Apparatus and method for characterizing at least one particle

Abstract

The present invention relates to an apparatus (10) having the features of claim 1 for characterizing at least one particle (12) and a method having the features of parallel claims for characterizing at least one particle (12).

Description

Technical Field

[0001] The present invention relates to an apparatus for characterizing at least one particle having the features of claim 1, and a method for characterizing at least one particle having the features of parallel claims. Prior Technology

[0002] Devices and methods for characterizing particles can be used in a variety of applications to determine, for example, particle position, particle velocity, or particle size. For instance, this can be used to monitor or regulate industrial manufacturing and processing processes.

[0003] An apparatus for determining particle characteristics is known, for example, from DE 10 2019 209 213 A1, and includes a light source by which a laser beam is generated along a beam axis. Beam-shaping optics are arranged along the beam axis. The beam-shaping optics are designed to adjust the position-dependent intensity distribution of the laser beam within a measurement volume that extends locally along the beam axis. The particle to be characterized, located within the measurement 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 uses the intensity signal to determine the particle characteristics within the measurement volume.

[0004] In principle, the goal is to characterize particles within the measurement volume with high precision. Summary of the Invention

[0005] Therefore, the object of the present invention is to provide an apparatus and method that achieves a good balance between the accuracy achievable in particle characterization and the associated costs.

[0006] The aforementioned objective is achieved by means of a device for characterizing at least one particle having the features of claim 1.

[0007] The device includes a light-emitting device for generating a light beam. The light-emitting device can be specifically designed as a laser device for generating a laser beam. The light-emitting device may include an LED (light-emitting diode), an SLED (superluminescent LED), a VCSEL (vertical-cavity surface-emitting laser), and / or a laser light source.

[0008] The device includes a beam-shaping optics element for aligning the beam along its axis. The beam axis is oriented along a first direction. The beam-shaping optics element is configured to generate a light distribution of the beam along a second direction and a third direction. The light distribution along the second direction and the third direction specifically corresponds to the cross-section of the beam after it has been shaped by the beam-shaping optics element. Here, the first direction, the second direction, and the third direction are each orthogonally oriented to each other. The first direction may be the Z direction, the second direction may be the X direction, and / or the third direction may be the Y direction.

[0009] The device includes a measuring volume that extends at least partially along the beam axis and / or the light distribution of the beam. Specifically, the measuring volume extends at least partially along the cross-section of the beam. The measuring volume may be located in a plane spanned by a second direction and a third direction and / or may be arranged parallel to that plane.

[0010] The device includes a detection unit. The detection unit is configured to detect light reflected and / or scattered by particles located in the measurement volume. The detection unit is arranged along the measurement axis and configured to generate an intensity signal. The measurement axis is arranged at a measurement angle relative to the beam axis. Therefore, specifically when there are no particles in the measurement volume, no light is reflected or scattered, and therefore no intensity is detected (or no intensity signal is generated).

[0011] The detection device includes a linear sensor and an imaging device. The imaging device can be designed as a focusing optics element or an imaging optics element. The linear sensor can be designed as a line sensor or a line camera. The linear sensor can be configured as a 1 x 1024 pixel one-dimensional sensor. The imaging device is configured to focus (or image) reflected and / or scattered light onto the linear sensor.

[0012] The linear sensor can be configured to record images at a rate of 250,000 frames per second or higher. The linear sensor can have dimensions of 250 μm x 13 mm. The extension dimension of the light distribution along the second direction can range from 10 μm to 300 μm. The extension dimension of the light distribution along the third direction can range from 500 μm to 10 mm. The linear sensor is preferably oriented such that the long axis of the light beam (i.e., the extension dimension of the light beam in the third direction) and the long axis of the linear sensor are aligned with each other. Specifically, the long axis of the light beam and the long axis of the linear sensor can extend in the same plane.

[0013] As particles pass through the measurement volume, the light beam is reflected and / or scattered by the particles. The imaging device may consist of an arrangement of mirrors and / or lenses that collect the reflected and / or scattered light and guide or focus it onto a linear sensor. Specifically, the imaging device produces an image of the measurement volume at the location of the linear sensor.

[0014] Since particles are typically very small (e.g., 5 μm to 100 μm), the image of a particle falls on only one or a few pixels of the linear sensor. Therefore, the position of the particle along a third direction can be determined with an accuracy given by dividing the pixel size p by the magnification M of the imaging device. Thus, the accuracy is proportional to p / M.

[0015] Therefore, particles can be accurately characterized. Specifically, the position of a particle along a third direction (within the micrometer range) can be precisely determined.

[0016] According to the improved version of the device, the beam-shaping optical element is configured to influence the intensity and / or polarization of the beam within the light distribution. Specifically, the beam-shaping optical element can be configured to influence the intensity along a second direction and / or a third direction. In other words, the intensity and / or polarization of the beam within the light distribution, specifically along the second direction and / or a third direction, can be adjusted by the beam-shaping optical element (as needed).

[0017] Therefore, the desired light distribution of the beam can be achieved, thereby generating an intensity signal as optimally as possible.

[0018] According to an improved version of the device, the device, specifically the beam shaping optical element, may include at least one transducer for converting the beam profile. The transducer can be configured to convert a Gaussian beam profile into a flat-top beam profile.

[0019] In this way, the desired beam profile, specifically a flat-top beam profile, can be achieved using simple means.

[0020] According to an improved version of the device, the device can be configured such that the intensity of the light distribution along a third direction has a flat-top beam profile. Specifically, the device can be configured such that the intensity of the light distribution is the same (or constant) along the third direction. Additionally or alternatively, the device can be configured such that the intensity of the light distribution has a Gaussian beam profile along a second direction.

[0021] Therefore, intensity signals can be generated with consistent quality, and specifically regardless of the position of the particle along a third direction.

[0022] According to an improved version of the device, the device may include an evaluation unit. The evaluation unit can be configured to determine, in particular, position-related characteristics of the particles within the measurement volume based on the intensity signal generated by the detection device. The particle characteristics may, in particular, be the particle's position along a third direction.

[0023] This feature could also be the particle's position 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 could be determined by evaluating the resulting intensity signal. The evaluation unit could, for example, be designed as a computer.

[0024] Therefore, a simple method can be used to assess the intensity of the generated signal.

[0025] According to the improved version of the device, the linear sensor can be configured to move along the measurement axis. In other words, the linear sensor can be located outside the focusing or imaging plane of the imaging device. In particular, the linear sensor can be moved out of the imaging plane of the imaging device.

[0026] Therefore, the image focused by the imaging device propagates across the linear sensor beyond one or a few pixels. In other words, due to the displacement of the linear sensor along the measurement axis, the image focused by the imaging device is stretched, distorted, or blurred to more pixels.

[0027] This allows for determining position with a higher accuracy than described above, which is proportional to p / M. Therefore, it allows for further optimization of the accuracy of determining particle position along a third direction.

[0028] According to the improved version of the device, the measuring angle can be less than 90°, specifically less than 45°, and preferably less than 15°.

[0029] Therefore, the device can be adjusted as optimally as possible, or the generated intensity signal can be further optimized.

[0030] According to an improved version of the device, the device may include a triggering device. The triggering device can be configured such that the linear sensor activates (or detects) only when a particle moves into the measurement volume. Specifically, when no particle moves into the measurement volume (the triggering device does not activate), the linear sensor does not detect (does not activate).

[0031] This allows the linear sensor to be activated upon particle arrival. This, in turn, allows for further optimization of the characterization of particles within the measurement volume, and specifically, the accuracy of position determination along a third direction. Additionally, this triggering mode can maximize the number of particles characterized within a given time period. In the current case, activation of the linear sensor specifically implies the detection or generation of an intensity signal.

[0032] According to an improved version of the device, the triggering device may include a grating. The grating may be arranged in front of the measuring volume relative to the second direction. The separation device may be configured such that when a particle passes through the grating, the particle activates the triggering device and / or the linear sensor. The activation of the triggering device and / or the linear sensor may be achieved through a time delay.

[0033] Therefore, a simple means can be used to activate the triggering device or linear sensor. In particular, time-delayed activation can prevent the triggering device or linear sensor from activating while the particle is still outside the measurement volume (before it has moved into the measurement volume).

[0034] The above objective is achieved by a method for characterizing at least one particle, characterized by having parallel request items. The method comprises the following steps:

[0035] The beam is generated and aligned along the beam axis. The beam axis is oriented along a first direction.

[0036] This produces a light distribution along the second and third directions. The first, second, and third directions are each orthogonally oriented to each other.

[0037] The particle is moved along a second direction through a measurement volume that extends at least locally along the beam axis and / or the light distribution of the beam.

[0038] Light reflected and / or scattered along the measurement axis by particles located in the measurement volume is detected by means of a linear sensor. The measurement axis is arranged at a measurement angle relative to the beam axis.

[0039] It generates a signal based on the intensity of the detected light. The detected light depends in particular on the position of the particles in the beam.

[0040] Therefore, particles can be accurately characterized. Specifically, the position of a particle along a third direction (within the micrometer range) can be precisely determined.

[0041] According to the improved version of this method, the method may include the following steps:

[0042] This affects the intensity and / or polarization of the light beam within the light distribution. In particular, the intensity and / or polarization can be affected (adjusted) along the second and / or third directions.

[0043] Therefore, the desired light distribution of the beam can be achieved, thereby generating an intensity signal as optimally as possible.

[0044] According to the improved version of this method, the method may include the following steps:

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

[0046] Therefore, intensity signals can be generated with consistent quality, and specifically regardless of the position of the particle along a third direction.

[0047] According to the improved version of this method, the method may include the following steps:

[0048] The characteristics of particles within the measurement volume, specifically position-related characteristics, are determined by evaluating the generated intensity signal. This characteristic can be, in particular, the particle's position along a third direction. It can also be the particle's position along a second direction, particle size, and / or particle velocity. Furthermore, in the case of multiple particles, the number of particles within the measurement volume can be determined by evaluating the generated intensity signal.

[0049] Therefore, simple methods can be used to determine the characteristics of particles, specifically location-related characteristics.

[0050] According to the improved version of this method, the method may include the following steps:

[0051] Align the measurement axis such that it is tilted relative to the beam axis at a measurement angle. Alternatively or additionally, move the linear sensor along the measurement axis. The measurement angle may be less than 90°, specifically less than 45°, and preferably less than 15°.

[0052] This allows for further optimization of particle characterization and, specifically, the accuracy of particle position determination along a third direction.

[0053] According to the improved version of this method, the method may include the following steps:

[0054] A linear sensor is activated by means of a triggering device. Here, the triggering device can be activated by a particle. The activation of the triggering device and / or the linear sensor can be achieved through a time delay.

[0055] This allows for further optimization of particle characterization and, specifically, the accuracy of particle position determination along a third direction.

[0056] According to an improved version of the method, the method can be performed using the apparatus described above.

[0057] Regarding the advantages achievable as a result, refer to the relevant statements concerning the apparatus. The measures described in conjunction with the apparatus and / or those explained below can be used to further develop the method. Simple Explanation of the Diagram

[0058] Other features, details, and advantages of the invention will become apparent from the terminology of the claim and the following description of exemplary embodiments based on the drawings. In the drawings:

[0059] Figure 1 shows a schematic diagram of a device for characterizing at least one particle; and

[0060] Figure 2 shows a schematic diagram of the particles and the measuring volume according to the device in Figure 1. Implementation

[0061] In the following description and figures, the corresponding components and elements have the same reference symbols.

[0062] Figure 1 shows a schematic diagram of a device 10 for characterizing at least one particle 12.

[0063] The device 10 includes a light-emitting device 14 for generating a light beam 16. The light-emitting device 14 may be designed as a laser or include a laser. The light-emitting device 14 may be designed to generate a laser beam.

[0064] The device 10 includes a beam-shaping optics 18 for aligning the beam 16 along a beam axis 20. The beam axis 20 is oriented along a first direction 22.

[0065] The beam-shaping optical element 18 is configured to generate a light distribution 24 for a beam 16 along a second direction 26 and a third direction 28. The first direction, the second direction, and the third direction 22, 26, and 28 are each orthogonally oriented to each other. 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 figure in Figure 1 and points out of the plane of the figure (towards the observer).

[0066] The device 10 includes a measuring volume 30 that extends at least partially along the beam axis 20 and / or along the light distribution 24 of the beam 16.

[0067] The apparatus 10 includes a detection device 32. The detection device 32 is configured to detect light 34 reflected and / or scattered by particles 12 (if they are located in the measurement volume 30). The detection device 32 is arranged along the measurement axis 36 and configured to generate an intensity signal. The reflected and / or scattered light 34 propagates particularly along the measurement axis 36.

[0068] The measurement axis 36 is arranged at an angle 38 relative to the beam axis 20. In this case, the measurement angle 38 refers to the smaller of the angles between the measurement axis 36 and the beam axis 20. The detection device 32 includes a linear sensor 40 and an imaging device 42. The imaging device 42 is configured to focus reflected and / or scattered light 34 onto the linear sensor 40.

[0069] The beam shaping optical element 18 is configured to influence the intensity and / or polarization of the beam 16 within the light distribution 24 in a specific manner along the second direction 26 and / or the third direction 28.

[0070] In the present case, the device 10 has a transducer 44 for converting the beam profile of the beam 16. It is also conceivable that the device 10 includes multiple transducers 44. The transducer 44 may be designed as part of the beam shaping optics 18. In the present case, the transducer 44 is designed to convert the Gaussian beam profile of the beam 16 into a flat-top beam profile.

[0071] In the current configuration, the intensity of the light distribution 24 configured by the device 10 has a flat-top beam profile along the third direction 28 and a Gaussian beam profile along the second direction 26. Therefore, in the current configuration, the intensity of the light distribution 24 along the third direction 28 is constant.

[0072] In the current configuration, device 10 includes an evaluation unit 46. Evaluation unit 46 is configured to determine, in particular, position-related characteristics of particle 12 within measurement volume 30 based on the intensity signal generated by detection device 32. In the current configuration, this characteristic is the position of particle 12 along a third direction 28.

[0073] The linear sensor 40 can be designed such that it can move along the measurement axis 36. In particular, the linear sensor 40 can be moved out of the imaging plane of the imaging device.

[0074] The measurement angle 38 can be less than 90°, specifically less than 45°, and preferably less than 15°.

[0075] Figure 2 shows a schematic diagram of the particle 12 and the measuring volume 30 of the apparatus 10 according to Figure 1. The particle 12 shown moves through the measuring volume 30 along the second direction 26 (indicated by a right-pointing arrow in Figure 2). 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 is oriented perpendicular to the drawing plane and points towards the drawing plane (away from the observer) in Figure 2.

[0076] In the current configuration, device 10 is configured such that linear sensor 40 is activated only when particle 12 moves into measurement volume 30. For this purpose, device 10 has a triggering device 48. In the current configuration, triggering device 48 includes a grating 50 arranged in front of measurement volume 30 relative to the second direction 26. In the current configuration, triggering device 48 is configured to activate triggering device 48 and / or linear sensor 40, specifically with a time delay, when particle 12 passes through grating 50. The spatial distance between grating 50 and measurement volume 30, and the velocity of particle 12, should be known for triggering to function. The time-delayed activation ensures that when particle 12 passes through grating 50, i.e., while still outside measurement volume 30 (or in front of measurement volume 30 relative to the second direction 26), linear sensor 40 has not yet been activated.

[0077] The method for characterizing at least one particle 12 is explained below with reference to Figures 1 and 2. The method includes the following steps:

[0078] Beam 16 is generated and aligned along beam axis 20. Beam axis 20 is oriented along first direction 22.

[0079] A light distribution 24 is generated for a beam 16 along the second direction 26 and the third direction 28. Here, the first direction, the second direction, and the third direction 22, 26, and 28 are each orthogonally oriented to each other.

[0080] Particle 12 moves along the second direction 26 through the measuring volume 30. The measuring volume 30 extends at least locally along the beam axis 20 and / or the light distribution 24 of the beam 16.

[0081] Light 34 reflected and / or scattered by particles 12 located in the measurement volume 30 along the measurement axis 36 is detected by means of a linear sensor 40. Here, the measurement axis 36 is arranged at a measurement angle 38 relative to the beam axis 20.

[0082] Generates a signal based on the intensity of the detected light 34.

[0083] This method may include the following steps:

[0084] Influences (or modulates) the intensity and / or polarization of the beam within the light distribution 24, specifically along the second direction 26 and / or the third direction 28.

[0085] This method may include the following steps:

[0086] The intensity of the light distribution 24 is adjusted so 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.

[0087] This method may include the following steps:

[0088] The characteristics of particle 12 within the measurement volume 30 are determined by evaluating the intensity signal generated, specifically position-related characteristics. These characteristics may, in particular, be the position of particle 12 along a third direction 28.

[0089] This method may include the following steps:

[0090] Align the measurement axis 36 such that the measurement axis 36 is arranged at an angle 38 relative to the beam axis 20. Alternatively or additionally, move the linear sensor 40 along the measurement axis 36. Here, the measurement angle 38 may be less than 90°, specifically less than 45°, and preferably less than 15°.

[0091] This method may include the following steps:

[0092] The linear sensor 40 is activated by triggering device 48. Triggering device 48 can be activated by particle 12. Activation of linear sensor 40 and / or triggering device 48 can be achieved with a time delay.

[0093] To perform this method, the apparatus 10 as described above can be used. Specifically, this can be the apparatus 10 shown in Figures 1 and 2. 10: Device 12: Particles 14: Light-emitting device 16: Beam 18: Beam Shaping Optical Elements 20: Beam axis 22: First Direction 24: Light Distribution 26: Second Direction 28: Third-party 30: Measuring volume 32: Detection device 34: Reflected and / or scattered light 36: Measuring the axis 38: Measuring Angle 40: Linear Sensor 42: Imaging device 44: Converter 46: Evaluation Unit 48: Triggering device 50: Grating

Claims

1. An apparatus (10) for characterizing at least one particle (12), the apparatus comprising: - a light-emitting 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) is 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 direction, the second direction, and the third direction (22, 26, 28) are each orthogonally oriented to each other; - at least one transducer (44) for connecting the light-emitting device (14) and the beam-shaping optics (18), the at least one transducer (44) for converting a Gaussian beam profile of the light beam (16) into a flat-top beam profile, wherein the apparatus (10) is configured such that the light distribution (24) The intensity has a flat-top profile along the third direction (28) and a Gaussian beam profile along the second direction (26); - a measurement volume (30) that extends at least locally along the beam axis (20) and / or the light distribution (24) of the beam (16); and - a detection device (32) configured to detect light (34) reflected and / or scattered by the particle (12) located in the measurement volume (30), wherein the detection device (32) is arranged and moved along the measurement axis (36) and configured to generate an intensity signal, wherein the measurement axis (36) is arranged at a measurement angle (38) relative to the beam axis (20), wherein the detection device (32) includes a linear sensor (40) and an imaging device (42), wherein the imaging device (42) is configured to receive the reflected and / or scattered light (34). Focus on the linear sensor (40).

2. The apparatus (10) as claimed in claim 1, characterized in that the beam shaping optical element (18) is configured to affect the intensity and / or polarization of the beam (16) within the light distribution (24), specifically along the second direction (26) and / or the third direction (28).

3. The apparatus (10) as claimed in claim 1 or 2, characterized in that the apparatus (10), specifically the beam shaping optical element (18), includes at least one converter (44) for converting the beam profile of the beam (16), specifically from a Gaussian beam profile to a flat-top beam profile.

4. The apparatus (10) as claimed in claim 1, characterized in that the apparatus (10) is configured 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).

5. The apparatus (10) as claimed in claim 1, characterized in that the apparatus (10) includes an evaluation unit (46) configured to determine, in particular, the position of the particle (12) within the measurement volume (30) based on the intensity signal generated by the detection device (32), in the third direction (28).

6. The apparatus (10) as claimed in claim 1, characterized in that the linear sensor (40) is configured such that the linear sensor (40) is configured to be displaced along the measurement axis (36).

7. The apparatus (10) as claimed in claim 1, characterized in that the measuring angle (38) is less than 90°, specifically less than 45°, and preferably less than 15°.

8. The apparatus (10) as claimed in claim 1, characterized in that the apparatus (10) includes a triggering device (48) configured such that the linear sensor (40) is activated only when the particle (12) moves into the measurement volume (30).

9. The apparatus (10) as claimed in claim 8, characterized in that the triggering device (48) includes a grating (50) arranged in front of the measuring volume (30) relative to the second direction (26) and configured such that the particle (12) activates the triggering device (48) and / or the linear sensor (40) in a time-delayed manner when passing through the grating (50).

10. A method for characterizing at least one particle (12), the method comprising the steps of: - generating and aligning a 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 beam (16) along a second direction (26) and a third direction (28), wherein the first direction, the second direction, and the third direction (22, 26, 28) are each orthogonally oriented to each other; - implementing at least one converter (44) connecting the light-emitting device (14) and the beam-shaping optics (18), wherein the at least one converter (44) is used to convert a Gaussian beam profile of the beam (16) into a flat-top beam profile, wherein the device (10) is configured such that the intensity of the light distribution (24) has a flat-top profile along the third direction (28) and a Gaussian beam profile along the second direction (26); - characterizing the particle (12). Moving along a second direction (26) through a measuring volume (30) that extends at least locally along the beam axis (20) and / or the light distribution (24) of the beam (16); - detecting light (34) reflected and / or scattered by the particle (12) located in the measuring volume (30) along the measuring axis (36) by means of a linear sensor (40), wherein the measuring axis (36) is arranged at a measuring angle (38) relative to the beam axis (20); and - generating an intensity signal based on the detected light (34).

11. The method as claimed in claim 10, characterized in that the method comprises the steps of: - influencing the intensity and / or polarization of the beam (16) within the light distribution (24), specifically along the second direction (26) and / or the third direction (28).

12. The method as claimed in claim 11, characterized in that the method comprises the following steps: - 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 has a Gaussian beam profile along the second direction (26).

13. The method as claimed in claim 10, characterized in that the method comprises the following steps: - determining the characteristics of the particle (12) within the measurement volume (30) by evaluating the intensity signal generated, specifically the position along the third direction (28).

14. The method as claimed in claim 10, characterized in that the method comprises the steps of: - aligning the measurement axis (36) such that the measurement axis (36) is arranged at an angle (38) relative to the beam axis (20) and / or moving the linear sensor (40) along the measurement axis (36), wherein the measurement angle (38) is less than 90°, more particularly less than 45°, preferably less than 15°.

15. The method as claimed in claim 10, characterized in that the method comprises the following steps: - activating the linear sensor (40) by means of a triggering device (48), wherein the triggering device (48) is activated by means of the particle (12), and specifically wherein the activation of the linear sensor (40) and / or the triggering device (48) is achieved in a time-delay manner.

16. The method as described in claim 10, characterized in that the method is performed using an apparatus (10) as described in any one of claims 1 to 9.

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