EP0025374B1 - Non-luminous-photons-into-luminous-photons converter and non-destructive testing apparatus using such a converter - Google Patents

Non-luminous-photons-into-luminous-photons converter and non-destructive testing apparatus using such a converter Download PDF

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Publication number
EP0025374B1
EP0025374B1 EP80401179A EP80401179A EP0025374B1 EP 0025374 B1 EP0025374 B1 EP 0025374B1 EP 80401179 A EP80401179 A EP 80401179A EP 80401179 A EP80401179 A EP 80401179A EP 0025374 B1 EP0025374 B1 EP 0025374B1
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Prior art keywords
photons
luminous
converter
radiation
source
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EP80401179A
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German (de)
French (fr)
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EP0025374A1 (en
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Jean-Claude Michel Dufay
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Laboratoire Central des Ponts et Chaussees
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Laboratoire Central des Ponts et Chaussees
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens

Definitions

  • the present invention relates to a converter of non-luminous input photons such as X or ⁇ photons, into light photons intended to be associated with a system for optical transmission and reproduction of the image formed on the converter, this converter being of the type formed by an independent screen arranged on the path of said non-luminous photons and comprising a layer of phosphor.
  • the invention also relates to an installation for the non-destructive testing of material such as reinforced or prestressed concrete.
  • the radioscopy or gammascopy systems existing in the medical and industrial field use low and medium energy X-rays: most often from 10 keV to 200 keV. These systems generally give an image of insufficient brightness, requiring observation in a dark room.
  • a palliative known by an article from Iron & Steel, published in the August 1966 issue, p. 381-387 by Halmshaw et al consists in amplifying the image obtained on leaving the screen by electronic means.
  • the screen is an integral part of an image intensifier and is no longer independent. In both cases, we have relatively heavy, bulky and fragile equipment. This type of apparatus gives very good quality images only if the radiation used is of low or medium energy and only if the controlled material is of low density and not very diffusing.
  • this same apparatus does not give a satisfactory result if the radiation used is high energy X or y radiation (up to 10 MeV), the conversion efficiency of the intensifier then not being high enough, and if the controlled material is dense and very diffusing (case of concrete).
  • the present invention firstly aims to propose an independent screen converter having a satisfactory efficiency for input photons of energy greater than 200 keV, by giving a satisfactory image which can be directly observed.
  • the present invention also aims to associate with the converter a non-destructive inspection installation by radioscopy or gamma-ray imaging giving good quality images on concrete thicknesses as large as possible, while being able to use the same sources of radiation as conventional radiography (Ir 192 and Cobalt 60).
  • radioscopy or gamma-ray imaging giving good quality images on concrete thicknesses as large as possible, while being able to use the same sources of radiation as conventional radiography (Ir 192 and Cobalt 60).
  • conventional radiography Ir 192 and Cobalt 60
  • the proposed device being intended for use on site, care should be taken to select components of low weight, small dimensions and very good mechanical strength, with the minimum of servitudes as to the electrical supplies necessary for its operation.
  • the converter according to the invention is characterized in that it comprises, from upstream to downstream, relative to the direction of movement of the non-luminous photons of entry, a light support, a metallic sheet in which said non-luminous photons are converted in non-luminous photons of lower energy, by Compton collision of said high energy photons on electrons of said metallic sheet, a thin layer reflecting light in titanium oxide, and the lumiphore layer.
  • the document FR-A-2345806 already discloses an image intensifier intended to be used with high energy radiation, associating with a layer of luminescent substance, a metal sheet in which the non-luminous photons input are converted into non-luminous photons of lower energy by Compton effect.
  • this intensifier is in the form of a glass vacuum tube, the fragility and size of which make use on site problematic.
  • the energy of the non-luminous input photons is substantially between 200 keV and 10 MeV.
  • the thickness of the metal sheet is between 100 and 500 k tm.
  • the metal sheet comprises at least one of the following metals: lead, gold.
  • the non-destructive testing installation is characterized in that it comprises: a source of non-luminous photonic radiation directing a flow of said radiation on the material to be checked, a lead filter disposed downstream of this material for stop low energy radiation from the scattering in said material of radiation from the source, a converter as described above, to transform the photons from said filter into light photons, a mirror inclined relative to the path of said light photons to receiving these photons and directing them onto the input objective of a television camera, and an image viewing device receiving the video signal supplied by said camera.
  • the source, on the one hand, and the detection assembly comprising the converter, the mirror and the television camera, on the other hand, are each associated with respective displacement means for moving them in at least two directions. spatial, these displacement means being remotely controllable.
  • the installation shown includes: a source of X or ⁇ radiation, 1 directing a beam of high energy radiation 2 towards a reinforced concrete or prestressed concrete to be inspected 3, a lead filter 4 stopping the low energy radiation from the scattering in the material 3 of the radiation 2 coming from the source 1, a converter 5 transforming the X or y photons coming from the filter 4 into light photons 6 forming an image of suitable format, for example of 30 cm x 40 cm, a mirror 7 disposed at 45 ° relative to the plane 5a of the converter 5, this mirror receiving the light 6 supplied by the converter 5 and having a high reflection coefficient, for example 0.97, for the emission wavelength of the converter 5, a television camera 8 analyzing line by line the image reflected by the mirror 7, this camera 8 preferably being at low light level, and being equipped with an optical objective 8a of high brightness and large aperture , for example open rant at f / 0.95, and a display device - or monitor - 9 displaying the image obtained from the video signal which is supplied by the camera 8 and
  • the radiation supplied by the source 1 is preferably of energy between 200 keV and 10 MeV.
  • This source 1 can be a Cobalt 60 or Iridium 192 source; alternatively, this source can be of the type comprising an accelerator directing a flow of electrically charged particles on a target.
  • Known y-visible or X-visible converters generally have a very low efficiency - or yield - as soon as the energy of the photons X or y exceeds 200 keV. It was therefore excluded to use one of these converters in the inspection and / or control installation presently described.
  • the converter represented in FIG. 2 has the advantage of giving, from high energy X or y photons, an image of sufficient quality for the search for defects in concrete.
  • a converter is not fragile, it is simple to use and, in particular, it does not require complicated electronic equipment, and it is thin, light, and available - or easy to make - in dimensions identical to those of commonly used x-ray films: 30 cm x 40 cm.
  • This converter comprises contiguously and from left to right in FIG. 2: a cardboard support 13, a metallic sheet of lead or gold, 14 of approximately 250 ⁇ m thick, arranged on one face of said support 13, a reflective layer of titanium oxide Ti0 2 , 15, of approximately 10 ⁇ m thick, a fluorescent layer of Zn SCd: Ag, 16 of approximately 1000 ⁇ m thick and a protective layer 17 of approximately 10 ⁇ .Lm thick.
  • the photons ⁇ or X - from the material to be checked 3 are transformed into visible light by the converter 5: the image thus formed on this converter is taken up by the mirror 7 with a high reflection coefficient (0.97), for the length emission wave of the converter 5, and analyzed by the television camera at low light level 8.
  • the video signal coming from the camera 8 forms, at a distance, the image sought on the television screen 9.
  • This image can be recorded either on the video recorder 11, for later examination, or on the graphic video image recorder 12 for archiving or insertion in a folder.
  • the quality of the image obtained can be improved at the output of the camera 8 by the storage-integration unit 10 (improvement of the signal / noise ratio, that is to say of the contrast).
  • This type of screen converter typically has a 12.8% improvement in brightness, compared to a known medical fluorescent screen used under the same conditions. The contrast is increased by 12%. Other measurements have also shown that the brightness of this screen is produced mainly by the primary radiation coming from the material to be checked, whereas in the case of the known medical screen, this luminosity is mainly due to the scattered radiation.
  • the limit resolution of the complete chain in Figure 1 is that of the converter, i.e. 1 ⁇ l / mm at 4% contrast.
  • the so-called televised radioscopy chain thus formed typically gives perfectly usable images up to a thickness of concrete traversed by 45 cm for a Cobalt 60 source of 250 Ci, and 1 m thick for a linear accelerator delivering 700 rad / min at 1 m at 10 MeV.
  • This televised radioscopy chain is advantageously applied to the control of the quality of concrete injections and to the positioning of prestressed cables in concrete.
  • the source 1 and the detector assembly 4 and 5, 7 and 8, designated below under the reference 19 must move in synchronism on either side of the concrete wall 30 to be inspected. This will be achieved by “piloting on sight of the assembly according to the principle of FIG. 3.
  • the source 1 and the detection sub-assembly 19 are each associated with means, respectively 20 and 21, for their displacement in X, and Z or in X, Y and Z; the means 20 and 21 are each remotely controlled by a respective manual control device 22 and 23.
  • Figures 4 box bridge
  • 5 beam bridge
  • 6 slab bridge
  • the source 1 is preferably a linear accelerator
  • Figures 3 to 6 the same elements are designated by the same references.
  • Figure 6 shows, on its right and left halves, two modes of arrangement of the inspection chain.
  • the displacement means 20 and 21 are mechanically independent from one another, while, according to FIG. 5, these means are joined together by a structural element 24. According to FIG. 6, a single displacement means 20 ensures the displacement of the units 1 and 19.
  • the so-called high-energy televised radioscopy installation which has just been described is mainly intended for the control of prestressed concrete engineering structures, using high energy X or y radiation (preferably from 200 keV to 10 MeV). It implements a special fluometallic converter specially designed and manufactured for this installation.
  • the televised radioscopy chain described can also find its application whenever an almost instantaneous visualization of defects existing in a more or less dense material is necessary, from X or ⁇ radiation of high energy (for example in industry building, wood, metallurgy, etc.) and where a limit resolution of 1 pl / mm at 4% contrast is sufficient.

Abstract

The invention relates to a converter for converting non-luminous, so-called input photons such as X or gamma photons, into luminous photons, and to an installation for the non-destructive inspection of a material, employing this converter. The converter comprises a layer of luminophore disposed on the path of said non-luminous photons and, upstream of said layer of luminophore, with respect to the direction of displacement of the non-luminous photons, a metal foil in which said non-luminous photons are converted into non-luminous photons of lower energy, by collision (Compton effect) of said input photons on electrons of said metal foil. The invention is more particularly applicable to the non-destructive inspection of concrete structures.

Description

La présente invention concerne un convertisseur de photons non lumineux d'entrée tels que photons X ou γ, en photons lumineux destiné à être associé à un système de transmission optique et de reproduction de l'image formée sur le convertisseur, ce convertisseur étant du type formé par un écran indépendant disposé sur le trajet desdits photons non lumineux et comportant une couche de luminophore.The present invention relates to a converter of non-luminous input photons such as X or γ photons, into light photons intended to be associated with a system for optical transmission and reproduction of the image formed on the converter, this converter being of the type formed by an independent screen arranged on the path of said non-luminous photons and comprising a layer of phosphor.

L'invention concerne aussi une installation pour le contrôle non destructif de matériau tel que le béton armé ou précontraint.The invention also relates to an installation for the non-destructive testing of material such as reinforced or prestressed concrete.

Les systèmes de radioscopie ou gammascopie existant dans le domaine médical et industriel utilisent des rayonnements X de basse et moyenne énergie : le plus souvent de 10 keV à 200 keV. Ces systèmes donnent en général une image de luminosité insuffisante, exigeant une observation en chambre obscure. Un palliatif connu par un article de Iron & Steel, paru dans le numéro d'août 1966, p. 381-387 par Halmshaw et al consiste à amplifier l'image obtenue à la sortie de l'écran par des moyens électroniques. Dans une autre solution, l'écran fait partie intégrante d'un amplificateur de brillance et n'est plus indépendant. Dans les deux cas, on a un matériel relativement lourd, encombrant et fragile. Ce type d'appareillage ne donne des images de très bonne qualité que si le rayonnement utilisé est de faible ou moyenne énergie et que si le matériau contrôlé est de faible densité et peu diffusant.The radioscopy or gammascopy systems existing in the medical and industrial field use low and medium energy X-rays: most often from 10 keV to 200 keV. These systems generally give an image of insufficient brightness, requiring observation in a dark room. A palliative known by an article from Iron & Steel, published in the August 1966 issue, p. 381-387 by Halmshaw et al consists in amplifying the image obtained on leaving the screen by electronic means. In another solution, the screen is an integral part of an image intensifier and is no longer independent. In both cases, we have relatively heavy, bulky and fragile equipment. This type of apparatus gives very good quality images only if the radiation used is of low or medium energy and only if the controlled material is of low density and not very diffusing.

En revanche, ce même appareillage ne donne pas de résultat satisfaisant si le rayonnement utilisé est un rayonnement X ou y de forte énergie (jusqu'à 10 MeV), l'efficacité de conversion de l'intensificateur n'étant pas alors assez élevée, et si le matériau contrôlé est dense et très diffusant (cas du béton).On the other hand, this same apparatus does not give a satisfactory result if the radiation used is high energy X or y radiation (up to 10 MeV), the conversion efficiency of the intensifier then not being high enough, and if the controlled material is dense and very diffusing (case of concrete).

C'est pourquoi la présente invention a d'abord pour but de proposer un convertisseur à écran indépendant ayant une efficacité satisfaisante pour des photons d'entrée d'énergie supérieure à 200 keV, en donnant une image satisfaisante directement observable.This is why the present invention firstly aims to propose an independent screen converter having a satisfactory efficiency for input photons of energy greater than 200 keV, by giving a satisfactory image which can be directly observed.

La présente invention a aussi pour but d'associer au convertisseur une installation de contrôle non destructif par radioscopie ou gammascopie donnant des images de bonne qualité sur des épaisseurs de bétons aussi importantes que possible, tout en pouvant utiliser les mêmes sources de rayonnement qu'en gammagraphie classique (Ir 192 et Cobalt 60). De plus, le dispositif proposé étant destiné à un emploi sur chantier, on doit s'attacher à sélectionner des composants de faible poids, faibles dimensions et de très bonne résistance mécanique, avec le minimum de servitudes quant aux alimentations électriques nécessaires à son fonctionnement.The present invention also aims to associate with the converter a non-destructive inspection installation by radioscopy or gamma-ray imaging giving good quality images on concrete thicknesses as large as possible, while being able to use the same sources of radiation as conventional radiography (Ir 192 and Cobalt 60). In addition, the proposed device being intended for use on site, care should be taken to select components of low weight, small dimensions and very good mechanical strength, with the minimum of servitudes as to the electrical supplies necessary for its operation.

Le convertisseur conforme à l'invention est caractérisé en ce qu'il comprend, d'amont en aval, relativement au sens de déplacement des photons non lumineux d'entrée, un support léger, une feuille métallique dans laquelle lesdits photons non lumineux sont convertis en photons non lumineux d'énergie inférieure, par collision Compton desdits photons de haute énergie sur des électrons de ladite feuille métallique, une couche mince réflectrice de la lumière en oxyde de titane, et la couche de lumiphore.The converter according to the invention is characterized in that it comprises, from upstream to downstream, relative to the direction of movement of the non-luminous photons of entry, a light support, a metallic sheet in which said non-luminous photons are converted in non-luminous photons of lower energy, by Compton collision of said high energy photons on electrons of said metallic sheet, a thin layer reflecting light in titanium oxide, and the lumiphore layer.

Il est à noter qu'on connait déjà par le document FR-A-2345806 un intensificateur d'image destiné à être utilisé avec un rayonnement de haute énergie, associant à une couche de substance luminescente, une feuille métallique dans laquelle les photons non lumineux d'entrée sont convertis en photons non lumineux d'énergie inférieure par effet Compton. Toutefois, cet intensificateur se présente sous forme d'un tube à vide en verre dont la fragilité et l'encombrement rendent l'emploi sur chantier problématique.It should be noted that the document FR-A-2345806 already discloses an image intensifier intended to be used with high energy radiation, associating with a layer of luminescent substance, a metal sheet in which the non-luminous photons input are converted into non-luminous photons of lower energy by Compton effect. However, this intensifier is in the form of a glass vacuum tube, the fragility and size of which make use on site problematic.

Avantageusement, l'énergie des photons non lumineux d'entrée est sensiblement comprise entre 200 keV et 10 MeV.Advantageously, the energy of the non-luminous input photons is substantially between 200 keV and 10 MeV.

Avantageusement, l'épaisseur de la feuille métallique est comprise entre 100 et 500 ktm.Advantageously, the thickness of the metal sheet is between 100 and 500 k tm.

Avantageusement, la feuille métallique comprend au moins l'un des métaux suivants : le plomb, l'or.Advantageously, the metal sheet comprises at least one of the following metals: lead, gold.

L'installation de contrôle non destructif conforme à l'invention est caractérisée en ce qu'elle comprend : une source de rayonnement photonique non lumineux dirigeant un flux dudit rayonnement sur le matériau à contrôler, un filtre au plomb disposé en aval de ce matériau pour arrêter le rayonnement de basse énergie provenant de la diffusion dans ledit matériau du rayonnement issu de la source, un convertisseur tel que décrit plus haut, pour transformer les photons issus dudit filtre en photons lumineux, un miroir incliné par rapport au trajet desdits photons lumineux pour recevoir ces photons et les diriger sur l'objectif d'entrée d'une caméra de télévision, et un dispositif de visualisation d'image recevant le signal vidéo fourni par ladite caméra.The non-destructive testing installation according to the invention is characterized in that it comprises: a source of non-luminous photonic radiation directing a flow of said radiation on the material to be checked, a lead filter disposed downstream of this material for stop low energy radiation from the scattering in said material of radiation from the source, a converter as described above, to transform the photons from said filter into light photons, a mirror inclined relative to the path of said light photons to receiving these photons and directing them onto the input objective of a television camera, and an image viewing device receiving the video signal supplied by said camera.

Avantageusement, la source, d'une part, et l'ensemble de détection comprenant le convertisseur, le miroir et la caméra de télévision, d'autre part, sont chacun associés à des moyens de déplacement respectifs pour les déplacer dans au moins deux directions spatiales, ces moyens de déplacement étant commandables à distance.Advantageously, the source, on the one hand, and the detection assembly comprising the converter, the mirror and the television camera, on the other hand, are each associated with respective displacement means for moving them in at least two directions. spatial, these displacement means being remotely controllable.

D'autres caractéristiques et avantages de l'invention seront mieux compris à la lecture de la description qui va suivre de plusieurs exemples de réalisation et en se référant aux dessins annexés dans lesquels :

  • la figure 1 est un schéma d'une installation de contrôle non destructif selon un mode de réalisation de l'invention ;
  • la figure 2 est une vue en coupe transversale du convertisseur utilisé par l'installation de la figure 1 ;
  • la figure 3 est un schéma d'un premier mode de mise en oeuvre de l'installation de la figure 1 ;
  • la figure 4 est un schéma d'un deuxième mode de mise en oeuvre de l'installation de la figure 1 ;
  • la figure 5 est un schéma d'un troisième mode de mise en oeuvre de l'installation de la figure 1 ; et
  • la figure 6 est un schéma d'un quatrième mode de mise en oeuvre de l'installation de la figure 1.
Other characteristics and advantages of the invention will be better understood on reading the description which follows of several exemplary embodiments and with reference to the appended drawings in which:
  • Figure 1 is a diagram of a non-destructive testing installation according to one embodiment of the invention;
  • Figure 2 is a cross-sectional view of the converter used by the installation of FIG. 1;
  • Figure 3 is a diagram of a first embodiment of the installation of Figure 1;
  • Figure 4 is a diagram of a second embodiment of the installation of Figure 1;
  • Figure 5 is a diagram of a third embodiment of the installation of Figure 1; and
  • FIG. 6 is a diagram of a fourth embodiment of the installation of FIG. 1.

L'installation représentée comprend : une source de rayonnement X ou γ, 1 dirigeant un faisceau de rayonnement de forte énergie 2 vers une masse en béton armé ou précontraint à inspecter 3, un filtre en plomb 4 arrêtant le rayonnement de basse énergie provenant de la diffusion dans le matériau 3 du rayonnement 2 issu de la source 1, un convertisseur 5 transformant les photons X ou y issus du filtre 4 en photons lumineux 6 formant une image de format convenable, par exemple de 30 cm x 40 cm, un miroir 7 disposé à 45° par rapport au plan 5a du convertisseur 5, ce miroir recevant la lumière 6 fournie par le convertisseur 5 et ayant un coefficient de réflexion élevé, par exemple de 0,97, pour la longueur d'onde d'émission du convertisseur 5, une caméra de télévision 8 analysant ligne par ligne l'image réfléchie par le miroir 7, cette caméra 8 étant, de préférence, à bas niveau de lumière, et étant équipée d'un objectif optique 8a de grande luminosité et de grande ouverture, par exemple ouvrant à f/0,95, et un dispositif de visualisation - ou moniteur - 9 visualisant l'image obtenue à partir du signal vidéo qui est fourni par la caméra 8 et qui est, le cas échéant, préalablement traité dans une unité de mémorisation-intégration 10 pour amélioration du rapport signal/bruit. Cette image peut également être enregistrée soit sur un magnétoscope 11, soit sur un enregistreur graphique d'image vidéo 12.The installation shown includes: a source of X or γ radiation, 1 directing a beam of high energy radiation 2 towards a reinforced concrete or prestressed concrete to be inspected 3, a lead filter 4 stopping the low energy radiation from the scattering in the material 3 of the radiation 2 coming from the source 1, a converter 5 transforming the X or y photons coming from the filter 4 into light photons 6 forming an image of suitable format, for example of 30 cm x 40 cm, a mirror 7 disposed at 45 ° relative to the plane 5a of the converter 5, this mirror receiving the light 6 supplied by the converter 5 and having a high reflection coefficient, for example 0.97, for the emission wavelength of the converter 5, a television camera 8 analyzing line by line the image reflected by the mirror 7, this camera 8 preferably being at low light level, and being equipped with an optical objective 8a of high brightness and large aperture , for example open rant at f / 0.95, and a display device - or monitor - 9 displaying the image obtained from the video signal which is supplied by the camera 8 and which is, if necessary, previously processed in a storage unit -integration 10 for improvement of the signal / noise ratio. This image can also be recorded either on a video recorder 11 or on a graphic video image recorder 12.

Le rayonnement fourni par la source 1 est, de préférence, d'énergie comprise entre 200 keV et 10 MeV.The radiation supplied by the source 1 is preferably of energy between 200 keV and 10 MeV.

Cette source 1 peut être une source au Cobalt 60 ou à l'Iridium 192 ; alternativement, cette source peut être du type comportant un accélérateur dirigeant un flux de particules chargées électriquement sur une cible.This source 1 can be a Cobalt 60 or Iridium 192 source; alternatively, this source can be of the type comprising an accelerator directing a flow of electrically charged particles on a target.

Les convertisseurs y-visible, ou X-visible connus ont généralement une efficacité - ou un rendement - très faible dès que l'énergie des photons X ou y dépasse 200 keV. Il était donc exclu d'utiliser un de ces convertisseurs dans l'installation d'inspection et/ou de contrôle présentement décrite.Known y-visible or X-visible converters generally have a very low efficiency - or yield - as soon as the energy of the photons X or y exceeds 200 keV. It was therefore excluded to use one of these converters in the inspection and / or control installation presently described.

Le convertisseur représenté sur la figure 2 présente l'avantage de donner, à partir de photons X ou y de haute énergie une image de qualité suffisante pour la recherche de défauts dans le béton. En outre, un tel convertisseur n'est pas fragile, il est simple d'emploi et, notamment, il ne nécessite pas d'équipement électronique compliqué, et il est peu épais, léger, et disponible - ou facile à réaliser - dans des dimensions identiques à celles des films radiographiques couramment employés : 30 cm x 40 cm.The converter represented in FIG. 2 has the advantage of giving, from high energy X or y photons, an image of sufficient quality for the search for defects in concrete. In addition, such a converter is not fragile, it is simple to use and, in particular, it does not require complicated electronic equipment, and it is thin, light, and available - or easy to make - in dimensions identical to those of commonly used x-ray films: 30 cm x 40 cm.

Ce convertisseur comprend de façon jointive et de gauche à droite sur la figure 2 : un support en carton 13, une feuille métallique de plomb ou d'or, 14 d'environ 250 µm d'épaisseur, disposée sur une face dudit support 13, une couche réflectrice en oxyde de titane Ti02, 15, d'environ 10 µm d'épaisseur, une couche fluorescente en Zn SCd : Ag, 16 d'environ 1 000 µm d'épaisseur et une couche protectrice 17 d'environ 10 ¡.Lm d'épaisseur.This converter comprises contiguously and from left to right in FIG. 2: a cardboard support 13, a metallic sheet of lead or gold, 14 of approximately 250 μm thick, arranged on one face of said support 13, a reflective layer of titanium oxide Ti0 2 , 15, of approximately 10 μm thick, a fluorescent layer of Zn SCd: Ag, 16 of approximately 1000 μm thick and a protective layer 17 of approximately 10 ¡ .Lm thick.

Le fonctionnement de l'installation d'inspection - ou contrôle - qui vient d'être décrite est le suivant ;The operation of the inspection installation - or control - which has just been described is as follows;

Les photons γ ­ ou X - issus du matériau à contrôler 3 sont transformés en lumière visible par le convertisseur 5 : l'image ainsi formée sur ce convertisseur est reprise par le miroir 7 de coefficient de réflexion élevé (0,97), pour la longueur d'onde d'émission du convertisseur 5, et analysée par la caméra de télévision à bas niveau de lumière 8. Le signal vidéo issu de la caméra 8 forme, à distance, l'image cherchée sur l'écran de télévision 9. Cette image peut être enregistrée soit sur le magnétoscope 11, pour examen ultérieur, soit sur l'enregistreur graphique d'images vidéo 12 pour archivage ou insertion dans un dossier. La qualité de l'image obtenue peut être améliorée à la sortie de la caméra 8 par l'unité de mémorisation-intégration 10 (amélioration du rapport signal/bruit, c'est-à-dire du contraste).The photons γ or X - from the material to be checked 3 are transformed into visible light by the converter 5: the image thus formed on this converter is taken up by the mirror 7 with a high reflection coefficient (0.97), for the length emission wave of the converter 5, and analyzed by the television camera at low light level 8. The video signal coming from the camera 8 forms, at a distance, the image sought on the television screen 9. This image can be recorded either on the video recorder 11, for later examination, or on the graphic video image recorder 12 for archiving or insertion in a folder. The quality of the image obtained can be improved at the output of the camera 8 by the storage-integration unit 10 (improvement of the signal / noise ratio, that is to say of the contrast).

Le fonctionnement du convertisseur 5 représenté à la figure 2 est le suivant :

  • Le rayonnement γ ­ ou X - 18 issu du matériau à contrôler 3 pénètre dans la feuille métallique de plomb ou d'or 14, disposée sur le support en carton 13 qui lui confère une rigidité suffisante. La feuille métallique 14 crée par diffusion Compton, des électrons et des photons diffusés d'énergie moindre, dont la somme est sensiblement égale à l'énergie primaire. Ces électrons et photons diffusés émergent de la feuille métallique 14 et pénètrent dans la couche fluorescente en Zn S Cd : Ag, 16 d'épaisseur 1 020 µm. Cette dernière émet alors une lumière visible de fluorescence. Une partie de la lumière ainsi créée étant dirigée vers l'arrière, une couche réflectrice en oxyde de titane 3 d'épaisseur 10 µm, renvoie la lumière vers l'avant et améliore donc la luminosité du convertisseur. Enfin la couche protectrice 17 de 10 µm assure à ce convertisseur une bonne tenue aux poussières, rayures, etc.
The operation of the converter 5 shown in FIG. 2 is as follows:
  • The γ or X - 18 radiation from the material to be checked 3 penetrates into the metallic lead or gold sheet 14, placed on the cardboard support 13 which gives it sufficient rigidity. The metal sheet 14 creates, by Compton scattering, scattered electrons and photons of energy, the sum of which is substantially equal to the primary energy. These scattered electrons and photons emerge from the metal sheet 14 and penetrate into the fluorescent layer of Zn S Cd: Ag, 16 with a thickness of 1020 μm. The latter then emits visible fluorescent light. Part of the light thus created being directed towards the rear, a reflective layer of titanium oxide 3 with a thickness of 10 μm, returns the light towards the front and therefore improves the brightness of the converter. Finally, the protective layer 17 of 10 μm ensures that this converter has good resistance to dust, scratches, etc.

Ce type d'écran-convertisseur présente typiquement une amélioration de luminosité de 12,8 %, par rapport à un écran fluorescent médical connu utilisé dans les mêmes conditions. Le contraste est augmenté de 12 %. D'autres mesures ont montré également que la luminosité de cet écran est produite en majeure partie par le rayonnement primaire issu du matériau à contrôler alors que dans le cas de l'écran médical connu, cette luminosité est due principalement au rayonnement diffusé.This type of screen converter typically has a 12.8% improvement in brightness, compared to a known medical fluorescent screen used under the same conditions. The contrast is increased by 12%. Other measurements have also shown that the brightness of this screen is produced mainly by the primary radiation coming from the material to be checked, whereas in the case of the known medical screen, this luminosity is mainly due to the scattered radiation.

La résolution limite de la chaîne complète de la figure 1 est celle du convertisseur, soit 1 pl/mm à 4 % de contraste.The limit resolution of the complete chain in Figure 1 is that of the converter, i.e. 1 µl / mm at 4% contrast.

La chaîne dite de radioscopie télévisée ainsi constituée donne typiquement des images parfaitement exploitables jusqu'à une épaisseur de béton traversé de 45 cm pour une source de Cobalt 60 de 250 Ci, et 1 m d'épaisseur pour un accélérateur linéaire délivrant 700 rad/mn à 1 m sous 10 MeV.The so-called televised radioscopy chain thus formed typically gives perfectly usable images up to a thickness of concrete traversed by 45 cm for a Cobalt 60 source of 250 Ci, and 1 m thick for a linear accelerator delivering 700 rad / min at 1 m at 10 MeV.

Cette chaîne de radioscopie télévisée est avantageusement appliquée au contrôle de la qualité des injections de béton et au positionnement des câbles de précontraintes dans le béton.This televised radioscopy chain is advantageously applied to the control of the quality of concrete injections and to the positioning of prestressed cables in concrete.

Pour effectuer ce contrôle, la source 1 et l'ensemble détecteur 4 et 5, 7 et 8, désigné ci-après sous la référence 19, doivent se déplacer en synchronisme de part et d'autre de la paroi en béton 30 à inspecter. Ceci sera réalisé par un « pilotage à vue de l'ensemble suivant le principe de la figure 3.To carry out this control, the source 1 and the detector assembly 4 and 5, 7 and 8, designated below under the reference 19, must move in synchronism on either side of the concrete wall 30 to be inspected. This will be achieved by “piloting on sight of the assembly according to the principle of FIG. 3.

Selon le schéma de la figure 3, la source 1 et le sous-ensemble de détection 19 sont chacun associés à des moyens, respectivement 20 et 21, pour leur déplacement en X, et Z ou en X, Y et Z ; les moyens 20 et 21 sont chacun commandés à distance par un dispositif de commande manuelle respectif 22 et 23.According to the diagram in FIG. 3, the source 1 and the detection sub-assembly 19 are each associated with means, respectively 20 and 21, for their displacement in X, and Z or in X, Y and Z; the means 20 and 21 are each remotely controlled by a respective manual control device 22 and 23.

L'utilisation de la chaîne d'inspection sur les trois principaux types d'ouvrages en béton est illustrée aux figures 4 (pont caisson), 5 (pont poutre) et 6 (pont dalle). Pour ce dernier type d'ouvrage, la source 1 est, de préférence, un accélérateur linéaire. Sur les figures 3 à 6 les mêmes éléments sont désignés par les mêmes références. La figure 6 montre, sur ses moitiés de droite et de gauche, deux modes de disposition de la chaîne d'inspection.The use of the inspection chain on the three main types of concrete structures is illustrated in Figures 4 (box bridge), 5 (beam bridge) and 6 (slab bridge). For the latter type of structure, the source 1 is preferably a linear accelerator. In Figures 3 to 6 the same elements are designated by the same references. Figure 6 shows, on its right and left halves, two modes of arrangement of the inspection chain.

Il est à noter que, selon les figures 3 et 4, les moyens de déplacement 20 et 21 sont mécaniquement indépendants l'un de l'autre, tandis que, selon la figure 5, ces moyens sont solidarisés entre eux par un élément de structure 24. Selon la figure 6, un seul moyen de déplacement 20 assure le déplacement des unités 1 et 19.It should be noted that, according to FIGS. 3 and 4, the displacement means 20 and 21 are mechanically independent from one another, while, according to FIG. 5, these means are joined together by a structural element 24. According to FIG. 6, a single displacement means 20 ensures the displacement of the units 1 and 19.

L'installation dite de radioscopie télévisée en haute énergie qui vient d'être décrite est principalement destinée au contrôle des ouvrages d'art en béton précontraint, à partir d'un rayonnement X ou y de forte énergie (de préférence de 200 keV à 10 MeV). Elle met en oeuvre un convertisseur spécial fluométallique spécialement étudié et fabriqué pour cette installation.The so-called high-energy televised radioscopy installation which has just been described is mainly intended for the control of prestressed concrete engineering structures, using high energy X or y radiation (preferably from 200 keV to 10 MeV). It implements a special fluometallic converter specially designed and manufactured for this installation.

La chaîne de radioscopie télévisée décrite peut également trouver son application à chaque fois qu'une visualisation quasi instantanée de défauts existant dans un matériau plus ou moins dense est nécessaire, à partir de rayonnement X ou γ de forte énergie (par exemple dans l'industrie du bâtiment, du bois, de la métallurgie, etc.) et là où une résolution limite de 1 pl/mm à 4 % de contraste est suffisante.The televised radioscopy chain described can also find its application whenever an almost instantaneous visualization of defects existing in a more or less dense material is necessary, from X or γ radiation of high energy (for example in industry building, wood, metallurgy, etc.) and where a limit resolution of 1 pl / mm at 4% contrast is sufficient.

Claims (9)

1. Converter of non-luminous photons, socal- led input photons such as X or photons, into luminous photons, designed to be associated with a system of optical transmission and reproduction of the image formed on the converter, this converter being of the type formed by an independent screen disposed on the path of said non-luminous photons, and comprising a layer of luminophore (16), characterized in that it comprises, from upstream to downstream, with respect to the direction of displacement of the non-luminous input photons, a light support (13), a metal foil in which said non-luminous photons are converted into non-luminous photons of lower energy, by collision (Compton effect) of said input photons on electrons of said metal foil, a thin reflecting layer made of titanium oxide, and the luminophore layer (16).
2. Converter according to claim 1, characterized in that the support (13) is made of cardboard.
3. Converter according to any one of claims 1 or 2, characterized in that the energy of the non-luminous input photons is substantially between 200 KeV and MeV.
4. Converter according to any one of claims 1 to 3, characterized in that the thickness of the metal foil (14) is between 100 and 500 ¡.Lm.
5. Converter according to any one of claims 1 to 4, characterized in that said metal foil (14) comprises at least one of the following metals : lead, gold.
6. Converter according to any one of claims 1 to 5, characterized in that the luminophore layer is made of Zn S Cd : Ag with a thickness of between 600 and 1,500 µm, and preferably about 1,000 µm.
7. Installation for a non-destructive inspection of a material, making use of a converter according to any one of claims 1 to 6, characterized in that it comprises a source of non-luminous photon radiation (1) directing a flux of said radiation (2) onto the material to be inspected, (3, 30, 31, 32, 33), a lead filter (4) disposed downstream of this material to stop the low-energy radiation coming from the diffusion in said material of the radiation (2) issuing from the source (1), the converter (5) for converting the photons issuing from said filter into luminous photons (6), a mirror (7) inclined with respect to the path of said luminous photons (6) to receive these photons and direct them onto the inlet lens (8a) of a television camera (8), and an image display (9) receiving the video signal furnished by said camera (8).
8. Installation according to claim 7, characterized in that, in addition, the source (1) contains at least one of the following radioactive substances : Iridium 192 and Cobalt 60.
9. Installation according to any one of claims 7 or 8, characterized in that, in addition, the source (1) on the one hand, and the detection assembly (19) comprising the converter (5), the mirror (7) and television camera (8), on the other hand, are each associated with respective displacement means (20, 21) for displacing them in at least two spatial directions, these displacement means being remotely controllable.
EP80401179A 1979-08-14 1980-08-12 Non-luminous-photons-into-luminous-photons converter and non-destructive testing apparatus using such a converter Expired EP0025374B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT80401179T ATE7087T1 (en) 1979-08-14 1980-08-12 CONVERTER OF NON-VISIBLE TO VISIBLE PHOTONS AND EQUIPMENT FOR NON-DESTRUCTIVE TESTING USING SUCH CONVERTER.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7920708 1979-08-14
FR7920708A FR2463420A1 (en) 1979-08-14 1979-08-14 NON-LUMINOUS PHOTON BRIGHT PHOTON CONVERTER AND NON-DESTRUCTIVE CONTROL PLANT USING SAID CONVERTER

Publications (2)

Publication Number Publication Date
EP0025374A1 EP0025374A1 (en) 1981-03-18
EP0025374B1 true EP0025374B1 (en) 1984-04-11

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US (1) US4398093A (en)
EP (1) EP0025374B1 (en)
JP (1) JPS56155900A (en)
AT (1) ATE7087T1 (en)
CA (1) CA1171559A (en)
DE (1) DE3067443D1 (en)
ES (1) ES8106210A1 (en)
FR (1) FR2463420A1 (en)

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JPS58122500A (en) * 1982-01-14 1983-07-21 富士写真フイルム株式会社 Radiation image conversion panel
JPS59148853A (en) * 1983-02-14 1984-08-25 Kansai Electric Power Co Inc:The Nondestructive testing method of concrete product or the like
NL8900040A (en) * 1989-01-09 1990-08-01 Philips Nv ROENTGEN IMAGE AMPLIFIER TUBE WITH SELECTIVE FILTER.
JP3741613B2 (en) 2001-01-29 2006-02-01 株式会社光子発生技術研究所 High energy X-ray imaging apparatus and method

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GB805802A (en) * 1955-09-26 1958-12-10 Gen Electric Improvements relating to radiant energy image intensifier systems
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DE1439344A1 (en) * 1964-03-11 1969-02-13 Siemens Ag Imager
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BE792387A (en) * 1971-12-31 1973-06-07 Agfa Gevaert Nv REINFORCEMENT SCREENS FOR X-RAY PHOTOGRAPHY
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Also Published As

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ES494236A0 (en) 1981-07-16
ES8106210A1 (en) 1981-07-16
JPS56155900A (en) 1981-12-02
EP0025374A1 (en) 1981-03-18
CA1171559A (en) 1984-07-24
ATE7087T1 (en) 1984-04-15
US4398093A (en) 1983-08-09
DE3067443D1 (en) 1984-05-17
FR2463420A1 (en) 1981-02-20
FR2463420B1 (en) 1982-11-12

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