Classifications

• • 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
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N21/49—Scattering, i.e. diffuse reflection within a body or fluid
  • G01N21/53—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke
  • G01N21/532—Scattering, i.e. diffuse reflection within a body or fluid within a flowing fluid, e.g. smoke with measurement of scattering and transmission
• • 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
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/85—Investigating moving fluids or granular solids
  • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
• • 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
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N2021/4704—Angular selective
  • G01N2021/4707—Forward scatter; Low angle scatter
• • 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
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N2021/4704—Angular selective
  • G01N2021/4709—Backscatter
• • 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
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/47—Scattering, i.e. diffuse reflection
  • G01N2021/4704—Angular selective
  • G01N2021/4726—Detecting scatter at 90°
• • 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
  • G01N21/645—Specially adapted constructive features of fluorimeters
  • G01N2021/6484—Optical fibres
• • 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
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/85—Investigating moving fluids or granular solids
  • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
  • G01N2021/8514—Probe photometers, i.e. with optical measuring part dipped into fluid sample with immersed mirror
  • G01N2021/8521—Probe photometers, i.e. with optical measuring part dipped into fluid sample with immersed mirror with a combination mirror cell-cuvette
• • 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
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
• • 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
  • G01N21/645—Specially adapted constructive features of fluorimeters
• • 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
  • G01N21/65—Raman scattering
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N2201/00—Features of devices classified in G01N21/00
  • G01N2201/08—Optical fibres; light guides

Definitions

• the present invention relates to a probe for performing optical measurements, in particular of diffusion, of Raman spectroscopy and of fluorescence, in fluids of a more or less complex nature (monophasic or multiphasic fluids such as comprising particles in suspension, foams or emulsions. ..). It also relates to a system and measurement methods implementing such a probe.
• the field of the invention is more particularly, but not exclusively, that of optical fluid characterization techniques.
• UV, Visible, Infrared, Medium Infrared and Raman fluorescence and more generally optical measurements of diffusion (for example of granulometry) and absorbance are commonly used techniques for the analysis of solid and liquid products.
• chemical characterization techniques whose purpose is, in particular, to identify or assay compounds or molecules.
• these are techniques based on spectroscopic, fluorescence, Raman, etc. type analyzes.
• Physical type characterization techniques which aim to characterize physical properties of the medium such as turbidity, or particle size (laser particle size).
• Characterization or optical measurement systems that implement these techniques typically include one or more sources of light detection means (spectrometers, cameras, ...) and probes for taking the measurement in the medium to be analyzed.
• These probes have the function of illuminating or irradiating the medium to be analyzed, and of collecting light from this medium in terms (orientation, distance, %) that depend on the application. They must also be able to fit into production or laboratory equipment, especially when used for on-line monitoring or control.
• the measurements are generally carried out in backscatter.
• the illumination of the medium and the collection of the light are performed on the same side, and the measurement is therefore carried out at an angle of 180 degrees with respect to the direction of illumination;
• the measurements are generally made in transmission through a thickness of product, with a measurement point facing the illumination source.
• the measurement is therefore performed with an angle of zero degrees with respect to the illumination source and with an optical path adapted to the level of absorption of the product (typically 2 or 5 mm);
• transflexion probes a mirror is placed in front of the light source and the measurement is close to the light source at 180 degrees. If the fluid is clear, the measurement is done through reflection on the mirror. If the fluid is not clear, the measurement is done directly backscattering. This technique nevertheless has the disadvantage of not making it possible to distinguish whether the information comes from the liquid or the solid;
• the measurement is generally carried out with a receiver placed at a 90-degree angle with respect to the illumination source; for characterizing distributions or measuring particle sizes, probe configurations are encountered with several receivers placed at different angles with respect to the illumination source (0, 5, 90, 160, 180, ... degrees) in a function of the desired sensitivity to small or large particles;
• probes with several receivers placed at different angles or distances from the illumination source can be used to perform spatially resolved spectroscopy measurements.
• spatially resolved spectroscopy measurements By using the theory of multiple diffusion, for example, one can then determine the physical properties from the calculation of a diffusion coefficient, thus separating the chemical effect.
• Probe configurations with multiple detectors distributed at different angles are generally large, making their implementation difficult in production environments on small diameter pipes or in reactors or fermenters.
• the reactors or fermentors generally have ports for inserting instrumentation that have a standardized diameter of 1 inch (25.4 mm) or Vi inch (12.7 mm). The use of larger diameter probes therefore requires expensive adaptations.
• a second configuration with a measurement zone in the form of a lateral notch on the body of the probe, and detectors placed at 90 degrees and zero degrees from the light source, respectively.
• the known probes are limited to particular measurement configurations, and thus require the implementation of several probes to perform various measurements.
• An object of the present invention is to provide a measurement probe of small size, which solves disadvantages of the prior art.
• Another object of the present invention is to provide a measurement probe suitable for measurements in a wide range of turbidity conditions.
• Another object of the present invention is to provide a measurement probe which allows a wide variety of measurement configurations, and which can be reconfigurable.
• optical measuring probe device for performing spectrometric and / or photometric measurements in a fluid
• At least one first and one second branch extending at the end of said body in its extension and delimiting a measuring cavity
• optical coupling means capable of transmitting light between at least a portion of said optical fibers and the measuring cavity, comprising (i) first optical coupling means opening into the measurement cavity at the level of the first branch, ii) second optical coupling means opening into the measurement cavity at the second branch, and (iii) third optical coupling means opening into the measurement cavity at the bottom of said cavity.
• the optical fibers may be multimode fibers or monomode fibers, depending on the applications. They can all be identical, or different depending on the signals they must convey. They can be composed of separated fibers and / or, at least partially, of fibers grouped in the form of fiber bundles or "bundle" in English.
• the probe according to the invention may furthermore comprise optical connection means for connecting the optical fibers to the optical illumination and / or detection means.
• optical connection means for connecting the optical fibers to the optical illumination and / or detection means.
• the probe according to the invention may further comprise fin-shaped branches making it possible to control a flow of liquid flowing in the measurement cavity, so as to make it substantially laminar and to compress it in order to reduce the parasitic effect of the gas bubbles.
• the measurement cavity is positioned at the end of the body, between the two branches.
• the probe of the invention is particularly well suited to perform measurements in a stream.
• the disturbances of the flow in the measurement zone due to the presence of the body are minimized, by comparison in particular with probes of the prior art with a measurement zone which has the shape of a lateral notch.
• This configuration also makes it possible to optimize the shape of the branches to control the flow in the measurement zone, and to make sure that the fluid that is measured is as representative as possible of all the fluid circulating around the probe.
• probe configuration makes it possible to carry out measurements with stops of fluid agitation, for example to evaluate settling or phase separation times.
• the probes are generally arranged vertically, with conventional probes that have a measuring zone in the form of a lateral notch on the body of the probe, a deposit phenomenon appears on the window located down the reactor.
• the particles can flow freely towards the bottom of the reactor without being deposited on the probe.
• measurements can be made at different depths, for example by moving the probe, in order to calculate a diffusion / absorption gradient without risk of fouling of this probe.
• the body of the probe according to the invention may have a diameter of less than 26 mm, or even less than 16 mm.
• the probe according to the invention can thus be of small diameter and easily integrable in a measurement environment, thanks in particular to the use of the optical fibers to transport the signals and to the disposition at the end of the measuring cavity.
• the probe according to the invention may comprise a body of circular section or of any other section that fits as needed in a reduced diameter.
• This body can be of any length. It can be for example very short, for example of the order of a centimeter, to allow measurements in a small space such as a pipe. It can also be lengthened, for example with a length greater than ten centimeters, to allow a measurement sufficiently far away from a wall to avoid disturbances due to agitation against this wall, or to allow measurements at different depths. moving the probe.
• the probe according to the invention may have a measuring length in the measuring cavity which is suitable for carrying out measurements in media with turbidity greater than 1000 NTU.
• the probe according to the invention may have a measurement length in the measurement cavity which is suitable for carrying out measurements in media with a turbidity greater than 10000 NTU.
• the measurement length corresponds to the length of the path of the light in the fluid, in the cavity or more precisely between the interfaces of the first and second optical coupling means with the fluid.
• the UTN Nephelometric Turbidity Unit - NTU
• a turbid water has a turbidity of the order of 50 NTU or more
• the milk has a turbidity of the order of 10000 NTU.
• the probe according to the invention can be used in very wide turbidity ranges, from less than 200 NTU to more than 10,000 NTU. This is possible for example with a measurement cavity whose length is of the order of 2 to 5 mm.
• the probe can then be used to perform laser particle size measurements (Fraunhofer theory and particle size above 100pm). Fibers for measuring at many different angles.
• the probe according to the invention may have a measurement length in the measuring cavity which is variable along the first and second branches.
• This variable measuring length makes it possible to simultaneously generate optical paths of different length in the fluid. It can be obtained with first and second branches that are not parallel in the measuring cavity.
• the first and / or second optical coupling means may include a right angle reflector and a window made of at least partially transparent material.
• the windows of the first and / or second optical coupling means may be of variable thickness and / or be inserted in the first and second branches so that their respective faces in contact with the fluid are not parallel. This makes it possible to obtain measurement lengths which vary according to the position relative to their surface.
• the first, second and / or third optical coupling means may furthermore include:
• At least one lens or a microlens of collimation or focusing at least one lens or a microlens of collimation or focusing
• At least one filter for example of the band-pass or notch type, placed in front of at least a portion of the optical fibers in order to block parasitic wavelengths (Raman laser or UV excitation).
• This or these filter (s) may in particular be included for performing Raman or UV spectroscopy measurements.
• optical fibers can follow the shape of the body to the immediate vicinity of the measuring cavity and it is not necessary to impose them small radii of curvature.
• the transparent windows can be of a calibrated thickness to precisely adjust the length of the measurement zone in the fluid, regardless of the length of the measuring cavity between the two branches.
• the probe may further include means for easily changing these windows.
• the body of the probe according to the invention may comprise separable parts of which:
• a second part comprising the first and second branches and the measuring cavity, and including the optical coupling means.
• measuring cavities with different geometrical or optical characteristics can easily be mounted on the same probe, or, alternatively, a bundle of optical fibers controlling a measurement cavity can be replaced.
• the probe may comprise fixing means (to the bioreactor or the pipe for example) integral with the first part.
• fixing means to the bioreactor or the pipe for example
• the probe may also comprise fixing means (to the bioreactor or the pipe for example) integral with the second part.
• fixing means to the bioreactor or the pipe for example
• the first part with the optical fibers can be inserted into the second part serves as a sheath.
• the probe according to the invention may furthermore comprise a first central optical fiber having an end coupled with the first coupling optical means, and a second central optical fiber having an end coupled to the first optical fibers.
• second optical coupling means, the first and second central optical fibers defining a measurement optical axis in the cavity.
• These first and second central optical fibers may, for example, be used to perform transmission measurements along the optical axis.
• the probe according to the invention may furthermore comprise:
• At least one lateral optical fiber having an end coupled with the first coupling means and placed near the end of the first central optical fiber, and / or
• At least one lateral optical fiber having an end coupled with the second optical neck means and placed near the end of the second central optical fiber.
• Such a lateral optical fiber may, for example, be used to perform backflushing measurements at 180 degrees.
• the probe according to the invention may furthermore comprise:
• At least two lateral optical fibers having an end coupled with the first coupling optical means, the ends being placed substantially at equal distance from the end of the first central optical fiber, and / or
• At least two lateral optical fibers having an end coupled with the first coupling optical means, the ends of which are placed substantially equal to the end of the second central optical fiber.
• Such pairs of lateral optical fibers can in particular be used to perform measurements of homogeneity in transmission or backscattering. Indeed, differences in measurements at the same angles and in The same distances relative to an illumination fiber are representative of inhomogeneities present in the fluid.
• the probe according to the invention may furthermore comprise:
• a plurality of optical fibers having an end coupled with the third optical coupling means, said ends being arranged in at least one line extending between the first and second branches;
• a plurality of optical fibers having an end coupled with the third optical coupling means, said ends being arranged along two lines extending between the first and second branches.
• the third optical coupling means may further comprise at least one cylindrical lens.
• the two lines can be confused or side by side. They can be substantially parallel.
• these optical fibers coupled with the third optical coupling means may be used to make measurements with varying angles depending on their position.
• They can also be used to make particle imaging in the moving fluid.
• some of them possibly arranged along a line, can be coupled to a light source to illuminate the fluid.
• the probe can then be used to measure turbidity, spectral measurements and imaging of the medium, for example by coupling it to two or more sources of illumination.
• optical fibers with one end coupled with the third optical coupling means may be grouped in the form of a sheet to maximize the number of measuring points.
• an optical measurement system comprising a probe according to the invention, and optical means of illumination and / or detection external to the probe and connected to the optical fibers of said probe.
• the optical measuring system according to the invention may furthermore comprise optical switching means capable of connecting means illumination optics and / or optical detection means to different optical fibers.
• the optical measuring system may furthermore comprise at least one light source connected to a first central optical fiber, and detection means of one of the following types: spectrometer, Raman spectrometer hyperspectral camera (for example of the "push broom" or filter type) connected to at least one of the following fibers: second central optical fiber, optical fiber (s) side (s), optical fiber (s) (s) coupled with the third optical coupling means.
• detection means of one of the following types: spectrometer, Raman spectrometer hyperspectral camera (for example of the "push broom" or filter type) connected to at least one of the following fibers: second central optical fiber, optical fiber (s) side (s), optical fiber (s) (s) coupled with the third optical coupling means.
• the optical measurement system may furthermore comprise a light source connected to at least one optical fiber having an end coupled with the third optical coupling means, and a detector of one of the following types: matrix detector, line detector, multi-channel spectrometer connected to a plurality of optical fibers having an end coupled with said third optical coupling means.
• the present invention provides a probe for measuring in a small space a fluid sample from different angles with the possibility of implementing different optical techniques: UV spectroscopy, visible, near infrared, Raman or fluorescence, imaging.
• the measurements can be made optionally by at least three channels (in transmission, at 90 degrees and / or in backscatter). Some of these channels (at 90 degrees and backscattering in particular) are less sensitive to parasitic primary radiation, in particular for fluorescence measurements or in Raman spectroscopy;
• the detectors can be connected to one of these channels; - an opportunity to characterize the physics and chemistry of the sample. Measurement methods (Raman, fluorescence and spectroscopy) can be combined and implemented simultaneously or sequentially using multiple optical fibers.
• the probe is particularly suitable for measurement in reactors containing liquid or pipes.
• the shape of the probe also allows a better control of the flow in front of the measuring points, and a limitation of the fouling. It thus makes it possible to make decantation and / or demixing measures under good conditions.
• FIG. 1 illustrates an overview of the probe according to the invention
• 2 (a) and FIG. 2 (b) illustrate perspective views of the end of the probe with the measuring cavity, respectively from the side and from the front
• FIG. 3 illustrates a sectional view of the end of the probe with the measuring cavity and the optical fibers represented
• FIG. 4 illustrates a front view of the measurement cavity with the optical fibers represented, according to a first embodiment
• FIG. 5 illustrates a front view of the measuring cavity with the optical fibers represented, according to a second embodiment
• FIG. 6 illustrates a front view of the measuring cavity with the optical fibers shown, according to a third embodiment.
• FIG. 7 illustrates a block diagram of a system implementing a probe according to the invention.
• FIGS. 1 to Fig. 6 do not show separate embodiments but illustrate features that can be combined in different ways in particular embodiments of the invention.
• a probe 1 according to the invention comprises a body 2, which is terminated at one end by two branches 3, 4 between which is a measurement cavity 10. These two branches 3, 4 are called, for reasons for clarity of the presentation first branch 3 and second branch 4, it being understood that these names may in no case be limiting in nature.
• the branches 3, 4 and the body 2 may be for example metal, glass, sapphire, or a polymeric material (plastic). . .
• the body 2 is terminated at its other end by an interface of the iaison
• q ui includes means of connection, especially optiq ues.
• the probe presented is designed in particular to be able to carry out measurements in a bioreactor, a fermentor or any other enclosure containing a fluid.
• the body 2 is of elongated shape to allow a measurement taken to the distance of the walls, and sufficiently thin to be easily inserted into the enclosure.
• the branches 3, 4 have a shape adapted to optimize the flow of fluid in the measuring cavity 10.
• the probe 1 comprises optical fibers 23 which make it possible to interface the measurement cavity 10 with means of illumination and measurement external to the probe 1. These optical fibers 23 are terminated by connectors at the level of the link interface 5.
• the optical fibers 23 may be decomposed into first optical fibers 30, second optical fibers 40 and third optical fibers 50 according to their arrangement with respect to the measuring cavity 10.
• the optical fibers 23 are multimode optical fibers, which allow the light to pass through most of the UV, visible and near infrared spectrum.
• the probe 1 also comprises optical coupling means that enable the optical fibers 23 to interface with the measuring cavity 10.
• optical coupling means comprise first and second optical coupling means which open into the measurement cavity 11 at the level of the first branch 3 and the second branch 4, respectively.
• the first and second optical coupling means comprise reflectors 22 which make it possible to return the beams of the first optical fibers 30 and second optical fibers 40 at a distance to the cavity 11, along an optical measurement axis 21. which relies on the two branches 3, 4.
• the first and second optical coupling means also comprise transparent windows 11, made of sapphire glass or possibly quartz, which allows the optical beams to pass while ensuring the seal.
• the thickness of these windows 11 also determines the measurement length which corresponds to the path length of the optical beams in the fluid along the measurement optical axis 21. This thickness can be adjusted for this purpose.
• the optical coupling means also comprise third optical coupling means which open into the measuring cavity 11 at the bottom of this cavity. They comprise a window 12 of sapphire glass or possibly quartz which pass through the optical beams of the third fibers 50 while sealing.
• the optical axes of beams originating from (or captured by) these third optical fibers 50 are perpendicular or close to the direction perpendicular to the optical measurement axis 21.
• the probe 1 further comprises a holding element integral with the body 2, which makes it possible to maintain the end of the various optical fibers 23 at the desired position, relative to the optical coupling means.
• optical fibers 23 shown in the figures is in no way limiting and should only be considered as an example.
• the first optical fibers 30 comprise at least this optical central illumination fiber 31.
• the first optical fibers 30 may also include at least one lateral optical fiber 32 placed near the central optical fiber 31 to collect backscattering light.
• the central optical fiber 31 can also be used to collect backscattered light.
• the first optical fibers 30 may also comprise a plurality of lateral optical fibers 32 placed equidistantly, in pairs, from the central optical fiber 31.
• This configuration makes it possible to make backscattering homogeneity measurements, by comparing the signals received by lateral optical fibers 32 located equidistant on both sides of the central optical fiber 31.
• the variations between the signals issuing from these fibers 32 can essentially be attributed to the local inhomogeneities (presence of particles, etc.) of the fluid in the measurement zone.
• this configuration can make it possible to improve the backscattering detection with respect to the inhomogeneities of the fluid, on average the signals coming from the lateral optical fibers 32 located equidistantly on either side of the central optical fiber 31.
• the second optical fibers 40 comprise at least one central optical fiber 41 for collecting the light in transmission.
• They may also include one or more lateral optical fiber (s) 42 placed near the central optical fiber 41, to make diffusion measurements, or diffusion profiles, at small angles. Indeed, the measurement angle (with respect to the illumination axis that corresponds to the optical axis 21) of a lateral optical fiber 42 depends on the distance between the central optical fiber 41 and this lateral optical fiber 42 .
• This configuration makes it possible to measure transmission homogeneity, by comparing the signals received by lateral optical fibers 42 situated at equal distances on either side of the central optical fiber 41. Indeed, the variations between the signals coming from of these fibers 42 may be essentially attributed to local inhomogeneities (presence of particles, ...) of the fluid in the measurement zone. Alternatively, this configuration can make it possible to improve the detection in transmission or at small angles with respect to the inhomogeneities of the fluid, on average the signals coming from the lateral optical fibers 42 located equidistantly on either side of the central optical fiber 41 .
• the third optical fibers 50 comprise at least one optical fiber 51 for collecting light perpendicular to the optical measurement axis 21.
• They may furthermore comprise a plurality of optical fibers 52 distributed along a line parallel to the optical measurement axis 21.
• This configuration may in particular be used to make wide-angle diffusion profile measurements, to the extent each these optical fibers 50 collect light from a diffusion center in the fluid at a different angle (with respect to the illumination axis that corresponds to the optical 21).
• the third optical fibers 50 can also be used to make imaging of the fluid that flows in the measurement cavity. They can be implemented in the form of a sheet, which makes it possible to obtain a large number of measurement points.
• Each fiber 50 constitutes a pixel, and an image of the particles of the fluid can be formed, for example with a linear detector, by using the scrolling fluid (which scroll is guided by the shape of the first and second branches 3, 4) for create the second dimension of the image.
• this imaging mode can be implemented on the same probe and with the same fibers 50 as those used to make diffusion measurements or diffusion profile.
• the body of the probe has a diameter of 25 mm and a length of 100 mm;
• the measurement cavity 10 has a useful length of 4 mm;
• the probe is adapted to perform measurements in fluids with a turbidity up to 12000 NTU;
• the optical fibers comprise 9 silica optical fibers with a low content of OH ions, a bandwidth of 350-2500 nm and a diameter of 220 ⁇ m, and a fiber diameter of 300 ⁇ m for the detection, and 7 optical fibers for illumination. These optical fibers 23 are terminated by SMA type connectors at the interface 5.
• the body 2 of the probe may comprise two separable parts:
• the branches 3, 4 and the measuring cavity 10 may be on a removable element 6 screwed or fixed by any other means on a rear portion 7 of the body 2.
• the removable element 6 may include the optical means coupling, while the rear portion 7 of the body 2 may include the optical fibers 23, the ends of which are held integral with the body 2 by a holding member. It is thus possible to change the measuring cavity 10, for example for maintenance reasons or to use different measurement cavities with different configurations or lengths of travel in the fluid;
• the body 2 may comprise an outer portion 71 which comprises the measuring cavity 10 and the optical coupling means.
• This outer portion 71 is designed such that it can be fixed on an enclosure for example.
• the body 2 then also includes an inner portion 70 which comprises the optical fibers 23.
• This inner portion 70 can be inserted into the outer portion 71 as in a sleeve and removed without risk of leakage or contamination of the enclosure. It is thus possible to replace the optical fibers 23, for example to use different fiber configurations 23 or to perform different types of measurement at different wavelengths without disassembling the probe.
• the two possibilities can be combined, to produce a probe whose body 2 comprises an outer portion 71 with an end 6 (including the measuring cavity and the optical coupling means) removable, and an inner sleeve 70 removable with the optical fiber.
• the optical coupling means may comprise lenses or microlenses 24 which make it possible to optimize the coupling with the optical fibers 23. They may also comprise filters, for example of the pass-band or cut-off type. band ("notch") for application in Raman spectroscopy or fluorescence).
• the probe 1 may comprise a reference path for allowing a measurement of the intensity of the illumination outside the measuring cavity 10.
• the probe may comprise a coupler inserted on a optical fiber 23 provided for illumination, such as the first central optical fiber 31. This coupler takes a fraction of the light it returns by means of an optical fiber to the instrumentation coupled to the probe 1. Thus, the measurement is made closer to the measuring cavity 10 and takes into account losses in the probe, for example at the optical connectors.
• the third optical fibers 50 may further comprise a second line or a second layer of optical fibers 53 substantially parallel to the optical measurement axis 21.
• a first fiber line 52 may be used to the measure, and the second line can be used for illumination.
• the third optical coupling means may further comprise a cylindrical lens 60 for improving imaging performance, in configurations with a single line of optical fibers 52 or with two lines of optical fibers 52, 53.
• the windows 11 may be of variable thickness depending on the position along a diameter or transverse dimension. They can be placed in the first and second branches 3, 4 so that their faces in contact with the fluid are not parallel.
• This configuration of the probe 1 makes it possible to carry out transmission measurements, possibly simultaneously, with different measurement lengths in the fluid depending on the optical fibers used. This can, for example, make it possible to use the probe over a larger range of turbidity values, or to make transmission measurements for different thicknesses of fluid.
• the probe 1 in the embodiment of FIG. 6 may comprise third optical fibers 50 and third optical coupling means according to the embodiments shown in FIGS. 4 and FIG. 5.
• a probe 1 may comprise first and second coupling means with at least two windows 11, arranged side by side on the first and second branches 4, 5, and arranged so as to form:
• FIG. 4 a first set of windows 11 with their parallel fluid interfaces, as illustrated in FIG. 4, and a second set of windows 11 with their non-parallel fluid interfaces, as illustrated in FIG. 5.
• the two side-by-side windows can also be made in the same transparent element 11.
• the windows 11, 12 of the coupling means can be made in the form of a single window, for example a semicircular window.
• the body 2, the distal portion 6 of the body 2 with the branches 3, 4 and the measurement cavity 10, or the branches 3, 4 can be made of a transparent material, such as quartz or glass. sapphire crystal.
• the windows 11 can then be part of this transparent element body 2.
• the optical coupling means are at least partially included in the body 2 and / or the first and second branches 4, 5.
• the probe 1 may comprise optical fibers 23 of different diameters according to their positions, for example to optimize the signal-to-noise ratio of the assembly.
• a measurement system that implements the probe 1 further comprises one or more illumination sources 71, and detection means 74.
• optical switching means 72 manual or computer-controlled, which make it possible to connect different sources of illumination 71, and / or different detection means 74, to different optical fibers 23.
• the probe 1 is configured so as to provide an illumination point by the first central optical fiber 31 and at least three measurement points:
• the system further comprises a coupler or circulator for separating the illumination and the backscattering signal;
• the illumination source 73 coupled to the central optical fiber 31 may be for example a halogen lamp, a tunable monochromatic light, or a white laser (supercontinum of white light).
• the detection means 74 comprise a spectrophotometer.
• This spectrometer may comprise a single measurement channel, and be sequentially coupled by optical switches 72 to the optical fibers 23 which collect the signals.
• a multichannel spectrophotometer or a hyperspectral camera can also be used to process at least a portion of the measurements simultaneously.
• the transmission measurement makes it possible to obtain the spectrum of this fluid.
• the three positions provide useful information.
• the transmission measurement provides spectral information more correlated to the liquid chemistry while the 90-degree and backscatter measurements provide information on the elements in suspension in the liquid (solid particles, cells, oil drops, etc.). ).
• the turbidity, the average particle size and / or their density can also be obtained in this way with a spectrophotometer 73.
• the diffusion theory (single or multiple) can be used according to the level of diffusion: technique of the two spheres of integration, Kubelka Munk equations, Fraunhofer diffraction, Mie theory.
• Probe 1 can be used for fluorescence measurements.
• the excitation being done by the first central optical fiber 31, the measurements give access respectively to the frontal fluorescence of the sample (fiber 32), the fluorescence at 90 ° (fiber 51), and the fluorescence in transmission (optical fiber 41). ).
• the measurement at 90 ° (fiber 51) makes it possible to avoid the effect of excitation radiation on the measure.
• the ability to perform frontal fluorescence measurements in transmission or at 90 ° makes it possible to optimize the sensitivity to particles or to the liquid in suspension.
• Probe 1 can be used to do Raman / Cars spectroscopy.
• the laser excitation being done by the first central optical fiber 31, the measurements give access respectively to the backscattering Raman spectrum (fiber 32), the Raman spectrum at 90 ° (fiber 51), and the Raman spectrum in transmission (optical fiber 41). ).
• the measurement at 90 ° (fiber 51) makes it possible to avoid the effect of the excitation radiation on the measurement.
• the measurement of Raman spectrum at different angles may allow a better separation of the Raman effect with respect to the fluorescence effect.
• the probe 1 may also comprise about ten measurement points (typically between 10 and 20 or even 30) distributed between the first, the second and the third optical fibers 30, 40, 50. This type of configuration makes it possible to 'get measurements at a multitude of different angles.
• a parallel spectrometer 74 may for example comprise a matrix detector whose columns corresponding to the different measurement channels or optical fibers 23, and on which the corresponding spectra are recorded along the lines.
• the illumination can be of different types depending on whether one wishes to make UV spectroscopy, visible, near infrared, fluorescence or Raman.
• Probe configurations with a plurality of measurement points allow for better evaluation of the effect of scattering. Indeed, the diffusion profile can be measured much more precisely at different angles. It may even be possible to carry out granulometric measurements in situ.
• a measure of homogeneity can be obtained by comparing the measurements of the first or second secondary optical fibers 32, 42 located on one side of the central fiber 31 or 41 with those of the first or second secondary optical fibers 32, 42 located on the other side.
• the detection of inhomogeneity can be done by comparing the spectra between them by division or by principal component analysis (detection of inhomogeneities by detection of outliers, or "outliers" in English).
• the homogeneity can also be obtained by illuminating the fluid by a third fiber 50 and by comparing the signals obtained by the first and second optical fibers 30, 40;
• the probe 1 can also be used to perform online imaging. Indeed, if the number of third optical fibers 50 is sufficiently large (for example of the order of 15 to 20) and the acquisition speed is fast enough, the system can produce an image by combining the simultaneous measurements.
• the illumination may be derived from a first central fiber 31, some of the third fibers 51, 52, or a second line of third lighting fibers 53.
• the illumination may also be at a wavelength of excitation to perform fluorescence imaging.
• a linear detector 74 may in particular be used.
• the shape of the probe facilitates a laminar flow, the passage of the liquid will allow a uniform scan pledge of a good quality image.
• a parallel spectrometer 74 may also be used to produce hyperspectral images, or a plurality of images at different wavelengths.
• the measurement possibilities make it possible to implement different types of processing depending on the information sought.
• the signal can be processed in particular:
• the signal at 90 ° and backscattering is strongly correlated to the signal of the particles, but it also contains the chemical information of the fluid.
• a principal component analysis is calculated on the transmission spectra. These spectra mainly contain the information of the liquid. The main components are then used to define a projection operator.
• the part containing the chemical information of the fluid is calculated by multiplying the spectrum by the projection operator;
• the particle information part is calculated by subtracting the raw spectrum by the spectrum multiplied by the projection operator.

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