Methods for detecting soiling
By irradiating particles with a laser to apply a force and measuring scattered light intensity, the method accurately detects side window contamination, ensuring high-quality analysis by correcting for soiling effects.
Patent Information
- Application Number
- JP2025503343
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-21
- Filing Date
- 2023-06-12
- Publication Date
- 2025-08-13
AI Technical Summary
Existing methods for analyzing fluid samples with dispersed particles suffer from contamination of the side window, which degrades the quality of spectroscopic data, necessitating a simple and accurate method to detect and correct for this soiling.
Irradiate particles with light, typically a laser, through the entrance window to apply a force affecting their movement, detect this movement using a camera outside the chamber based on scattered light, calculate target scattered light intensity, and compare it with actual intensity to determine side window contamination.
Accurately determines side window contamination, allowing for high-quality analysis by correcting measurement results or deciding on window cleaning, thereby maintaining analysis integrity.
Smart Images
Figure 2025526358000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to a method for determining contamination of a side window of a chamber containing a fluid sample with dispersed particles.
[0002] The invention further relates to a device for analyzing a fluid sample with dispersed particles, comprising a chamber with a side window, an entrance window, a light source, in particular a laser, a camera by which scattered light passing through the side window can be detected, and a data processing device connected to the camera. [Background technology]
[0003] From the prior art it is known to analyse particles of a fluid sample by optical fluid force induction, conventionally denoted as OF2i, in which a force is applied to particles of the fluid sample using a light source, typically a laser, and the velocity of the particles is measured, so that based on the velocity of the particles and the known relationship between the intensity of the light applied using the light source and the size of the particles it is possible to infer the particle size.
[0004] Furthermore, document EP 1 096 248 A2 discloses a method for measuring the concentration of a solution, in which the transmitted light intensity is measured. Document EP 1 102 059 A1 discloses a method for measuring scattered light that occurs when light propagates through the solution to be detected. Document DE 10 2017 204 037 A1 discloses an optical sensor with a sensor coating.
[0005] Methods and devices of the first-mentioned type are known, for example, from document WO 2019 / 002286 A1. In the corresponding device, particles move together with the fluid sample in the flow direction through a chamber, where a force in the flow direction or against the flow direction is applied to the particles approximately in the flow direction or in the opposite direction to the flow direction using a laser coupled to the chamber through a front window. The movement of the particles in the flow direction or in the opposite direction to the flow direction is thereby detected through a side window of the chamber using a camera.
[0006] Through the side window, other properties of the particles can also be analyzed by spectroscopy.
[0007] It has been shown that as the age of the corresponding device increases, the side window becomes dirty due to particles transported in the fluid sample or suspension, resulting in a decrease in the quality of the data obtained by spectroscopy.
[0008] This is addressed by the present invention, whose purpose is to specify how the soiling of the corresponding side window can be determined in a simple manner, so that the soiling can be ascertained in such a way that it is possible either to correct the measurement result or to decide to clean the side window. Summary of the Invention
[0009] According to the present invention, this object is achieved using a method of the type mentioned at the beginning, in which particles are irradiated with light, in particular a laser, through an entrance window of the chamber, in which the light is used to apply a force to the particles, which force affects the movement of the particles, in particular depending on the size of the particles, in which the movement of the particles is detected using a camera arranged outside the chamber based on the scattered light of the particles passing through a side window, in which the size of the particles is confirmed via the velocity of the particles, then a target scattered light intensity is calculated based on the intensity of the light acting on the particles and the confirmed size of the particles, then the target scattered light intensity is compared with the measured actual scattered light intensity, and the contamination of the side window is determined based on the difference between the target scattered light intensity and the actual scattered light intensity.
[0010] In this case, in particular a liquid or gas in which particles are distributed is to be understood as a fluid sample with dispersed particles. Naturally, the fluid sample may also comprise or consist of a corresponding mixture of gas and liquid with particles.
[0011] The inventors have discovered that the target scattered light intensity (which indicates how intense the scattered light of a particle passing through the side window should be) can be derived directly via the particle's velocity and the known light intensity acting on the particle, and as a result, contamination of the side window is a direct result of the particle's velocity, the light intensity to which the particle is exposed, and the actual scattered light intensity ascertained, for example using a camera (which essentially corresponds to the target scattered light intensity attenuated by the intensity reduction caused by contamination of the side window).
[0012] The contamination of the side window thus determined with high accuracy can later be used to make decisions about cleaning the side window and / or to therefore correct measurement results obtained based on scattered light passing through the side window, in particular measurement results regarding one or more properties of the particles, such as composition, weight, size and the like.
[0013] It is possible to refer to methods known from the prior art for determining particle size based on the light intensity acting on the particles and the velocity of the particles. Typically, a fluid sample moves through a chamber. It should be understood that due to the light acting on the particles, in this case the flow characteristics of the sample are also included in the evaluation of the particle's movement, so that the relative velocity of the particle with respect to the flow can, for example, be relevant for evaluating the particle's size.
[0014] In particular, it has proven useful to continuously determine the intensity of light coupled into the tube of the coupled laser in order to calculate a target scattered light intensity based on said intensity. In this manner, the effect of contamination of the entrance window through which the laser is coupled into the chamber can be evaluated as well, so that contamination of the side window can be determined in an even more rigorous manner.
[0015] It is particularly advantageous if a sensor, positioned outside the tube, on which light, in particular a laser, impinges, determines the intensity after said light has passed through an entrance window, the tube and an exit window opposite the entrance window.
[0016] The intensity of the light emitted by the light source, particularly the laser, with which the particles are irradiated in the chamber is typically known, for example, based on the rated power of the light source or laser. By detecting the intensity the light or laser still has after passing through the entrance window, the fluid sample in the chamber, and the exit window, it is possible to identify the contamination of the entrance and exit windows with a very high degree of accuracy. Typically, the entrance and exit windows are affected by contamination to the same extent, and the optical properties of the sample are known. As a result, contamination of the entrance window can be easily detected if the reduction in the intensity of light from the light source to the sensor is known. For this purpose, for example, the reduction in intensity due to the fluid sample, typically a particle-containing fluid or suspension, can be subtracted from the overall reduction in intensity, and the remaining portion of the reduction in intensity can be allocated equally to the entrance and exit windows to identify the contamination of these two windows.
[0017] The method according to the invention is preferably used in a method for analyzing a fluid sample, in order to make it possible to achieve a high quality of the analysis regardless of the contamination of the side window. In this context, in a method for analyzing a fluid sample with dispersed particles in a chamber with a side window, in which a force is applied to the particles using light, in particular using a laser, and the movement of the particles affected by the force is detected through the side window by a camera, and the particle size is determined based on the determination of the particles, it is advantageous if the contamination of the side window is determined using the method according to the invention and said contamination is taken into account in the analysis of the particles.
[0018] Then, in an analysis in which the actual scattered light intensity through a side window is detected, for example using a camera, it is possible to take into account that said actual scattered light intensity is already reduced by dirt on the side window, so that said intensity is higher by a determinable amount than without dirt on the side window. Therefore, a correction factor taking said dirt into account can be applied, for example for the spectral analysis. In addition, of course, the method can also be carried out so that cleaning of the side window is carried out at a certain degree of dirt ascertained using the method according to the invention.
[0019] The method is preferably carried out such that a fluid sample with particles having a particle size of 20 nm to 500 nm is analyzed. Other features of the method may be embodied by analogous application of the teachings of document WO2019 / 002286A1, which is incorporated herein by reference in its entirety.
[0020] It is preferred if the chamber has a cross section with an extension perpendicular to the flow direction of less than 10 mm, in particular between 0.5 mm and 3 mm, although the method can of course also be implemented with larger or smaller chambers.
[0021] It is particularly advantageous if the chamber has a substantially circular cross section perpendicular to the flow direction, which results in particularly advantageous flow conditions. Along the flow direction, the chamber may have a cylindrical shape, or even a conical or constant or varying cross section.
[0022] In principle, the method can also be performed with a stationary fluid sample in the chamber. However, it is preferred that the method be used to analyze particles in a continuous process in which a suspension or a sample containing particles moves through the chamber at a flow rate. In assessing the size of the particles, the relative velocity of the particles is then naturally determined with respect to the liquid, the relative velocity being caused by a laser acting on the particles. In this context, it has proven particularly useful if the sample moves through the chamber at a flow rate of 0.01 mm / s to 100 mm / s, in particular 0.2 mm / s to 10 mm / s.
[0023] Other objects are achieved according to the invention with a device of the first-mentioned type embodied for carrying out the method according to the invention. This is particularly the case when the data processing device is configured such that a target scattered light intensity can be calculated and said intensity compared with the measured actual scattered light intensity in order to determine soiling.
[0024] In a corresponding device, a pressure application device is provided, which is used to transport a fluid sample through the chamber at a flow rate of preferably 0.01 mm / s to 100 mm / s, particularly 0.2 mm / s to 10 mm / s. Flow conditions useful for precise measurements can thus be achieved. The size of the particles can then be ascertained via the difference between the velocity of the particles and the velocity of the fluid sample inside the chamber, which difference can be detected using a camera via scattered light emitted by the particles.
[0025] It is advantageous if the entrance window is oriented approximately perpendicular to the flow direction of the sample in the region of the side window, as a result of which particularly good coupling of the light or laser into the chamber is achieved in the region that is particularly relevant for the analysis of particles, namely in the region of the entrance window.
[0026] In order to be able to determine the contamination of the entrance window in a particularly precise and simple manner, it is preferred if an exit window is provided opposite the entrance window, the exit window preferably being approximately parallel to the entrance window.
[0027] The chamber may thus be embodied, for example, by a tube comprising an entrance window and an exit window parallel to the entrance window, where an analysis segment of the tube is arranged between the entrance and exit windows, the axis of the tube being typically perpendicular to the entrance and exit windows, the analysis segment comprising a side window through which particles located in said analysis segment of the tube can be detected with a camera, the camera preferably being aligned with the analysis segment such that the optical axis of the camera is perpendicular to the axis of the tube in the analysis segment.
[0028] Adjacent to the entrance window there is usually provided an entrance segment of the chamber formed by a tube or the like, through which the fluid sample is guided to the analysis segment where the analysis takes place, the axis of the entrance segment can in principle be oriented at any desired angle, for example at an angle of about 60 degrees, relative to the chamber or to the axis of the tube in the analysis segment.
[0029] Adjacent to the exit window is typically provided an exit segment of the chamber formed by a tube or the like, through which the fluid sample is guided out of the analysis segment after said sample has been analyzed. The axis of the exit segment can in principle be aligned at any desired angle, for example about 60 degrees, with respect to the chamber or to the axis of the tube of the chamber in the analysis segment.
[0030] Typically, the entrance and exit segments are arranged at similar or identical angles relative to the axis of the tube or relative to the entrance and exit windows, so that similar flow conditions, and therefore equivalent fouling, occur in the area of the entrance and exit windows. To this end, the entrance and exit segments may have corresponding tubes, resulting in a Z-shape for the device, for example, the entrance and exit segments are typically parallel.
[0031] Typically, the laser is arranged so as to produce a laser beam that impinges perpendicularly on the entrance and exit windows. The laser beam is preferably approximately parallel to the axis of the tube or to the direction of fluid flow in the tube in the analysis segment. In principle, the laser beam can of course be directed at an angle other than 90 degrees to the entrance and exit windows, for example, between 30 and 150 degrees.
[0032] In this context, it is particularly preferred if a sensor for detecting the intensity of light passing through the entrance window, the chamber, and the exit window is arranged outside the chamber. The degree of contamination of the entrance window and the exit window can be easily determined via the light intensity before the entrance window (which intensity is generally known) and the light intensity after passing through the entrance window, the chamber, and the exit window. This generally assumes that the entrance window and the exit window are approximately equally contaminated. The intensity attenuation in the region of the chamber due to the fluid sample can be mathematically determined based on the optical properties of the fluid sample, which are also typically known.
[0033] In particular, in order to achieve uniform contamination of the entrance and exit windows, it is preferred if the chamber is embodied approximately symmetrically, so that the flow in the area of the exit window is equivalent to the flow in the area of the entrance window.
[0034] Additional features, advantages and benefits of the invention will become apparent from the exemplary embodiments described below, and to which reference is made the following drawings, in which: [Brief explanation of the drawings]
[0035] [Figure 1] In a schematic diagram, a device for carrying out the method according to the invention is shown. DETAILED DESCRIPTION OF THE INVENTION
[0036] 1 shows in a schematic diagram a device according to the invention 1 for carrying out a method according to the invention. As shown, the device 1 comprises a chamber 2, in which a fluid sample with particles 12 moves along a flow direction 11 from an inlet 3 to an outlet 4, for example at a speed of 1 mm / s.
[0037] Chamber 2 thereby includes an entrance segment 15 connected to inlet 3, an analytical segment 17 adjacent to entrance segment 15, and an exit segment 16 adjacent to analytical segment 17 and connected to outlet 4, such that sample is transported from inlet 3 through chamber 2 via entrance segment 15, analytical segment 17, exit segment 16, and outlet 4. Entrance segment 15, analytical segment 17, and exit segment 16 may be formed, for example, by tubes.
[0038] In the exemplary embodiment shown, the longitudinal axes of the entrance segment 15 and exit segment 16 are oriented at an angle α of about 60 degrees relative to the tube axis 14 of the analysis segment 17, resulting in the horizontal Z shape shown for the chamber 2. In principle, the entrance segment 15 and exit segment 16 can be oriented at any desired, and possibly different, angle α relative to the analysis segment 17, but preferably the same angle α is chosen to achieve similar flow conditions.
[0039] In order to better explain the method according to the invention, the particles 12 are shown only in a partial area of the chamber 2. However, it is understood that said particles 12 are contained in the fluid sample in a uniformly distributed manner, and therefore the particles 12 are naturally arranged in a distributed manner throughout the chamber 2.
[0040] A laser 6 may be coupled to the chamber 2 through an entrance window 7 and using the laser 6 a force or pulse may be applied to particles 12 in a fluid sample located within the chamber 2 .
[0041] As a result of the movement caused through the forces or changes in the movement of the particles 12 in the chamber 2, it is possible to infer the size of the particles 12, since the pulse applied to the particles 12, and therefore the movement of the particles 12 relative to the fluid, depends on the size of the particles 12 and the intensity of the laser 6 or light acting on the particles 12.
[0042] To enable detection of the movement or changes in movement of the particles 12, a side window 5 is provided in the analysis segment 17 of the chamber 2, in this case formed by a tube, through which the movement of the particles 12 can be detected with a camera 10 placed outside the chamber 2 via scattered light 9 that the particles 12 transmit through the side window 5 to the camera 10. The side window 5 is placed in the analysis segment of the tube, which segment is located between the entrance window 7 and the exit window 8. In said analysis segment, the axis 14 of the tube is also perpendicular to the entrance window 7 and the exit window 8.
[0043] As can be seen, the camera 10 is aimed towards the side window 5 so that the optical axis of the camera 10 is approximately perpendicular to the tube axis 14 in the analysis segment of the tube behind the side window 5. Movement of particles 12 along the tube axis 14 or along the fluid flow direction 11 in said analysis segment can thus be detected essentially without distortion using the camera 10.
[0044] The actual scattered light intensity of the scattered light 9 of the individual particles 12 passing through the side window 5 can thus be detected using the camera 10. Furthermore, the velocity of the individual particles 12 can also be detected using the camera 10, this velocity being represented on the sensor 13 of the camera 10 by the change in the individual points of light or light streaks.
[0045] Therefore, if the intensity of the light impinging on the particles 12 is known, it is possible to infer the size of the particles 12 via the velocity of the individual particles 12. The size of the particles 12, combined with the intensity of the light or laser 6 impinging on the particles 12, allows for the calculation of the target scattered light intensity, i.e. the intensity of the light emitting from the particles 12 onto the side window 5.
[0046] The difference between this target scattered light intensity and the actual scattered light intensity increases as the dirt on the side window 5 increases, and as a result, it is possible to infer the dirt via the target scattered light intensity and the actual scattered light intensity using a data processing device of the device 1, which data processing device is connected to the camera 10.
[0047] This knowledge of the contamination of the side window 5 can be used to achieve high quality analysis of the particles 12 regardless of the contamination of the side window 5 .
[0048] In order to be able to determine in a particularly precise manner the intensity of the light or laser 6 acting on the particle 12, an exit window 8 is provided opposite the entrance window 7, behind which a sensor 13 is arranged, by means of which the intensity of the light passing through the entrance window 7, the chamber 2 and therefore the fluid sample placed therein, and the exit window 8 can be determined.
[0049] The difference in the intensity of the light emitted by the laser 6 and measured using the sensor 13, or the intensity of the laser beam after passing through the entrance window 7, the chamber 2, and the exit window 8, can essentially be divided into three sources of loss: first, losses due to contamination of the entrance window 7; second, losses due to intensity attenuation in the region of the chamber 2 as a result of the fluid sample; and third, intensity losses due to contamination of the exit window 8. Contamination due to the fluid sample in the chamber 2 can be calculated in a relatively precise manner, especially since the optical properties of the sample are generally known. In the device 1 embodied in accordance with the invention, the remaining difference in light intensity is divided equally between the entrance window 7 and the exit window 8, so that contamination of the entrance window 7 and the exit window 8 can also be well determined, which, like contamination of the side window 5, typically depends on the duration of use and increases with increasing duration, as particles 12 accumulate on the windows.
[0050] For this purpose, the device 1 is typically embodied approximately symmetrically, so that the flow conditions in the region of the entrance window 7 correspond to the flow conditions in the region of the exit window 8, and the contamination of the entrance window 7 and the exit window 8 occurs approximately synchronously. In the exemplary embodiment shown, the entrance window 7 and the exit window 8 are for this purpose arranged approximately parallel and perpendicular to the flow direction 11 of the fluid sample in the chamber 2 in the region of the side window 5. This further allows for the beneficial transmission of light from the laser 6 into the chamber 2. The laser 6 thus impinges on the entrance window 7 and the exit window 8, in this case approximately perpendicularly.
[0051] In order to be able to achieve a high analytical quality independent of contamination, by means of the method according to the invention and the device 1 embodied for this purpose, window contamination can be detected simultaneously in a particularly simple and very precise manner, referred to as the OF2i method. (Other possible items) (Item 1) A method for determining the contamination of a side window (5) of a chamber (2) containing a fluid sample with dispersed particles (12), wherein the particles (12) are irradiated with light, in particular a laser (6), through an entrance window (7) of the chamber (2), wherein the light is used to apply a force to the particles (12), which influences the movement of the particles (12), in particular depending on the size of the particles (12), wherein the movement of the particles (12) is determined based on the scattered light (9) of the particles (12) passing through the side window (5). and the particle (12) is detected using a camera (10) arranged outside the chamber (2), wherein the size of the particle (12) is confirmed via the velocity of the particle (12), then a target scattered light intensity is calculated based on the intensity of the light acting on the particle (12) and the confirmed size of the particle (12), then the target scattered light intensity is compared with the measured actual scattered light intensity, and the contamination of the side window (5) is determined based on the difference between the target scattered light intensity and the actual scattered light intensity. (Item 2) 2. The method according to item 1, wherein the intensity of the light coupled into the tube, in particular of the coupled laser (6), is continuously determined in order to calculate the target scattered light intensity based on said intensity. (Item 3) 3. The method according to claim 2, wherein the intensity is determined by a sensor (13) arranged outside the tube, on which the light, in particular the laser (6), impinges, after the light has passed through the entrance window (7), the tube, and the exit window (8) opposite the entrance window (7). (Item 4) 1. A method for analyzing a fluid sample with dispersed particles (12) in a chamber (2) with a side window (5), wherein a force is applied to the particles (12) using light, in particular using a laser (6), wherein the movement of the particles (12) affected by the force is detected through the side window (5) by a camera (10), the size of the particles is determined based on the movement of the particles (12), and contamination of the side window (5) is determined using the method according to any one of items 1 to 3, wherein the contamination is taken into account in the analysis of the particles (12). (Item 5) 5. The method according to item 4, wherein a fluid sample with particles (12) having a particle size of 20 nm to 500 nm is analyzed. (Item 6) 6. The method according to any one of items 1 to 5, wherein the chamber (2) has a cross section with an extension perpendicular to the flow direction (11) of less than 10 mm, in particular between 0.5 mm and 3 mm. (Item 7) 7. The method according to any one of items 1 to 6, wherein the fluid sample moves through the chamber (2) at a flow rate of between 0.01 mm / s and 100 mm / s, in particular between 0.2 mm / s and 10 mm / s. (Item 8) 8. A device (1) for analyzing a fluid sample with dispersed particles (12), comprising a chamber (2) with a side window (5), an entrance window (7), a light source, in particular a laser (6), a camera (10) that can be used to detect scattered light (9) passing through the side window (5), and a data processing device connected to the camera (10), wherein the device (1) is configured to perform the method according to any one of items 1 to 7. (Item 9) Item 9. The device (1) according to item 8, wherein a pressure application device is provided for transporting the fluid sample through the chamber (2) at a flow rate of 0.01 mm / s to 100 mm / s, particularly 0.2 mm / s to 10 mm / s. (Item 10) 10. The device (1) according to item 8 or 9, wherein an exit window (8) is provided opposite the entrance window (7), the exit window (8) preferably being substantially parallel to the entrance window (7). (Item 11) 11. The device (1) according to any one of items 8 to 10, wherein a sensor (13) for detecting the intensity of the light passing through the entrance window (7), the chamber (2), and the exit window (8) is arranged outside the chamber (2). (Item 12) 12. The device (1) according to any one of items 8 to 11, wherein the chamber (2) is embodied approximately symmetrically in order to achieve uniform contamination of the entrance window (7) and the exit window (8), so that the flow in the area of the exit window (8) is comparable to the flow in the area of the entrance window (7).
Claims
1. A method for determining contamination of a side window of a chamber containing a fluid sample with dispersed particles, wherein the particles are irradiated with light, in particular a laser, through an entrance window of the chamber, wherein a force is applied to the particles using the light, the force influencing the movement of the particles in particular depending on the size of the particles, wherein the movement of the particles is detected using a camera positioned outside the chamber based on the scattered light of the particles passing through the side window, wherein the size of the particles is confirmed via the velocity of the particles, then a target scattered light intensity is calculated based on the intensity of the light acting on the particles and the confirmed size of the particles, then the target scattered light intensity is compared with the measured actual scattered light intensity, and the contamination of the side window is determined based on the difference between the target scattered light intensity and the actual scattered light intensity.
2. 2. The method of claim 1, wherein the intensity of the light coupled into the tube, in particular of a coupled laser, is continuously determined to calculate the target scattered light intensity based on said intensity.
3. 3. The method of claim 2, wherein the intensity is determined by a sensor arranged outside the tube and impinged by the light, in particular the laser, after the light has passed through the entrance window, the tube, and an exit window opposite the entrance window.
4. 1. A method for analyzing a fluid sample with dispersed particles in a chamber with a side window, wherein a force is applied to the particles using light, in particular using a laser, wherein the movement of the particles affected by the force is detected through the side window by a camera, the size of the particles is determined based on the movement of the particles, and contamination of the side window is determined using the method of claim 1, wherein the contamination is taken into account in the analysis of the particles.
5. The method of claim 4, wherein a fluid sample with particles having a particle size between 20 nm and 500 nm is analyzed.
6. 2. The method according to claim 1, wherein the chamber has a cross section with an extension perpendicular to the flow direction of less than 10 mm, in particular between 0.5 mm and 3 mm.
7. The method of claim 1, wherein the fluid sample moves through the chamber at a flow rate of 0.01 mm / s to 100 mm / s, in particular 0.2 mm / s to 10 mm / s.
8. 8. A device for analyzing a fluid sample with dispersed particles, comprising a chamber with a side window, an entrance window, a light source, in particular a laser, a camera that can be used to detect scattered light passing through the side window, and a data processing device connected to the camera, the device being configured to perform the method of any one of claims 1 to 7.
9. 9. The device according to claim 8, wherein a pressure application device is provided by which the fluid sample can be transported through the chamber at a flow rate of 0.01 mm / s to 100 mm / s, in particular 0.2 mm / s to 10 mm / s.
10. 9. The device of claim 8, wherein an exit window is provided opposite the entrance window, the exit window preferably being substantially parallel to the entrance window.
11. The device of claim 8 , wherein a sensor is located outside the chamber for detecting the intensity of the light passing through the entrance window, the chamber, and the exit window.
12. 9. The device according to claim 8, wherein the chamber is embodied approximately symmetrically to achieve uniform contamination of the entrance and exit windows, so that the flow in the area of the exit window is equivalent to the flow in the area of the entrance window.