Real-time crystal formation monitoring and control

Abstract

Systems and methods for monitoring crystal formation at a ferromagnetic sample. The method includes applying a laser pump pulse and a delayed laser probe pulse to the sample; detecting, in response to the applied laser pulses, reflectivity changes at the sample; determining, based on the reflectivity changes, at least one transient characteristic; and determining, based on the at least one transient characteristic, at least one crystal formation characteristic related to the sample.

Description

ORS-020PCREAL-TIME CRYSTAL FORMATION MONITORING AND CONTROL CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of and priority to United States Provisional Application No. 63 / 756,443, filed on February 10, 2025, the entire content of which is hereby incorporated by reference as if set forth in its entirety herein.TECHNICAL FIELD

[0002] Embodiments described herein generally relate to systems and methods for real-time crystal formation monitoring and control and, more specifically but not exclusively, to systems and methods for real-time nanocrystalline formation monitoring and control using picosecond transient reflectometry.BACKGROUND

[0003] Electrical steel is widely used in the cores of electromagnetic devices such as motors, generators, transformers, inductors, and other magnetic components. Currently, much of the electrical steel used in transformer cores is grain-oriented electrical steel (GOES). GOES is often processed through manufacturing steps that impart a strong crystalline texture aligned with the rolling direction of the sheet. This texture results in improved magnetic permeability and higher magnetic flux density in the rolling direction, as well as reduced core losses when the material is magnetized along that direction. However, GOES remains constrained by relatively high core losses and limited performance at higher frequencies or under rapidly varying magnetic fields.

[0004] In recent years, nanocrystalline amorphous alloys (NCAs) have emerged as promising candidates to replace GOES in a variety of applications. NCAs can perform better than either GOES or existing amorphous alloys and can be manufactured using less capital-intensive processes.

[0005] Existing techniques for manufacturing NCAs generally rely on casting an amorphous alloy and then heat cycling the material to grow crystals. The final properties of the crystal formation, such as crystal size, size dispersion, and volume fraction of the crystals, can determine the magnetic properties of an NCA. Higher temperatures and shorter growth times are often viewed as favorable, but shorter growth times can asymptotically increase the variation in steel characteristics under small variations of temperature and composition.

[0006] Accordingly, there is a need for improved systems and methods for monitoring and controlling crystal formation in real-time.ORS-020PCSUMMARY

[0007] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description section. This summary is not intended to identify or exclude key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0008] In one aspect, the techniques described herein relate to a method for monitoring crystal formation at a ferromagnetic sample, the method including: applying a laser pump pulse and a delayed laser probe pulse to the sample; detecting, in response to the applied laser pulses, reflectivity changes at the sample; determining, based on the reflectivity changes, at least one transient characteristic; and determining, based on the at least one transient characteristic, at least one crystal formation characteristic related to the sample.

[0009] In some embodiments, the techniques described herein relate to a method, wherein the at least one crystal formation characteristic is determined in real-time during a manufacturing process.

[0010] In some embodiments, the at least one transient characteristic includes at least one of an electronic characteristic or an acoustic characteristic.

[0011] In some embodiments, the at least one crystal formation characteristic includes at least one of a crystal size, crystal distribution, degree of crystallinity, or crystal volume fraction.

[0012] In some embodiments, the reflectivity changes are detected over a range of delay values for the laser probe pulse.

[0013] In some embodiments, the method further includes preheating the sample before the laser pulses are applied.

[0014] In some embodiments, the method further includes: configuring, based on the at least one crystal formation characteristic, a stimulus source; applying a stimulus to the sample using the configured stimulus source; determining at least one additional crystal formation characteristic related to the sample; and reconfiguring, based on the at least one additional crystal formation characteristic, the stimulus source.

[0015] In some embodiments, configuring the stimulus source includes determining an optimal stimulus distribution for inducing a desired crystal formation.

[0016] In another aspect, the techniques described herein relate to a system for monitoring crystal formation at a ferromagnetic sample, including: a laser oscillator configured to apply a laser pump pulse and a delayed laser probe pulse to the sample; a sensor configured to detect, inORS-020PCresponse to the applied laser pulses, reflectivity changes at the sample; and a processor configured to determine, based on the reflectivity changes, at least one crystal formation characteristic related to the sample.

[0017] In some embodiments, the system further includes: a beam splitter configured to separate the paths of the laser pump pulse and the laser probe pulse; and a chopper configured to modulate the path of the laser pump pulse.

[0018] In some embodiments, the system further includes a variable delay line configured to control the delay of the laser probe pulse.

[0019] In some embodiments, the delay is between 0 to 400 picoseconds.

[0020] In some embodiments, the processor is further configured to determine, based on the reflectivity changes, at least one transient characteristic.

[0021] In some embodiments, the at least one crystal formation characteristic includes at least one of a crystal size, crystal distribution, degree of crystallinity, or crystal volume fraction.

[0022] In yet another aspect, the techniques described herein relate to a system for controlling nanocrystalline formation, the system including: at least one sensor configured to detect reflectivity changes at a ferromagnetic alloy sample in response to laser pulses applied to the sample; a stimulus source configured to apply a stimulus to the sample for inducing a desired crystal formation at the sample; and a processor configured to configure the stimulus source based on the reflectivity changes.

[0023] In some embodiments, the stimulus includes at least one of heat, pressure, or an electromagnetic environment.

[0024] In some embodiments, the stimulus source includes a heat array configured to be modulated in at least one of a time-dependent way or a spatially-dependent way via the processor.

[0025] In some embodiments, the stimulus source includes at least one of a spatially-modulated laser projector or a spatially-modulated laser diode.

[0026] In some embodiments, the at least one sensor includes a first sensor and a second sensor, wherein the first and second sensors are configured to detect the reflectivity changes at different manufacturing stages.

[0027] In some embodiments, the processor is further configured to: determine at least one additional crystal formation characteristic related to the sample after the stimulus is applied; andORS-020PCreconfigure, based on the at least one additional crystal formation characteristic, the stimulus source.BRIEF DESCRIPTION OF DRAWINGS

[0028] Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.

[0029] FIG. 1 illustrates a graph representing transient reflectivity measurements;

[0030] FIG. 2 illustrates a flowchart of a method for real-time monitoring of crystal formation;

[0031] FIG. 3 illustrates a flowchart of a method for real-time control of crystal formation;

[0032] FIG. 4 illustrates a system for real-time monitoring and control of crystal formation;

[0033] FIG. 5 illustrates one embodiment of the control system depicted in FIG. 4; and

[0034] FIG. 6 illustrates one embodiment of the monitoring system depicted in FIG. 4.DETAILED DESCRIPTION

[0035] Various embodiments are described more fully below with reference to the accompanying drawings, which form a part hereof, and which show specific exemplary embodiments. However, the concepts of the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided as part of a thorough and complete disclosure, to fully convey the scope of the concepts, techniques and implementations of the present disclosure to those skilled in the art. Embodiments may be practiced as methods, systems or devices. Accordingly, embodiments may take the form of a hardware implementation, an entirely software implementation or an implementation combining software and hardware aspects. The following detailed description is, therefore, not to be taken in a limiting sense.

[0036] Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one example implementation or technique in accordance with the present disclosure. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment. The appearances of the phrase “in some embodiments” in various places in the specification are not necessarily all referring to the same embodiments.ORS-020PC

[0037] Unless specifically stated otherwise as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system memories or registers or other such information storage, transmission or display devices. Portions of the present disclosure include processes and instructions that may be embodied in software, firmware or hardware, and when embodied in software, may be downloaded to reside on and be operated from different platforms used by a variety of operating systems.

[0038] The present disclosure also relates to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may comprise a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including standard hard drives, solid state storage, floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, application specific integrated circuits (ASICs), or any type of media suitable for storing electronic instructions, and each may be coupled to a computer system bus. Furthermore, the computers referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability.

[0039] The processes and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may also be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform one or more method steps. The structure for a variety of these systems is discussed in the description below. In addition, any particular programming language that is sufficient for achieving the techniques and implementations of the present disclosure may be used. A variety of programming languages may be used to implement the present disclosure as discussed herein.

[0040] In addition, the language used in the specification has been principally selected for readability and instructional purposes and may not have been selected to delineate or circumscribe the disclosed subject matter. Accordingly, the present disclosure is intended to be illustrative, and not limiting, of the scope of the concepts discussed herein.ORS-020PC

[0041] Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0042] Embodiments described herein include systems and methods for real-time monitoring and control of crystal formation during manufacturing. The described embodiments may include monitoring crystal formation using picosecond transient reflectometry and dynamically adjusting stimulus sources based on the monitoring to steer the crystallization process toward a desired crystal formation. The described embodiments may perform the monitoring and control as part of a manufacturing process for forming NCAs.

[0043] Using picosecond optical transient reflectometry may allow for precise, rapid, and in-situ measurements of crystal formation. The measurements may be performed in real-time without interrupting the manufacturing process. The described embodiments may enable a closed-loop feedback control architecture in which manufacturing stimuli are continuously or repeatedly adjusted based on monitored characteristics of crystal formation. This may permit precise control of the crystallization process rather than reliance on open-loop techniques.

[0044] Transient reflectometry refers to a class of measurement techniques where a sample is excited by a short-duration stimulus and the resulting reflectivity changes of the sample are measured. Transient reflectometry may be used to observe dynamic physical processes occurring in the sample by monitoring how the optical reflectance of a surface changes over time after the material is perturbed from an initial state.

[0045] In some embodiments, laser pulses may be used as short-duration stimuli in a timedomain transient reflectometry process. A high-intensity laser pulse (referred herein as a “pump” pulse) may be directed to a surface of the sample, such as a ferromagnetic alloy. The pump pulse may have a duration under a picosecond. When the pump pulse strikes the surface of the sample, its energy may be absorbed by electrons in a volume hundreds of atoms deep. Over a brief duration (e.g., 5 picoseconds), the electrons may thermalize to the lattice.

[0046] The initial electron cooling may produce a transient change in reflectivity at the sample, which may persist for a few picoseconds following excitation. The lattice heating may produce an acoustic pulse that propagates for up to several nanoseconds depending on pulse energy.

[0047] To detect these transient changes, a second laser pulse (referred to herein as a “probe” pulse) may be directed to the surface. The probe pulses may be time-delayed with respect to the pump pulses using an adjustable delay value. By measuring the intensity of the probe light reflected from the surface as a function of this delay, a time-domain transient reflectivity responseORS-020PCfrom the sample may be obtained. In some embodiments, the temporal resolution of the response may be determined by the probe pulse width and may be on the order of hundreds of femtoseconds.

[0048] The transient electronic response, in the form of the transient reflectivity response, may be used to determine characteristics of crystal formation at the sample. Experimental observations indicate that the transient reflectivity changes are correlated with crystal formation characteristics such as crystal size and distribution. Using the electronic transient response may be advantageous as it may be detected at relatively low pump pulse energies, such as energy levels on the order of single nanojoules. In contrast, detection of the acoustic pulse typically requires substantially higher pulse energies, often on the order of microjoules.

[0049] FIG. 1 illustrates a graph 100 representing transient reflectivity measurements of various materials. As shown, the graph 100 contains a plot line 102 for a nanocrystalline FeSiB alloy, a plot line 104 for an amorphous FeSiB alloy, and a plot line 106 for gold. The graph 100 indicates that amorphous materials often exhibit little or no discernible electronic transient response, whereas nanocrystalline materials exhibit a significantly larger and distinct response that is still distinguishable from that of fully crystalline, coarse-grained materials. As described in detail herein, this correlation may allow the use of transient reflectometry systems and methods to measure crystal formation at a sample.

[0050] FIG. 2 illustrates a flowchart of a method 200 for real-time monitoring of crystal formation in accordance with one embodiment. While FIG. 2 shows illustrative operations according to one embodiment, other embodiments may omit, add to, reorder, and / or modify any of the operations shown in FIG. 2. Moreover, each of the operations depicted in FIG. 2 may be performed in any of the ways described herein. The operations shown in FIG. 2 may be performed by any of the illustrative systems described herein. Any of the operations shown in FIG. 2 may be performed in real-time, such as during a manufacturing process.

[0051] Operation 202 may include applying a laser pump pulse and a delayed laser probe pulse to a sample. The sample may include any metallic and / or partially metallic material, such as ironbased alloys, nickel-based alloys, cobalt-based alloys, etc. In some embodiments, the sample may include a ferromagnetic material. In some embodiments, the sample may include an amorphous and / or partially amorphous material. The sample may be shaped into any suitable configuration, such as a strip, sheet, ribbon, foil, wire, rod, bar, plate, tube, and / or bulk part.

[0052] In some embodiments, the laser pulses may be directed to a surface of the sample. The laser probe pulse may be applied with a variable delay after the laser pump pulse. For example, the delay value may be between 0 to 400 femtoseconds, such as approximately 200 femtoseconds.ORS-020PCThe delay may be controlled using a variable delay line, a multi-pulse timing architecture, a duallaser or dual-repetition-rate system, and / or any other suitable timing control mechanism.

[0053] In some embodiments, the pump and probe pulses may be derived from a common laser source (e.g., a laser oscillator) and are separated using beam-splitting and / or optical path length techniques. In other embodiments, the pump and probe pulses may be generated by separate laser sources that are electronically or optically synchronized.

[0054] Operation 204 may include detecting, in response to the applied laser pulses, reflectivity changes at the sample. As described above, the laser pulses may cause a transient response that includes reflectivity changes at the sample. The reflectivity changes may be detected as a time-domain transient reflectivity response. In some embodiments, reflectivity changes may be detected over a range of delay values for the probe pulse. In some embodiments, an acoustic pulse may be detected in addition to and / or alternatively to the reflectivity changes.

[0055] Operation 206 may include determining at least one transient characteristic. The transient characteristic may indicate any suitable aspect of the detected reflectivity changes and / or acoustic pulse. For example, the transient characteristic may include at least one of a peak amplitude, a rise time, a fall time, and / or a time at which a selected characteristic (e.g., a peak amplitude) is reached.

[0056] In some embodiments, multiple transient characteristics may be aggregated to form a feature vector or descriptor representing the reflectivity changes. The transient characteristics may be normalized, scaled, filtered, averaged over multiple measurements, and / or otherwise processed prior to further processing.

[0057] Operation 208 may include determining, based on the at least one transient characteristic, at least one crystal formation characteristic related to the sample. The crystal formation characteristic may indicate any suitable aspect of crystal formation at the sample. For example, the crystal formation characteristic may include at least one of an average crystal size, a crystal size distribution, a volume fraction of crystal formation, a degree of crystallinity, a spatial distribution of crystal formation, a density of crystal formation, and / or a rate of change of any other crystal formation characteristic. The crystal formation characteristic may indicate a current state of the sample and / or a predicted future state of the sample.

[0058] In some embodiments, determining the crystal formation characteristic may include applying a model to the transient characteristic. For example, the model may include an empirical or calibration-based model derived from prior measurements and / or a machine learning model.ORS-020PC

[0059] FIG. 3 illustrates a flowchart of a method 300 for real-time control of crystal formation in accordance with one embodiment. While FIG. 3 shows illustrative operations according to one embodiment, other embodiments may omit, add to, reorder, and / or modify any of the operations shown in FIG. 3. Moreover, each of the operations depicted in FIG. 3 may be performed in any of the ways described herein. The operations shown in FIG. 3 may be performed by any of the illustrative systems described herein.

[0060] In some embodiments, crystal formation at a sample may be measured to dynamically control crystal formation during manufacturing. The manufacturing process may process the sample to induce crystal formation, which may convert the sample from an amorphous alloy into an NCA. The manufacturing process may include application of various stimuli (e.g., heat) for inducing crystal formation. As described in detail, the method 300 may allow real-time control of crystal formation based on measurements derived using the method 200 and / or any other suitable method.

[0061] Operation 302 may include an estimator determining at least one crystal formation characteristic related to a sample during the manufacturing process. The operation 302 may be similar to the operation 208. The crystal formation characteristic may indicate crystal formation before a particular stimulus is applied to the sample. In some embodiments, the crystal formation characteristic may be expressed as a distribution function indicating the distribution of crystal formation. The distribution function may be a probability distribution indicating the likelihood of crystal formation at a given location and / or time. The estimator may be implemented using any suitable processing unit and / or system for generating the prediction.

[0062] In some embodiments, the estimator may determine the crystal formation characteristic using a machine learning model. The model may be configured to implement one or more decision tree learning algorithms, association rule learning algorithms, artificial neural network learning algorithms, deep learning algorithms, bitmap algorithms, and / or any other suitable data analysis technique as may serve a particular implementation. In some embodiments, the model may be implemented by one or more neural networks, such as one or more deep convolutional neural networks (CNN) using internal memories of its respective kernels (filters), recurrent neural networks (RNN), and / or long / short term memory neural networks (LSTM). The model may be multi-layer. For example, the model may be implemented by a neural network that includes an input layer, one or more hidden layers, and / or an output layer. The model may be trained on data from past manufacturing processes and / or monitoring sessions.

[0063] Operation 304 may include a planner configuring a stimulus source based on the crystal formation characteristic. The planner may configure the stimulus source to apply a stimulus (e.g.,ORS-020PCheat) to the sample in a desired manner. For example, the stimulus source may be a controlled heat array configured to apply a desired heat distribution to the stimulus.

[0064] In some embodiments, the objective of the planner may be to induce a desired crystal formation at the sample. The stimulus source may be configured to apply an optimal stimulus configuration (e.g., an optimal heat distribution) that is predicted to induce the desired crystal formation at the sample. For example, the planner may use an objective function that aims to minimize the difference between the current state of crystal formation state (e.g., as indicated by the crystal formation characteristic) and the desired crystal formation. The planner may be implemented using any suitable processing unit and / or system for generating the prediction.

[0065] Operation 306 may include the stimulus source applying a stimulus to the sample based on its configuration. The applied stimulus may induce crystal formation at the sample. For example, the stimulus source may apply a desired heat distribution to the stimulus, thus inducing crystal formation at the sample.

[0066] Operation 308 may include a sensor measuring crystal formation at the sample. The crystal formation may be measured using any of the methods described herein. For example, the sensor may detect reflectivity changes at the sample (e.g., at the operation 204).

[0067] In some embodiments, the method 300 may repeat until the desired crystal formation is achieved. For example, after the operation 308, the sensor may send its measurements to the estimator. The estimator may determine updated crystal formation characteristics based on the measurements. The estimator may determine that the desired crystal formation has not been achieved based on the updated crystal formation characteristics. The planner may reconfigure the stimulus source based on the determination. The stimulus source may reapply the stimulus to the sample. The sensor may then remeasure the crystal formation.

[0068] In this manner, the method 300 may form a closed-loop feedback control process that continuously monitors and controls crystal formation during manufacturing. The feedback control process may allow dynamic adjustment to applied stimuli in real time to produce a desired crystal formation.

[0069] FIG. 4 illustrates a system 400 for real-time monitoring and control of crystal formation. The system 400 may be configured to monitor and / or control crystal formation at a sample 402. As shown, the system 400 may control crystal formation using a control system 404 and monitor crystal formation using a monitoring system 406. The control system 404 and monitoring system 406 may use any of the methods described herein for monitoring and / orORS-020PCcontrolling crystal formation, such as the methods 200 and 300. Additional details regarding the control system 404 and the monitoring system 406 are provided below.

[0070] As shown, the system 400 may include a processing unit 408. The processing unit 408 may be configured to perform various processing operations related to real-time monitoring and control of crystal formation. For example, the processing unit 408 may determine crystal formation characteristics based on sensor measurements from the monitoring system 406 (e.g., at the operation 302). The processing unit 408 may determine a configuration plan 410 for at least one stimulus source at the control system 404. The configuration plan 410 may include various configuration parameters for applying a stimulus in a desired manner using the stimulus source. The processing unit 408 may configure the stimulus source using the configuration plan 410 (e.g., at the operation 304). The processing unit 408 may direct the configured stimulus source to apply the stimulus (e.g., at the operation 306).

[0071] FIG. 5 illustrates one embodiment of the control system 404 depicted in FIG. 4. The control system 404 may be configured to control crystal formation at the sample 402 (not shown) in real-time during a manufacturing process. The manufacturing process may include any suitable process for the sample 402, such as a heat-treatment process for inducing crystal formation at the sample 402.

[0072] In some embodiments, the control system 404 may include various components for processing the sample 402. As shown, for example, the control system 404 may include a supply roll 502, a tension control device 504, a pre-heater 506, a stimulus source 508, sensors 510 (e.g., sensors 510-1 and 510-2), a quench surface 512, and a take-up roll 514. The control system 404 may receive the sample 402 and induce crystal formation at the sample 402 to produce an NCA. During that process, the control system 404 may dynamically control the crystal formation based on sensor measurements.

[0073] In some embodiments, the control system 404 may include a processing line for processing the sample 402. For example, the supply roll 502 may feed the sample 402 through the processing line in sheet form. The workpiece may be drawn from the supply roll 502 and pass through the tension control device 504. The tension control device 504 may be configured to keep the sample 402 flat and stable as the sample 402 travels through the processing line. The tension control device 504 may include at least one roller, dancer arm, and / or any other active tensioning mechanism. The sample 402 may pass through the pre-heater 506, which may warm the sample 402 to a temperature that does not induce crystal formation. The pre-heater 506 may include any suitable heating device, such as radiant heaters, induction heaters, and / or contact heaters.ORS-020PC

[0074] The stimulus source 508 may be configured to apply at least one stimulus to the sample 402. The stimulus may include any suitable stimulus type, such as heat, pressure, strain, vibrations, electromagnetic fields, and / or controlled atmospheres. The stimulus source 508 may include any suitable stimulus device, such as heat arrays, induction coils, laser projectors, laser diode arrays, coolers, magnetic field coils, rollers, actuators, vibrators, and / or controlled-atmosphere chambers. For example, the stimulus source 508 may be a heat array configured to apply heat distributions to the sample 402. The stimulus may cause crystal formation (e.g., nanocrystalline formation) at the sample 402.

[0075] In some embodiments, the stimulus source 508 may be configured to apply the stimulus according to predetermined configurations. The configurations may be defined by various configuration parameters, such as a spatial pattern, temporal pattern, power level, and / or duty cycle. For example, the stimulus source may be configured in a time-dependent way and / or a spatially-dependent way to apply a controlled stimulus, such as a controlled heat distribution. The configurations may be set by a processing unit, such as the processing unit 408. The processing unit may set the configurations according to real-time data related to the sample 402, such as transient reflectivity changes.

[0076] The sensors 510 may be configured to measure crystal formation at the sample 402 in real-time. The sensors 510 may use any of the methods described herein to measure the crystal formation, such as the method 200. For example, the sensors 510 may detect transient reflectivity changes at the sample 402 in response to laser pulses applied to the sample 402.

[0077] The sensors 510 may be located at any suitable stage of the processing line. For example, as shown, the sensor 510-1 may be located upstream from the stimulus source 508, and the sensor 510-2 may be located downstream from the stimulus source 508. The sensor 510-1 may measure the state of crystal formation at the sample 402 before the stimulus is applied to the sample 402. The sensor 510-2 may measure the state of crystal formation at the sample 402 after the stimulus is applied to the sample 402.

[0078] In some embodiments, the sensor data may be provided to a processing unit, such as the processing unit 408. For example, the processing unit may determine crystal formation characteristics based on the sensor data from the sensor 510-1. The processing unit may configure any of the components of the control system 404 based on the crystal formation characteristics. For example, the processing unit may configure the stimulus source 508 before applying the stimulus to the sample 402. The stimulus source 508 may then apply the stimulus to the source according to its configuration. The sensor 510-2 may provide sensor data to the processing unit after the stimulus is applied to the sample 402. The processing unit may configure the stimulusORS-020PCsource 508 after applying the stimulus has been applied. The stimulus source 508 may then apply additional stimulus to the source according to its configuration.

[0079] The quench surface 512 may be configured to cool the sample 402 after the stimulus is applied. The cooling may halt further crystal formation at the sample 402. The quench surface 512 may include any suitable cooling device, such as cooled surfaces, gas jets, and / or liquid sprays.

[0080] The take-up roll 514 may be configured to collect the sample 402 after the sample 402 is cooled. It is to be appreciated, however, that any suitable collection mechanism may be used to collect the sample 402, such as a container, bin, cutting or shearing station, and / or conveyor belt.

[0081] FIG. 6 illustrates one embodiment of the monitoring system 406 depicted in FIG. 4. The monitoring system 406 may be configured to monitor crystal formation at the sample 402 and output measurements of crystal formation. The measurements may be used to control crystal formation during manufacturing processes, such as processes occurring at the control system 404. The monitoring system 406 may monitor crystal formation using laser pulses directed at the sample 402.

[0082] The monitoring system 406 may include various components for monitoring crystal formation. For example, the monitoring system 406 may include a laser oscillator 602, a harmonic generation crystal 604, an on-off chopper 606, a variable delay line 608, an objective lens 610, a spatial filter 612, and a detector 614.

[0083] The laser oscillator 602 may be configured to generate short laser pulses at various durations, center wavelengths, and / or repetition rates. For example, the laser oscillator may generate laser pulses on the order of hundreds of femtoseconds to a few picoseconds (e.g., 200 femtoseconds) for the duration, hundreds of nanometers to thousands of nanometers (e.g., 1030 nanometers) for the wavelength, and / or a few megahertz to hundreds of megahertz (e.g., 40 megahertz) for the repetition rate.

[0084] In some embodiments, the laser oscillator 602 may be directed to a nonlinear optical element, such as the harmonic generation crystal 604. The crystal 604 may be a second-harmonic generation crystal. The crystal 604 may emit a low power pump pulse (e.g., at 1030 nanometers) and a lower power probe pulse (e.g., at 515 nanometers). The probe and pump pulses may be emitted simultaneously. The pump pulse may traverse along a pump path 616 (represented by the thicker gray path), and the probe pulse may traverse along a probe path 618 (represented by the narrower gray path). The paths 616 and 618 may be separated using a beam splitter and / or any other separation optics. The path lengths may be arranged to be nominally matched, for example within tens of microns.ORS-020PC

[0085] In some embodiments, the pump path 616 may be modulated by the chopper 606 and / or the variable delay line 608. The chopper 606 may modulate the pump pulse in intensity, such as in a periodic (e.g., on-off) manner. The variable delay line 608 may adjust the relative delay between the pump pulse and the probe pulse.

[0086] In some embodiments, the pump pulse may be focused onto the sample 402 using the objective lens 610 and / or any other focusing optics. The reflected light may be discarded. The probe pulse may be focused onto the sample 402 after a delay, such as onto the same location illuminated by the pump pulse. Light reflected from the sample 402 in response to the probe pulse may carry a small modulation component at the pump chopper frequency, which may be attributed to transient reflectivity changes at the sample 402.

[0087] In some embodiments, the reflected probe light may pass through the spatial filter 612 before being collected by the detector 614. The spatial filter 612 may preferentially pass light originating from the in-focus region of the sample 402 and reject out-of-focus light. The detector 614 may receive the reflected light and measure the intensity of the received light. By removing light that is out of focus, changes in both pure reflectance and pump-heating-induced curvature of the reflecting surface may be measured. The detector 614 may include at least one photodetector (e.g., a photodiode) for receiving the reflected light. The detector 614 may be a component of any of the sensors described herein, such as the sensors 510.

[0088] In some embodiments, the measurements from the detector 614 may be used to measure and / or control crystal formation at the sample 402. For example, the detector 614 may send its measurements to the processing unit 408, which may determine crystal formation characteristics based on the measurements.

[0089] While the monitoring system 406 is shown with a single laser oscillator 602, it is to be appreciated that any number of laser components may be used. For example, the monitoring system 406 may use a frequency-beat method, where two separate lasers at different repetition rates provide the pump and probe pulses. The difference in repetition rates may set the relative delay between the pump and probe pulses without requiring movement of optical components. In this manner, the relative timing between pump and probe pulses may be varied while the pulse paths remain stationary.

[0090] In some embodiments, the monitoring system 406 may measure across multiple delay values simultaneously rather than sequentially. For example, the probe pulses may be temporally stretched and spectrally chirped such that different frequency components of a single probe pulse correspond to different delay values relative to the pump pulse. The reflectivity of the sample 402ORS-020PCchanging over time may change the color of the reflected light, thereby enabling simultaneous coverage of a range of delay values.

[0091] The methods, systems, and devices discussed above are examples. Various configurations may omit, substitute, or add various procedures or components as appropriate. For instance, in alternative configurations, the methods may be performed in an order different from that described, and that various steps may be added, omitted, or combined. Also, features described with respect to certain configurations may be combined in various other configurations. Different aspects and elements of the configurations may be combined in a similar manner. Also, technology evolves and, thus, many of the elements are examples and do not limit the scope of the disclosure or claims.

[0092] Embodiments of the present disclosure, for example, are described above with reference to block diagrams and / or operational illustrations of methods, systems, and computer program products according to embodiments of the present disclosure. The functions / acts noted in the blocks may occur out of the order as shown in any flowchart. For example, two blocks shown in succession may in fact be executed substantially concurrent or the blocks may sometimes be executed in the reverse order, depending upon the functionality / acts involved. Additionally, or alternatively, not all of the blocks shown in any flowchart need to be performed and / or executed. For example, if a given flowchart has five blocks containing functions / acts, it may be the case that only three of the five blocks are performed and / or executed. In this example, any of the three of the five blocks may be performed and / or executed.

[0093] A statement that a value exceeds (or is more than) a first threshold value is equivalent to a statement that the value meets or exceeds a second threshold value that is slightly greater than the first threshold value, e.g., the second threshold value being one value higher than the first threshold value in the resolution of a relevant system. A statement that a value is less than (or is within) a first threshold value is equivalent to a statement that the value is less than or equal to a second threshold value that is slightly lower than the first threshold value, e.g., the second threshold value being one value lower than the first threshold value in the resolution of the relevant system.

[0094] Specific details are given in the description to provide a thorough understanding of example configurations (including implementations). However, configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the configurations. This description provides example configurations only, and does not limit the scope, applicability, or configurations of the claims. Rather, the preceding description of theORS-020PCconfigurations will provide those skilled in the art with an enabling description for implementing described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the disclosure.

[0095] Having described several example configurations, various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosure. For example, the above elements may be components of a larger system, wherein other rules may take precedence over or otherwise modify the application of various implementations or techniques of the present disclosure. The systems and methods involving hardware and software and / or functional parts therefore may be physically integrated into or housed inside or attached to another device, be it an imaging device, a stimulus or electrophysiological recording device, and patient audio device, etc. Also, a number of steps may be undertaken before, during, or after the above elements are considered.

[0096] Having been provided with the description and illustration of the present application, one skilled in the art may envision variations, modifications, and alternate embodiments falling within the general inventive concept discussed in this application that do not depart from the scope of the following claims.

Claims

ORS-020PCCLAIMSWhat is claimed is:

1. A method for monitoring crystal formation at a ferromagnetic sample, the method comprising:applying a laser pump pulse and a delayed laser probe pulse to the sample; detecting, in response to the applied laser pulses, reflectivity changes at the sample; determining, based on the reflectivity changes, at least one transient characteristic; and determining, based on the at least one transient characteristic, at least one crystal formation characteristic related to the sample.

2. The method of claim 1, wherein the at least one crystal formation characteristic is determined in real-time during a manufacturing process.

3. The method of claim 1, wherein the at least one transient characteristic comprises at least one of an electronic characteristic or an acoustic characteristic.

4. The method of claim 1, wherein the at least one crystal formation characteristic comprises at least one of a crystal size, crystal distribution, degree of crystallinity, or crystal volume fraction.

5. The method of claim 1, wherein the reflectivity changes are detected over a range of delay values for the laser probe pulse.

6. The method of claim 1, further comprising preheating the sample before the laser pulses are applied.

7. The method of claim 1, further comprising:configuring, based on the at least one crystal formation characteristic, a stimulus source; applying a stimulus to the sample using the configured stimulus source; determining at least one additional crystal formation characteristic related to the sample; andreconfiguring, based on the at least one additional crystal formation characteristic, the stimulus source.ORS-020PC8. The method of claim 7, wherein configuring the stimulus source comprises determining an optimal stimulus distribution for inducing a desired crystal formation.

9. A system for monitoring crystal formation at a ferromagnetic sample, comprising:a laser oscillator configured to apply a laser pump pulse and a delayed laser probe pulse to the sample;a sensor configured to detect, in response to the applied laser pulses, reflectivity changes at the sample; anda processor configured to determine, based on the reflectivity changes, at least one crystal formation characteristic related to the sample.

10. The system of claim 9, further comprising:a beam splitter configured to separate the paths of the laser pump pulse and the laser probe pulse; anda chopper configured to modulate the path of the laser pump pulse.

11. The system of claim 9, further comprising a variable delay line configured to control the delay of the laser probe pulse.

12. The system of claim 11, wherein the delay is between 0 to 400 picoseconds.

13. The system of claim 9, wherein the processor is further configured to determine, based on the reflectivity changes, at least one transient characteristic.

14. The system of claim 9, wherein the at least one crystal formation characteristic comprises at least one of a crystal size, crystal distribution, degree of crystallinity, or crystal volume fraction.

15. A system for controlling nanocrystalline formation, the system comprising:at least one sensor configured to detect reflectivity changes at a ferromagnetic alloy sample in response to laser pulses applied to the sample;a stimulus source configured to apply a stimulus to the sample for inducing a desired crystal formation at the sample; anda processor configured to configure the stimulus source based on the reflectivity changes.ORS-020PC16. The system of claim 15, wherein the stimulus comprises at least one of heat, pressure, or an electromagnetic environment.

17. The system of claim 15, wherein the stimulus source comprises a heat array configured to be modulated in at least one of a time-dependent way or a spatially-dependent way via the processor.

18. The system of claim 15, wherein the stimulus source comprises at least one of a spatially-modulated laser projector or a spatially-modulated laser diode.

19. The system of claim 15, wherein the at least one sensor comprises a first sensor and a second sensor, wherein the first and second sensors are configured to detect the reflectivity changes at different manufacturing stages.

20. The system of claim 15, wherein the processor is further configured to:determine at least one additional crystal formation characteristic related to the sample after the stimulus is applied; andreconfigure, based on the at least one additional crystal formation characteristic, the stimulus source.

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