Device for analyzing a metallic sample using a laser beam, including means for shaping the laser beam
The introduction of a diaphragm to shape the laser beam, masking the central cone, addresses the challenge of beam geometry in elemental analysis, enhancing ablation efficiency and analysis quality.
Patent Information
- Application Number
- FR2022013975
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-12-20
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2042-12-20
AI Technical Summary
Existing elemental analysis methods using laser-produced plasma optical emission spectrometry face challenges in achieving high-quality analysis due to the interaction between the laser beam and the sample, particularly influenced by the geometry of the focusing beam, which can result in reduced ablation efficiency and analysis quality.
A diaphragm is introduced to shape the laser beam, masking the central cone of the focusing beam, ensuring a tubular shape without a small aperture, thereby improving interaction with the sample and maintaining homogeneous ablation.
The solution enhances the quality of elemental analysis by ensuring better interaction between the laser beam and the sample, leading to improved ablation and mapping of elements, adaptable to various beam sizes and easy to implement.
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Abstract
Description
Title of the invention: Device for analyzing a metallic sample by laser beam, comprising means for shaping the laser beam
[0001] The present invention relates to the field of high-resolution mapping and analysis of elements in solids.
[0002] More particularly, the invention relates, in particular but not exclusively, to a high-resolution analysis device for mapping elements in metallic solids.
[0003] The invention can in particular be applied to the elemental analysis of hydrogen and oxygen by optical emission spectrometry on laser-produced plasma, in the field of the nuclear industry, or even the aeronautical or space industry.
[0004] In applications such as the characterization of devices subjected to radioactive sources, or the characterization of the aging ability of devices used in particularly severe environments, for example in aircraft or spacecraft, it may prove essential to carry out the elemental analysis of metallic samples.
[0005] More specifically, it may be necessary to be able to map these elements within the analyzed sample. By mapping, we mean an identification of the elements composing the analyzed sample and, possibly, the distribution and the relationship between the different elements.
[0006] Such an analysis can prove particularly useful in studies of hydrogen embrittlement of metals, or in studies of aging of fuel cladding in the presence of oxygen, or in studies of embrittlement of fuel cladding caused by the formation of hydrides, the latter promoting the propagation of cracks.
[0007] There are various known methods of mapping elements present in samples.
[0008] One of these methods is elemental analysis by "SEOPPL", an acronym for Laser-Produced Plasma Optical Emission Spectrometry, a technique which is carried out in a natural atmosphere.
[0009] This method is particularly applicable to the control and in situ characterization of samples of parts to be analyzed.
[0010] A method for elemental analysis by optical emission spectrometry on laser-produced plasma in the presence of argon is described in patent document published under number EP 0 654 663.
[0011] Conventionally, an analysis device comprises a frame on which are mounted: - a laser beam generation module, - a diaphragm for selecting a portion of the laser beam emitted by the generation module, - optical means of focusing the laser beam onto a sample to be studied; - means for collecting optical emissions, and, - means of elementary determination of the sample to be studied.
[0012] Once generated by the generation module, the laser beam travels until it reaches the sample to be studied.
[0013] A plasma is then created at the point of impact of the laser beam on the sample to be studied, the plasma generating an optical emission to be analyzed in order to map the elements composing the sample studied.
[0014] The collection of the optical emission of the plasma is carried out by the collection means, this optical emission is then analyzed by the determination means to map the elements composing the sample studied.
[0015] However, the interaction between the laser and the material of the sample to be studied is directly related to the geometry of the plasma and the opening of the focusing beam.
[0016] The focusing beam is the part of the laser beam located between the last lens and the sample.
[0017] This focusing beam has a cone shape that thins out from the last lens.
[0018] In an analysis situation, the larger the opening of the focusing beam, the less the plasma absorbs the beam, to the benefit of the ablation of the sample surface by the laser beam, and therefore to the benefit of the quality of the analysis.
[0019] In other words, the larger the cone is at its base, the better the interaction between the beam and the sample material, therefore the better the results of the analysis.
[0020] On the contrary, the smaller the focusing beam opening, the more the plasma absorbs the beam, to the detriment of the ablation of the sample surface by the laser beam, and therefore to the detriment of the quality of the analysis.
[0021] In other words, the smaller the cone is at its base, the less good the interaction between the beam and the sample material, therefore the less good the results of the analysis.
[0022] However, increasing the aperture of the focusing beam results in the presence of a central cone with a small aperture, this central cone growing as a function of the aperture of the focusing beam.
[0023] The presence of this central cone with a small aperture then leads to a reduction in the quality of the analysis as explained previously.
[0024] The invention aims in particular to overcome the disadvantages of the prior art.
[0025] More specifically, the invention aims to provide a solution for generating a large aperture beam, improving the quality of the analysis compared to prior art solutions.
[0026] The invention also aims to provide such a solution which adapts to all sizes of focusing beams.
[0027] The invention further aims to provide such a solution which is simple to implement.
[0028] These objectives, as well as others which will appear subsequently, are achieved thanks to the invention which relates to a diaphragm for an elemental analysis device, comprising a body provided with an opening for selecting a part of a laser beam, characterized in that the diaphragm carries an element impenetrable by waves of the laser beam, positioned in the selection opening to reduce the selection opening to an annular shape.
[0029] Such a diaphragm makes it possible to mask the central portion of a laser beam. Therefore, when a laser beam is intended to become an open beam at the output of the focusing optical means, it is then devoid of a central cone that degrades the properties of said laser beam.
[0030] According to an advantageous aspect, the impenetrable element has a shape complementary to the shape of the selection opening.
[0031] Such a complementarity of shape makes it possible to obtain a laser beam of tubular shape whose external contour of the masked section corresponds to the external contour of the diaphragm selection opening.
[0032] This allows for maintaining homogeneity of the laser beam and, when the laser beam is used for the ablation of a sample, for maintaining a homogeneous shape of the ablation, which facilitates its analysis by a technician.
[0033] According to another advantageous aspect, the impenetrable element is connected to the body by at least one support arm.
[0034] This makes it possible to maintain the position of the impenetrable element under all circumstances, in particular when the diaphragm is moved from one position to another.
[0035] In other words, when the diaphragm is moved, it is not necessary to reposition the impenetrable element relative to the selection aperture, only the position of the diaphragm relative to the laser generation module needs to be adjusted.
[0036] According to another advantageous aspect, the impenetrable element came from matter with the body.
[0037] In this case, the diaphragm can, for example, be made by extruding material, cutting from a blank (i.e., machining a rough blank or a piece of material) debited)
[0038] In addition, this ensures that the impenetrable element retains its position relative to the selection opening.
[0039] According to another advantageous aspect, the impenetrable element is attached to a film.
[0040] Positioning the impenetrable element on a film allows for changes in the shape and / or size of the impenetrable element. Indeed, simply changing the film is enough to modify the shape of the beam exiting the diaphragm, as needed.
[0041] According to another advantageous aspect, the film is transparent to the waves of a laser beam for which the diaphragm is selected.
[0042] The film thus does not obstruct the passage of laser radiation, which limits the risks of degradation of the quality of the laser radiation.
[0043] The invention also relates to an elemental analysis device for a sample to be studied, the analysis device comprising a frame on which are mounted: - a laser beam generation module, - optical means of focusing the laser beam onto a sample to be studied; - means of collecting optical emissions, and - means of elementary determination of the sample to be studied, characterized in that the analysis device also includes a diaphragm as previously described.
[0044] The use of such a diaphragm makes it possible to obtain, at the output of the focusing means, a focusing laser beam devoid of a central cone of small aperture.
[0045] This then directly benefits the quality of the ablation of the sample by the laser radiation, which promotes the exploitation of the ablation results to map the elements composing said sample.
[0046] The invention further relates to a method for elemental analysis of a sample to be studied using an analytical device as previously described, the method comprising the steps of: - generate a laser beam via the generation module, - focus the laser beam using optical focusing means to obtain a focusing beam, and - to determine the elemental composition of the sample to be studied using collection and determination methods, in which, the step of focusing the laser beam includes a substep of masking a central cone in the focusing beam, via the diaphragm.
[0047] This method makes it possible to guarantee the obtaining of a focusing beam, that is to say of a beam exiting the focusing means, which is devoid of a central cone of small aperture.
[0048] Other features and advantages of the invention will become more apparent from the following description of preferred embodiments of the invention, given by way of illustrative and non-limiting examples, and the accompanying drawings described below.
[0049] [Fig-1] Fig. 1 is a schematic representation of an analysis system including an analysis device according to the invention.
[0050] [Fig.2] Fig.2 is a schematic detail representation of a focal beam the information obtained by optical means of focusing the analysis device according to the invention.
[0051] [Fig.3] The [Fig.3] is a schematic perspective representation of a diaphragm of the analysis device according to the invention, according to a first embodiment.
[0052] [Fig.4] The [Fig.4] is a schematic perspective representation of a diaphragm of the analysis device according to the invention, according to a second embodiment.
[0053] Fig. 1 illustrates a system 1 of elemental analysis of a sample 2 to be studied.
[0054] The system 1 includes an analysis device 3 as described below, this analysis device 3 comprising a base 31 for receiving the sample 2.
[0055] The analysis device 3 also includes a frame on which are mounted: - a laser beam generation module 4, 5, - a laser beam shaping module 5 incorporating at least one lens 6 and a selection diaphragm 7 for a portion of the laser beam 5 emitted by the generation module 4, - optical means of focusing 8 the laser beam 5 onto the sample 2 to be studied.
[0056] As illustrated by [Fig.1], the analysis device 3 comprises, depending on the direction of emission of the laser beam 5 from the generation module 4 to the sample 4, a plurality of lenses 6 and a diaphragm 7.
[0057] The analysis device 3 also includes a plurality of mirrors 32 allowing the laser beam 5 to be deflected from the generation module 4 to the focusing means 8, in order to limit the size of the analysis device 3.
[0058] At the output of the optical focusing means 8, the laser beam 5 becomes a focusing beam 51. In this case, the focusing beam 51 has a conical shape that thins out towards the sample 2, while between the generation module 4 and the focusing means 8, the laser beam 5 has a substantially cylindrical shape.
[0059] In addition, system 1 includes collection means 9 and determination means 10, the role of which will be described below.
[0060] As described previously, system 1 allows analysis of a sample 2 to map its elemental composition.
[0061] For this purpose, the laser beam 5 is emitted by the generation module 4 to be directed towards the sample 2 to impact its surface.
[0062] When the laser beam 5 impacts the sample 2 to be studied, a plasma P is created, generating an optical emission to be analyzed to map the elements composing the sample 2.
[0063] The collection of the optical emission from the plasma is carried out by the collection means 9.
[0064] For this purpose, as illustrated by Figures 2 and 3, the collection means 9 com take an optical fiber 91 whose free end defining a terminal portion is brought as close as possible to the plasma P.
[0065] The collection means 9 also include first means of communication 95 intended to establish a communication channel with second means of communication 101 and determination means 10.
[0066] The first means of communication 95 and the second means of communication 101 may be wireless. Alternatively, the first means of communication 95 and the second means of communication 101 may be in the form of connectors for receiving the plug of a wired connecting cable.
[0067] The focusing beam 51 may have a large aperture or a small aperture.
[0068] More specifically, the focusing beam 51 has a cone shape that tapers from the last lens, i.e., from the focusing optical means 8. As illustrated in [Fig. 2], the focusing beam 51 has a frustoconical shape between the focusing optical means 8 and the sample 2. This frustoconical shape is due to the fact that the sample 2 is positioned at a predetermined distance from the focusing optical means 8 such that the cross-section of the focusing beam 51 is larger than a simple point formed by the tip of the conical shape of the focusing beam. In other words, the distance between the focusing optical means 8 and the sample 2 is strictly less than the height of the cone formed by the focusing beam 51, it being recalled that a cone height is measured from the base to the apex of the cone.
[0069] In an analysis situation, the larger the opening of the focusing beam 51, the less the plasma P absorbs the beam 5, to the benefit of the ablation of the surface of the sample 2 by the laser beam 5, and therefore to the benefit of the quality of the analysis.
[0070] In other words, the larger the cone is at its base, the better the interaction between the beam 5 and the sample material 2, and therefore the better the results of the analysis.
[0071] On the contrary, the smaller the opening of the focusing beam 51, the more the plasma P absorbs the beam, to the detriment of the ablation of the surface of the sample 2 by the laser beam 5, and therefore to the detriment of the quality of the analysis.
[0072] In other words, the smaller the cone is at its base, the less good the interaction between the beam 5 and the material of the sample 2, therefore the less good the results of the analysis.
[0073] However, as illustrated by [Fig.2], increasing the aperture of the focusing beam 51 results in the presence of a central cone 52 with a small aperture, this central cone growing as a function of the aperture of the focusing beam 51.
[0074] The presence of this central cone 52 with a small aperture then leads to a reduction in the quality of the analysis as explained previously.
[0075]
[0076] The diaphragm 7 of the laser beam shaping module 5 is specially designed to suppress this central cone 52, or at the very least to limit it.
[0077] More specifically, with reference to Figures 3 and 4, the diaphragm 7 comprises a body 71 provided with a selection aperture 72.
[0078] When the laser beam 5 passes through the diaphragm 7, part of its section is then blocked by the body 71 of the diaphragm 7 so that only the part located opposite the selection aperture 72 can pass through the diaphragm 7.
[0079] In addition, the diaphragm 7 carries an element 73 impenetrable to the waves of the laser beam 5.
[0080] This impenetrable element 73 is positioned in the selection opening 72 as illustrated by figures 3 and 4.
[0081] The impenetrable element 73 then forms a barrier to the waves of the laser beam 5, and thus reduces the selection opening 72 to an annular shape.
[0082] The laser beam 5 emerging from the diaphragm 7 then has a tubular shape, unlike a solid cylindrical shape before reaching the diaphragm 7.
[0083] In Figures 3 and 4, the body 71 of the diaphragm 7 has a length substantially equal to its width (here its diameter, since it is shown in circular section) and is therefore substantially cylindrical. Alternatively, the diaphragm 7 could have a short length so that it takes on a substantially annular shape.
[0084] According to a first embodiment illustrated by [Fig.3], the impenetrable element 73 is connected to the body 71 by means of at least one retaining arm 74.
[0085] According to the particular embodiment of [Fig. 3], the diaphragm 7 comprises three arms 74 regularly spaced apart from each other. More specifically, each arm 74 is spaced at an angle of 120° relative to the other arms 74.
[0086] The arms 74 and the impenetrable element 73 may have come from matter with the body 71. In other words, the arms 74 and the impenetrable element 73 are made of the same material as the body 71, so that the diaphragm 7 is obtained, for example, by machining or cutting a block of material, or directly from a mold.
[0087] According to other embodiments, the diaphragm could comprise only two arms 74 or, conversely, more than three arms 74.
[0088] According to a second embodiment illustrated by [Fig.4], the impenetrable element 73 is attached to a film 75.
[0089] The film 75 is then brought onto the body 71 of the diaphragm 7 and is held there by ad hoc means.
[0090] Film 75 is advantageously permeable to the waves of the laser beam 5.
[0091] In other words, the film 5 is transparent to the waves of the laser beam 5 for which the diaphragm 7 is selected.
[0092] Alternatively, the film 75 can be independent of the body 71 by being, for example, mounted on a support positioned in front of the body 71 of the diaphragm 7.
[0093] This allows the full power and spectrum of the laser beam 5 passing through the diaphragm 7 to be retained.
[0094] The analysis of a sample 2 using the analysis device 3, as just described, is carried out by means of a process comprising the steps of: - generating a laser beam 5 via the generation module 4, - focus the laser beam 5 via the optical means 8 to obtain a beam of focusing 51, and - determine an elemental composition of sample 2 to be studied via collection methods 9 and determination methods 10.
[0095] According to the invention, the step of focusing the laser beam 5 includes a substep of masking a central cone 52 in the focusing beam 51, via the diaphragm 7.
[0096] The masking of the central cone 52 is achieved, as described previously, by the impenetrable element 73.
Claims
Demands
1. Elementary analysis device (3) of a sample (2) to be studied, the analysis device (3) comprising a frame on which are mounted: - a generation module (4) of a laser beam (5), - optical means for focusing (8) the laser beam (5) on a sample (2) to be studied;- means for collecting (9) the optical emission, and - means for determining (10) the elemental sample (2) to be studied, characterized in that the analysis device (3) also includes a laser beam shaping module (5) integrating at least one lens (6) and a diaphragm (7) for selecting a portion of the laser beam (5) emitted by the generation module (4), the diaphragm (7) comprising a body (71) having a selection aperture (72) for a portion of a laser beam (5), the diaphragm (7) being coupled to an impenetrable element (73) by waves of the laser beam (5), positioned in the selection aperture (72) to reduce the selection aperture (72) to an annular shape.
2. Analysis device (3) according to the preceding claim, characterized in that the impenetrable element (73) has a shape complementary to the shape of the selection opening (72).
3. Analytical device (3) according to any one of the preceding claims, characterized in that the impenetrable element (73) is connected to the body (71) by at least one retaining arm (74).
4. Analytical device (3) according to the preceding claim, characterized in that the impenetrable element (73) came of matter with the body (71).
5. Analytical device (3) according to claim 1 or 2, characterized in that the impenetrable element (73) is integral with a film (75).
6. Analytical device (3) according to the preceding claim, characterized in that the film (75) is transparent to the waves of a laser beam (5) for which the diaphragm (7) is selected.
7. Method for elemental analysis of a sample (2) to be studied by means of an analytical device (3) according to any one of the claims Previously, the process included the steps of: - generate a laser beam (5) via the generation module (4), - focus the laser beam (5) via optical focusing means lization (8) to obtain a focusing beam (51), and - determine an elemental composition of the sample (2) to be studied via the collection methods (9) and the determination methods (10), in which, the step of focusing the laser beam (5) includes a substep of masking a central cone (52) in the focusing beam (51), via the diaphragm (7).