Method and apparatus for detecting and / or measuring impurities in droplets

Abstract

The present invention relates to a measuring device (1) for the detection and / or measurement of particles in a fluid, the measuring device comprising: a fluid source (11) for generating a fluid flow (111) along a fluid flow path; a first laser source (12) positioned to emit a first laser beam (120) of laser light in a measurement space of the fluid flow path for light scattering; a scattered light detection device (13) for detecting the presence of the particles in the fluid flow path by detecting and measuring the laser beam light scattered by the particles at different angles, characterized in that the measuring device further comprises: a second laser source (14) positioned to emit a second laser beam (140) of laser light in the measurement space of the fluid flow path for Raman and fluorescence excitation; a Raman and fluorescence detection device (15) for detecting a Raman scattering signal emitted by the fluid and a fluorescence signal emitted by the particles when excited by the second laser beam (140).

Description

Technical Field

[0001] The present invention relates to methods and devices for the detection and / or measurement of impurities in, and more particularly, the present invention relates to methods and devices for the on-line detection of the concentration of organic impurities in atomized water droplets. The described methods and devices of the present invention are intended for the immediate and instantaneous detection of the presence and concentration measurement of organic molecules or mixtures of organic molecules in an aerosol of water droplets. Background Art

[0002] The present invention relates to the field of preventive and / or protective devices for detecting and / or characterizing fluid-borne particles, such as but not limited to air-borne particles (such as air pollutants, airborne biological and chemical pollutants, and / or airborne allergens), water-borne particles (such as water pollutants, water biological contaminants, and chemical contaminants), etc. The concentration of different types of aerosols in the atmosphere continues to grow. For example, the number of airborne pollen has been increasing continuously, which has become an increasingly important public health issue. Therefore, there is a great expectation in the market for a reliable, operator-free, and cost-effective detector for fluid-borne particles, such as an aerosol detector, which is fast and highly discriminative. There is a need for a detector that allows real-time detection of particles present in a specific fluid environment (such as the atmosphere, river channels, drinking water distribution systems, etc.).

[0003] Various types of aerosol particles (such as pollen and spores) have a great impact on human health. According to statistical analysis, some of these types of aerosol particles are responsible for health problems, such as allergies affecting approximately 20% of the European population.

[0004] The counting and identification of these particles are still mostly done manually under a microscope. The size of air-borne particles ranges from a fraction of a micron to several hundred microns, which poses additional difficulties for particle detection and identification.

[0005] There are measurement devices and methods for detecting air-borne particles that allow the estimation of the size of particles contained in an aerosol based on the measurement of light scattered by individual particles. These devices and methods use a light source (laser, laser diode, LED, etc.) directed at the air stream, and a photodetector that collects the light scattered by individual air-borne particles at large angles, or in some cases, multiple detectors or array detectors (1D or 2D) for collecting scattered light independently of the different directions from the particles. The collected scattered light provides a static representation of the air-borne particles. Single-detector devices only allow very limited determination of the morphology of individual particles, while devices with multiple detectors or array detectors generally allow more precise determination of these parameters.

[0006] When studying particle chemistry, non-invasive methods such as light scattering provide little or no insight into particle composition. Some emerging invasive (destructive) methods such as mass spectrometry (MS), laser-induced breakdown spectroscopy (LIBS), or atomic emission spectroscopy (AES) provide very good instant chemical analysis at the molecular (for MS) and atomic (e.g., for LIBS and AES) levels. However, in addition to being invasive, these methods suffer from several technical problems (limited particle size range, difficulty in operating under highly polluted conditions, short continuous monitoring time, high cost, complex data output requiring expertise, etc.), which hinder wide-scale promotion and cost reduction.

[0007] In the case of instant analysis of water-embedded particles, the morphology provides little information related to the nature of the embedded particles because, due to water, the morphology will tend to be almost an ideal sphere. The presence of water affects or interferes with the use of MS, LIBS, and AES because all these methods are based on evaporating air-borne particles by strong laser emission or flame. The most promising results can be obtained by non-invasive methods that can detect chemical composition, such as laser-induced fluorescence or Raman scattering.

[0008] For example, patents US 5,270,548 and US 5,315,122 describe devices and methods for characterizing particles using (especially) time-resolved fluorescence of particles after they are compliant with a laser. The drawback of these devices and methods is that the information that can be obtained regarding the properties and characteristics of individual particles is limited. In most cases, it only allows for a distinction between particles with slow fluorescence decay (on the order of dozens of nanoseconds, usually attributed to hydrocarbon-containing non-biological particles) and particles with short fluorescence decay (on the order of a few nanoseconds or less, usually considered biological particles). Just given the fluorescence decay, there are still quite a number of molecular compositions that will give false responses in this biological and non-biological classification.

[0009] In this regard, the main object of the present invention is to solve the problems mentioned above and, more particularly, to provide a device and method that allow for the instant and instantaneous detection of the presence and concentration of organic molecules in aerosol water droplets using concentration estimation.

[0010] Another object of the present invention is to provide a device and method for cost-effectively detecting and / or characterizing individual fluid-borne particles, which have much better identification of the chemical composition of individual particles and thus a lower false counting rate.

[0011] These objects and other advantages are achieved by the device and method according to the corresponding independent claims. Summary of the Invention

[0012] The methods and devices can find many applications in the following fields: such as pharmaceutical manufacturing and quality control (measurement of drug dose concentration in sprays and aerosols); detection of organic impurities in water droplets (presence of Legionella in public bathrooms and hotel rooms); quality control of real-time viable particle detectors for clean rooms (as a reference instrument for quantitative detection thresholds and response times), etc.

[0013] The above problems are solved by the present invention.

[0014] A first aspect of the present invention is a measuring device for the detection and / or measurement of particles in a fluid, the measuring device comprising: a fluid source for generating a fluid flow along a fluid flow path; a laser source positioned to emit a laser beam of laser light in a measurement space of the fluid flow path for light scattering; and scattered light detection means for detecting the presence of the particles in the fluid flow path by detecting and measuring the light of the laser beam scattered by the particles at different angles.

[0015] Meanwhile, the mentioned laser source-induced fluorescence and Raman emission result from the interaction of the laser with the molecules present in the particles. In this regard, the intensity and wavelength of this laser beam and the sensitivity of all detectors are adjusted in such a way as to keep all respective signal-to-noise ratios at an optimal level while avoiding saturation.

[0016] Preferably, in this regard, the central wavelength of the laser is in the region of 200 nm to 400 nm to provide a relatively high photon absorption efficiency and thus high fluorescence emission. In addition, the Raman scattering efficiency is inversely proportional to the fourth power of the optical wavelength, making the mentioned region the most convenient choice. The wavelength spectral width of the laser source should be narrow enough not to interfere with the Raman emission spectrum.

[0017] Another aspect of the present invention is a measuring device for the detection and / or measurement of particles in a fluid, the measuring device comprising: a fluid source for generating a fluid flow along a fluid flow path; a first laser source positioned to emit a first laser beam of laser light in a measurement space of the fluid flow path for light scattering; scattered light detection means for detecting the presence of particles in the fluid flow path by detecting and measuring the light of the laser beam scattered by the particles at different angles; characterized in that the measuring device further comprises: a second laser source positioned to emit a second laser beam of laser light in a measurement space of the fluid flow path for Raman and fluorescence excitation; and Raman and fluorescence detection means for detecting the Raman scattering signal emitted by the fluid and the fluorescence signal emitted by the particles when excited by the second laser beam.

[0018] According to a preferred embodiment of the present invention, the second laser source is triggered only when light scattering is detected by the light scattering detection device.

[0019] Advantageously, the fluid source is a nozzle for generating a stream of water droplets having a flow path that exceeds the nozzle.

[0020] Preferably, the fluid source includes a tube for generating a stream of water droplets having a flow path along the tube.

[0021] According to a preferred embodiment of the present invention, the measuring device further includes a first lens group for collecting the first laser scattered by the particles contained in the fluid flow in the measurement space.

[0022] Advantageously, the first lens group is configured to focus the scattered light into a line at the focal length of the lens group, the line being transverse to the flow direction of the fluid flow in the measurement space.

[0023] Preferably, the first lens group is configured to focus the scattered light into a line by focusing the scattered light in a direction parallel to the flow direction, and to make the rays of the scattered light parallel to each other in a plane perpendicular to the flow direction.

[0024] According to a preferred embodiment of the present invention, the light scattering detection device is a multi-pixel light scattering detector.

[0025] Advantageously, the measuring device further includes a second lens group for collecting the Raman signal emitted by the fluid molecules and the fluorescence signal emitted by the particles when excited by the second laser beam.

[0026] According to a preferred embodiment of the present invention, the Raman and fluorescence detection device is a photodetector positioned to detect the laser collected by the second lens group.

[0027] Preferably, the photodetector is a linear multi-pixel detector for capturing the laser focused by the lens group, wherein the linear multi-pixel detector is positioned at a distance from the focal length of the lens group and is oriented such that the longitudinal axis of the linear multi-pixel detector is parallel to the line.

[0028] Advantageously, the first laser source is configured to emit a continuous laser beam.

[0029] Preferably, the first laser source is configured to emit a laser beam having a wavelength in the range of 200 nm to 800 nm.

[0030] According to a preferred embodiment of the present invention, the first laser source is configured to emit a laser beam having an emission spectrum of up to several tens of nanometers.

[0031] Advantageously, the first laser source is configured to emit a laser beam having an output optical power range from several milliwatts up to several watts.

[0032] Preferably, the second laser source is configured to emit a pulsed laser beam.

[0033] According to a preferred embodiment of the present invention, the second laser source is configured to emit a laser beam having a wavelength of 200 nm to 450 nm.

[0034] Preferably, the second laser source is configured to emit a laser beam having an optical peak power of more than several kilowatts per pulse.

[0035] Advantageously, the second laser source is configured to emit a laser beam having an emission spectrum of less than several nanometers.

[0036] According to a preferred embodiment of the present invention, the measuring device further includes a diffraction grating for wavelength separation.

[0037] A second aspect of the present invention is a measuring method for the detection and / or analysis of fluid-borne particles, the measuring method comprising the steps of: generating a fluid flow along a fluid flow path, the fluid flow potentially containing fluid-borne particles to be detected; emitting a first laser beam in a measurement space of the fluid flow path; collecting the laser scattered by the fluid-borne particles contained in the fluid flow in the measurement space and focusing the scattered light into a line; detecting the scattered laser with a scattered light detection device and acquiring a light scattering pattern; emitting a second laser beam in the measurement space of the fluid flow path; collecting the laser scattered by the particles contained in the fluid flow in the measurement space and focusing the scattered light into a line; detecting the scattered laser with a Raman and fluorescence detection device and acquiring a Raman signal intensity and a fluorescence signal intensity; and calculating the number of measured impurity particles. Specific advantages of this device of the present invention are similar to those in the method of the first aspect of the present invention and will not be repeated here.

[0038] According to a preferred embodiment of the present invention, the measuring method includes a correction factor calculation step by obtaining a ratio between the number of measured Stokes photons and the number of desired Stokes photons. Thus, the measurement is even more accurate.

[0039] Advantageously, the measuring method includes an impurity mass concentration calculation step. In this way, the number of impurities in the droplet can be accurately indicated. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Additional specific advantages and features of the present invention will become more apparent from the following non - limiting description of at least one embodiment of the invention with reference to the accompanying drawings, in which:

[0041] - Figure 1 represents a measuring device according to a first embodiment of the present invention.

[0042] - Figure 2 represents a measuring device according to a second embodiment of the present invention.

[0043] - Figure 3 represents an example of the desired light scattering pattern from spherical particles with diameters of 0.5 μm, 1 μm, and 2 μm, and the refractive index of water is 1.331.

[0044] - Figure 4 schematically represents the Raman emission spectrum of typical distilled water. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The present detailed description aims to illustrate the present invention in a non - limiting manner, since any feature of an embodiment can be advantageously combined with any other feature of different embodiments.

[0046] As mentioned above, the described methods and devices of the present invention are intended for the immediate and instantaneous detection (preferably, in an aerosol of water droplets) of the presence and concentration measurement of organic molecules or mixtures of organic molecules.

[0047] Basically, the methods and devices of the present invention simultaneously use three basic physical effects:

[0048] @ Angular - resolved light Mie scattering, also known as elastic light scattering;

[0049] @ Raman scattering of water molecules, also known as inelastic light scattering;

[0050] · Laser - induced fluorescence.

[0051] More particularly, the method uses elastic light scattering and fluorescence emission to estimate the number of impurity molecules present within the water droplets. On the other hand, Raman scattering is used as a reference signal to correct the final errors caused by the position of particles in the laser beam, non - uniform laser beam intensity, or any other factors affecting the lamp collection efficiency.

[0052] With a single laser Figure 1FIG. 0 shows a schematic diagram of an embodiment of the device 1 according to the first embodiment of the present invention. The device 1 is a measuring device 1 for detecting and / or measuring particles in a fluid. The measuring device 1 includes a fluid source 11 for generating a fluid flow 111 along a fluid flow path. The fluid flow path may be a nozzle for generating a stream of water droplets having a flow path exceeding the nozzle, or the fluid flow path may include a tube for generating a stream of water droplets having a flow path along the tube. More particularly, the measuring device 1 preferably includes a single laser source 12, which is preferably a continuous laser source and is used for light scattering, Raman, and fluorescence excitation.

[0053] Preferably, the first laser source 12 is positioned to emit a continuous laser beam 120 in the measurement space of the fluid flow path. The laser beam 120 has a wavelength in the range of 200 nm to 450 nm (preferably 200 nm to 400 nm), a narrow emission spectrum up to several tens of nanometers, and an output optical power range from several hundred mW to several tens of W. The central emission wavelength in the short UV region of this laser is necessary because it efficiently induces a fluorescence response from organic molecules. In addition, the shorter wavelength is also more effective for Raman scattering excitation (~λ 4 ). The laser source 12 preferably also has a narrow emission spectrum (e.g., less than several nanometers).

[0054] The measuring device 1 further includes a scattered light detection device 13 (preferably a multi-pixel light scattering detector) and Raman and fluorescence detection devices 15. The scattered light detection device 13 detects the presence of particles in the fluid flow path by detecting and measuring the laser beam light scattered by the particles at different angles. The Raman and fluorescence detection devices 15 are used to detect the Raman scattering signal emitted by the fluid and the fluorescence signal emitted by the particles when excited by the laser beam 120.

[0055] In addition, the measuring device 1 further includes a first lens group 16 for collecting the first laser 121 scattered by the particles contained in the fluid flow 111 in the measurement space. The first lens group 16 is preferably configured to focus the scattered light 121 into a line at the focal length f2 of the lens group 16, where the line is transverse to the flow direction of the fluid flow in the measurement space.

[0056] In addition, the first lens group 16 is configured to focus the scattered light into a line by focusing the scattered light in a direction parallel to the flow direction y and to make the scattered light rays parallel to each other in a plane perpendicular to the flow direction.

[0057] In addition, the measuring device 1 includes a second lens group 17 for collecting Raman signals emitted by fluid molecules and fluorescence signals emitted by particles when excited by the laser beam 120. Preferably, the Raman and fluorescence detection device 15 is a photodetector positioned to detect the laser 141 collected by the second lens group 17.

[0058] Figure 2 FIG. shows a schematic diagram of an embodiment of a device 1 according to a second embodiment of the present invention based on the method of the present invention, where 11 is an injection nozzle, 13 is a multi-pixel light scattering detector, 16 is a collection lens for light scattering signals; 17 is a collection lens for Raman and fluorescence signals, 18 is a diffraction grating for wavelength separation, 15 is a multi-pixel Raman and fluorescence signal detector, 12 is a laser for light scattering, and 14 is a laser for Raman and fluorescence excitation.

[0059] More particularly, the measuring device 1 of the present invention preferably includes a first laser source 12 for light scattering (preferably a continuous laser source) and a second laser source 14 for Raman and fluorescence excitation (preferably a pulsed laser source).

[0060] The first laser source 12 can have any central wavelength (such as from 300 nm to 800 nm) and a relatively wide emission spectrum (for example, up to several tens of nanometers), since it is only used for light scattering. Preferably, the output optical power ranges from several milliwatts to several hundreds of nW.

[0061] For example, the second laser source 14 preferably exhibits a UV or deep UV wavelength (such as from 200 nm to 450 nm) and a high optical peak power per pulse (preferably more than several kilowatts). The second laser source 14 preferably exhibits a short wavelength, which is necessary because it efficiently induces a fluorescence response from organic molecules. In addition, the shorter wavelength is more effective for Raman scattering excitation (~λ 4 ). The second laser source 14 preferably also has a narrow emission spectrum (for example, less than several nanometers).

[0062] The measuring device 13 of the present invention also preferably includes a detector for detecting the presence of individual particles in the beam of the first laser source 12 and measuring the light scattered at different angles. At the same time, when the particles are detected, the second laser source 14 shoots at the particles with a single pulse or multiple pulses, which induces Raman scattering on water molecules and fluorescently emitting organic impurities (if present in the droplets).

[0063] Now, the following paragraphs will more precisely describe the measurement method performed by the device described above. In addition to controlling the laser sources of the device, the measurement method of the present invention includes a light scattering measurement step, a Raman scattering detection step, and a fluorescence measurement step.

[0064] Light scattering measurements are preferably in the Mie light scattering regime. Mie light scattering is a common and very powerful tool for the accurate measurement of microparticles. The light scattering measurement of the method preferably uses a multi-pixel detector D1 to measure the scattered light, which is preferably in the angular range of 60 degrees to 120 degrees relative to the laser direction (side scattering), and the unpolarized or circularly polarized laser source S1 has a resolution of 2 degrees / pixel. Then the desired scattering pattern will look like Figure 3 that shown on the graph in, which shows examples of the desired light scattering patterns from spherical particles with diameters of 0.5 μm, 1 μm, and 2 μm, and the refractive index of water is 1.331.

[0065] In addition, this step preferably uses advanced pattern recognition algorithms such as gradient boosting trees or support vector machines, where very accurate size estimates (+ / - 0.1 μm) can be extracted.

[0066] Such measurements allow for an instantaneous and accurate estimate of the equivalent optical diameter. Considering that due to surface tension, water droplets always have an ideal spherical shape, this measurement provides a direct droplet size and volume estimate. Using the standard water density of 1000 kg / m 3 and a molecular mass of approximately 3×10 -26 kg / mol, the droplet mass and approximate number of H2O molecules can also be estimated from the following equation:

[0067]

[0068] where D is the measured particle diameter and ρ w is the mass density of water.

[0069] The second step of the method is Raman scattering detection. In this step, the second laser source S2 is a pulsed laser that emits laser pulses, and the laser pulses hit the droplets to induce Raman scattering. The number of Stokes photons (photons generated by Raman scattering) detected on the detector D2 can be estimated from the following equation:

[0070]

[0071] where σ R is the Raman scattering cross-sectional area, typically 10 -29 for resonance scattering and 10 -33 for non-resonance scattering, m is the number of atoms in the molecule, N mol is the number of H2O molecules, E is the laser (S2) pulse energy, A is the cross-sectional area of the laser (S2), h is Planck's constant, ν is the frequency of the electromagnetic field of the laser (S2), and σ Dis the detection efficiency of the optical system (L2 + G1 + D2).

[0072] To give a rough estimate of the expected number of photons from a water droplet with a diameter of 1 μm, the following assumptions are made:

[0073] The main contribution to the Raman spectrum of water comes from the valence band at 3400 cm -1 −1. Figure 4 presents a typical spectrum therein, which is a typical Raman emission spectrum of distilled water.

[0074] Preferably, a nitrogen laser source with an emission wavelength of, for example, 337 nm is used for the measurement. In such a case, most of the Stokes photons generated by the Raman scattering of 1-μm water droplets will have a wavelength of approximately 380 nm, and this wavelength can be easily resolved by the diffraction grating G1 from the excitation wavelength of the laser.

[0075] As an example, the Raman emission is resonant, and thus

[0076]

[0077] the laser pulse energy is taken as 100 μJ, the laser cross-sectional area is 8×10 -9 m 2 −6 cm2 (corresponding to a focused beam with a diameter of 100 μm), and the detection efficiency is taken as 10%. The result is that 5000 Stokes photons are detected at a wavelength of approximately 380 nm, which is a very important number for modern detectors (such as vacuum tube photomultiplier tubes and silicon photomultiplier tubes (avalanche photodiode matrices)).

[0078] At this point, it is important that distilled water does not exhibit any fluorescence emission when excited in the wavelength range of 200 to 400 nm, because water molecules do not have any π- or σ-electron orbits that can absorb such photons.

[0079] Therefore, if the water droplet does not contain any organic impurities or other complex impurities, the only signal observed will be Raman scattering when excited by UV light.

[0080] Therefore, the third measurement step is fluorescence measurement. The fluorescence emission is preferably estimated according to the following equation:

[0081]

[0082] where σ A is the photon absorption cross-sectional area, typically 10 -20 −16 cm2 for endogenous fluorophores, N molis the number of fluorophore molecules (organic impurities), Q is the quantum efficiency of the radiative de-excitation of the fluorophore, typically 10%, E is the laser (S2) pulse energy, A is the cross-sectional area of the laser (S2), h is Planck's constant, and v is the frequency of the electromagnetic field of the laser (S2), σ D is the detection efficiency of the optical system (L2 + G1 + D2).

[0083] Compared with Raman scattering, the fluorescence efficiency measured under the same conditions is much higher. For example, if a water droplet contains only 10 5 fluorophore molecules, then the water droplet will have emitted approximately 2 * 10 5 fluorescent photons scattered over a relatively large wavelength range (at room temperature).

[0084] The last step of the method consists of measuring the concentration of organic impurities in the droplet.

[0085] As mentioned previously, the described method is intended for the instantaneous measurement of organic impurities in water droplets. Thus, the entire process can be divided into the following steps: generating a fluid flow 111 along a fluid flow path, the fluid flow potentially containing fluid-borne particles to be detected; emitting a first laser beam 120 in a measurement space of the fluid flow path; collecting the laser light 121 scattered by the fluid-borne particles contained in the fluid flow in the measurement space and focusing the scattered light into a line; using a scattered light detection device 13 to detect the scattered laser light 121 and obtaining a light scattering pattern; emitting a second laser beam 140 in the measurement space of the fluid flow path; collecting the laser light 141 scattered by the particles contained in the fluid flow in the measurement space and focusing the scattered light into a line; using a Raman and fluorescence detection device (15) to detect the scattered laser light 141 and obtaining a Raman signal intensity and a fluorescence signal intensity; calculating the number of measured impurity particles.

[0086] The number of measured impurity molecules is preferably given by the following equation:

[0087]

[0088] where, is the number of desired Stokes photons from Raman scattering, which is calculated by the above equation; is the number of Stokes photons from Raman scattering, which is detected by the device; is the number of fluorescent photons detected by the device.

[0089] By inserting the first equation above into this equation, the expression becomes:

[0090]

[0091] By simplifying this equation and applying a constant for H2O, the expression takes the following form:

[0092]

[0093] When the molecular mass of the impurity is known, the mass concentration can also be estimated using the following equation:

[0094]

[0095] It can be noted that the result depends only on the number of photons measured from fluorescence emission and Raman scattering, and the cube of the measured optical size. The result does not depend on the detection efficiency of the system or the second laser energy. If all the constants in this equation are grouped, the expression becomes:

[0096]

[0097] The resulting expression allows for a simple and direct mass estimate of the impurity molecules in each water droplet detected by the described device.

[0098] Although these embodiments have been described in connection with multiple embodiments, it is obvious that many alternatives, modifications, and variations are obvious to those of ordinary skill in the art of the application field. Accordingly, this disclosure is intended to embrace all such alternatives, modifications, equivalents, and variations that fall within the scope of this disclosure. For example, this can especially be the case when different devices are involved.

Claims

1. A measuring device (1) for the detection and / or measurement of particles in a fluid, the measuring device comprising: A fluid source (11) for generating a fluid flow (111) along a fluid flow path; A first laser source (12) positioned to emit a first laser beam (120) of laser light in a measurement space of the fluid flow path; A first lens group (16) for collecting the first laser light (121) scattered in the measurement space by particles contained in the fluid flow (111); A scattered light detection device (13) for detecting the presence of the particles in the fluid flow path by detecting and measuring the laser beam light scattered by the particles at different angles; Characterized in that the measuring device further comprises: A second laser source (14) positioned to emit a second laser beam (140) of laser light in the measurement space of the fluid flow path for Raman and fluorescence excitation, while the first laser source (12) is only used for light scattering; A Raman and fluorescence detection device (15) for detecting the Raman scattering signal emitted by the fluid and the fluorescence signal emitted by the particles when excited by the second laser beam (140); A second lens group (17) for collecting the Raman signal emitted by fluid molecules and the fluorescence signal emitted by the particles when excited by the second laser beam (140); The first lens group (16) is configured to focus the scattered first laser light (121) into a line at the focal length (f2) of the first lens group (16), the line being transverse to the flow direction (y) of the fluid flow in the measurement space, the first lens group (16) being configured to focus the scattered light into a line by focusing the scattered light in a direction parallel to the flow direction (y), and for causing the rays of the scattered light to be parallel to each other in a plane perpendicular to the flow direction.

2. The measuring device according to claim 1, wherein, The fluid source (11) is a nozzle for generating a stream of water droplets having a flow path exceeding the nozzle.

3. The measuring device according to claim 1, wherein, The fluid source (11) comprises a tube for generating a stream of water droplets having a flow path along the tube.

4. The measuring device according to any one of the preceding claims, wherein, The scattered light detection device (13) is a multi-pixel light scattering detector.

5. The measuring device according to any one of claims 1 to 3, wherein, The Raman and fluorescence detection device (15) is a photodetector positioned to detect the laser light (141) collected by the second lens group (17).

6. The measuring device according to claim 5, wherein, The photodetector is a linear multi-pixel detector for capturing the laser light focused by the second lens group (17), wherein the linear multi-pixel detector is positioned at a distance from the focal length (f2) of the second lens group (17) and is oriented such that the longitudinal axis of the linear multi-pixel detector is parallel to the line.

7. The measuring device according to any one of claims 1 to 3, wherein, The first laser source (12) is configured to emit a continuous first laser beam (120).

8. The measuring device according to any one of claims 1 to 3, wherein, The first laser source (12) is configured to emit a first laser beam (120) having a wavelength in the range of 200 nm to 800 nm.

9. The measuring device according to any one of claims 1 to 3, wherein, The first laser source (12) is configured to emit a first laser beam (120) having an emission spectrum of up to several tens of nanometers.

10. The measuring device according to any one of claims 1-3, wherein, The first laser source (12) is configured to emit a first laser beam (120) having an output optical power range from several milliwatts up to several watts.

11. The measuring device according to claim 1, wherein, The second laser source (14) is triggered only when light scattering is detected by the light scattering detection device (13).

12. The measuring device according to any one of claims 1 or 11, wherein, The second laser source (14) is configured to emit a pulsed second laser beam (140).

13. The measuring device according to any one of claims 1 to 3, wherein, The second laser source (14) is configured to emit a second laser beam (140) having a wavelength in the range of 200 nm to 450 nm.

14. The measuring device according to any one of claims 1 to 3, wherein, The second laser source (14) is configured to emit a second laser beam (140) having an optical peak power of more than several kilowatts per pulse.

15. The measuring device according to any one of claims 1 to 3, wherein, The second laser source (14) is configured to emit a second laser beam (140) having an emission spectrum of less than several nanometers.

16. The measuring device according to any one of claims 1 to 3, further comprising a diffraction grating (18) for wavelength separation.

17. A measuring method for detecting and / or analyzing fluid-borne particles, comprising the steps of: generating a fluid flow (111) along a fluid flow path, the fluid flow potentially containing fluid-borne particles to be detected; emitting a first laser beam (120) in a measurement space of the fluid flow path; collecting the first laser light (121) scattered by fluid-borne particles contained in the fluid flow in the measurement space, and focusing the scattered light into a line, the line being transverse to the flow direction (y) of the fluid flow in the measurement space, and focusing the scattered light into a line by focusing the scattered light in a direction parallel to the flow direction, and for making the rays of the scattered light parallel to each other in a plane perpendicular to the flow direction; detecting the scattered first laser light (121) using a light scattering detection device (13) and acquiring a light scattering pattern; collecting the second laser light (141) scattered by fluid-borne particles contained in the fluid flow in the measurement space, and focusing the scattered light into a line; detecting the scattered second laser light (141) using a Raman and fluorescence detection device (15) and acquiring a Raman signal intensity and a fluorescence signal intensity, the second laser source (14) being triggered only when light scattering is detected by the light scattering detection device (13); calculating the number of measured impurity particles.

18. The measuring method according to claim 17, further comprising a correction factor calculation step by obtaining a ratio between the number of measured Stokes photons and the number of desired Stokes photons.

19. The measuring method according to claim 17, further comprising an impurity mass concentration calculation step.

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