Apparatus for analyzing a sample by means of a laser beam, comprising means for collecting the information to be analyzed

Abstract

The invention relates to an apparatus 3 for the elemental analysis of a sample 2 to be examined, comprising a frame on which are mounted a base for supporting the sample 2 to be examined, a module 4 for generating a laser beam 5 for generating a plasma which generates an optical emission, and means 9 for collecting the optical emission, comprising an optical fiber 91 having a free end defining an end face, characterized in that the free end has a bevel cut which defines an end face.

Description

[Technical Field]

[0001] The present invention relates to the field of high resolution mapping and analysis of elements in solids.

[0002] More particularly, the present invention relates to high resolution analytical instruments, particularly but not exclusively for mapping elements within metallic solids.

[0003] The invention is particularly applicable to the elemental analysis of hydrogen and oxygen by optical emission spectroscopy on laser-produced plasmas in the field of the nuclear industry or in the aeronautical or space industry. [Background technology]

[0004] Elemental analysis of metal samples can be essential in applications such as characterizing equipment exposed to radioactive sources or characterizing the aging capabilities of equipment used in particularly harsh environments, such as aircraft or spacecraft.

[0005] More specifically, it may be necessary to be able to map these elements in the sample being analyzed, where mapping means identifying the elements that make up the sample being analyzed and, optionally, the distribution of the various elements and the chemical bonds between them.

[0006] Such analyses can be particularly useful in studying metal embrittlement by hydrogen, or fuel cladding aging in the presence of oxygen, or fuel cladding embrittlement caused by the formation of hydride compounds, which promote crack propagation.

[0007] There are a variety of known methods for mapping the elements present in a sample.

[0008] One of these methods is elemental analysis by optical emission spectroscopy on laser-produced plasma, a technique performed in natural air, also referred to by the English acronym "LIBS," which stands for "laser induced breakdown spectroscopy."

[0009] The method is particularly applicable to the in situ examination and characterization of samples of analyte moieties.

[0010] A method and apparatus for elemental analysis by optical emission spectroscopy on laser-produced plasma in the presence of argon is described in US Pat. No. 5,649,999.

[0011] Conventionally, analytical devices have - a module for generating a laser beam; - a beam shaping module incorporating at least one lens and a diaphragm for selecting a portion of the laser beam emitted by the generating module; - optical means for focusing the laser beam onto the sample under study; - means for collecting luminescence; The device has a frame to which the

[0012] The laser beam generated by the generating module is shaped by the shaping module and then applied to the sample under study via focusing optics.

[0013] A plasma is then generated upon impingement of the laser beam on the sample under study, this plasma producing an optical emission that is analyzed to map the elements that make up the sample under study.

[0014] Collection of the plasma's emitted light is performed by a collection means.

[0015] For this purpose, the collecting means comprises an optical fiber whose free end is closest to the plasma. The closer the free end of the fiber is to the plasma, the more optical noise is removed. In other words, the closer the optical fiber is to the plasma, the less ambient light is captured by the plasma. Therefore, the analysis of the light captured by the optical fiber will be better than when the optical fiber is further from the plasma.

[0016] More specifically, the free end of the optical fiber has an end face that is transverse to the direction in which the fiber extends, and the plasma light is collected through this end face.

[0017] For good collection, the optical fiber must be positioned so that its cross section forms an angle of approximately 60 degrees with the direction of emergence of the laser beam.

[0018] The emitted light is collected and analyzed by a determination means connected to an optical fiber.

[0019] Nevertheless, the use of optical fibers has significant drawbacks.

[0020] In fact, optical fibers cannot be bent because they are made of silica, and as a result the collection means occupy a considerable volume of the analysis device.

[0021] Moreover, the angle formed with the laser beam is large, since this angle allows the best possible collection of emitted light, without the risk of obscuring the laser beam, by optimal positioning of the end face of the optical fiber, and thus makes it possible to obtain an optimal quality plasma generated by the reaction between the laser beam and the sample under consideration.

[0022] This further increases the total footprint of the collection means and consequently the total footprint of the analysis device.

[0023] More specifically, this angle is determined so as to satisfy the following: - the collecting means, in particular the optical fiber, are not in contact with the lens of the device, i.e. the optical means for focusing the laser beam; and - The optical fiber must not come into contact with the surface of the sample to be analyzed and must not be too close to the generated plasma, as this could destroy the fiber. [Prior art documents] [Patent documents]

[0024] [Patent Document 1] European Patent No. 0,654,663 Summary of the Invention [Problem to be solved by the invention]

[0025] In particular, it is an object of the present invention to overcome the drawbacks of the prior art.

[0026] More specifically, it is an object of the present invention to provide a collection means that has a reduced footprint or, more generally, an optimized spatial positioning with respect to the space available around the sample to be analyzed, while allowing reliable collection of the emitted light of the plasma.

[0027] Another object of the present invention is to provide such a collection means which provides optimum quality of the collected luminescence.

[0028] It is a further object of the present invention to provide such a collection means that is easy to implement and install. [Means for solving the problem]

[0029] These objectives, and others that will become apparent later, a stand intended to support the sample under consideration; a module for generating a laser beam intended to impinge on the sample under study in a direction perpendicular to the stand and to generate a plasma that generates light emission; a means for collecting the emitted light, the means comprising an optical fiber having a free end defining an end disposed proximate to the plasma; 1. An apparatus for the elemental analysis of a sample under consideration, comprising a frame on which are mounted: This is achieved by the invention in a device in which the end of the optical fiber of the collecting means is characterized in that it extends along a major axis forming an angle A with the stand that is strictly less than 30 degrees, and the free end has a bevel cutout that defines the end face.

[0030] The bevel cutout allows for a reduction in the angle of the optical fiber relative to the stand.

[0031] This has direct benefits for the compactness of the analytical device.

[0032] Furthermore, by reducing the angle between the optical fiber and the stand, the end face of the optical fiber can be brought closest to the plasma, which is beneficial to the quality of the analysis since it minimizes the distance between the emission light and the end face.

[0033] Additionally, the bevel provides better capture and propagation of the light beam throughout the optical fiber.

[0034] According to an advantageous embodiment, the end face is oriented towards the top of the plasma.

[0035] On the other hand, tests have demonstrated that pointing the end face towards the top of the plasma provides a higher quality of analysis than conventional solutions.

[0036] According to another advantageous embodiment, the optical fiber has a diameter of 1000 μm.

[0037] This optical fiber diameter ensures sufficient emission collection to allow elemental mapping of the composition of the studied sample, while allowing for easy creation of bevel cutouts.

[0038] The invention also relates to a method for the elemental analysis of a sample, characterized in that it implements an analytical device such as that described above.

[0039] Other characteristics and advantages of the invention will become more apparent on reading the following description of a preferred embodiment of the invention, given as an illustrative and non-limiting example, and also from the accompanying drawings, which are described below. [Brief explanation of the drawings]

[0040] [Figure 1] 1 is a schematic diagram of an analytical system including an analytical device according to the present invention; [Figure 2] FIG. 2 is a detailed schematic diagram of an analytical device according to the present invention showing the means for collecting the plasma's optical emissions. [Figure 3] 3 is a detailed schematic view of the free end of the optical fiber of the collecting means of the analytical device according to the invention; FIG. [Figure 4] 1 is a detailed schematic diagram of an analyzer showing the means for collecting the plasma's optical emissions according to the prior art; FIG. [Figure 5] 3 is a detailed schematic view of the free ends of the optical fibers of the collecting means of an analysis device according to a variant of the invention; DETAILED DESCRIPTION OF THE INVENTION

[0041] FIG. 1 shows a system 1 for elemental analysis of a sample 2 under consideration.

[0042] The system 1 includes an analytical device 3, which will be described below. The analytical device 3 comprises a stand 31 for receiving a sample 2.

[0043] The analysis device 3 also a module 4 for generating a laser beam 5; a module for shaping the laser beam 5 incorporating at least one lens 6 and a diaphragm 7 for selecting a portion of the laser beam 5 emitted by the generation module 4; optical means 8 for focusing the laser beam 5 onto the sample 2 under study; It also has a frame on which it is attached.

[0044] As shown by FIG. 1, the analysis device 3 comprises a number of lenses 6 and diaphragms 7 along the direction of emission of the laser beam 5 from the generation module 4 towards the sample 2 .

[0045] The analysis device 3 also comprises a number of mirrors 32 making it possible to deflect the laser beam 5 from the generation module 4 until it reaches the focusing means 8 in order to limit the footprint of the analysis device 3 .

[0046] At the output of the focusing optical means 8, the laser beam 5 becomes a focused beam 51. In this case, the focused beam 51 has a conical shape that tapers in the direction of the sample 2, whereas between the generating module 4 and the focusing means 8 the laser beam 5 has a substantially cylindrical shape.

[0047] Furthermore, the system 1 comprises collecting means 9 and determining means 10. The role of these means will be explained below.

[0048] As previously mentioned, the system 1 allows for the analysis of a sample 2 to map its elemental composition.

[0049] For this purpose, a laser beam 5 is emitted by the generation module 4 so as to be directed towards the sample 2 and to impinge on its surface.

[0050] When the laser beam 5 strikes the sample 2 under consideration, a plasma P is generated, producing an optical emission that is analyzed to map the elements that make up the sample 2 .

[0051] Collection of the plasma emission is performed by collection means 9 .

[0052] To this end, as shown by Figures 2 and 3, the collecting means 9 comprises an optical fiber 91 whose free end defining an end 92 is closest to the plasma P. Preferably, the optical fiber 91 has a diameter of 1000 µm.

[0053] End 92 extends along a major axis AA that forms an angle A with stand 31 that is strictly less than 30 degrees.

[0054] End 92 has an end face 93 positioned closest to plasma P.

[0055] According to the embodiment illustrated by FIGS. 2 and 3, end 92 has a bevel cutout 94 that defines end face 93 .

[0056] The end surface 93 faces upward in the direction opposite to the plasma P.

[0057] In other words, the end face 93 is oriented towards the top P1 of the plasma P. The top P1 is located away from the impact area between the laser beam 5 and the sample 2 in the direction of the focusing optics 8.

[0058] The collecting means 9 also comprise first communication means 95 intended to establish a communication path with the second communication means 101 of the determining means 10 .

[0059] The first communication means 95 and the second communication means 101 may be of the wireless type, or they may be in the form of connectors intended to receive plugs of wired connection cables.

[0060] This makes it possible to protect the optical fiber 91 and ensure optimal collection of the luminescence.

[0061] Furthermore, the needle makes it possible to maintain the position of the end face 93 facing the plasma P and as close to it as possible.

[0062] With reference to FIG. 4, which shows a schematic representation of an analytical device 3 according to the prior art, it can be noted that the use of collection means 9 according to the invention results in a space saving and at the same time an improved quality of collection.

[0063] Indeed, by reducing the angle A it is possible to free up a considerable amount of space above the collecting means 9, which may therefore make it possible to accommodate other equipment of the analysis device 3 and / or to reduce the size of the protective casing of the analysis device 3.

[0064] Furthermore, the bevel cutout 94 allows the end face 93 to be closest to the plasma P, as can be noticed between FIGS. 2 and 3 on the one hand and FIG. 4 on the other.

[0065] In addition, the bevel cutout 94 makes it possible to obtain an end face 93 with a larger surface area compared to prior art end faces 93. As a result, the optical fiber 91 of the collecting means 9 of the analysis device 3 according to the invention is able to capture a greater light intensity of the plasma P, thereby benefiting from an improved quality of the analysis performed by the determining means 10.

[0066] 5, the end face 93 is oriented towards the plasma P. More specifically, the end face 93 is oriented towards the area Z where the laser beam 5 impinges on the sample 2.

[0067] More specifically, the end face 93 is oriented towards the sample 2 and the support 31 .

[0068] This particular orientation makes it possible to maintain a sufficient capture of the light intensity emitted by the plasma P.

Claims

1. a stand (31) intended to support the sample (2) under study; a module (4) for generating a laser beam intended to impinge on the sample (2) under study in a direction perpendicular to the stand (31) and generate a plasma (P) that generates an optical emission; a means (9) for collecting said emitted light comprising an optical fiber (91) having a free end defining an end (92) having an end face (93) disposed closest to said plasma (P); An apparatus (3) for the elemental analysis of a sample (2) to be studied, comprising a frame on which are mounted:

1. A device, characterized in that the end (92) of the optical fiber (91) of the collecting means (9) extends along a main axis (AA) forming an angle (A) strictly less than 30 degrees with the stand (31), and the free end has a bevel cutout (94) defining the end face (93).

2. 2. The device according to claim 1, wherein said end face (93) faces upward.

3. 3. Analysis device (3) according to claim 1 or 2, characterized in that the optical fiber (91) has a diameter of 1000 μm.

4. A method for the elemental analysis of a sample (2), characterized in that it is carried out with an analytical device (3) according to any one of claims 1 to 3.

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