EP1236055A1 - Device and method for measuring luminous intensity using a photomultiplier comprising a calibration source - Google Patents

Device and method for measuring luminous intensity using a photomultiplier comprising a calibration source

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Publication number
EP1236055A1
EP1236055A1 EP00958735A EP00958735A EP1236055A1 EP 1236055 A1 EP1236055 A1 EP 1236055A1 EP 00958735 A EP00958735 A EP 00958735A EP 00958735 A EP00958735 A EP 00958735A EP 1236055 A1 EP1236055 A1 EP 1236055A1
Authority
EP
European Patent Office
Prior art keywords
radiation
source
photomultiplier
measured
measuring
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP00958735A
Other languages
German (de)
French (fr)
Inventor
Yves Prat
André ZIE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zietronic
USINOR SA
Original Assignee
Zietronic
Sollac SA
Lorraine de Laminage Continu SA SOLLAC
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 Zietronic, Sollac SA, Lorraine de Laminage Continu SA SOLLAC filed Critical Zietronic
Publication of EP1236055A1 publication Critical patent/EP1236055A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/208—Circuits specially adapted for scintillation detectors, e.g. for the photo-multiplier section
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/36—Measuring spectral distribution of X-rays or of nuclear radiation spectrometry
    • G01T1/40—Stabilisation of spectrometers

Definitions

  • Device and method for measuring light intensity using a photomultiplier comprising a calibration source.
  • the invention relates to the measurement of light intensity using photomultipliers.
  • the gain of a photomultiplier is subject to short-term fluctuations, such as those resulting from temperature variations of this photomultiplier, and to long-term fluctuations or drifts, such as those resulting from wear and age. photomultiplier.
  • the invention aims to avoid this drawback.
  • the subject of the invention is a device for measuring the light intensity of a radiation comprising a photomultiplier comprising a main window for entering said radiation and an input photocathode arranged in the field of said window, characterized in that it also includes a calibration source adapted to emit radiation of constant intensity directed towards said photocathode.
  • the invention may also have one or more of the following characteristics: - said calibration source is a light-emitting diode.
  • the wavelength of the maximum emission intensity of said diode belongs to the range of wavelengths of maximum sensitivity of said photomultiplier.
  • the device comprises a scintillator element arranged across the main input window and adapted to convert the radiation to be measured into radiation of wavelength adapted to the sensitivity of said photomultiplier, the calibration source emitting directly to said photocathode without cross the scintillator.
  • the calibration radiation can be applied directly to the photomultiplier without passing through the scintillator.
  • the invention also relates to a device for measuring the interaction of radiation with a material comprising a main source of radiation, a device for measuring the light intensity of the radiation having interacted with said material according to the invention, and means for placing said material on the path of the radiation between said main source and said measuring device.
  • Said main source of radiation may be a source of radiation
  • the device according to the invention also comprises:
  • a pulsed X-ray source is used to ensure the periodic extinction of said source; preferably, this pulsed source then comprises an X-ray emission tube comprising a filament, an anode and a cathode, and means for applying a high alternating voltage between said anode and said cathode.
  • Such an X-ray source is robust and economical.
  • the invention also relates to a method for measuring the light intensity of a radiation using the device according to the invention in which the measurement of the radiation to be measured is related to that of the radiation from the calibration source; more precisely, this process comprises the stages in which, successively:
  • the calibration source being switched off or closed, using the photomultiplier, the intensity of the radiation to be measured is measured
  • the radiation to be measured being extinguished or closed, using the photomultiplier maintained under the same adjustment conditions, the intensity of the radiation from the calibration source is measured, - And the final radiation intensity value is deduced by relating the measurement of the radiation to be measured to that of the radiation from the calibration source.
  • the invention finally relates to the use of the device or method according to the invention for measuring the thickness of a material interacting by absorption with said radiation to be measured.
  • FIG. 1 is a simplified diagram of a device for measuring thickness of material comprising the light intensity measuring device according to the invention
  • - Figure 2 is a diagram of the successive measurement sequences of the method according to the invention
  • - Figures 3A and 3B are simplified electrical diagrams of pulsed and continuous X-ray source respectively.
  • the invention is implemented in a device for measuring the thickness of a material 3; the thickness measurement is based in a conventional manner on that of the absorption of radiation by this material.
  • the thickness measurement device comprises a main source 1 of radiation, a device 2 for measuring the light intensity of the radiation which has interacted by absorption with the material 3 and means not shown for placing the material 3 on the path of the radiation. between main source 1 and measuring device 2.
  • the measuring device 2 comprises a photomultiplier 4.
  • the photomultiplier 4 comprises in a conventional manner a main window for entering the radiation to be measured and an input photocathode, not shown, arranged in the field of said window, according to the invention, the measuring device 2 comprises a calibration source 5 adapted to emit radiation of constant light intensity directed towards the photocathode.
  • this device 2 also comprises means 6 for preamplification and coding of the signal delivered by the photomultiplier 4 and means 7 for decoding connected both to the preamplification means 6 and to the calibration source 5.
  • main source 1 if the material 3 is opaque to visible radiation, an X-ray source is used which emits in a wavelength range suitable for measuring the thickness of this material; as the photomultipliers are generally not very sensitive for the detection of X-ray radiation, the photomultiplier 4 is provided with a scintillator element 8 arranged across its main input window and adapted to convert the radiation to be measured into radiation of length d wave adapted to the sensitivity of the photomultiplier.
  • the calibration source is arranged so as to emit directly to the photocathode of the photomultiplier 4, without passing through the scintillator 8.
  • a pulsed X-ray source which comprises an X-ray emission tube 1 - or tube "X" - comprising a filament, an anode and a cathode , and means for applying an alternating high voltage between said anode and said cathode:
  • FIG. 3A represents the diagram of such a pulsed source, without rectifier on the high voltage circuit, as opposed to the diagram of a so-called continuous source represented in FIG. 3B, which includes a rectifier on the high voltage circuit.
  • the pulsed emission mode of this source advantageously forms means for periodically switching off the main source 1 of radiation.
  • a light-emitting diode is preferably used as the calibration source 5.
  • the measuring device 2 finally comprises means for activating the calibration source 5 only during the periods of extinction of the radiation source 1 and the decoding means 7 are adapted to report the measurement carried out by the photomultiplier 4 subjected to the radiation at measure during an emission pulse from the source main 1 to the measurement made by the photomultiplier 4 under the same conditions during a period of emission from the calibration source 5.
  • the calibration source 5 does not emit and is switched off , and, using the photomultiplier, the intensity of the radiation coming from this source 1 is measured through the material 3,
  • the calibration source 5 emits (“on” mode) and, using the photomultiplier maintained under the same adjustment conditions, the intensity of the radiation from the calibration source 5 is measured.
  • the decoding means 7 are adapted to separate the signals delivered by the photomultiplier during the phases B (actual measurement) and the signals delivered by the photomultiplier during the phases C
  • the final radiation intensity values are deduced by relating the radiation measurements carried out during phases B to those carried out during phases C.
  • the values obtained are then independent of the fluctuations or drifts of the photomultiplier.
  • the temperature of the light-emitting diode is stabilized in a temperature range where its emissivity is the most stable and the most independent of the temperature.
  • the thickness of the material 3 is then deduced in a manner known per se from the radiation intensity values obtained.
  • the radiation measuring device according to the invention can be used for a wide variety of applications which go far beyond the field of measurement of material thickness or the wavelength range of X-rays.
  • the radiation intensity measurement device makes it possible to know the influence of spurious signals on the measurement delivered by the photomultiplier.
  • the device and method according to the invention thus make it possible to control the “reception” section independently of the “transmission” section of an installation.
  • many devices use photomultiplier type detectors equipped with scintillators, in particular conventional “X” ray gauges; with reference to FIGS. 3A and 3B, the invention makes it possible, without interrupting the measurement of light intensity, to take special advantage of the pulsed emission gauges which remain by far the most reliable due to the rusticity of their X-ray source. »Which is only composed (fig. 3A) of a filament heating transformer, a high voltage transformer direct supply of the tube between anode and cathode and of the tube" X "itself.
  • a continuous source comprising a possible rectification and filtering by capacitor (FIG. 3B) would not have made it possible to implement the invention so simply and economically and the device obtained would have been less reliable.

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Length-Measuring Devices Using Wave Or Particle Radiation (AREA)
  • Measurement Of Radiation (AREA)

Abstract

The invention relates to a device (2) for measuring the luminous intensity of radiation, comprising a photomultiplier (4) which has a photoelectric input cathode and a calibration source (5). Said calibration source is adapted to emit radiation of a constant intensity towards said photoelectric cathode. According to the inventive method, the measurement for the radiation to be measured is related to that of the radiation of the calibration source. The advantages of the invention include the elimination of fluctuations and/or deviations of the photomultiplier gain. The invention can be advantageously used with pulsed X-rays.

Description

Dispositif et procédé de mesure d'intensité lumineuse à l'aide d'un photomultiplicateur comportant une source de calibrage. Device and method for measuring light intensity using a photomultiplier comprising a calibration source.
L'invention concerne la mesure d'intensité lumineuse à l'aide de photomultiplicateurs. Le gain d'un photomultiplicateur est soumis à des fluctuations à court terme, comme celles résultant de variations de température de ce photomultiplicateur, et à des fluctuations ou dérives à long terme, comme celles résultant de l'usure et de l'âge de ce photomultiplicateur.The invention relates to the measurement of light intensity using photomultipliers. The gain of a photomultiplier is subject to short-term fluctuations, such as those resulting from temperature variations of this photomultiplier, and to long-term fluctuations or drifts, such as those resulting from wear and age. photomultiplier.
Ces fluctuations ou dérives du gain entachent d'erreurs les mesures délivrées directement par le photomultiplicateur.These fluctuations or drift in the gain taint the measurements delivered directly by the photomultiplier with errors.
L'invention a pour but d'éviter cet inconvénient.The invention aims to avoid this drawback.
A cet effet, l'invention a pour objet un dispositif de mesure de l'intensité lumineuse d'un rayonnement comprenant un photomultiplicateur comportant une fenêtre principale d'entrée dudit rayonnement et une photocathode d'entrée disposée dans le champ de ladite fenêtre, caractérisé en ce qu'il comprend également une source de calibrage adaptée pour émettre un rayonnement d'intensité constante orienté vers ladite photocathode.To this end, the subject of the invention is a device for measuring the light intensity of a radiation comprising a photomultiplier comprising a main window for entering said radiation and an input photocathode arranged in the field of said window, characterized in that it also includes a calibration source adapted to emit radiation of constant intensity directed towards said photocathode.
L'invention peut également présenter une ou plusieurs des caractéristiques suivantes : - ladite source de calibrage est une diode électroluminescente.The invention may also have one or more of the following characteristics: - said calibration source is a light-emitting diode.
- la longueur d'onde de l'intensité maximale d'émission de ladite diode appartient au domaine de longueurs d'onde de sensibilité maximale dudit photomultiplicateur.the wavelength of the maximum emission intensity of said diode belongs to the range of wavelengths of maximum sensitivity of said photomultiplier.
- le dispositif comprend un élément scintillateur disposé en travers de la fenêtre principale d'entrée et adapté pour convertir le rayonnement à mesurer en un rayonnement de longueur d'onde adaptée à la sensibilité dudit photomultiplicateur, la source de calibrage émettant directement vers ladite photocathode sans traverser le scintillateur.- The device comprises a scintillator element arranged across the main input window and adapted to convert the radiation to be measured into radiation of wavelength adapted to the sensitivity of said photomultiplier, the calibration source emitting directly to said photocathode without cross the scintillator.
Comme l'élément scintillateur n'est en général soumis à aucune fluctuation ou dérive, le rayonnement de calibration peut être appliqué directement au photomultiplicateur sans passer par le scintillateur.As the scintillator element is generally not subject to any fluctuation or drift, the calibration radiation can be applied directly to the photomultiplier without passing through the scintillator.
L'invention a également pour objet un dispositif de mesure d'interaction d'un rayonnement avec un matériau comprenant une source principale de rayonnement, un dispositif de mesure de l'intensité lumineuse du rayonnement ayant interagi avec ledit matériau selon l'invention, et des moyens pour disposer ledit matériau sur le trajet du rayonnement entre ladite source principale et ledit dispositif de mesure. Ladite source principale de rayonnement peut être une source de rayonsThe invention also relates to a device for measuring the interaction of radiation with a material comprising a main source of radiation, a device for measuring the light intensity of the radiation having interacted with said material according to the invention, and means for placing said material on the path of the radiation between said main source and said measuring device. Said main source of radiation may be a source of radiation
X.X.
De préférence, le dispositif selon l'invention comprend également :Preferably, the device according to the invention also comprises:
- des moyens pour éteindre la source de rayonnement ou obturer le rayonnement à mesurer, - des moyens pour activer ladite source de calibrage uniquement pendant les périodes d'extinction ou d'obturation dudit rayonnement,- means for switching off the radiation source or closing off the radiation to be measured, - means for activating said calibration source only during the periods of extinction or shutter of said radiation,
- et des moyens pour rapporter la mesure effectuée par le photomultiplicateur soumis au rayonnement à mesurer pendant une période où ce rayonnement n'est ni éteint ni obturé à la mesure effectuée par le photomultiplicateur dans les mêmes conditions pendant une période où la source de calibrage est activée.- And means for reporting the measurement carried out by the photomultiplier subjected to the radiation to be measured during a period when this radiation is neither extinguished nor closed at the measurement carried out by the photomultiplier under the same conditions during a period when the calibration source is activated.
Dans le cas d'une source de rayonnement X, de préférence, on utilise une source de rayonnement X puisée pour assurer l'extinction périodique de ladite source ; de préférence, cette source puisée comprend alors un tube d'émission de rayons X comportant un filament, une anode et une cathode, et des moyens pour appliquer une haute tension alternative entre ladite anode et ladite cathode.In the case of an X-ray source, preferably, a pulsed X-ray source is used to ensure the periodic extinction of said source; preferably, this pulsed source then comprises an X-ray emission tube comprising a filament, an anode and a cathode, and means for applying a high alternating voltage between said anode and said cathode.
Une telle source de rayonnement X est robuste et économique.Such an X-ray source is robust and economical.
L'invention a également pour objet un procédé de mesure de l'intensité lumineuse d'un rayonnement à l'aide du dispositif selon l'invention dans lequel on rapporte la mesure du rayonnement à mesurer à celle du rayonnement de la source de calibrage ; plus précisément, ce procédé comprend les étapes dans lesquelles, successivement :The invention also relates to a method for measuring the light intensity of a radiation using the device according to the invention in which the measurement of the radiation to be measured is related to that of the radiation from the calibration source; more precisely, this process comprises the stages in which, successively:
- la source de calibrage étant éteinte ou obturée, à l'aide du photomultiplicateur, on mesure l'intensité du rayonnement à mesurer,- the calibration source being switched off or closed, using the photomultiplier, the intensity of the radiation to be measured is measured,
- puis, le rayonnement à mesurer étant éteint ou obturé, à l'aide du photomultiplicateur maintenu dans les mêmes conditions de réglage, on mesure l'intensité du rayonnement de la source de calibrage, - et on déduit la valeur finale d'intensité du rayonnement en rapportant la mesure du rayonnement à mesurer à celle du rayonnement de la source de calibrage.- then, the radiation to be measured being extinguished or closed, using the photomultiplier maintained under the same adjustment conditions, the intensity of the radiation from the calibration source is measured, - And the final radiation intensity value is deduced by relating the measurement of the radiation to be measured to that of the radiation from the calibration source.
L'invention a enfin pour objet l'utilisation du dispositif ou du procédé selon l'invention pour mesurer l'épaisseur d'un matériau interagissant par absorption avec ledit rayonnement à mesurer.The invention finally relates to the use of the device or method according to the invention for measuring the thickness of a material interacting by absorption with said radiation to be measured.
L'invention sera mieux comprise à la lecture de la description qui va suivre, donnée à titre d'exemple non limitatif, et en référence aux figures annexées sur lesquelles : - la figure 1 est un schéma simplifié d'un dispositif de mesure d'épaisseur de matériau comprenant le dispositif de mesure d'intensité lumineuse selon l'invention,The invention will be better understood on reading the description which follows, given by way of nonlimiting example, and with reference to the appended figures in which: - Figure 1 is a simplified diagram of a device for measuring thickness of material comprising the light intensity measuring device according to the invention,
- la figure 2 est un diagramme des séquences successives de mesure du procédé selon l'invention, - les figures 3A et 3B sont des schémas électriques simplifiés de source à rayonnement X respectivement puisée et continue.- Figure 2 is a diagram of the successive measurement sequences of the method according to the invention, - Figures 3A and 3B are simplified electrical diagrams of pulsed and continuous X-ray source respectively.
Selon cette description non limitative, l'invention est mise en œuvre dans un dispositif pour mesurer l'épaisseur d'un matériau 3 ; la mesure d'épaisseur repose d'une manière classique sur celle de l'absorption d'un rayonnement par ce matériau.According to this nonlimiting description, the invention is implemented in a device for measuring the thickness of a material 3; the thickness measurement is based in a conventional manner on that of the absorption of radiation by this material.
Le dispositif de mesure d'épaisseur comprend une source principale 1 de rayonnement, un dispositif 2 de mesure de l'intensité lumineuse du rayonnement ayant interagi par absorption avec le matériau 3 et des moyens non représentés pour disposer le matériau 3 sur le trajet du rayonnement entre la source principale 1 et le dispositif de mesure 2.The thickness measurement device comprises a main source 1 of radiation, a device 2 for measuring the light intensity of the radiation which has interacted by absorption with the material 3 and means not shown for placing the material 3 on the path of the radiation. between main source 1 and measuring device 2.
Le dispositif de mesure 2 comporte un photomultiplicateur 4. Le photomultiplicateur 4 comporte d'une manière classique une fenêtre principale d'entrée du rayonnement à mesurer et une photocathode d'entrée non représentée disposée dans le champ de ladite fenêtre, Selon l'invention, le dispositif de mesure 2 comprend une source de calibrage 5 adaptée pour émettre un rayonnement d'intensité lumineuse constante orienté vers la photocathode. D'une manière classique, ce dispositif 2 comporte également des moyens 6 de préamplification et de codage du signal délivré par le photomultiplicateur 4 et des moyens 7 de décodage reliés à la fois aux moyens de préamplification 6 et à la source de calibrage 5. Comme source principale 1 , si le matériau 3 est opaque au rayonnement visible, on utilise une source de rayons X qui émet dans un domaine de longueurs d'onde adapté à la mesure d'épaisseur de ce matériau ; comme les photomultiplicateurs sont en général peu sensibles pour la détection de rayonnement X, le photomultiplicateur 4 est doté d'un élément scintillateur 8 disposé en travers de sa fenêtre principale d'entrée et adapté pour convertir le rayonnement à mesurer en un rayonnement de longueur d'onde adaptée à la sensibilité du photomultiplicateur.The measuring device 2 comprises a photomultiplier 4. The photomultiplier 4 comprises in a conventional manner a main window for entering the radiation to be measured and an input photocathode, not shown, arranged in the field of said window, according to the invention, the measuring device 2 comprises a calibration source 5 adapted to emit radiation of constant light intensity directed towards the photocathode. In a conventional manner, this device 2 also comprises means 6 for preamplification and coding of the signal delivered by the photomultiplier 4 and means 7 for decoding connected both to the preamplification means 6 and to the calibration source 5. As main source 1, if the material 3 is opaque to visible radiation, an X-ray source is used which emits in a wavelength range suitable for measuring the thickness of this material; as the photomultipliers are generally not very sensitive for the detection of X-ray radiation, the photomultiplier 4 is provided with a scintillator element 8 arranged across its main input window and adapted to convert the radiation to be measured into radiation of length d wave adapted to the sensitivity of the photomultiplier.
On remarque que la source de calibrage est disposée de façon à émettre directement vers la photocathode du photomultiplicateur 4, sans traverser le scintillateur 8.It will be noted that the calibration source is arranged so as to emit directly to the photocathode of the photomultiplier 4, without passing through the scintillator 8.
En référence à la figure 3A, comme source principale 1 , on utilise de préférence une source de rayons X puisée, qui comprend un tube d'émission 1 de rayons X - ou tube « X » - comportant un filament, une anode et une cathode, et des moyens pour appliquer une haute tension alternative entre ladite anode et ladite cathode : la figure 3A représente le schéma d'une telle source puisée, sans redresseur sur le circuit de haute tension, par opposition au schéma d'une source dite continue représentée en figure 3B, qui comporte un redresseur sur le circuit de haute tension.With reference to FIG. 3A, as the main source 1, a pulsed X-ray source is preferably used, which comprises an X-ray emission tube 1 - or tube "X" - comprising a filament, an anode and a cathode , and means for applying an alternating high voltage between said anode and said cathode: FIG. 3A represents the diagram of such a pulsed source, without rectifier on the high voltage circuit, as opposed to the diagram of a so-called continuous source represented in FIG. 3B, which includes a rectifier on the high voltage circuit.
Le mode puisé d'émission de cette source forme avantageusement des moyens pour éteindre périodiquement la source principale 1 de rayonnement.The pulsed emission mode of this source advantageously forms means for periodically switching off the main source 1 of radiation.
Comme source de calibrage 5, on utilise de préférence une diode électroluminescente.As the calibration source 5, a light-emitting diode is preferably used.
Le dispositif de mesure 2 comprend enfin des moyens pour activer la source de calibrage 5 uniquement pendant les périodes d'extinction de la source de rayonnement 1 et les moyens de décodage 7 sont adaptés pour rapporter la mesure effectuée par le photomultiplicateur 4 soumis au rayonnement à mesurer pendant une pulsation d'émission de la source principale 1 à la mesure effectuée par le photomultiplicateur 4 dans les mêmes conditions pendant une période d'émission de la source de calibrage 5.The measuring device 2 finally comprises means for activating the calibration source 5 only during the periods of extinction of the radiation source 1 and the decoding means 7 are adapted to report the measurement carried out by the photomultiplier 4 subjected to the radiation at measure during an emission pulse from the source main 1 to the measurement made by the photomultiplier 4 under the same conditions during a period of emission from the calibration source 5.
On va maintenant décrire le procédé pour mettre en œuvre l'invention.We will now describe the process for implementing the invention.
En référence à la figure 2, se succèdent alternativement les deux séquences de mesure d'intensité lumineuse suivantes :With reference to FIG. 2, the following two light intensity measurement sequences alternate one after the other:
- pendant l'alternance positive (+) d'alimentation du tube « X » correspondant à l'émission de la source 1 (phase B sur le diagramme de la figure 2), la source de calibrage 5 n'émet pas et est éteinte, et, à l'aide du photomultiplicateur, on mesure l'intensité du rayonnement provenant de cette source 1 au travers du matériau 3,- during the positive (+) alternation of supply of the tube “X” corresponding to the emission of the source 1 (phase B on the diagram of FIG. 2), the calibration source 5 does not emit and is switched off , and, using the photomultiplier, the intensity of the radiation coming from this source 1 is measured through the material 3,
- puis, pendant l'alternance négative (-) d'alimentation du tube « X », qui correspond à l'alternance inverse de polarisation anode-cathode où la source 1 n'émet pas et est ainsi éteinte (phase C sur le diagramme de la figure 2), la source de calibrage 5 émet (mode « allumée ») et, à l'aide du photomultiplicateur maintenu dans les mêmes conditions de réglage, on mesure l'intensité du rayonnement de la source de calibrage 5.- then, during the negative alternation (-) supply of the tube "X", which corresponds to the reverse alternation of anode-cathode polarization where the source 1 does not emit and is thus extinguished (phase C on the diagram in FIG. 2), the calibration source 5 emits (“on” mode) and, using the photomultiplier maintained under the same adjustment conditions, the intensity of the radiation from the calibration source 5 is measured.
Les moyens de décodage 7 sont adaptés pour séparer les signaux délivrés par le photomultiplicateur pendant les phases B (mesure à proprement parler) et les signaux délivrés par le photomultiplicateur pendant les phases CThe decoding means 7 are adapted to separate the signals delivered by the photomultiplier during the phases B (actual measurement) and the signals delivered by the photomultiplier during the phases C
(calibrage).(calibration).
On déduit les valeurs finales d'intensité du rayonnement en rapportant les mesures de rayonnement effectuées pendant les phases B à celles effectuées pendant les phases C. Avantageusement, les valeurs obtenues sont alors indépendantes des fluctuations ou des dérives du photomultiplicateur.The final radiation intensity values are deduced by relating the radiation measurements carried out during phases B to those carried out during phases C. Advantageously, the values obtained are then independent of the fluctuations or drifts of the photomultiplier.
De préférence, on stabilise la température de la diode électroluminescente dans un domaine de température où son émissivité est la plus stable et la plus indépendante de la température. On déduit ensuite d'une manière connue en elle-même l'épaisseur du matériau 3 des valeurs d'intensité de rayonnement obtenues.Preferably, the temperature of the light-emitting diode is stabilized in a temperature range where its emissivity is the most stable and the most independent of the temperature. The thickness of the material 3 is then deduced in a manner known per se from the radiation intensity values obtained.
Le dispositif de mesure de rayonnement selon l'invention peut être utilisé pour des applications très diverses qui débordent largement le domaine de la mesure d'épaisseur de matériau ou le domaine de longueur d'onde des rayons X.The radiation measuring device according to the invention can be used for a wide variety of applications which go far beyond the field of measurement of material thickness or the wavelength range of X-rays.
A la mise en route d'une jauge à rayons « X » ou sur dysfonctionnement, le dispositif de mesure d'intensité de rayonnement selon l'invention permet de connaître l'influence de signaux parasites sur la mesure délivrée par le photomultiplicateur.When an “X” ray gauge is started or when there is a malfunction, the radiation intensity measurement device according to the invention makes it possible to know the influence of spurious signals on the measurement delivered by the photomultiplier.
En stoppant la source d'émission « X » comme décrit ci-dessus et en activant la source de calibrage seule, il est alors très facile de mettre en évidence ces signaux parasites et d'effectuer les modifications pour désensibiliser, le cas échéant, l'installation (modification des régimes de zéro, blindages et masses par exemple ).By stopping the emission source "X" as described above and activating the calibration source alone, it is then very easy to highlight these spurious signals and to make the modifications to desensitize, if necessary, the 'installation (modification of zero regimes, shields and masses for example).
Le dispositif et le procédé selon l'invention permettent ainsi de contrôler la section « réception » indépendamment de la section « émission » d'une installation. Par ailleurs, de nombreux équipements utilisent des détecteurs de type photomultiplicateurs dotés de scintillateurs, en particulier les jauges classiques à rayons « X » ; en référence aux figures 3A et 3B, l'invention permet, sans interrompre la mesure d'intensité lumineuse, de tirer spécialement parti des jauges à émission puisée qui restent de loin les plus fiables du fait de la rusticité de leur source à rayons « X » qui n'est composée (fig. 3A) que d'un transformateur de chauffage filament, un transformateur haute tension d'alimentation directe du tube entre anode et cathode et du tube « X » lui même. Une source continue comprenant un redressement et filtrage éventuel par condensateur (fig. 3B) n'aurait pas permis de mettre en œuvre aussi simplement et économiquement l'invention et le dispositif obtenu aurait été moins fiable. The device and method according to the invention thus make it possible to control the “reception” section independently of the “transmission” section of an installation. In addition, many devices use photomultiplier type detectors equipped with scintillators, in particular conventional “X” ray gauges; with reference to FIGS. 3A and 3B, the invention makes it possible, without interrupting the measurement of light intensity, to take special advantage of the pulsed emission gauges which remain by far the most reliable due to the rusticity of their X-ray source. »Which is only composed (fig. 3A) of a filament heating transformer, a high voltage transformer direct supply of the tube between anode and cathode and of the tube" X "itself. A continuous source comprising a possible rectification and filtering by capacitor (FIG. 3B) would not have made it possible to implement the invention so simply and economically and the device obtained would have been less reliable.

Claims

REVENDICATIONS
1.- Dispositif (2) de mesure de l'intensité lumineuse d'un rayonnement comprenant un photomultiplicateur (4) comportant une fenêtre principale d'entrée dudit rayonnement et une photocathode d'entrée disposée dans le champ de ladite fenêtre, caractérisé en ce qu'il comprend également une source de calibrage (5) adaptée pour émettre un rayonnement d'intensité constante orienté vers ladite photocathode.1.- Device (2) for measuring the light intensity of a radiation comprising a photomultiplier (4) comprising a main window for entering said radiation and an input photocathode arranged in the field of said window, characterized in that that it also includes a calibration source (5) adapted to emit radiation of constant intensity directed towards said photocathode.
2.- Dispositif selon la revendication 1 caractérisé en ce que ladite source de calibrage est une diode électroluminescente.2.- Device according to claim 1 characterized in that said calibration source is a light emitting diode.
3.- Dispositif selon la revendication 2 caractérisé en ce que la longueur d'onde de l'intensité maximale d'émission de ladite diode appartient au domaine de longueurs d'onde de sensibilité maximale dudit photomultiplicateur.3.- Device according to claim 2 characterized in that the wavelength of the maximum emission intensity of said diode belongs to the range of wavelengths of maximum sensitivity of said photomultiplier.
4.- Dispositif selon l'une quelconque des revendications précédentes caractérisé en ce qu'il comprend un élément scintillateur (8) disposé en travers de la fenêtre principale d'entrée et adapté pour convertir le rayonnement à mesurer en un rayonnement de longueur d'onde adaptée à la sensibilité dudit photomultiplicateur, la source de calibrage émettant directement vers ladite photocathode sans traverser l'élément scintillateur (8).4.- Device according to any one of the preceding claims characterized in that it comprises a scintillator element (8) disposed across the main entrance window and adapted to convert the radiation to be measured into radiation of length wave adapted to the sensitivity of said photomultiplier, the calibration source emitting directly towards said photocathode without passing through the scintillator element (8).
5.- Dispositif de mesure d'interaction d'un rayonnement avec un matériau (3) comprenant une source principale de rayonnement (1 ), un dispositif (2) de mesure de l'intensité lumineuse du rayonnement ayant interagi avec ledit matériau (3) selon l'une quelconque des revendications 1 à 4, et des moyens pour disposer ledit matériau (3) sur le trajet du rayonnement entre ladite source principale (1 ) et ledit dispositif de mesure (2).5.- Device for measuring the interaction of radiation with a material (3) comprising a main source of radiation (1), a device (2) for measuring the light intensity of the radiation having interacted with said material (3 ) according to any one of claims 1 to 4, and means for placing said material (3) on the radiation path between said main source (1) and said measuring device (2).
6.- Dispositif selon la revendication 5 caractérisé en ce que ladite source principale de rayonnement est une source de rayons X. 6.- Device according to claim 5 characterized in that said main source of radiation is a source of X-rays.
7.- Dispositif selon l'une quelconque des revendications précédentes caractérisé en ce qu'il comprend :7.- Device according to any one of the preceding claims, characterized in that it comprises:
- des moyens pour éteindre la source de rayonnement (1 ) ou obturer le rayonnement à mesurer, - des moyens pour activer ladite source de calibrage (5) uniquement pendant les périodes d'extinction ou d'obturation dudit rayonnement,- means for switching off the radiation source (1) or closing off the radiation to be measured, - means for activating said calibration source (5) only during the periods of extinction or shutter of said radiation,
- et des moyens pour rapporter la mesure effectuée par le photomultiplicateur (4) soumis au rayonnement à mesurer pendant une période où ce rayonnement n'est ni éteint ni obturé à la mesure effectuée par le photomultiplicateur (4) dans les mêmes conditions pendant une période où la source de calibrage (5) est activée.- And means for reporting the measurement carried out by the photomultiplier (4) subjected to the radiation to be measured during a period when this radiation is neither extinguished nor blocked at the measurement carried out by the photomultiplier (4) under the same conditions for a period where the calibration source (5) is activated.
8.- Dispositif selon la revendication 7 dépendant de la revendication 6, caractérisé en ce que ladite source de rayons X est puisée pour assurer l'extinction périodique de ladite source (1 ).8.- Device according to claim 7 dependent on claim 6, characterized in that said X-ray source is pulsed to ensure the periodic extinction of said source (1).
9.- Dispositif selon la revendication 8 caractérisé en ce que ladite source puisée comprend un tube d'émission de rayons X comportant un filament, une anode et une cathode, et des moyens pour appliquer une haute tension alternative entre ladite anode et ladite cathode.9.- Device according to claim 8 characterized in that said pulsed source comprises an X-ray emission tube comprising a filament, an anode and a cathode, and means for applying a high alternating voltage between said anode and said cathode.
10.- Procédé de mesure de l'intensité lumineuse d'un rayonnement à l'aide du dispositif selon l'une quelconque des revendications 1 à 4 dans lequel on rapporte la mesure du rayonnement à mesurer à celle du rayonnement de la source de calibrage (5).10.- A method of measuring the light intensity of a radiation using the device according to any one of claims 1 to 4 in which the measurement of the radiation to be measured is related to that of the radiation from the calibration source. (5).
11.- Procédé de mesure de l'intensité lumineuse d'un rayonnement à l'aide du dispositif (2) selon l'une quelconque des revendications 1 à 4 caractérisé en ce qu'il comprend les étapes dans lesquelles, successivement : - la source de calibrage (5) étant éteinte ou obturée, à l'aide du photomultiplicateur (4), on mesure l'intensité du rayonnement à mesurer, - puis, le rayonnement à mesurer étant éteint ou obturé, à l'aide du photomultiplicateur (4) maintenu dans les mêmes conditions de réglage, on mesure l'intensité du rayonnement de la source de calibrage (5), - et on déduit la valeur finale d'intensité du rayonnement en rapportant la mesure du rayonnement à mesurer à celle du rayonnement de la source de calibrage.11.- A method of measuring the light intensity of a radiation using the device (2) according to any one of claims 1 to 4 characterized in that it comprises the steps in which, successively: - the calibration source (5) being switched off or closed, using the photomultiplier (4), the intensity of the radiation to be measured is measured, - then, the radiation to be measured being turned off or closed, using the photomultiplier (4) maintained under the same adjustment conditions, the intensity of the radiation from the calibration source (5) is measured, - and the final radiation intensity value by relating the measurement of the radiation to be measured to that of the radiation from the calibration source.
12.- Utilisation du dispositif selon l'une quelconque des revendications 1 à 9 ou du procédé selon l'une quelconque des revendications 10 à 1 1 pour mesurer l'épaisseur d'un matériau (3) interagissant par absorption avec ledit rayonnement à mesurer. 12. Use of the device according to any one of claims 1 to 9 or of the method according to any one of claims 10 to 1 1 for measuring the thickness of a material (3) interacting by absorption with said radiation to be measured .
EP00958735A 1999-08-26 2000-08-25 Device and method for measuring luminous intensity using a photomultiplier comprising a calibration source Withdrawn EP1236055A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR9910833A FR2797961B1 (en) 1999-08-26 1999-08-26 DEVICE AND METHOD FOR MEASURING LIGHT INTENSITY USING A PHOTOMULTIPLIER INCLUDING A CALIBRATION SOURCE
FR9910833 1999-08-26
PCT/FR2000/002370 WO2001014909A1 (en) 1999-08-26 2000-08-25 Device and method for measuring luminous intensity using a photomultiplier comprising a calibration source

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WO2007085060A1 (en) * 2006-01-30 2007-08-02 The University Of Sydney Fibre optic dosimeter
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WO2001014909A1 (en) 2001-03-01
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FR2797961B1 (en) 2001-12-07
AU7016200A (en) 2001-03-19

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