Device and method for characterizing at least one particle

Abstract

The invention relates to a device (10) for characterizing at least one particle (12), having features of claim 1, and to a method for characterizing at least one particle (12), having features of the additional independent claim.

Description

[0001] Device and method for characterizing at least one particle

[0002] Description

[0003] The invention relates to a device for characterizing at least one particle having the features of claim 1 and to a method for characterizing at least one particle having the features of the independent claim.

[0004] Devices and methods for characterizing particles can be used in various applications, for example, to determine particle position, particle velocity, or particle size. This can be used, for example, to monitor or control industrial manufacturing and processing processes.

[0005] A device for determining the particle characteristics is known, for example, from DE 10 2019 209 213 A1 and comprises a light source by means of which a laser beam is directed along a

[0006] beam axis is generated. Beam shaping optics are arranged along the beam axis. The beam shaping optics are designed to set a location-dependent intensity distribution of the laser beam in a measuring volume which extends sectionally along the beam axis. A particle to be characterized, which is located in the measuring volume, reflects or scatters the laser beam. The reflected or scattered light is detected by a detector which outputs an intensity signal to an evaluation unit. The evaluation unit is used to determine the particle characteristics within the measuring volume as a function of the intensity signal.

[0007] In principle, it is desirable to be able to characterize the particle within the measuring volume with a high degree of accuracy.

[0008] It is therefore an object of the present invention to provide a device and a method which offer a good relationship between the achievable accuracy in particle characterization and the costs involved.

[0009] The above object is achieved by a device for characterizing at least one particle having the features of claim 1.

[0010] The device comprises a light device for generating a light beam. The light device can be designed, in particular, as a laser device for generating a laser beam. The light device can comprise an LED (light-emitting diode), SLED (superluminescent light-emitting diode), VCSEL (vertical-cavity surface-emitting laser) and / or a laser source.

[0011] The device comprises beam shaping optics for aligning the light beam along a beam axis. The beam axis is oriented along a first direction. The beam shaping optics are configured to generate a light distribution of the light beam along a second direction and a third direction. The light distribution along the second direction and the third direction corresponds in particular to a cross-section of the light beam after shaping by means of the beam shaping optics. The first, the second and the third direction are each aligned orthogonally to one another. The first direction can be a Z direction, the second direction can be an X direction and / or the third direction can be a Y direction.

[0012] The device comprises a measuring volume which extends at least partially along the beam axis and / or the light distribution of the light beam. In particular, the measuring volume extends at least partially along the cross-section of the light beam. In particular, the measuring volume can lie in a plane spanned by the second and third directions and / or be arranged parallel to this plane.

[0013] The device comprises a detection device. The detection device is designed to detect light reflected and / or scattered by the particle located in the measurement volume. The detection device is arranged along a measurement axis and designed to generate an intensity signal. The measurement axis is inclined to the beam axis by a measurement angle. This means that in particular no light is reflected or scattered when no particle is present in the measurement volume, so that then no intensity is detected (or no intensity signal is generated).

[0014] The detection device comprises a line sensor and an imaging device. The imaging device can be designed as a focusing optics or imaging optics. The line sensor can be designed as a line sensor or as a line camera. The line sensor can be configured as a one-dimensional detector with 1 x 1024 pixels. The imaging device is configured to focus (or image) the reflected and / or scattered light onto the line sensor.

[0015] The line sensor can be set up to take images at a speed of greater than or equal to 250,000 images per second. The line sensor can have dimensions of 250 pm (micrometers) by 13 mm (millimeters). The extension of the light distribution of the light beam along the second direction can be in the range from 10 pm to 300 pm. The extension of the light distribution of the light beam along the third direction can be between 500 pm and 10 mm. The line sensor is preferably aligned such that a long axis of the light beam (i.e. the extension of the light beam in the third direction) and a long axis of the line sensor are aligned with one another. In particular, the long axis of the light beam and the long axis of the line sensor can run in the same plane. When the particle moves through the measuring volume, the light beam is reflected and / or scattered by the particle.The imaging device can consist of an arrangement of mirrors and / or lenses that collect the reflected and / or scattered light and direct or focus it onto the line sensor. In particular, the imaging device generates an image of the measurement volume at the location of the line sensor.

[0016] Since the particle is usually small (e.g., 5 pm to 100 pm), the image of the particle falls on only one or a few pixels of the line sensor. The position of the particle along the third direction can therefore be determined with an accuracy given by the pixel size p divided by the magnification M of the imaging device. Thus, the accuracy is proportional to p / M.

[0017] This allows for precise characterization of the particle. In particular, the position of the particle along the third direction (in the range of micrometers) can be determined precisely.

[0018] According to a further development of the device, the beam-shaping optics are configured to influence the intensity and / or the polarization of the light beam within the light distribution. The beam-shaping optics can, in particular, be configured to influence the intensity along the second direction and / or along the third direction. In other words, the intensity and / or the polarization of the light beam within the light distribution, in particular along the second and / or along the third direction, can be adjusted (as desired) by means of the beam-shaping optics.

[0019] This allows the desired light distribution of the light beam and thus the most optimal generation of the intensity signal to be implemented.

[0020] According to a further development of the device, the device, in particular the beam-shaping optics, can comprise at least one converter for converting a light beam profile of the light beam. The converter can be configured to convert a Gaussian beam profile into a flat-top beam profile.

[0021] This allows the desired beam profile, in particular a flat-top beam profile, to be implemented using simple means.

[0022] According to a further development of the device, the device can be configured such that the intensity of the light distribution along the third direction has a flat-top beam profile. In particular, the device can be configured such that the intensity of the light distribution along the third direction is the same (or constant). Additionally or alternatively, the device can be configured such that the intensity of the light distribution along the second direction has a Gaussian beam profile.

[0023] This allows the intensity signal to be generated with a consistent quality, in particular independent of the position of the particle along the third direction.

[0024] According to a further development of the device, the device can comprise an evaluation unit. The evaluation unit can be configured to determine a characteristic, in particular a position-dependent characteristic, of the particle within the measurement volume as a function of the intensity signal generated by the detection device. The characteristic of the particle can, in particular, be a position of the particle along the third direction.

[0025] The characteristic can also be a position of the particle along the second direction, particle size, and / or particle velocity. It is also conceivable that, in the case of multiple particles, the number of particles within the measurement volume is determined by evaluating the generated intensity signal. The evaluation unit can, for example, be implemented as a computer.

[0026] This allows an evaluation of the generated intensity signal to be implemented using simple means.

[0027] According to a development of the device, the line sensor can be configured such that the line sensor can be moved along the measuring axis. In other words, the line sensor can be located outside a focusing or imaging plane of the imaging device. In particular, the line sensor can be moved out of the imaging plane of the imaging device. The image focused by means of the imaging device thus spreads over more than one or a few pixels on the line sensor. In other words, the image focused by means of the imaging device is stretched or distorted or blurred over more pixels by the displacement of the line sensor along the measuring axis.

[0028] This allows the position to be determined with an accuracy better than the accuracy mentioned above, which is proportional to p / M. This allows the accuracy of the particle's position determination along the third direction to be further optimized.

[0029] According to a further development of the device, the measuring angle can be less than 90 °, in particular less than 45 °, preferably less than 15 °.

[0030] This allows the device to be adjusted as optimally as possible and the generated intensity signal to be further optimized.

[0031] According to a further development of the device, the device can comprise a trigger device. The trigger device can be configured such that the line sensor only triggers (or detects) when the particle moves into the measurement volume. In particular, the line sensor does not detect (or triggers) when no particle moves into the measurement volume (the trigger device is not triggered).

[0032] This allows the line sensor to be triggered upon the arrival of the particle. This allows the accuracy of the particle characterization within the measurement volume, particularly the position determination along the third direction, to be further optimized. In addition, such a triggered mode can maximize the number of particles characterized within a specific time period. Triggering the line sensor, in this case, refers in particular to the detection or generation of an intensity signal.

[0033] According to a further development of the device, the triggering device can comprise a light barrier. The light barrier can be arranged upstream of the measuring volume with respect to the second direction. The separating device can be configured such that the particle triggers the triggering device and / or the line sensor upon passing through the light barrier. The triggering of the triggering device and / or the line sensor can be implemented with a time delay.

[0034] This allows for simple triggering of the trigger device or the line sensor. In particular, the time-delayed triggering prevents the trigger device or the line sensor from being triggered when the particle is still outside the measurement volume (has not yet moved into the measurement volume).

[0035] The above object is achieved by a method for characterizing at least one particle having the features of the independent claim. The method comprises the steps:

[0036] Generating and aligning a light beam along a beam axis. The beam axis is oriented along a first direction. Generating a light distribution of the light beam along a second direction and a third direction. The first, second, and third directions are each aligned orthogonally to one another.

[0037] Moving the particle in a second direction through a measuring volume which extends at least partially along the beam axis and / or the light distribution of the light beam.

[0038] Detecting light that is reflected and / or scattered by the particle in the measurement volume along a measurement axis using a line sensor. The measurement axis is arranged at a measurement angle to the beam axis.

[0039] Generating an intensity signal that depends on the detected light. The detected light depends in particular on the position of the particle in the light beam.

[0040] This allows for precise characterization of the particle. In particular, the position of the particle along the third direction (in the range of micrometers) can be determined precisely.

[0041] According to a further development of the method, the method may comprise the step:

[0042] Influencing the intensity and / or polarization of the light beam within the light distribution. The intensity and / or polarization can be influenced (adjusted) particularly along the second direction and / or the third direction.

[0043] This allows the desired light distribution of the light beam and thus the most optimal generation of the intensity signal to be implemented.

[0044] According to a further development of the method, the method may comprise the step:

[0045] Adjusting the intensity of the light distribution such that the intensity of the light distribution has a flat-top beam profile along the third direction and / or a Gaussian beam profile along the second direction.

[0046] This allows the intensity signal to be generated with a consistent quality, in particular independent of the position of the particle along the third direction.

[0047] According to a further development of the method, the method may comprise the step:

[0048] Determining a characteristic, in particular a position-dependent characteristic, of the particle within the measurement volume by evaluating the generated intensity signal. The characteristic can in particular be a position of the particle along the third direction. The characteristic can also be a position of the particle along the second direction, particle size and / or particle speed. It is also conceivable that, in the case of several particles, a number of particles within the measurement volume is determined by evaluating the generated intensity signal.

[0049] In this way, a characteristic of the particle, particularly a position-dependent one, can be determined using simple means.

[0050] According to a further development of the method, the method may comprise the step:

[0051] Aligning the measuring axis such that the measuring axis is inclined at a measuring angle to the beam axis. Alternatively or additionally, moving the line sensor along the measuring axis. The measuring angle can be less than 90°, in particular less than 45°, preferably less than 15°.

[0052] This allows the accuracy of the characterization of the particle, in particular the position determination of the particle along the third direction, to be further optimized.

[0053] According to a further development of the method, the method may comprise the step:

[0054] Triggered activation of the line sensor by means of a trigger device. The trigger device can be triggered by the particle. The activation of the trigger device and / or the line sensor can be implemented with a time delay.

[0055] This allows the accuracy of the particle characterization, in particular the position determination of the particle along the third direction, to be further optimized. According to a further development of the method, a device as described above can be used to carry out the method.

[0056] With regard to the advantages that can be achieved, reference is made to the relevant explanations of the device. The measures described in connection with the device and / or those explained below can be used to further refine the method.

[0057] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of an embodiment with reference to the drawings. They show:

[0058] Fig. 1 is a schematic representation of a device for characterizing at least one particle and

[0059] Fig. 2 is a schematic representation of a particle and a measuring volume of the device according to Figure 1.

[0060] In the following description and in the figures, corresponding components and elements have the same reference symbols.

[0061] Figure 1 shows a schematic representation of a device 10 for characterizing at least one particle 12.

[0062] The device 10 comprises a light device 14 for generating a light beam 16. The light device 14 can be designed as a laser or comprise a laser. The light device 14 can be designed to generate a laser beam.

[0063] The device 10 comprises a beam-shaping optic 18 for aligning the light beam 16 along a beam axis 20. The beam axis 20 is oriented along a first direction 22.

[0064] The beam shaping optics 18 are configured to generate a light distribution 24 of the light beam 16 along a second direction 26 and a third direction 28. The first, second and third directions 22, 26, 28 are each aligned orthogonally to one another. The first direction 22 is oriented to the right in Figure 1. The third direction 28 is oriented upwards in Figure 1. The second direction 26 is oriented perpendicular to the plane of the drawing, pointing out of the plane of the drawing (towards the viewer).

[0065] The device 10 comprises a measuring volume 30 which extends at least in sections along the beam axis 20 and / or along the light distribution 24 of the light beam 16.

[0066] The device 10 comprises a detection device 32. The detection device 32 is configured to detect light 34 reflected and / or scattered by the particle 12 (when the particle 12 is located in the measurement volume 30). The detection device 32 is arranged along a measurement axis 36 and configured to generate an intensity signal. The reflected and / or scattered light 34 propagates in particular along the measurement axis 36. The measurement axis 36 is arranged at a measurement angle 38 to the beam axis 20. In the present case, the measurement angle 38 means the smaller of the angles included between the measurement axis 36 and the beam axis 20. The detection device 32 comprises a line sensor 40 and an imaging device 42. The imaging device 42 is configured to focus the reflected and / or scattered light 34 onto the line sensor 40.

[0067] The beam shaping optics 18 can be configured to influence an intensity and / or a polarization of the light beam 16 within the light distribution 24, in particular along the second direction 26 and / or the third direction 28.

[0068] In the present case, the device 10 has a converter 44 for converting a beam profile of the light beam 16. It is also conceivable for the device 10 to comprise a plurality of converters 44. The converter 44 can be formed as part of the beam-shaping optics 18. The converter 44 is designed in the present case to convert a Gaussian beam profile of the light beam 16 into a flat-top beam profile.

[0069] In the present case, the device 10 is configured such that the intensity of the light distribution 24 along the third direction 28 has a flat-top beam profile and a Gaussian beam profile along the second direction 26. The intensity of the light distribution 24 along the third direction 28 is thus constant in the present case.

[0070] The device 10 comprises an evaluation unit 46.

[0071] The evaluation unit 46 is configured to determine a characteristic, in particular a position-dependent characteristic, of the particle 12 within the measurement volume 30 as a function of the intensity signal generated by the detection device 32. In the present case, the characteristic is a position of the particle 12 along the third direction 28.

[0072] The line sensor 40 can be designed such that the line sensor 40 can be displaced along the measuring axis 36. The line sensor 40 can, in particular, be moved out of the imaging plane of the imaging device.

[0073] The measuring angle 38 can be less than 90 ° , in particular less than 45 ° , preferably less than 15 ° .

[0074] Figure 2 shows a schematic representation of the particle 12 and a measuring volume 30 of the device 10 according to Figure 1. The represented particle 12 moves along the second direction 26 through the measuring volume 30 (indicated in Figure 2 by an arrow pointing to the right). The second direction 26 is oriented to the right in Figure 2. The third direction 28 is oriented upwards in Figure 2. The first direction in Figure 2 is oriented perpendicular to the plane of the drawing, pointing into the plane of the drawing (away from the observer).

[0075] In the present case, the device 10 is set up such that the line sensor 40 is only triggered when the particle 12 moves into the measuring volume 30. For this purpose, the device 10 has a trigger device 48. In the present case, the trigger device 48 comprises a light barrier 50 arranged in front of the measuring volume 30 with respect to the second direction 26. The trigger device 48 is set up such that the particle 12 triggers the trigger device 48 and / or the line sensor 40, in particular with a time delay, when it passes through the light barrier 50. If there is a spatial distance between the light barrier 50 and the measuring volume 30, the speed of the particle 12 should be known in order for the triggering to work. The time-delayed triggering ensures that the line sensor 40 does not trigger when the particle 12 passes through the light barrier 50, i.e. is still outside the measuring volume 30 (or .in relation to the second direction 26 in front of the measuring volume 30 ) .

[0076] In the following, a method for characterizing at least one particle 12 is explained with reference to Figures 1 and 2. The method comprises the following steps:

[0077] Generating and aligning a light beam 16 along a beam axis 20. The beam axis 20 is oriented along a first direction 22.

[0078] Generating a light distribution 24 of the light beam 16 along a second direction 26 and along a third direction 28. The first, second and third directions 22, 26, 28 are each aligned orthogonally to one another.

[0079] Moving the particle 12 in a second direction 26 through a measuring volume 30. The measuring volume 30 extends at least partially along the beam axis 20 and / or the light distribution 24 of the light beam 16.

[0080] Detecting light 34, which is reflected and / or scattered by the particle 12 located in the measuring volume 30, along a measuring axis 36 by means of a line sensor 40. The measuring axis 36 is arranged at an angle 38 to the beam axis 20.

[0081] Generating an intensity signal which is dependent on the detected light 34 .

[0082] The method may comprise the step of:

[0083] Influencing (or adjusting) the intensity and / or polarization of the light beam within the light distribution 24, in particular along the second direction 26 and / or the third direction 28.

[0084] The method may comprise the step of:

[0085] Adjusting the intensity of the light distribution 24 such that an intensity of the light distribution 24 along the third direction 28 has a flat-top beam profile and / or along the second direction 26 has a Gaussian beam profile.

[0086] The method may comprise the step of:

[0087] Determining a characteristic, in particular a position-dependent characteristic, of the particle 12 within the measurement volume 30 by evaluating the generated intensity signal. In particular, the characteristic can be a position of the particle 12 along the third direction 28.

[0088] The method may comprise the step of aligning the measuring axis 36 such that the measuring axis 36 is inclined by a measuring angle 38 relative to the beam axis 20. Alternatively or additionally, displacing the line sensor 40 along the measuring axis 36. The measuring angle 38 may be less than 90°, in particular less than 45°, preferably less than 15°.

[0089] The method may comprise the step of:

[0090] Triggered activation of the line sensor 40 by means of a trigger device 48. The trigger device 48 can be triggered by the particle 12. The activation of the line sensor 40 and / or the trigger device 48 can be implemented with a time delay.

[0091] To carry out the method, a device 10 according to the above explanations can be used. In particular, this device 10 can be shown in Figures 1 and 2.

Claims

Patent claims 1. Device (10) for characterizing at least one particle (12), comprising: a light device (14) for generating a light beam (16); a beam-shaping optics (18) for aligning the light beam (16) along a beam axis (20), wherein the beam axis (20) is oriented along a first direction (22), wherein the beam-shaping optics (18) are configured to generate a light distribution (24) of the light beam (16) along a second direction (26) and a third direction (28), wherein the first, second, and third directions (22, 26, 28) are each aligned orthogonally to one another, a measuring volume (30) which extends at least partially along the beam axis (20) and / or the light distribution (24) of the light beam (16), a detection device (32) which is configured to detect light (34) reflected and / or scattered by the particle (12) which is located in the measuring volume (30),wherein the detection device (32) is arranged along a measuring axis (36) and is arranged to generate an intensity signal, wherein the measuring axis (36) is arranged inclined by a measuring angle (38) to the beam axis (20), wherein the detection device (32) comprises a line sensor (40) and an imaging device (42), wherein the imaging device (42) is for, Focusing the reflected and / or scattered light (34) is aligned with the line sensor (40).

2. Device (10) according to claim 1, characterized in that the beam-shaping optics (18) are configured to influence an intensity and / or a polarization of the light beam (16) within the light distribution (24), in particular along the second direction (26) and / or the third direction (28).

3. Device (10) according to claim 1 or 2, characterized in that the device (10), in particular the beam shaping optics (18), comprises at least one converter (44) for converting a beam profile of the light beam (16), in particular from a Gaussian to a flat-top beam profile.

4. Device (10) according to one of the preceding claims, characterized in that the device (10) is arranged such that an intensity of the light distribution (24) along the third direction (28) has a flat-top beam profile and / or along the second direction (26) has a Gaussian beam profile.

5. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises an evaluation unit (46) which is configured to determine a characteristic, in particular a position along the third direction (28), of the particle (12) within the measuring volume (30) as a function of the intensity signal generated by the detection device (32).

6. Device (10) according to one of the preceding claims, characterized in that the line sensor (40) is arranged such that the line sensor (40) is designed to be displaceable along the measuring axis (36).

7. Device (10) according to one of the preceding claims, characterized in that the measuring angle (38) is less than 90°, in particular less than 45°, preferably less than 15°.

8. Device (10) according to one of the preceding claims, characterized in that the device (10) comprises a trigger device (48), wherein the trigger device (48) is configured such that the line sensor (40) only triggers when the particle (12) moves into the measuring volume (30).

9. Device (10) according to claim 8, characterized in that the trigger device (48) comprises a light barrier (50) arranged in front of the measuring volume (30) with respect to the second direction (26) and is set up in such a way that the particle (12) triggers the trigger device (48) and / or the line sensor (40), in particular with a time delay, when passing through the light barrier (50).

10. A method for characterizing at least one particle (12), comprising the steps: Generating and aligning a light beam (16) along a beam axis (20), wherein the beam axis (20) is oriented along a first direction (22), Generating a light distribution (24) of the light beam (16) along a second direction (26) and a third direction (28), wherein the first, the second and the third direction (22, 26, 28) are each aligned orthogonally to each other, Moving the particle (12) in a second direction (26) through a measuring volume (30) which extends at least partially along the beam axis (20) and / or the light distribution (24) of the light beam (16); Detecting light (34) which is reflected and / or scattered by the particle (12) located in the measuring volume (30) along a measuring axis (36) by means of a line sensor (40), wherein the measuring axis (36) is arranged inclined by a measuring angle (38) to the beam axis (20), Generating an intensity signal that is dependent on the detected light (34).

11. The method according to claim 10, characterized in that the method comprises the step: Influencing the intensity and / or polarization of the light beam (16) within the light distribution (24), in particular along the second direction (26) and / or the third direction (28).

12. The method according to claim 11, characterized in that the method comprises the step: Adjusting the intensity of the light distribution (24) such that the intensity of the light distribution (24) has a flat-top beam profile along the third direction (28) and / or a Gaussian beam profile along the second direction (26).

13. Method according to one of claims 10 to 12, characterized in that the method comprises the step: Determining a characteristic, in particular a Position along the third direction (28) of the particle (12) within the measuring volume (30) by evaluating the generated intensity signal.

14. Method according to one of claims 10 to 13, characterized in that the method comprises the step: Aligning the measuring axis (36) such that the measuring axis (36) is arranged inclined by a measuring angle (38) to the beam axis (20) and / or moving the line sensor (40) along the measuring axis (36), in particular wherein the measuring angle (38) is less than 90°, in particular less than 45°, preferably less than 15°.

15. Method according to one of claims 10 to 14, characterized in that the method comprises the step: Triggered triggering of the line sensor (40) by means of a trigger device (48), wherein the trigger device (48) is triggered by means of the particle (12), in particular wherein the triggering of the line sensor (40) and / or the trigger device (48) is implemented with a time delay.

16. Method according to one of claims 10 to 15, characterized in that a device (10) according to one of claims 1 to 10 is used to carry out the method.

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