CA2347401A1 - Method and device for isotope- selective measurement of chemical elements in materials - Google Patents
Method and device for isotope- selective measurement of chemical elements in materials Download PDFInfo
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- CA2347401A1 CA2347401A1 CA002347401A CA2347401A CA2347401A1 CA 2347401 A1 CA2347401 A1 CA 2347401A1 CA 002347401 A CA002347401 A CA 002347401A CA 2347401 A CA2347401 A CA 2347401A CA 2347401 A1 CA2347401 A1 CA 2347401A1
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- 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
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
- G01N21/718—Laser microanalysis, i.e. with formation of sample plasma
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- 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
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
- G01N21/64—Fluorescence; Phosphorescence
- G01N21/6402—Atomic fluorescence; Laser induced fluorescence
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Abstract
The invention relates to a method and device for isotope-selective measureme nt of chemical elements, especially radioactive elements, in materials, especially radioactive materials. The aim of the invention is to provide a method and a device which permits measurement of the total concentration and the isotope composition of the contained elements in a manner which is as ea sy as possible. To this end, an optical emission spectroscopy method, according to which plasma in the form of a sample vapor cloud is generated by laser ablation from a sample to be analyzed, is combined with a laser-induced fluorescence spectroscopy method, according to which the sample vapor cloud is analyzed by laser-induced excitation of fluorescence.
Description
Method and apparatus for isotope-selective measurement of chemical elements in materials 1o The present invention concerns a method and an apparatus for isotope-selective measurement of chemical elements in materials. It can be used in particular in relation to isotope-selective measurement of radioactive elements, in particular uranium and plutonium, in radioactive materials, such as for example in highly active waste glasses. The method according to the invention and the apparatus according to the invention can also be put to use in the context of measuring the isotope composition of lead for the determining the age of minerals. In a further configuration the invention also concerns the so-called remote measurement of radioactive isotopes and elements, in particular of uranium and plutonium, in radioactive materials, that is to say the measurement of those isotopes and elements from great distances, in order to minimize the danger both to human beings and equipment due to radioactivity.
In the reprocessing of depleted nuclear fuels for the recovery of fissile material radioactive wastes are produced in the various steps in the process. Accordingly for example the vitrification of highly active liquid waste (HLLW) results in an end product with a non-negligible content of uranium and plutonium. Hitherto, systematic on-line analysis of the glasses and other waste objects has been possible only at a comparatively high level of technical complication and expenditure if a large amount of 3o analysis data is to be acquired. In particular there is a wish on the part of the operators of reprocessing and vitrification installations to be able to analyze for example both the content of plutonium and uranium and also the corresponding isotope composition, by means of an analysis device which is easy to handle.
DE 195 31 988 A1 discloses an apparatus which is easy to handle, for the measurement of uranium or plutonium in radioactive materials, having a measuring head which can be put onto the sample to be analyzed. The known apparatus operates on the basis of pure optical emission spectroscopy and makes it possible in a comparatively simple manner to ascertain the content of plutonium and uranium in radioactive materials. It will be noted however that in the context of measurement operations with that apparatus, it is not possible to acquire further analysis data such as for example the isotope ratio of the material being analyzed. Further measurement operations are required for that purpose, which represent an undesirable additional expenditure.
Accordingly the object of the present invention is to provide a method and an apparatus for isotope-selective measurement of chemical elements, in particular radioactive elements in materials, in particular radioactive materials, by means of which, besides the content of chemical elements, in particular radioactive elements, it is also possible to analyze the corresponding isotope composition as rapidly and accurately as possible without in that respect having to implement additional measurement procedures.
That object is attained by a method as set forth in claim 1 and an apparatus as set forth in claim 6. Further embodiments of the invention are set forth in the appendant claims.
In accordance with the invention there is proposed a method of isotope-selective measurement of chemical elements, in particular radioactive elements, in materials, in particular radioactive materials, in which for measurement purposes the per se known optical emission spectroscopy method in which a plasma is generated in the form of a sample vapor cloud by laser ablation of a sample to be analyzed is coupled or combined with the per se known laser-induced fluorescence spectroscopy method in which laser-induced fluorescence excitation of the sample vapor cloud is effected.
Optical emission spectroscopy (referred to hereinafter as OES for the sake of brevity) with laser ablation is based on the following principle:
On the sample to be investigated, an amount of sample of the order of magnitude of Ng or less is ablated by laser bombardment and at the same time a plasma with thermally excited atoms is generated by the high level of laser output. The wavelength spectrum of the radiation from the plasma is characteristic in respect of the contained elements and the intensity of the radiation is proportional to the concentration of the associated element. The plasma has a life of between about 200 and 400 Ns and glows for between about 20 and 50 Ns, in each case in dependence on the ambient pressure and the irradiated laser power. Analysis of the radiation with a spectrograph or another dispersive element affords quantitative information about the composition of the sample. Detection is effected with photosensitive elements such as for example photomultipliers, photodiodes or photodiode arrays (referred to hereinafter as PDA for the sake of brevity) and photodiode panels (referred to hereinafter as CCD for the sake of brevity). In order to be able to implement accurate sensitive measurements, laser power, the measurement moment and the measurement duration as well as the pressure, and the atmosphere at which the measurement operations take place must be optimised. It will be appreciated that careful adjustment of all optical elements, in particular the converging and focusing units, is the basic prerequisite for success with the measurement operations and can represent a major problem depending on the respective measurement location involved.
In contrast thereto, laser-induced fluorescence spectroscopy (hereinafter referred to as LIF for the sake of brevity) is based on the following principle:
In the reprocessing of depleted nuclear fuels for the recovery of fissile material radioactive wastes are produced in the various steps in the process. Accordingly for example the vitrification of highly active liquid waste (HLLW) results in an end product with a non-negligible content of uranium and plutonium. Hitherto, systematic on-line analysis of the glasses and other waste objects has been possible only at a comparatively high level of technical complication and expenditure if a large amount of 3o analysis data is to be acquired. In particular there is a wish on the part of the operators of reprocessing and vitrification installations to be able to analyze for example both the content of plutonium and uranium and also the corresponding isotope composition, by means of an analysis device which is easy to handle.
DE 195 31 988 A1 discloses an apparatus which is easy to handle, for the measurement of uranium or plutonium in radioactive materials, having a measuring head which can be put onto the sample to be analyzed. The known apparatus operates on the basis of pure optical emission spectroscopy and makes it possible in a comparatively simple manner to ascertain the content of plutonium and uranium in radioactive materials. It will be noted however that in the context of measurement operations with that apparatus, it is not possible to acquire further analysis data such as for example the isotope ratio of the material being analyzed. Further measurement operations are required for that purpose, which represent an undesirable additional expenditure.
Accordingly the object of the present invention is to provide a method and an apparatus for isotope-selective measurement of chemical elements, in particular radioactive elements in materials, in particular radioactive materials, by means of which, besides the content of chemical elements, in particular radioactive elements, it is also possible to analyze the corresponding isotope composition as rapidly and accurately as possible without in that respect having to implement additional measurement procedures.
That object is attained by a method as set forth in claim 1 and an apparatus as set forth in claim 6. Further embodiments of the invention are set forth in the appendant claims.
In accordance with the invention there is proposed a method of isotope-selective measurement of chemical elements, in particular radioactive elements, in materials, in particular radioactive materials, in which for measurement purposes the per se known optical emission spectroscopy method in which a plasma is generated in the form of a sample vapor cloud by laser ablation of a sample to be analyzed is coupled or combined with the per se known laser-induced fluorescence spectroscopy method in which laser-induced fluorescence excitation of the sample vapor cloud is effected.
Optical emission spectroscopy (referred to hereinafter as OES for the sake of brevity) with laser ablation is based on the following principle:
On the sample to be investigated, an amount of sample of the order of magnitude of Ng or less is ablated by laser bombardment and at the same time a plasma with thermally excited atoms is generated by the high level of laser output. The wavelength spectrum of the radiation from the plasma is characteristic in respect of the contained elements and the intensity of the radiation is proportional to the concentration of the associated element. The plasma has a life of between about 200 and 400 Ns and glows for between about 20 and 50 Ns, in each case in dependence on the ambient pressure and the irradiated laser power. Analysis of the radiation with a spectrograph or another dispersive element affords quantitative information about the composition of the sample. Detection is effected with photosensitive elements such as for example photomultipliers, photodiodes or photodiode arrays (referred to hereinafter as PDA for the sake of brevity) and photodiode panels (referred to hereinafter as CCD for the sake of brevity). In order to be able to implement accurate sensitive measurements, laser power, the measurement moment and the measurement duration as well as the pressure, and the atmosphere at which the measurement operations take place must be optimised. It will be appreciated that careful adjustment of all optical elements, in particular the converging and focusing units, is the basic prerequisite for success with the measurement operations and can represent a major problem depending on the respective measurement location involved.
In contrast thereto, laser-induced fluorescence spectroscopy (hereinafter referred to as LIF for the sake of brevity) is based on the following principle:
In LIF an optical transition of a given kind of atom in an atomized sample vapor cloud which already in existence is selectively excited. By irradiation with a very narrow-band laser, the line width of the laser preferably being less than that of the transition to be excited, a kind of atom is transformed into an excited state and the radiation intensity which is emitted upon subsequent decay and which is proportional to the atom concentration is measured. Detection of the fluorescence is effected as in the case of OES using photosensitive elements such as for example photomultipliers or in the simplest case photodiodes. In this case local 1o resolution as afforded by PDAs and CCDs is not absolutely necessary. LIF
is extremely sensitive and accurate and is usually employed for isotope-selective measurement procedures. As in the case of OES the measurement moment and the measurement duration as well as the pressure and the atmosphere at which the measurement operations take place must also be optimized in LIF. The same applies in regard to adjustment of the necessary optical systems.
The core of the LIF method is a laser of tunable wavelength in order to be able to find and excite the appropriate atomic transition. It is possible for that purpose to use for example dye lasers which however are Zo comparatively expensive and relatively complicated in terms of handling.
It is also possible to use small inexpensive diode lasers. The type of diode laser is selected according to the desired wavelength and power as the tunable and useable wavelength range is not as great for the individual laser diode, as in the case of dye lasers. It is however possible to find for most kinds of atoms transitions for which there are suitable, commercially available diode,lasers. Diode lasers often have even a narrower line width than the conventional dye lasers.
In accordance with the invention the two above-outlined OES and LIF measurement methods are combined together in such a way that the 3o plasma which is generated by laser ablation in the context of OES
functions as an atomized sample vapor cloud whose existence is a prerequisite for excitation of an optical transition in accordance with LIF.
The method according to the invention has the advantage that only a single measurement pass is required in order on the one hand to ascertain the total concentration of the individual elements by means of the OES
measurement procedure and on the other hand to determine the isotope composition of the sample to be analyzed, by means of the LIF
measurement procedure.
Two different kinds of radiation occur in the context of the method according to the invention. The first kind involves the light which is emitted by the plasma and which is fed to a spectrograph for implementing the OES procedure. That kind of radiation is referred to hereinafter as emission radiation. The second kind of radiation involves that radiation which is radiated by the sample vapor cloud upon decay of the excited kind of atom in the context of the LIF procedure. That kind of radiation is referred to hereinafter as fluorescence radiation.
Depending on the structure of the apparatus for carrying out the method according to the invention, it is possible firstly to implement OES
measurement of the emission radiation and only then, using the sample vapor cloud generated for OES, to implement LIF measurement of the fluorescence radiation, or it is possible for OES and LIF measurement to be effected substantially simultaneously. If the measurement operations are carried out in succession, it is particularly advantageous if excitation for measurement of the fluorescence radiation is effected only when the plasma previously generated for emission radiation measurement is already substantially recombined.
If a laser diode is used for the LIF method, then this is correspondingly referred to as diode laser-induced fluorescence spectroscopy. This specific LIF method is referred to hereinafter as the DILF method.
In accordance with the invention, there is proposed an apparatus for isotope-selective measurement of chemical elements, in particular radioactive elements, in materials, in particular radioactive materials, comprising a first laser whose laser beam can be focused by means of a first focusing unit on a sample to be analyzed, so that light-emitting plasma is produced in the form of a sample vapor cloud for the purposes of OES, and a radiation analysis unit in which the image of the radiation emitted by the plasma can be formed by means of an imaging unit, which is characterized in that there is provided a second laser whose laser beam can be focused by means of a second focusing unit onto that space in which the plasma is produced so that laser-induced fluorescence excitation of the sample vapor cloud is possible.
Preferably a diode laser is selected for the second laser. The apparatus according to the invention serves moreover in particular for carrying out the method according to the invention.
The radiation analysis unit of the apparatus according to the invention, besides serving for detection of the emission radiation, can also serve for detection of the fluorescence radiation. A separate detection device for detection of the fluorescence radiation in the context of the LIF
measurement procedure can admittedly be provided but is not absolutely necessary. The radiation analysis unit is preferably a spectrograph but it z0 is also possible to use other dispersive elements.
Advantageously, the optical axes of the first and second focusing units are oriented in such a way that the laser beam of the first laser, that is to say the laser for implementing OES measurement, impinges substantially perpendicularly onto a substantially flat sample and the laser beam of the second laser, that is to say the laser for implementing LIF
measurement, passes through the sample vapor cloud without in that case impinging on the sample itself. Preferably, for that purpose, the optical axis of the first focusing unit can extend vertically and that of the second focusing unit can extend horizontally so that they are mutually perpendicular. In that situation they are disposed substantially in the same plane and are thus not inclined relative to each other.
is extremely sensitive and accurate and is usually employed for isotope-selective measurement procedures. As in the case of OES the measurement moment and the measurement duration as well as the pressure and the atmosphere at which the measurement operations take place must also be optimized in LIF. The same applies in regard to adjustment of the necessary optical systems.
The core of the LIF method is a laser of tunable wavelength in order to be able to find and excite the appropriate atomic transition. It is possible for that purpose to use for example dye lasers which however are Zo comparatively expensive and relatively complicated in terms of handling.
It is also possible to use small inexpensive diode lasers. The type of diode laser is selected according to the desired wavelength and power as the tunable and useable wavelength range is not as great for the individual laser diode, as in the case of dye lasers. It is however possible to find for most kinds of atoms transitions for which there are suitable, commercially available diode,lasers. Diode lasers often have even a narrower line width than the conventional dye lasers.
In accordance with the invention the two above-outlined OES and LIF measurement methods are combined together in such a way that the 3o plasma which is generated by laser ablation in the context of OES
functions as an atomized sample vapor cloud whose existence is a prerequisite for excitation of an optical transition in accordance with LIF.
The method according to the invention has the advantage that only a single measurement pass is required in order on the one hand to ascertain the total concentration of the individual elements by means of the OES
measurement procedure and on the other hand to determine the isotope composition of the sample to be analyzed, by means of the LIF
measurement procedure.
Two different kinds of radiation occur in the context of the method according to the invention. The first kind involves the light which is emitted by the plasma and which is fed to a spectrograph for implementing the OES procedure. That kind of radiation is referred to hereinafter as emission radiation. The second kind of radiation involves that radiation which is radiated by the sample vapor cloud upon decay of the excited kind of atom in the context of the LIF procedure. That kind of radiation is referred to hereinafter as fluorescence radiation.
Depending on the structure of the apparatus for carrying out the method according to the invention, it is possible firstly to implement OES
measurement of the emission radiation and only then, using the sample vapor cloud generated for OES, to implement LIF measurement of the fluorescence radiation, or it is possible for OES and LIF measurement to be effected substantially simultaneously. If the measurement operations are carried out in succession, it is particularly advantageous if excitation for measurement of the fluorescence radiation is effected only when the plasma previously generated for emission radiation measurement is already substantially recombined.
If a laser diode is used for the LIF method, then this is correspondingly referred to as diode laser-induced fluorescence spectroscopy. This specific LIF method is referred to hereinafter as the DILF method.
In accordance with the invention, there is proposed an apparatus for isotope-selective measurement of chemical elements, in particular radioactive elements, in materials, in particular radioactive materials, comprising a first laser whose laser beam can be focused by means of a first focusing unit on a sample to be analyzed, so that light-emitting plasma is produced in the form of a sample vapor cloud for the purposes of OES, and a radiation analysis unit in which the image of the radiation emitted by the plasma can be formed by means of an imaging unit, which is characterized in that there is provided a second laser whose laser beam can be focused by means of a second focusing unit onto that space in which the plasma is produced so that laser-induced fluorescence excitation of the sample vapor cloud is possible.
Preferably a diode laser is selected for the second laser. The apparatus according to the invention serves moreover in particular for carrying out the method according to the invention.
The radiation analysis unit of the apparatus according to the invention, besides serving for detection of the emission radiation, can also serve for detection of the fluorescence radiation. A separate detection device for detection of the fluorescence radiation in the context of the LIF
measurement procedure can admittedly be provided but is not absolutely necessary. The radiation analysis unit is preferably a spectrograph but it z0 is also possible to use other dispersive elements.
Advantageously, the optical axes of the first and second focusing units are oriented in such a way that the laser beam of the first laser, that is to say the laser for implementing OES measurement, impinges substantially perpendicularly onto a substantially flat sample and the laser beam of the second laser, that is to say the laser for implementing LIF
measurement, passes through the sample vapor cloud without in that case impinging on the sample itself. Preferably, for that purpose, the optical axis of the first focusing unit can extend vertically and that of the second focusing unit can extend horizontally so that they are mutually perpendicular. In that situation they are disposed substantially in the same plane and are thus not inclined relative to each other.
If laser ablation takes place in a vacuum or under a reduced gas pressure, the atoms retain their propagation direction after ablation.
There are no or only a few interatomic collisions which change the speed (in terms of magnitude and/or direction). That means that the atoms at the center of the rapidly propagating sample vapor cloud retain their preferential direction, more specifically perpendicularly to the surface of the sample. If now the atoms are excited by means of narrow-band laser radiation perpendicularly to the propagation direction and the fluorescence is additionally observed perpendicularly to the propagation direction, the l0 Doppler broadening of spectral lines is quite considerably reduced. That effect is of significance in particular in connection with the laser ablation effect. In order to achieve the highest possible level of spectral resolution the fluorescence must be measured from the center of the expanding sample vapor cloud. That is achieved on the one hand by a closely collimated diode laser beam and on the other hand by an operation involving forming an image of the central region of the expanding sample vapor cloud on (i) the photodetector (for example with apertures in front of the detector), (ii) the entrance opening of a glass fiber, or (iii) the entry slit of a spectrograph. In the last case the slit side members of the entry 2o slit mask out the decentral fluorescence region.
With an improvement in the spectral resolution by virtue of a reduction in the Doppler width isotope components can be better separated. That means that the level of selectivity of optical isotope measurement upon laser ablation is substantially increased. In addition it is possible quite generally to separate isotope components which have substantially smaller isotope shifts than uranium.
The reduction in Doppler broadening of spectral lines was observed for the first time by the inventors of the present invention on Z35U. It was possible to resolve the slight hyperfine splitting of the 682.88 nm line by 3o laser-induced fluorescence in the expanding ablation plasma.
There are no or only a few interatomic collisions which change the speed (in terms of magnitude and/or direction). That means that the atoms at the center of the rapidly propagating sample vapor cloud retain their preferential direction, more specifically perpendicularly to the surface of the sample. If now the atoms are excited by means of narrow-band laser radiation perpendicularly to the propagation direction and the fluorescence is additionally observed perpendicularly to the propagation direction, the l0 Doppler broadening of spectral lines is quite considerably reduced. That effect is of significance in particular in connection with the laser ablation effect. In order to achieve the highest possible level of spectral resolution the fluorescence must be measured from the center of the expanding sample vapor cloud. That is achieved on the one hand by a closely collimated diode laser beam and on the other hand by an operation involving forming an image of the central region of the expanding sample vapor cloud on (i) the photodetector (for example with apertures in front of the detector), (ii) the entrance opening of a glass fiber, or (iii) the entry slit of a spectrograph. In the last case the slit side members of the entry 2o slit mask out the decentral fluorescence region.
With an improvement in the spectral resolution by virtue of a reduction in the Doppler width isotope components can be better separated. That means that the level of selectivity of optical isotope measurement upon laser ablation is substantially increased. In addition it is possible quite generally to separate isotope components which have substantially smaller isotope shifts than uranium.
The reduction in Doppler broadening of spectral lines was observed for the first time by the inventors of the present invention on Z35U. It was possible to resolve the slight hyperfine splitting of the 682.88 nm line by 3o laser-induced fluorescence in the expanding ablation plasma.
It is particularly advantageous to provide a measurement head which can be applied to the sample or which can be fitted over the sample and which can be positioned as desired. If the surface area extent of the sample to be analyzed is greater than the opening of the chamber of the measurement head then the sample itself serves as a support or supporting surface for the measurement head. The sample is then not in the strict sense disposed within the chamber of the measurement head, but it is only ensured that the resulting plasma or the sample vapor cloud is within the measurement head. If the surface area extent of the sample is smaller than the opening of the chamber of the measurement head then the latter is inverted over the sample and requires some other support or supporting surface. In that case it is not only the resulting plasma but also the actual sample to be analyzed which are disposed within the measurement head.
As the measurement head carries the first and second focusing units and the imaging unit in a fixed arrangement relative to each other, no adjustment operations on those optical components are required, in a radioactive environment. The measurement head is small, mobile and sufficiently robust to be able to reliably carry the optical components. It is 2o the only part of the apparatus according to the invention, in an advantageous development thereof, that comes into contact with the sample to be analyzed. Both plasma generation by laser ablation, fluorescence production and also collection of the emission radiation which is used for the analysis procedure takes place in the measurement head.
The measurement head which for example is freely placed on the sample by means of a manipulator arm can be connected to the other components of the measurement apparatus by way of optical fibers and electric cables of any length. In the case of a radioactive sample those other components are disposed completely outside the radioactive area in 3o a transportable unit.
As the measurement head carries the first and second focusing units and the imaging unit in a fixed arrangement relative to each other, no adjustment operations on those optical components are required, in a radioactive environment. The measurement head is small, mobile and sufficiently robust to be able to reliably carry the optical components. It is 2o the only part of the apparatus according to the invention, in an advantageous development thereof, that comes into contact with the sample to be analyzed. Both plasma generation by laser ablation, fluorescence production and also collection of the emission radiation which is used for the analysis procedure takes place in the measurement head.
The measurement head which for example is freely placed on the sample by means of a manipulator arm can be connected to the other components of the measurement apparatus by way of optical fibers and electric cables of any length. In the case of a radioactive sample those other components are disposed completely outside the radioactive area in 3o a transportable unit.
The entire measurement apparatus can be of a transportable nature. Flexible use in various environments outside laboratories is possible. There is no need for chemical decomposition procedures or other sample preparation operations prior to measurement. The total material ablation by the first laser, the ablation laser, in a measurement procedure, is less than 1 Ng.
The measurement head which is flexible in terms of handling permits remote measurement of radioactive elements, in particular uranium and plutonium, in radioactive materials. It is possible to 1o implement both investigations of extensive sample surfaces and also random-type point measurement operations.
An embodiment of the present invention is described by way of example hereinafter with reference to the accompanying drawings in which Figure 1 is a diagrammatic view of the apparatus according to the invention with measurement units which are necessary for the measurement operation and their networking, Figure 2 is a diagrammatic view of a measurement head according to the invention with its individual components, zo Figures 3a/b show an example of fluorescence measurement of the uranium isotope z38U with fluorescence excitation by frequency-modulated diode laser radiation of the wavelength ~, = 682.880 - 0.01 nm, wherein Figure 3a shows a comparison of the spectra with and without DLIF
measurement, wherein the measurement procedure was effected with a z5 photodiode detection unit for detection of the fluorescence radiation and an oscilloscope with a respective laser shot and the DLIF is amplitude-modulated at 50 kHz, and Figure 3b shows a frequency spectrum of the DLIF spectrum as shown in Figure 3a after Fourier analysis.
The measurement head which is flexible in terms of handling permits remote measurement of radioactive elements, in particular uranium and plutonium, in radioactive materials. It is possible to 1o implement both investigations of extensive sample surfaces and also random-type point measurement operations.
An embodiment of the present invention is described by way of example hereinafter with reference to the accompanying drawings in which Figure 1 is a diagrammatic view of the apparatus according to the invention with measurement units which are necessary for the measurement operation and their networking, Figure 2 is a diagrammatic view of a measurement head according to the invention with its individual components, zo Figures 3a/b show an example of fluorescence measurement of the uranium isotope z38U with fluorescence excitation by frequency-modulated diode laser radiation of the wavelength ~, = 682.880 - 0.01 nm, wherein Figure 3a shows a comparison of the spectra with and without DLIF
measurement, wherein the measurement procedure was effected with a z5 photodiode detection unit for detection of the fluorescence radiation and an oscilloscope with a respective laser shot and the DLIF is amplitude-modulated at 50 kHz, and Figure 3b shows a frequency spectrum of the DLIF spectrum as shown in Figure 3a after Fourier analysis.
Figure 1 diagrammatically illustrates the apparatus according to the invention, while the details of the measurement head 17 are shown in Figure 2.
The evacuatable measurement head 17 can be freely positioned and preferably comprises aluminum. Its inside walls are matt black and it is of an approximately hemispherical shape of a diameter of about 8 cm. Its height is 5 cm. In the illustrated embodiment, the first and second focusing units 19 and 29 which are integrated in the measurement head wall 31 and the two imaging units 28 each comprise double-lens quartz optics which are arranged in blackened metal sleeves, preferably aluminum sleeves, of a diameter of 1 cm. They serve as focusing, imaging and collimating units and are commercially available or can be easily manufactured in-house. The measurement head 17 also has inlet nozzles 20 for the argon gas which promotes plasma generation and measurement.
Depending on the respective shape of the sample 23 the measurement head 17 can be fitted directly onto the surface 18 with a sealing ring 22, in particular a plastic sealing ring. The sample 23 can equally be disposed in a sample holder which is of a simple design 2o configuration and which is adapted to the measurement head 17, for example a smooth surface, onto which the measurement head 17 is set.
Adjustments of the optical system, that is to say the focusing units 19 and 29 and the two imaging units 28, are not necessary as they have already been effected upon assembly of the measurement head 17.
In order to achieve the best possible ablation conditions and an undisturbed plasma, argon gas is passed by way of the two inlet nozzles 20 into the measurement head 17 and the latter is evacuated by way of a valve 21 to a pressure of between 1 and 100 haPa.
By way of optical waveguides 13 (wavelength 1064 nm, diameter 600 Vim), the plasma-generating radiation 26 of a pulsed Nd:YAG laser 2 (1064 nm, pulse 40 mJ max., 5-10 ns, with optical waveguide coupling-in) is passed into the measurement head 17 and there focused by means of the first focusing unit 19 onto the surface of the sample 23. The emission radiation of the plasma 24 produced is passed by way of the two imaging units 28 and two optical waveguides 14 (each being an optical waveguide bundle with 200 ~m fibers, about 35 fibers) to a spectrograph 5 with a time-resolving intensified CCD-detector unit (hereinafter referred to as the ICCD-detector unit for the sake of brevity) as indicated at 6 and measured. The ICCD-detector unit 6 has a resolution of at least 578 x 384 pixels and can be cooled by a Pettier element and a through-flow cooler. The spectrograph 5 is a 0.5 m spectrograph with a wavelength range of between 250 and 750 nm and of a resolution of 20 pm or better.
For measurement value acquisition, evaluation and for starting the measurement procedure, the arrangement uses a fast Personal Computer (PC) 1 which is connected by way of electric cables 15, preferably BNC-cables, to the ICCD-controller 4 (intensified CCD-camera) and the Nd:YAG
laser 2.
Illumination of the ICCD-detector unit 6 is effected only after a certain delay time (in the us-range) with respect to plasma formation and with an illumination time of between about 20 and 50 ~s (light duration of 2o the plasma). For that purpose the ICCD-detector unit 6 is switched with pulse and delay times of between 1 us and 1 ms by way of a pulse-delay generator 3 connected to the ICCD-controller 4.
For the purposes of DLIF excitation, the narrow-band radiation 27 of the diode laser 7, with optical waveguide coupling-in and through-flow cooler, is focused onto the sample vapor cloud through the second focusing unit 29 which is integrated in the measurement head 17. The radiation is passed to the measurement head 17 by way of optical waveguides 13a of a diameter of 200 ~m or smaller. Wavelength adjustment is effected by way of the diode laser driver 8. The diode laser 7 radiates continuously.
In accordance with the invention, DLIF measurement can be effected in two different ways:
In accordance with the first method, the fluorescence radiation is passed by way of optical waveguides 14 to the spectrograph 5 and measured with the ICCD-detector unit 6. In order to avoid excessively intensive background radiation due to emission that measurement procedure is started at a time when the laser-generated plasma 24 has extensively recombined, that is to say after about 50 ~s. In a particularly advantageous manner, the ICCD-detector unit 6 can moreover be used to control by way of stray light the wavelength of the diode laser radiation. A
specific wavelength measuring device is redundant as a result.
In accordance with the second method, measurement of the DLIF is effected by way of a detection unit which is integrated in the measurement head 17, preferably a photodiode detection unit 25. In this case, detection can be effected at an earlier time, while troublesome emission and stray radiation can be separated from the DLIF by modulation methods. Frequency modulation of the diode laser radiation is effected by way of the frequency or function generator 9. The associated amplitude-modulated signal of the photodiode 32 can be further boosted by a lock-in amplifier 11 and is recorded by a digital storage oscilloscope 10 with PC-interface and passed to the PC 1 for evaluation (for example Fourier analysis). A higher level of sensitivity is to be expected with that measurement procedure than when effecting measurement with the ICCD-detector unit 6.
As indicated by the broken circular line in Figure 2, the photodiode detection unit (PDDE) 25 can be integrated either in front of or behind the plane of the drawing in Figure 2, in the wall 31 of the measurement head 17. It comprises a metal sleeve of a diameter of 2.5 cm and a length of about 4 cm. Besides the photodiode 32 it contains a lens system 33 for focusing the DLIF or fluorescence radiation onto the photodiode 32. For the purposes of screening troublesome scattered and emission radiation, a polarization or band pass filter 34 is additionally disposed between the lens system 33 which in the illustrated embodiment comprises two lenses and the photodiode 32. The spatial proximity of the PDDE 25 to the plasma 24 and the large diameter afford a high level of collecting efficiency. A further optical waveguide for radiation transport and thus possible coupling-in and attenuation losses are avoided, thereby giving a better level of detection efficiency than in the case of DLIF measurement with the ICCD-detector unit 6. Furthermore, with the additional use of the PDDE 25, it is possible for the OES and LIF to be measured at the same to time or simultaneously.
Figures 3a and 3b show measurement of the diode laser-induced fluorescence of the uranium isotope 238U with the photodiode 32. Figure 3a shows the original recording of the oscilloscope, wherein for pure emission measurement the wavelength of the diode laser 7 was detuned by 10 pm with respect to the transition (broken line). Figure 3b shows the result after Fourier analysis. Lock-in amplification was waived in this measurement procedure.
Quantification of the measurement results is effected in the OES
spectrum by way of internal standardization with intensive lines of main constituents of the sample 23 of known concentration. In the case of isotope-selective DLIF measurements quantification is effected directly from the levels of intensity of the signals.
In accordance with the invention the measurement head 17 shown in Figure 2 is disposed for example in a glove box or so-called hot cell and is thus radioactively contaminated. All other components of the measuring system and the gas supply, that is to say all components denoted by references 1 through 16, are disposed outside and are not exposed to any radioactivity. Serving as the interface between the outside and the inside are the optical waveguides 13, 13a and 14 which are thus disposed partially within the radioactive area. No limits are set on the length of the optical waveguides. In addition the measurement head 17 is connected by way of two plastic hozes 16 (argon feed and evacuation) and a BNC electric cable 15 to the photodiode 32, to the measurement apparatus. The pre-vacuum pump 12 serves to generate the vacuum, for pressures below 1 hPa and with a suction capacity of about 5 m3/h.
For analysis of a new sample location the measurement head 17 is fitted as a whole onto the appropriate sample location. The sample does not have to be moved nor do any fresh adjustments have to be made.
The new measurement procedure can begin immediately.
l0 The dimensions of the measurement head 17 are variable and can be varied according to the location of use. The approximate shape of a hemisphere appears however to be suitable for all possible uses.
As however the spacing of the focusing units 19 and 29 and the imaging units 28 from the plasma 24 should be at least 4 cm, the dimensions of the inside diameter should correspond at a minimum to a hemisphere of a 4 cm radius. If the spacing becomes less the optical systems of the focusing and imaging units suffer from vapor deposition of the ablated sample material and become opaque after a few 100 measurement procedures.
The height of the measurement head 17 is so selected that the optical axes of all the lens systems present intersect about 1 cm above the sample surface.
The lens systems permit 1:2 imaging of the plasma 24 onto the optical waveguide end or onto the photodiode 32. Focusing of the two laser beams corresponds to 1:1 imaging of the respective optical waveguide end onto the plasma 24.
Finally the essential advantages of the described embodiment should be set forth once again:
1. By virtue of the closed environment within the measurement head 17 the consumption of the argon which flows directly onto the ablation location by way of inlet nozzles 20 is extremely minimized.
2. Only the measurement head 17 and a part of the optical waveguides 13, 13a, 14 and the electric cables 15 and the plastic hozes 16 come into contact with the radioactive environment.
3. Adjustment operations on the measurement head 17 in the radioactive environment are not necessary.
4. The measurement head 17 can be placed virtually anywhere that may be desired.
5. The chamber 30 of the measurement head 17 can be evacuated by positioning with the sealing ring 22 on a smooth sample surface l0 18/23, by way of the valve 21.
6. The analysis operation can generally be implemented without previous mechanical or chemical preparation.
7. Fluorescence radiation or DLIF or LIF radiation can be measured both with the ICCD-detector unit 6 and also with the photodiode detection unit 25.
8. In the case of measurements with the photodiode detection unit 25 it is possible for DLIF and OES to be measured at the same time.
9. The photodiode detection unit 25 is a very compact unit with lens system 33, band pass filter 34 and photodiode 32.
2o 10. By virtue of wavelength monitoring of the diode laser scatter light with the spectrograph 5 it is possible to avoid using a further wavelength measuring unit.
The evacuatable measurement head 17 can be freely positioned and preferably comprises aluminum. Its inside walls are matt black and it is of an approximately hemispherical shape of a diameter of about 8 cm. Its height is 5 cm. In the illustrated embodiment, the first and second focusing units 19 and 29 which are integrated in the measurement head wall 31 and the two imaging units 28 each comprise double-lens quartz optics which are arranged in blackened metal sleeves, preferably aluminum sleeves, of a diameter of 1 cm. They serve as focusing, imaging and collimating units and are commercially available or can be easily manufactured in-house. The measurement head 17 also has inlet nozzles 20 for the argon gas which promotes plasma generation and measurement.
Depending on the respective shape of the sample 23 the measurement head 17 can be fitted directly onto the surface 18 with a sealing ring 22, in particular a plastic sealing ring. The sample 23 can equally be disposed in a sample holder which is of a simple design 2o configuration and which is adapted to the measurement head 17, for example a smooth surface, onto which the measurement head 17 is set.
Adjustments of the optical system, that is to say the focusing units 19 and 29 and the two imaging units 28, are not necessary as they have already been effected upon assembly of the measurement head 17.
In order to achieve the best possible ablation conditions and an undisturbed plasma, argon gas is passed by way of the two inlet nozzles 20 into the measurement head 17 and the latter is evacuated by way of a valve 21 to a pressure of between 1 and 100 haPa.
By way of optical waveguides 13 (wavelength 1064 nm, diameter 600 Vim), the plasma-generating radiation 26 of a pulsed Nd:YAG laser 2 (1064 nm, pulse 40 mJ max., 5-10 ns, with optical waveguide coupling-in) is passed into the measurement head 17 and there focused by means of the first focusing unit 19 onto the surface of the sample 23. The emission radiation of the plasma 24 produced is passed by way of the two imaging units 28 and two optical waveguides 14 (each being an optical waveguide bundle with 200 ~m fibers, about 35 fibers) to a spectrograph 5 with a time-resolving intensified CCD-detector unit (hereinafter referred to as the ICCD-detector unit for the sake of brevity) as indicated at 6 and measured. The ICCD-detector unit 6 has a resolution of at least 578 x 384 pixels and can be cooled by a Pettier element and a through-flow cooler. The spectrograph 5 is a 0.5 m spectrograph with a wavelength range of between 250 and 750 nm and of a resolution of 20 pm or better.
For measurement value acquisition, evaluation and for starting the measurement procedure, the arrangement uses a fast Personal Computer (PC) 1 which is connected by way of electric cables 15, preferably BNC-cables, to the ICCD-controller 4 (intensified CCD-camera) and the Nd:YAG
laser 2.
Illumination of the ICCD-detector unit 6 is effected only after a certain delay time (in the us-range) with respect to plasma formation and with an illumination time of between about 20 and 50 ~s (light duration of 2o the plasma). For that purpose the ICCD-detector unit 6 is switched with pulse and delay times of between 1 us and 1 ms by way of a pulse-delay generator 3 connected to the ICCD-controller 4.
For the purposes of DLIF excitation, the narrow-band radiation 27 of the diode laser 7, with optical waveguide coupling-in and through-flow cooler, is focused onto the sample vapor cloud through the second focusing unit 29 which is integrated in the measurement head 17. The radiation is passed to the measurement head 17 by way of optical waveguides 13a of a diameter of 200 ~m or smaller. Wavelength adjustment is effected by way of the diode laser driver 8. The diode laser 7 radiates continuously.
In accordance with the invention, DLIF measurement can be effected in two different ways:
In accordance with the first method, the fluorescence radiation is passed by way of optical waveguides 14 to the spectrograph 5 and measured with the ICCD-detector unit 6. In order to avoid excessively intensive background radiation due to emission that measurement procedure is started at a time when the laser-generated plasma 24 has extensively recombined, that is to say after about 50 ~s. In a particularly advantageous manner, the ICCD-detector unit 6 can moreover be used to control by way of stray light the wavelength of the diode laser radiation. A
specific wavelength measuring device is redundant as a result.
In accordance with the second method, measurement of the DLIF is effected by way of a detection unit which is integrated in the measurement head 17, preferably a photodiode detection unit 25. In this case, detection can be effected at an earlier time, while troublesome emission and stray radiation can be separated from the DLIF by modulation methods. Frequency modulation of the diode laser radiation is effected by way of the frequency or function generator 9. The associated amplitude-modulated signal of the photodiode 32 can be further boosted by a lock-in amplifier 11 and is recorded by a digital storage oscilloscope 10 with PC-interface and passed to the PC 1 for evaluation (for example Fourier analysis). A higher level of sensitivity is to be expected with that measurement procedure than when effecting measurement with the ICCD-detector unit 6.
As indicated by the broken circular line in Figure 2, the photodiode detection unit (PDDE) 25 can be integrated either in front of or behind the plane of the drawing in Figure 2, in the wall 31 of the measurement head 17. It comprises a metal sleeve of a diameter of 2.5 cm and a length of about 4 cm. Besides the photodiode 32 it contains a lens system 33 for focusing the DLIF or fluorescence radiation onto the photodiode 32. For the purposes of screening troublesome scattered and emission radiation, a polarization or band pass filter 34 is additionally disposed between the lens system 33 which in the illustrated embodiment comprises two lenses and the photodiode 32. The spatial proximity of the PDDE 25 to the plasma 24 and the large diameter afford a high level of collecting efficiency. A further optical waveguide for radiation transport and thus possible coupling-in and attenuation losses are avoided, thereby giving a better level of detection efficiency than in the case of DLIF measurement with the ICCD-detector unit 6. Furthermore, with the additional use of the PDDE 25, it is possible for the OES and LIF to be measured at the same to time or simultaneously.
Figures 3a and 3b show measurement of the diode laser-induced fluorescence of the uranium isotope 238U with the photodiode 32. Figure 3a shows the original recording of the oscilloscope, wherein for pure emission measurement the wavelength of the diode laser 7 was detuned by 10 pm with respect to the transition (broken line). Figure 3b shows the result after Fourier analysis. Lock-in amplification was waived in this measurement procedure.
Quantification of the measurement results is effected in the OES
spectrum by way of internal standardization with intensive lines of main constituents of the sample 23 of known concentration. In the case of isotope-selective DLIF measurements quantification is effected directly from the levels of intensity of the signals.
In accordance with the invention the measurement head 17 shown in Figure 2 is disposed for example in a glove box or so-called hot cell and is thus radioactively contaminated. All other components of the measuring system and the gas supply, that is to say all components denoted by references 1 through 16, are disposed outside and are not exposed to any radioactivity. Serving as the interface between the outside and the inside are the optical waveguides 13, 13a and 14 which are thus disposed partially within the radioactive area. No limits are set on the length of the optical waveguides. In addition the measurement head 17 is connected by way of two plastic hozes 16 (argon feed and evacuation) and a BNC electric cable 15 to the photodiode 32, to the measurement apparatus. The pre-vacuum pump 12 serves to generate the vacuum, for pressures below 1 hPa and with a suction capacity of about 5 m3/h.
For analysis of a new sample location the measurement head 17 is fitted as a whole onto the appropriate sample location. The sample does not have to be moved nor do any fresh adjustments have to be made.
The new measurement procedure can begin immediately.
l0 The dimensions of the measurement head 17 are variable and can be varied according to the location of use. The approximate shape of a hemisphere appears however to be suitable for all possible uses.
As however the spacing of the focusing units 19 and 29 and the imaging units 28 from the plasma 24 should be at least 4 cm, the dimensions of the inside diameter should correspond at a minimum to a hemisphere of a 4 cm radius. If the spacing becomes less the optical systems of the focusing and imaging units suffer from vapor deposition of the ablated sample material and become opaque after a few 100 measurement procedures.
The height of the measurement head 17 is so selected that the optical axes of all the lens systems present intersect about 1 cm above the sample surface.
The lens systems permit 1:2 imaging of the plasma 24 onto the optical waveguide end or onto the photodiode 32. Focusing of the two laser beams corresponds to 1:1 imaging of the respective optical waveguide end onto the plasma 24.
Finally the essential advantages of the described embodiment should be set forth once again:
1. By virtue of the closed environment within the measurement head 17 the consumption of the argon which flows directly onto the ablation location by way of inlet nozzles 20 is extremely minimized.
2. Only the measurement head 17 and a part of the optical waveguides 13, 13a, 14 and the electric cables 15 and the plastic hozes 16 come into contact with the radioactive environment.
3. Adjustment operations on the measurement head 17 in the radioactive environment are not necessary.
4. The measurement head 17 can be placed virtually anywhere that may be desired.
5. The chamber 30 of the measurement head 17 can be evacuated by positioning with the sealing ring 22 on a smooth sample surface l0 18/23, by way of the valve 21.
6. The analysis operation can generally be implemented without previous mechanical or chemical preparation.
7. Fluorescence radiation or DLIF or LIF radiation can be measured both with the ICCD-detector unit 6 and also with the photodiode detection unit 25.
8. In the case of measurements with the photodiode detection unit 25 it is possible for DLIF and OES to be measured at the same time.
9. The photodiode detection unit 25 is a very compact unit with lens system 33, band pass filter 34 and photodiode 32.
2o 10. By virtue of wavelength monitoring of the diode laser scatter light with the spectrograph 5 it is possible to avoid using a further wavelength measuring unit.
11. The overall structure in accordance with the embodiment by way of example is transportable whereby only the measurement head 17 has to be renewed when displacing the measurement location.
List of references 1 Personal Computer 2 Nd:YAG laser 3 pulse-delay generator 4 ICCD controller 5 spectrograph 6 ICCD-detector unit 7 diode laser 8 diode laser driver 9 frequency or function generator 10 digital storage oscilloscope 11 lock-in amplifier 12 pre-vacuum pump 13 first optical waveguide 13a second optical waveguide 14 third optical waveguide 15 electric cable 16 plastic hozes 17 measurement head 18 smooth surface, support or sample to be analyzed 19 first focusing unit 20 inlet nozzles 21 valve 22 sealing ring 23 sample to be analyzed 24 glowing plasma generated by Nd:YAG laser ablation 25 photodiode detection unit 26 plasma-generating laser radiation 27 narrow-band laser radiation 28 imaging unit 29 second focusing unit 30 chamber 31 measurement head wall 32 photodiode 33 lens system 34 polarization or band pass filter.
List of references 1 Personal Computer 2 Nd:YAG laser 3 pulse-delay generator 4 ICCD controller 5 spectrograph 6 ICCD-detector unit 7 diode laser 8 diode laser driver 9 frequency or function generator 10 digital storage oscilloscope 11 lock-in amplifier 12 pre-vacuum pump 13 first optical waveguide 13a second optical waveguide 14 third optical waveguide 15 electric cable 16 plastic hozes 17 measurement head 18 smooth surface, support or sample to be analyzed 19 first focusing unit 20 inlet nozzles 21 valve 22 sealing ring 23 sample to be analyzed 24 glowing plasma generated by Nd:YAG laser ablation 25 photodiode detection unit 26 plasma-generating laser radiation 27 narrow-band laser radiation 28 imaging unit 29 second focusing unit 30 chamber 31 measurement head wall 32 photodiode 33 lens system 34 polarization or band pass filter.
Claims (9)
1. A method of isotope-selective measurement of chemical elements, in particular radioactive elements in materials, in particular radioactive materials wherein for measurement purposes the optical emission spectroscopy (OES) method in which a plasma (24) is generated in the form of a sample vapor cloud by laser ablation from a sample (18, 23) to be analyzed is coupled to the laser-induced fluorescence spectroscopy (LIF) method in which laser-induced fluorescence excitation of the sample vapor cloud is effected, characterized in that measurement is effected simultaneously with the optical emission spectroscopy method (OES) and the laser-induced fluorescence spectroscopy method (LIF).
2. A method as set forth in claim 1 characterized in that a diode laser (7) is used in the laser-induced fluorescence spectroscopy method (LIF).
3. An apparatus for isotope-selective measurement of chemical elements, in particular radioactive elements, in materials, in particular radioactive materials, comprising - a first laser (2) whose laser beam can be focused by means of a first focusing unit (19) onto a sample (23) to be analyzed, so that light-emitting plasma (24) is produced in the form of a sample vapor cloud for the purposes of optical emission spectroscopy, - a radiation analysis unit (5) in which the image of the emission radiation emitted by the plasma (24) can be formed by means of at least one imaging unit (28), and - a second laser (7) whose laser beam can be focused by means of a second focusing unit (29) onto that space in which the plasma (24) is produced so that laser-induced fluorescence excitation of the sample vapor cloud is possible, characterized in that - there is provided a measurement head (17) which can be applied to the sample (23) or which can be fitted over the sample (23) and which can be positioned as desired so that at least the plasma (24) produced is within a chamber (30) of the measurement head (17), - the first focusing unit (19), the second focusing unit (29) and the imaging unit (28) are integrated in the measurement head wall (31) and a first optical waveguide (13) connects the first laser (2) to the first focusing unit (19), a second optical waveguide (13a) connects the second laser (7) to the second focusing unit (29) and a third optical waveguide (14) connects the imaging unit (28) to the radiation analysis unit (5), and - there is provided a detection unit (25) for detection of the fluorescence radiation which occurs by virtue of the laser-induced fluorescence excitation wherein the detection unit (25) is integrated in the measurement head (17) so that simultaneous measurement of emission radiation and fluorescence radiation is possible.
4. Apparatus as set forth in claim 3 characterized in that the measurement head (17) has at least one inlet nozzle (20) for feeding argon gas into the chamber (30).
5. Apparatus as set forth in claim 3 or claim 4 characterized in that the measurement head (17) has a valve (21), by means of which its chamber (30) can be evacuated.
6. Apparatus as set forth in one of claims 3 through 5 characterized in that the measurement head (17) has a sealing means (22) which seals off the chamber (30) with respect to the environment when the measurement head (17) is applied to the sample (23) or when the measurement head (17) is inverted over the sample (23).
7. Apparatus as set forth in one of claims 3 through 6 characterized in that the detection unit (25) has a photodiode (32) and a focusing unit (33).
8. Apparatus as set forth in claim 7 characterized in that a polarization or band pass filter (34) is arranged between the photodiode (32) and the focusing unit (33).
9. Apparatus as set forth in one of claims 3 through 8 characterized in that the second laser is a diode laser (7).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| LU90296 | 1998-10-07 | ||
| LU90296 | 1998-10-07 | ||
| PCT/EP1999/006214 WO2000020847A1 (en) | 1998-10-07 | 1999-08-24 | Method and device for isotope- selective measurement of chemical elements in materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2347401A1 true CA2347401A1 (en) | 2000-04-13 |
Family
ID=19731773
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002347401A Abandoned CA2347401A1 (en) | 1998-10-07 | 1999-08-24 | Method and device for isotope- selective measurement of chemical elements in materials |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP1119764A1 (en) |
| JP (1) | JP2002526767A (en) |
| CA (1) | CA2347401A1 (en) |
| NO (1) | NO20011777D0 (en) |
| WO (1) | WO2000020847A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2359886A (en) * | 2000-03-04 | 2001-09-05 | Applied Photonics Ltd | Laser spectroscopic remote detection of surface contamination |
| EP1720002A1 (en) | 2005-05-04 | 2006-11-08 | Oxford Instruments Analytical Oy | Method and arrangement for non-destructive composition analysis of delicate samples |
| FR2929011B1 (en) * | 2008-03-20 | 2013-01-04 | Commissariat Energie Atomique | METHOD AND DEVICE FOR HIGH QUANTITATIVE QUANTITATIVE MEASUREMENT OF BIOMOLECULAR TARGETS PRESENTED ON OR IN A BIOLOGICAL ANALYSIS MEDIUM. |
| JP5630165B2 (en) * | 2010-09-09 | 2014-11-26 | 国立大学法人金沢大学 | Sporation evaluation system, image processing program, and arc extinguishing apparatus |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4247770A (en) * | 1978-09-07 | 1981-01-27 | Welch Albert B | Aerial mineral survey method and apparatus using pulsed laser beam to vaporize surface material |
| US5424841A (en) * | 1993-05-28 | 1995-06-13 | Molecular Dynamics | Apparatus for measuring spatial distribution of fluorescence on a substrate |
| DE19531988A1 (en) * | 1995-08-30 | 1997-03-06 | Europaeische Kommission | Remote measurement of U (Pu) in glasses |
| US5781289A (en) * | 1996-11-05 | 1998-07-14 | Sabsabi; Mohamad | Method and apparatus for rapid in situ analysis of preselected components of homogeneous solid compositions, especially pharmaceutical compositions |
-
1999
- 1999-08-24 CA CA002347401A patent/CA2347401A1/en not_active Abandoned
- 1999-08-24 JP JP2000574914A patent/JP2002526767A/en active Pending
- 1999-08-24 EP EP99944504A patent/EP1119764A1/en not_active Withdrawn
- 1999-08-24 WO PCT/EP1999/006214 patent/WO2000020847A1/en not_active Application Discontinuation
-
2001
- 2001-04-06 NO NO20011777A patent/NO20011777D0/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NO20011777L (en) | 2001-04-06 |
| NO20011777D0 (en) | 2001-04-06 |
| WO2000020847A1 (en) | 2000-04-13 |
| EP1119764A1 (en) | 2001-08-01 |
| JP2002526767A (en) | 2002-08-20 |
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