface normal and parallel to the surface, solved in that the radiation sources are followed by a concentrator which has the shape of a
  • the concentrator advantageously consists of any transparent material with a lacquer layer produced by dipping or spraying on as a lower-refractive coating.
  • the concentrator consists of glass, in particular quartz glass, the lower-refractive coating of which is produced by tapping the glass.
  • half the cone angle of the quartz glass concentrator is preferably about one fifth of the numerical aperture of an optical waveguide made of the same material.
  • the concentrator is preferably glued to the window of the LED used, the adhesive layer being the refractive index of window material of the LED and that of the
  • the radiation sources are preferably arranged as separate LEDs around the receiver arranged in the direction of the surface normal at a uniform angular distance from one another and at approximately 45 ° to the surface normal.
  • the light exit surfaces of the concentrators are expediently designed spherically.
  • the radiation sources In order to realize a particularly small measuring head, it is generally favorable to arrange the radiation sources at any point away from the surface and to glue optical fibers to the light exit surface of the concentrators, the ends of the optical fibers being around those in the direction of the surface normal
  • Receivers are arranged at an even angular distance and at approximately 45 ° to the surface normal.
  • the radiation divergence is expediently reduced by spherical design of the light exit surfaces of the optical fibers.
  • a fundamentally different advantageous design of the arrangement according to the invention is achieved by using a three-color LED, in that only a single concentrator follows the LED (as a combination of three radiation sources) and the three-color LED and concentrator are arranged in the direction of the surface normals and a fiber bundle arranged concentrically thereto of fiber optic cables (LWL), which transmits reflected light at an angle of about 45 ° to the receiver, the
  • the colors of the three-color LED can be switched on in series.
  • the fiber optic cables (with the end surface perpendicular to the fiber optic axis) can easily be arranged at an angle of approx. 45 °.
  • the measuring head with its light entry and exit surfaces has a uniform, smooth surface and the fiber optic cables are therefore beveled at their ends.
  • LWL air refractive index ratio
  • Quartz glass results in an angular position of approximately 30 ° to the surface normal for the FO. It is furthermore expedient to rigidly connect the concentrator to the three-color LED by means of an adhesive layer, the adhesive layer in turn adapting the refractive indices of the LED window and the concentrator to one another.
  • the light exit surface of the concentrator is advantageously also spherically shaped.
  • 0745 ° - measurement geometry are known, and adapted and modified according to the special features of the point remission measurement according to the invention. With the arrangements according to the invention, it is possible to align the remission measurements on the smallest areas of a body surface and to utilize the radiation from divergent light sources of low power for precise remission measurements with low radiation losses.
  • the reflectance measurements for color matching can be used particularly advantageously in a wide variety of industrial and commercial sectors.
  • the invention proves to be advantageous and suitable for use in dentistry (manufacture of dentures) and forensic medicine (e.g. determining the age of hematomas), since the critical surfaces are easy to keep sterile.
  • Fig. 1 shows the schematic diagram of an arrangement according to the invention in a
  • FIG. 1 shows the top view of FIG. 1
  • Fig. 3 shows the schematic diagram of a further arrangement according to the invention in
  • the arrangement according to the invention for measuring the reflectance of surfaces 1 of solid and liquid bodies preferably contains in its basic structure a 0745 ° measurement geometry from radiation sources 3 of different spectral ranges, wherein according to the invention a radiation concentrator 2 is arranged downstream of each radiation source 3 to collect its diverging light.
  • the concentrator 2 is made of transparent material and is in the form of a truncated cone, the outer surface of which reflects the radiation totally and at the same time concentrates.
  • FIG. 1 - An arrangement according to the invention - as shown schematically in FIG. 1 - shows the 0745 ° structure typical for reflectance measurements, with the receiver 5 in here
  • Each of the red, green and blue LEDs 3.1 to 3.3 forms together with the concentrator 2 one of the assemblies 4, which in this case are arranged at 120 ° around the receiver 5, as shown in FIG. 2 as a top view.
  • the area 1 to be examined is successively irradiated by the red, green and blue LEDs 3.1, 3.2 and 3.3 at an angle of essentially 45 ° in a pulsed manner.
  • the respective downstream concentrator 2 detects the radiation emitted by the LED and concentrates it on a narrowly limited section of the area to be examined 1.
  • the size of this section does not depend on the different radiation characteristics of the LEDs, but is dependent on parameters of the concentrators 2 ( Cone angle, refractive index ratio between the higher refractive truncated cone and the lower refractive cladding) and the distance between the light exit surface of the concentrator 2 and surface 1.
  • the refractive index ratio of the concentrators 2 is therefore similar to that of conventional optical fibers, with approximately 1.45 and n M being approximately 1.43.
  • the concentrators 2 essentially match the fiber optics from Ensign-Bickford Optics Company (USA). Because of the divergence of the emerging light that also occurs at the light exit of the concentrators 2 and that is somewhat larger than conventional optical fibers, the distance to the surface 1 must be chosen to be small.
  • a conflicting condition is the fact that the distance must always remain so large that the light cones of all radiation sources 3, starting from the light exit of the concentrators 2, illuminate the area 1 detected by the receiver 5 as completely as possible. Since the receiver 5 advantageously receives the remitted light via an optical fiber 6, which is embedded in a metal cannula 7 to avoid the incidence of extraneous light, the distance from the surface 1 can hardly be less than 2 mm. The distance is realized with respect to the metal cannula 7, while the entry surface of the fiber optic cable 6 is slightly shifted back by the
  • the half cone angle is approximately 2.5 °, a length of less than 2 cm.
  • the half cone angle should not be more than 10% larger than a fifth of the numerical aperture. Because of the relatively short length of the concentrators 2 and the advantageous 45 ° position with respect to the surface normal to the surface 1, it is advantageous in the interest of a compact, slim design of the arrangement according to the invention not to arrange the light sources 3 directly in the vicinity of the surface 1, but instead to bring their light to the appropriate position via fiber optics (not shown in this configuration).
  • the light exit surfaces of the concentrators 2 are advantageously glued to the end faces of the optical fiber. Those of the HCG-MO365T-10 type from Ensign-Bickford Optics Company (USA) are expediently used as optical fibers.
  • FIG. 3 shows an arrangement according to the invention which is fundamentally different, which is changed compared to the first example in the position of radiation sources 3 and receiver 5.
  • the radiation sources 3 are arranged in the direction of the surface normal of the surface 1.
  • a three-color LED 8 (for example of the type CMS 124 from ELCOS GmbH Pfaffenhofen, Germany), the color segments in turn being driven in a pulsed, serial manner.
  • the three-color LED 8 is in turn advantageously coupled via an adhesive layer 9 to the concentrator 2, which is designed in the same way as in the first example. The coupling is carried out in such a way that the window material of the three-color LED 8 via the adhesive layer
  • the remitted light is received by means of a receiver 5 via a fiber bundle composed of a plurality of optical fibers 6 which is concentric, even around the radiation sources arranged along the surface normal.
  • Concentrator unit is distributed.
  • step index fibers of the type HCG-M 0200 T-10 (numerical aperture: 0.22, manufacturer: Ensign-Bickford Optics Company, USA) are advantageously used.
  • the FO 6 are advantageously arranged so that they receive the remitted light at an angle of preferably 45 ° with respect to the surface normal. Two constructive solutions are possible for this.
  • the ends of the FO 6 are adjusted under the selected angle setting (e.g. exactly 45 °) and cast in advantageously.
  • the end faces of the FO 6 remain perpendicular to the fiber axis and practically protrude from the composite surface.
  • Fig. 3 illustrates the other variant in which the refractive index of quartz glass and the often advantageous fact that the surface of a sensor should be as smooth as possible are taken into account.
  • the fiber optic cables 6 are adjusted at an angle of 30 ° to the surface normal of surface 1 (e.g. by embedding them in a casting resin).
  • the ends of the LWL 6 have bevels with the same angle of 30 °, so that the sensor has a flat, smooth surface parallel to the surface 1.
  • the angular dimension of 30 ° results from the selection of an optical fiber 6 made of quartz glass and a receiving angle for the reflected light of 45 ° and for this reason does not limit the scope of the teaching according to the invention as a fixed angle. It is important that preferably the light remitted at 45 ° is broken into the fiber optic cable 6 almost parallel to the fiber axis due to the refractive index jump at the slanted light entry surface of the fiber optic cable 6.
  • An additional advantage is that the distance between the sensor and the surface can be reduced from 1 to almost 1 mm, so that with a light exit surface the Concentrator 2 of 1.4 mm a measured area 1 of about 2 mm in diameter is realized.
  • the smooth sensor surface fulfills the requirement of medical technology that it can be kept sterile particularly easily.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Spectrometry And Color Measurement (AREA)

Abstract

L'invention concerne un système pour mesurer la luminance de réflexion de petites surfaces de corps solides, liquides ou gazeux dans plusieurs zones spectrales (visible, infrarouge proche/moyen), qui permet de déterminer la répartition superficielle du degré spectral de luminance de réflexion et/ou de la couleur des corps. A cet effet, des concentrateurs spéciaux sont placés derrière des sources de rayonnement individuelles, ce qui permet, sans nécessiter une grande complexité technique en termes de conception et d'ajustage et en n'occasionnant que de faibles déperditions d'énergie rayonnée, de concentrer le rayonnement sur une très petite partie de la surface à examiner.
PCT/EP1994/001305 1993-04-30 1994-04-26 Systeme permettant de mesurer ponctuellement la luminance de reflexion de surfaces WO1994025849A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP94914419A EP0648327A1 (fr) 1993-04-30 1994-04-26 Systeme permettant de mesurer ponctuellement la luminance de reflexion de surfaces
JP6523869A JPH07508590A (ja) 1993-04-30 1994-04-26 面の拡散反射の点状測定用構成

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4314219.2 1993-04-30
DE19934314219 DE4314219A1 (de) 1993-04-30 1993-04-30 Anordnung zur punktuellen Messung der Remission

Publications (1)

Publication Number Publication Date
WO1994025849A1 true WO1994025849A1 (fr) 1994-11-10

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ID=6486793

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1994/001305 WO1994025849A1 (fr) 1993-04-30 1994-04-26 Systeme permettant de mesurer ponctuellement la luminance de reflexion de surfaces

Country Status (4)

Country Link
EP (1) EP0648327A1 (fr)
JP (1) JPH07508590A (fr)
DE (1) DE4314219A1 (fr)
WO (1) WO1994025849A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998003842A1 (fr) * 1996-07-17 1998-01-29 Valtion Teknillinen Tutkimuskeskus Spectrometre
US6018607A (en) * 1996-04-22 2000-01-25 Byk-Gardner, Gmbh Fiber optic light guide for measurement of illumination devices

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19511534C2 (de) * 1995-03-29 1998-01-22 Fraunhofer Ges Forschung Verfahren und Vorrichtung zur Erfassung von 3D-Fehlstellen bei der automatischen Inspektion von Oberflächen mit Hilfe farbtüchtiger Bildauswertungssysteme
DE19617009C2 (de) * 1996-04-27 1999-05-20 Roland Man Druckmasch Photoelektrische Meßeinrichtung
JP2005172814A (ja) * 2003-11-19 2005-06-30 Kansai Paint Co Ltd 反射紫外線測定装置
DE102004014532B3 (de) 2004-03-23 2005-03-03 Koenig & Bauer Ag Optisches System zur Erzeugung eines beleuchteten Gebildes
DE102004014541B3 (de) 2004-03-23 2005-05-04 Koenig & Bauer Ag Optisches System zur Erzeugung eines Beleuchtungsstreifens

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3566119A (en) * 1967-10-06 1971-02-23 California Computer Products Infrared scanning device using a spherical lens
US3846027A (en) * 1972-08-03 1974-11-05 Align O Tron Corp Reflection densitometer
US3910701A (en) * 1973-07-30 1975-10-07 George R Henderson Method and apparatus for measuring light reflectance absorption and or transmission
JPS60205414A (ja) * 1984-03-29 1985-10-17 Olympus Optical Co Ltd 高倍率内視鏡用照明光学系
GB2180367A (en) * 1985-09-09 1987-03-25 Ord Inc Tapered optical fibre for immunoassay
EP0360738A1 (fr) * 1988-09-05 1990-03-28 Ciba-Geigy Ag Procédé et dispositif pour déterminer la formulation de peinture
EP0367097A2 (fr) * 1988-11-04 1990-05-09 Miles Inc. Spectromètre optique par transmission
DE4001954A1 (de) * 1990-01-24 1991-07-25 Giese Erhard Distanzsensor

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3566119A (en) * 1967-10-06 1971-02-23 California Computer Products Infrared scanning device using a spherical lens
US3846027A (en) * 1972-08-03 1974-11-05 Align O Tron Corp Reflection densitometer
US3910701A (en) * 1973-07-30 1975-10-07 George R Henderson Method and apparatus for measuring light reflectance absorption and or transmission
JPS60205414A (ja) * 1984-03-29 1985-10-17 Olympus Optical Co Ltd 高倍率内視鏡用照明光学系
GB2180367A (en) * 1985-09-09 1987-03-25 Ord Inc Tapered optical fibre for immunoassay
EP0360738A1 (fr) * 1988-09-05 1990-03-28 Ciba-Geigy Ag Procédé et dispositif pour déterminer la formulation de peinture
EP0367097A2 (fr) * 1988-11-04 1990-05-09 Miles Inc. Spectromètre optique par transmission
DE4001954A1 (de) * 1990-01-24 1991-07-25 Giese Erhard Distanzsensor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 10, no. 64 (P - 436) 14 March 1986 (1986-03-14) *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6018607A (en) * 1996-04-22 2000-01-25 Byk-Gardner, Gmbh Fiber optic light guide for measurement of illumination devices
DE19615971B4 (de) * 1996-04-22 2008-04-24 Byk Gardner Gmbh Anordnung mit einem Lichtleiter,- und ein damit aufgebautes Mess-und Beleuchtungssystem und ihr Herstellungsverfahren
WO1998003842A1 (fr) * 1996-07-17 1998-01-29 Valtion Teknillinen Tutkimuskeskus Spectrometre

Also Published As

Publication number Publication date
DE4314219A1 (de) 1994-11-03
EP0648327A1 (fr) 1995-04-19
JPH07508590A (ja) 1995-09-21

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