A device for analyzing a sample using a laser beam, including means for collecting information to be analyzed.

Abstract

Title: Laser beam analysis device, comprising means for collecting information to be analyzed. The invention relates to an elementary analysis device (3) for a sample (2) to be studied, comprising a frame on which are mounted: a base for supporting a sample (2) to be studied; a generation module (4) for a laser beam (5) to generate a plasma producing optical emission; and means for collecting the optical emission (9), comprising an optical fiber (91) having a free end defining a terminal portion, characterized in that the free end has a beveled cut defining the terminal section. Figure for the abstract: Fig. 1

Description

Title of the invention: Device for analyzing a sample by laser beam, comprising means for collecting information to be analyzed

[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 samples, in particular 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 beam shaping module integrating at least one lens and a diaphragm for selecting a portion of the laser beam emitted by the generation module, - optical means for focusing the laser beam onto a sample to be studied, and, - means of collecting optical emission.

[0012] The laser beam generated by the generation module, after shaping by the shaping module, is applied to a sample to be studied via the optical focusing means.

[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 from the plasma is carried out by the collection means.

[0015] To this end, the collection means include an optical fiber, one free end of which is brought as close as possible to the plasma. The closer the free end of the fiber is to the plasma, the more light noise is eliminated. In other words, the closer the optical fiber is to the plasma, the less surrounding light is captured by the plasma. The analysis of the light captured by the optical fiber is therefore of higher quality than when the optical fiber is further from the plasma.

[0016] More specifically, the free end of the optical fiber has a terminal section transverse to the direction of extension of the fiber, through which the optical emission of the plasma is collected.

[0017] To obtain quality collection, the optical fiber must be positioned so that its cross-section forms an angle of approximately 60° with the projection direction of the laser beam.

[0018] Once collected, the optical emission is analyzed by determination means to which the optical fiber is connected.

[0019] However, the use of an optical fiber entails a major drawback.

[0020] Indeed, since the optical fiber is made of silica, it cannot be bent. Consequently, the collection means have a significant footprint in the analysis device.

[0021] The angle formed with the laser beam is also important since it allows the best possible collection of the optical emission, thanks to the optimal positioning of the terminal section of the optical fiber, without risking occulting the laser beam, which makes it possible to obtain an optimal quality of the plasma generated by the reaction between the laser beam and the sample to be studied.

[0022] This then increases the overall bulk of the collection means and therefore of the analysis device.

[0023] More specifically, this angle is determined such that: - the collection methods, particularly the optical fiber, do not come into contact with the device's objectives, i.e., the optical means for focusing the laser beam, and - the optical fiber should not be in contact with the surface of the sample to be analyzed or even too close to the generated plasma, at the risk of destroying the fiber.

[0024] The invention aims in particular to overcome the disadvantages of the prior art.

[0025] More specifically, the invention aims to provide collection means enabling the collection of the optical emission of a plasma while having a reduced size or, more generally, an optimized spatial positioning in relation to the space available around the sample to be analyzed.

[0026] The invention also aims to provide such collection means which offer optimal quality of the collected optical emission.

[0027] The invention further aims to provide such collection means which are simple to make and install.

[0028] These objectives, as well as others that will appear subsequently, are achieved thanks to the invention, which relates to a device for the elemental analysis of a sample to be studied, comprising a frame on which are mounted: - a base intended to support a sample to be studied; - a laser beam generation module designed to impact a sample to be studied in a direction perpendicular to the base, to generate a plasma producing optical emission, and - means for collecting the optical emission, including an optical fiber having a free end defining a terminal portion to be placed near the plasma, characterized in that the terminal portion of the optical fiber of the collection means extends along a principal axis forming with the base an angle A strictly less than 30°, and in that the free end has a beveled cut defining the terminal section.

[0029] Thanks to the bevel cut, it is possible to reduce the angle of the optical fiber relative to the base.

[0030] This directly benefits the compactness of the analysis device.

[0031] Furthermore, by reducing the angle between the optical fiber and the base, the terminal section of the optical fiber can be brought closer to the plasma, which benefits the quality of the analysis since the distance between the optical emission and the terminal section is minimal.

[0032] In addition, the bevel offers good capture and propagation of the light flux through the optical fiber.

[0033] According to an advantageous aspect, the terminal section is oriented towards an upper part of the plasma.

[0034] However, tests have shown that orienting the terminal section towards the upper part of the plasma offers a superior quality of analysis compared to conventional solutions.

[0035] According to another advantageous aspect, the optical fiber has a diameter of 1000 pm.

[0036] This optical fiber diameter ensures sufficient optical amission collection to allow elemental mapping of the composition of the sample studied and allows for easy bevel cutting.

[0037] The invention also relates to a method for elemental analysis of a sample, characterized in that the method implements an analysis device as previously described.

[0038] Other features and advantages of the invention will become more apparent from the following description of a preferred embodiment of the invention, given by way of illustrative and non-limiting example, and the accompanying drawings described below.

[0039] [Fig.1] Fig.1 is a schematic representation of an analysis system comprising an analysis device according to the invention.

[0040] [Fig.2] Fig.2 is a detailed schematic representation of the analysis device according to the invention, illustrating means of collecting an optical plasma emission.

[0041] [Fig. 3] [Fig. 3] is a schematic detail representation of a free end of an optical fiber of the means of collection of the analysis device according to the invention.

[0042] [Fig.4] Fig.4 is a schematic detail representation of a device analysis, illustrating means of collecting an optical plasma emission, according to the prior art.

[0043] [Fig. 5] [Fig. 5] is a schematic detail representation of a free end of an optical fiber of the means of collection of the analysis device according to an alternative embodiment of the invention.

[0044] Fig. 1 illustrates a system 1 of elemental analysis of a sample 2 to be studied.

[0045] The system 1 includes an analysis device 3 as described below, this analysis device 3 comprising a base 31 for receiving the sample 2.

[0046] 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 701, 702, 703 of 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.

[0047] As illustrated in [Fig. 1], the analysis device 3 comprises, depending on the direction of emission of the laser beam 5 from the generation module 4 towards the sample 2, a plurality of lenses 6 and a diaphragm 7

[0048]

[0049] 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.

[0050] 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.

[0051] In addition, system 1 includes collection means 9 and determination means 10, the role of which will be described below.

[0052] As described previously, system 1 allows analysis of a sample 2 to map its elemental composition.

[0053] 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.

[0054] 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.

[0055] The collection of the optical emission from the plasma is carried out by the collection means 9.

[0056] For this purpose, as illustrated by Figures 2 and 3, the collection means 9 comprise an optical fiber 91, a free end of which, defining a terminal portion 92, is brought as close as possible to the plasma P. The optical fiber 91 preferably has a diameter of 1000 pm.

[0057] The terminal portion 92 extends along a main axis AA forming with the base 31 an angle A strictly less than 30°.

[0058] The terminal portion 92 has a terminal section 93 which is positioned closest to the plasma P.

[0059] According to the embodiment illustrated by figures 2 and 3, the terminal portion 92 has a beveled cut 94 defining the terminal section 93.

[0060] The terminal section 93 is oriented upwards, in the opposite direction to the plasma P.

[0061] In other words, the terminal section 93 is oriented towards an upper part PI of the plasma P. The upper part PI is distant from the impact zone between the laser beam 5 and the sample 2, in the direction of the focusing optical means 8.

[0062] The collection means 9 also include first means of communication 95 intended to establish, with second means of communication 101 and determination means 10, a means of communication.

[0063] 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.

[0064] This helps to protect the optical fiber 91 to ensure that the collection of the optical emission is carried out optimally.

[0065] In addition, the needle makes it possible to maintain the position of the terminal section 93 opposite and as close as possible to the plasma P.

[0066] With reference to [Fig.4] which schematically represents an analysis device 3 according to the prior art, we can see the reduction in bulk obtained by the use of collection means 9 according to the invention, as well as the gain in collection quality.

[0067] Indeed, by reducing the angle A, it is possible to free up a significant amount of space above the collection means 9. This can thus allow other equipment of the analysis device 3 to be housed, and / or reduce the size of a protective housing for the analysis device 3.

[0068] Furthermore, as can be seen between figures 2 and 3 on the one hand, and [Fig.4] on the other hand, thanks to the bevel cut 94, the terminal section 93 can be approached as closely as possible to the plasma P.

[0069] Furthermore, the beveled cut 94 makes it possible to obtain an end section 93 with a larger surface area compared to the end section 93 of the prior art. As a result, the optical fiber 91 of the collection means 9 of the analysis device 3 according to the invention can capture a greater light intensity from the plasma P, thus improving the quality of the analysis performed by the determination means 10.

[0070] According to an alternative embodiment illustrated by [Fig.5], the terminal section 93 is oriented in the direction of the plasma P. More specifically, the terminal section 93 is oriented towards an impact zone of the laser beam 5 on the sample 2.

[0071] More specifically, the terminal section 93 is turned towards sample 2 and support 31.

[0072] This particular orientation allows for the retention of a significant capture of the light intensity emitted by the P plasma.

Claims

1.

2.

3.

4. Demands Elemental analysis device (3) for a sample (2) to be studied, comprising a frame on which are mounted: - a base (31) intended to support a sample (2) to be studied; - a laser beam generation module (4) intended to impact a sample (2) to be studied in a direction perpendicular to the base (31), to generate a plasma (P) producing optical emission, and - means for collecting (9) the optical emission, comprising an optical fiber (91) having a free end defining a terminal portion (92) having a terminal section (93) to be placed near the plasma (P), characterized in that the terminal portion (92) of the optical fiber (91) of the collection means (9) extends along a principal axis (AA) forming with the base (31) an angle (A) strictly less than 30°, and in that the free end has a beveled cut (94) defining the terminal section (93). Device according to the preceding claim characterized in that the terminal section (93) is oriented upwards. Analytical device (3) according to any one of the preceding claims, characterized in that the optical fiber (91) has a diameter of 1000 pm. Elemental analysis method for a sample (2), characterized in that the method employs an analysis device (3) according to any one of the preceding claims.

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