WO2024147138A1 - System and method of contactless sensing of material properties in a sample - Google Patents

Abstract

A method and system for contactless sensing of material properties in a sample may include: configuring a light source component to direct a first ray of light to interact with the sample in a predetermined location; adapting a magnetic field generator to apply a modulated magnetic field to the sample; configuring a detector module to receive a second ray of light from the predetermined location, and produce at least one electric signal, indicative of a change in polarization between the first ray and the second ray; receiving a reference signal, corresponding to a frequency of the modulation of the magnetic field; demodulating the at least one electric signal based on the reference signal, to produce at least one respective demodulated signal; and analyzing the at least one demodulated signal, by at least one processor, to calculate a value of a material property of the sample at the predetermined location.

Description

SYSTEM AND METHOD OF CONTACTLESS SENSING OF MATERIAL

PROPERTIES IN A SAMPLE

CROSS-REFERENCE TO RELATED APPLICATIONS

[001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63/478,615, filed on January 05, 2023 and entitled CORRELATION BETWEEN DC HALL AND ALL-OPTICAL MEASUREMENTS / THE NORMAL METAL MAGNETO OPTICAL KERR EFFECT, the contents of which are all incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

[002] The present invention relates generally to the field materials engineering. More specifically, the present invention relates to contactless sensing of material properties in a sample.

BACKGROUND OF THE INVENTION

[003] Reference is made to Figs. 1 A- ID, which are schematic diagrams, depicting variants of the Hall effect phenomenon, as discussed herein.

[004] As shown in Fig. 1A, the Hall effect is a physical phenomenon that occurs when a current (T) of charge carriers (e.g., electrons), generated by an electric field, is deflected perpendicularly to an applied magnetic field (H), resulting in a measurable Hall voltage (VH).

[005] As known in the art, Hall transport measurements provide information of the carrier density in non-magnetic normal metals (NMs). In this measurement electrons are accelerated by applying an electrical field from the contacts which by the Lorentz force are deflected orthogonally resulting in a build-up of an electrical potential difference in the orthogonal dimension.

[006] As shown in Fig. IB, the anomalous Hall effect (AHE) is a related phenomenon that takes place in ferromagnetic materials. It occurs when a current (T) of charge carriers (e.g., electrons), generated by an electric field, is deflected perpendicularly due to the perpendicular magnetization (M). The AHE is characterized by a relatively large electric field signal (measurable as Hall voltage VH), which saturates with the applied magnetic field (H). [007] The AHE effect was puzzling and controversial for many years and eventually contributed to the development of modem Berry-phase concepts that linked the AHE and the topological nature of the Hall currents.

[008] Another method that is commonly used to study FMs is the Magneto-Optical Kerr Effect (MOKE). A MOKE configuration is shown in Fig. ID. In this configuration, a linearly polarized light is projected on a sample of ferromagnetic material, and the polarization state of the reflected light is analyzed from which a magnetization state of the material may be induced.

[009] The MOKE measurement can be regarded as the optical analog of the AHE measurement: an electrical laser light field is applied along one axis and the response of the FM material along a perpendicular axis is measured. As in the AHE, the MOKE response saturates with an externally applied magnetic field and the anomalously large response facilitates probing of FM material as thin as a single atomic layer.

[0010] As depicted in Fig. 1C, the optical analog of the Hall effect in normal metals (NM) is the Optical Hall Effect (OHE), which is also referred to as the “normal-metal Kerr effect”. In this configuration, the DC electrical field of the electrical Hall effect is replaced by an oscillatory AC electrical field which is a composite of an incident, polarized light beam. Due to the Lorentz force, a cyclotron motion of charge carriers is induced, giving rise to an orthogonal polarization component of a reflected light beam.

SUMMARY OF THE INVENTION

[0011] Measurement of the OHE effect holds promise for pin-point accuracy of contactless measurement of material properties, that is not limited to magnetic materials. This may give rise to a variety of applications in material engineering. However, due to the very weak manifestation of this effect in non-ferromagnetic materials, this opportunity has not been explored yet.

[0012] In this work, the inventors have achieved the required optical sensitivity for analyzing OHE using magnetic field amplitude modulation. The results of this configuration were demonstrated on thin films of various materials such as Platinum (Pt), Tantalum (Ta) and Bismuth (Bi). [0013] The measurements were carried out using visible light frequencies having a period shorter than the materials’ extrinsic Drude mean free path. Therefore, the measured optical response reflects properties of the intrinsic electronic band structure of the material system. [0014] As elaborated herein, embodiments of the invention may facilitate contact-free Hall characterization that is crucial for rapid material prototyping and band structure engineering as well as to novel microscopy methods in which electron density of a sample may be imaged, rather than imaging the morphology of the sample.

[0015] Previous works included measurement of the Hall effect under alternating current (AC) electrical fields, ranging from the Gigahertz (GHz), up to far-infrared frequencies, and were primarily applied to semiconductors. Few observations have been made in normal metals such as Silver (Ag), Gold (Au) and Copper (Cu) in visible light. At the optical frequencies, an electron’s effective displacement is often shorter than the Drude mean free path. Therefore, the effect of scattering may be weak, and OHE measurements may well indicate intrinsic properties of the material’s band structure and Fermi surface. This emphasizes the potential in using OHE measurements in visible light for material sciences. [0016] While the MOKE has been utilized for such purposes, OHE was less so: Just as the signal produced by the Hall effect is much weaker than that of the AHE effect, so is the signal produced by OHE much weaker, and harder to detect than that of MOKE.

[0017] Embodiments of the invention may include a system for contactless sensing of material properties in a sample. The system may include, for example, a light source component, configured to direct a first ray of light to interact with the sample in a predetermined location; a magnetic field generator, adapted to apply a modulated magnetic field to the sample; and a detector module.

[0018] The detector module may be configured to: (i) receive a second ray of light from the predetermined location, and (ii) detect a change in polarization between the first ray and the second ray, thereby sensing material properties in the predetermined location.

[0019] As elaborated herein, embodiments of the invention may include, or may be associated with a computing device, that includes at least one processor. For example, the at least one processor may be communicatively connected via wired, or wireless connection to at least one processor. The at least one processor may be configured to analyze the detected change in polarization, to determine a value of a material property of the sample in the predetermined location. [0020] According to some embodiments, the light source component may include, for example, a first illuminant, configured to generate the first light ray, and a first polarization element, adapted to apply a first polarization to the first light ray.

[0021] Additionally, or alternatively, the detector module may include a second polarization element, adapted to apply a second polarization to the second light ray, thereby producing a third light ray; and at least one first photodetector, adapted to produce at least one respective electric signal representing measured intensity of the third light ray. As elaborated herein, the measured intensity may be indicative of the change in polarization between the first ray and the second ray.

[0022] According to some embodiments, the first polarization may be a linear polarization along a first axis, and the second polarization may be a linear polarization along a second, substantially perpendicular axis.

[0023] Additionally, or alternatively, the detector module may include a demodulation module. The demodulation module may be configured to receive a reference signal, corresponding to a frequency of the modulation of the magnetic field. Based on the reference signal, the demodulation module may demodulate the at least one electric signal of the at least one first photodetector, to produce the at least one respective demodulated signal.

[0024] For example, the demodulation module may be, or may include phase-sensitive detector device, a homodyne detector device, a lock-in amplifier device and a heterodyne detector device. As elaborated herein, by demodulating the photodetector’s electric signal according to the magnetic field’s modulation frequency, embodiments of the invention may extract, or enhance a voltage signal representative of phase shift in the sample of interest. By subsequent analysis of this voltage signal (e.g., via equations such as Eq. 1 elaborated herein), the at least one processor may produce information indicative of at least one material property of the sample.

[0025] The material property may be, for example, include an effective mass of a charge carrier (e.g., electron) in the predetermined location of the sample, a carrier density at the predetermined location, a type of material at the predetermined location, a type or level of doping at the predetermined location, a thickness of the sample at the predetermined location, an optical Hall coefficient value characterizing the material at the predetermined location, a conductivity or resistivity of material at the predetermined location, a texture of magnetization of the material at the predetermined location, and the like. [0026] According to some embodiments, the magnetic field generator may include a movable platform; one or more permanent magnets, mounted on the movable platform; and at least one motor or actuator configured to apply a first movement to the platform. This first movement (also referred to herein as a modulation movement) may be configured to change a distance between the one or more permanent magnets and the predetermined location, thereby modulating the magnetic field at a frequency that corresponds to the modulation movement.

[0027] For example, the movable platform may include a rotatable platform (e.g., a disk). In such embodiments, the at least one motor may be configured to rotate the rotatable platform about a rotational axis that may be perpendicular to the rotatable platform, thereby modulating the magnetic field at a frequency that corresponds to the rotatable platform’s rotation rate.

[0028] According to some embodiments, the at least one motor or actuator may be configured to move the platform in relation to the predetermined location. Embodiments of the invention may further include a magnetic field sensor, configured to: (i) measure the magnetic field substantially at the predetermined location, and (ii) produce the reference signal based on this measurement, to indicate a rate, or frequency of movement of the movable platform.

[0029] Additionally, or alternatively, embodiments of the invention may include a second illuminant, adapted to direct a second light beam to the rotatable platform; and a second photodetector. The second photodetector may be adapted to receive (a) reflection of the second light beam from one or more reflecting elements on the rotatable platform, or (b) transmission of the second light through one or more apertures in the rotatable platform. The second photodetector may subsequently produce the reference signal based on the received reflection or transmission, to indicate a rate of rotation of the rotatable platform.

[0030] As elaborated herein, embodiments of the invention may include a non-transitory memory device, wherein modules of instruction code are stored, and at least one processor associated with the memory device, and configured to execute the modules of instruction code. Upon execution of said modules of instruction code, the at least one processor may be configured to obtain one or more readings of the at least one demodulated signal, e.g., readings of the voltage signal (also denoted herein as VPD) produced by the photodetector module. The at least one processor may subsequently analyze these readings, to calculate a value of the at least one material property of the sample at the predetermined location.

[0031] Additionally, or alternatively, the at least one motor or actuator may be further configured to apply a second, translation movement (also referred to herein as an “amplitude movement”) to the movable platform, so as to change a distance between the one or more permanent magnets and the predetermined location. The at least one motor or actuator may thereby change an amplitude of the modulated magnetic field at the predetermined location. [0032] The at least one processor may obtain a plurality of readings of the at least one demodulated signal, corresponding to a plurality of translation positions of the platform, and obtain, (e.g., from the magnetic field sensor), a corresponding plurality of measurements of maximal magnetic field values at the plurality of translation positions. As elaborated herein (e.g., in relation to Figs. 6A and 6B), the at least one processor may calculate a mathematical relation between the readings of the at least one demodulated signal and the corresponding maximal magnetic field values. For example, this relation may be a relation (e.g., a slope) between a square-root of the photodetector’s voltage output (VPD) and the amplitude, or maximal value of a component of the modulated magnetic field. As elaborate herein (e.g., in relation to Eq. 1), based on this relation, the at least one processor may calculate a material property value such as electron effective mass (denoted m*) or charge carrier density (denoted m).

[0033] Embodiments of the system may further include a first lens, positioned along a trace of the first ray, to focus the first ray onto the predetermined location; and a second lens, positioned along a trace of the second ray, to focus the second ray onto the at least one photodetector.

[0034] Additionally, or alternatively, embodiments of the system may include at least one pinhole, positioned along a trace of at least one of the first ray and second ray. The first lens, second lens and at least one pinhole may be arranged in a confocal microscope configuration. [0035] Additionally, or alternatively, the first ray and the second ray may be substantially collinear. Embodiments of the system may include a beam splitter, positioned along a trace of the second ray, thereby splitting the second ray to a first portion and a second portion. The second portion of the second ray may be directed toward the detector module. In such configuration, embodiments of the invention may function as a reflectance microscope, allowing the first lens and second lens to be the same lens. [0036] Embodiments of the system may include at least one scan motor, adapted to move the sample, e.g., in a scanning motion. The at least one processor may be configured to: control the at least one scan motor, to move the sample through a plurality of positions. The at least one processor may consequently receive a plurality of readings of demodulated signals, respectively originating from the plurality of positions, and calculate a plurality material property values, respectively based on the plurality of readings. Additionally, or alternatively, the at least one processor may produce a matrix, or an image of the material property values, corresponding to the plurality of positions. The at least one processor may subsequently present the image of the material property values, e.g., via a monitor of an associated computing device.

[0037] Additionally, or alternatively, the at least one first photodetector may include a plurality of photodetectors, arranged in an array, such as a CCD array. In such embodiments, the at least one processor may be configured to receive a plurality of readings of demodulated signals, respectively originating from the plurality of photodetectors of the array; calculate a plurality material property values, each corresponding to a specific photodetector of the array, and/or respectively based on the plurality of readings. Additionally, or alternatively, the at least one processor may produce a matrix, or an image of the material property values, corresponding to the array of photodetectors.

[0038] Embodiments of the invention may include method of contactless sensing of material properties in a sample.

[0039] Embodiments of the method may include: configuring a light source component to direct a first ray of light to interact with the sample in a predetermined location; adapting a magnetic field generator to apply a modulated magnetic field to the sample; configuring a detector module to receive a second ray of light from the predetermined location, and produce at least one electric signal, indicative of a change in polarization between the first ray and the second ray; receiving a reference signal, corresponding to a frequency of the modulation of the magnetic field; demodulating the at least one electric signal based on the reference signal, to produce at least one respective demodulated signal; and analyzing the at least one demodulated signal, by at least one processor, to calculate a value of a material property of the sample at the predetermined location. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

[0041] Figs. 1A-1D are schematic diagrams, depicting variants of the Hall effect phenomenon, as discussed herein;

[0042] Fig. 2 is a block diagram, depicting a computing device which may be included in a system for contactless sensing of material properties in a sample, according to some embodiments;

[0043] Fig. 3 is a block diagram, depicting a general view of a system for contactless sensing of material properties in a sample, according to some embodiments of the invention;

[0044] Fig. 4 is a schematic diagram depicting an example of a microscope configuration based on the system for contactless sensing of material properties in a sample, according to some embodiments of the invention;

[0045] Fig. 5 is a graph showing examples of modulated magnetic fields, according to some embodiments of the invention;

[0046] Figs. 6A and 6B are graphs showing examples of experimental measurements, where relation between an amplitude of an applied modulated magnetic field (e.g., a maximal magnetic field intensity value) and corresponding measurements of voltage, generated by a photodetector of the present invention are presented;

[0047] Fig. 7 is a schematic diagram depicting an example of a scanning, confocal microscope configuration based on the system for contactless sensing of material properties in a sample, according to some embodiments of the invention;

[0048] Fig. 8 is a schematic diagram depicting an example of an array-based, confocal microscope configuration, based on the system for contactless sensing of material properties in a sample, according to some embodiments of the invention;

[0049] Figs. 9A-9D are graphs showing examples of experimental measurements, where modulation of a light source (L) is compared with modulation of a magnetic field (B), according to some embodiments of the invention; [0050] Fig. 10 is a flow diagram, depicting a method of contactless sensing of material properties in a sample, according to some embodiments of the invention;

[0051] Figs. 11A and 11B are graphs depicting experimental measurements of a photodetector signal as a function of a component of the magnetic field (B_z), where the magnetic field in turn is affected by distance from a source of a modulated magnetic field, according to some embodiments of the invention.

[0052] Fig. 11A shows a demodulated voltage signal 410DS (VPD) as a function of a component (B_z) of the magnetic field 30MF for Pt, Bi and Ta, using the OHE configuration (e.g., Fig. 1C), using a blue 440 nanometer laser according to some embodiments of the invention.

[0053] Fig. 11B shows a square root of demodulated voltage signal 410DS (VPD) as a function of the magnetic field component B_z as measured by embodiments of the invention for Pt, Bi and Ta, using the OHE configuration (e.g., Fig. 1C).

[0054] Fig. 11C is a graph showing measurement of a Hall resistance (e.g., Hall voltage / Applied current) under a static magnetic field, using electrical contacts in the standard Hall configuration (e.g., Fig. 1A), as known in the art.

[0055] Fig. 12A is a graph depicting a normalized measurements of a square root of demodulated photodetector voltage signal 410DS (VPD) as a function of a component (B_z) of the magnetic field 30MF for Pt, Bi and Ta, using the OHE configuration (e.g., Fig. 1C), according to some embodiments of the invention. The magnetic field component (B_z) was affected by distance from a source 30 of a modulated magnetic field 30MF. The measurements were normalized so as to cancel an effect of sample thickness d.

[0056] Fig. 12B is a graph depicting measurement of a Hall resistance multiplied by sample thickness d under a static magnetic field, using electrical contacts in the standard Hall configuration (e.g., Fig. 1A), as known in the art. The measurements were multiplied by sample thickness d so as to cancel an effect of sample thickness d.

[0057] It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0058] One skilled in the art will realize the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting of the invention described herein. Scope of the invention is thus indicated by the appended claims, rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

[0059] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention. Some features or elements described with respect to one embodiment may be combined with features or elements described with respect to other embodiments. For the sake of clarity, discussion of same or similar features or elements may not be repeated.

[0060] Although embodiments of the invention are not limited in this regard, discussions utilizing terms such as, for example, “processing,” “computing,” “calculating,” “determining,” “establishing”, “analyzing”, “checking”, or the like, may refer to operation(s) and/or process(es) of a computer, a computing platform, a computing system, or other electronic computing device, that manipulates and/or transforms data represented as physical (e.g., electronic) quantities within the computer’s registers and/or memories into other data similarly represented as physical quantities within the computer’s registers and/or memories or other information non-transitory storage medium that may store instructions to perform operations and/or processes.

[0061] Although embodiments of the invention are not limited in this regard, the terms “plurality” and “a plurality” as used herein may include, for example, “multiple” or “two or more”. The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. The term “set” when used herein may include one or more items.

[0062] Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Additionally, some of the described method embodiments or elements thereof can occur or be performed simultaneously, at the same point in time, or concurrently.

[0063] Reference is now made to Fig. 2, which is a block diagram depicting a computing device, which may be included within an embodiment of a system for contactless sensing of material properties in a sample, according to some embodiments.

[0064] Computing device 1 may include a processor or controller 2 that may be, for example, a central processing unit (CPU) processor, a chip or any suitable computing or computational device, an operating system 3, a memory 4, executable code 5, a storage system 6, input devices 7 and output devices 8. Processor 2 (or one or more controllers or processors, possibly across multiple units or devices) may be configured to carry out methods described herein, and/or to execute or act as the various modules, units, etc. More than one computing device 1 may be included in, and one or more computing devices 1 may act as the components of, a system according to embodiments of the invention.

[0065] Operating system 3 may be or may include any code segment (e.g., one similar to executable code 5 described herein) designed and/or configured to perform tasks involving coordination, scheduling, arbitration, supervising, controlling or otherwise managing operation of computing device 1, for example, scheduling execution of software programs or tasks or enabling software programs or other modules or units to communicate. Operating system 3 may be a commercial operating system. It will be noted that an operating system 3 may be an optional component, e.g., in some embodiments, a system may include a computing device that does not require or include an operating system 3.

[0066] Memory 4 may be or may include, for example, a Random- Access Memory (RAM), a read only memory (ROM), a Dynamic RAM (DRAM), a Synchronous DRAM (SDRAM), a double data rate (DDR) memory chip, a Flash memory, a volatile memory, a nonvolatile memory, a cache memory, a buffer, a short term memory unit, a long term memory unit, or other suitable memory units or storage units. Memory 4 may be or may include a plurality of possibly different memory units. Memory 4 may be a computer or processor non-transitory readable medium, or a computer non-transitory storage medium, e.g., a RAM. In one embodiment, a non-transitory storage medium such as memory 4, a hard disk drive, another storage device, etc. may store instructions or code which when executed by a processor may cause the processor to carry out methods as described herein. [0067] Executable code 5 may be any executable code, e.g., an application, a program, a process, task, or script. Executable code 5 may be executed by processor or controller 2 possibly under control of operating system 3. For example, executable code 5 may be an application that may calculate values of material properties in a sample as further described herein. Although, for the sake of clarity, a single item of executable code 5 is shown in Fig. 2, a system according to some embodiments of the invention may include a plurality of executable code segments similar to executable code 5 that may be loaded into memory 4 and cause processor 2 to carry out methods described herein.

[0068] Storage system 6 may be or may include, for example, a flash memory as known in the art, a memory that is internal to, or embedded in, a micro controller or chip as known in the art, a hard disk drive, a CD-Recordable (CD-R) drive, a Blu-ray disk (BD), a universal serial bus (USB) device or other suitable removable and/or fixed storage unit. Data pertaining to physical measurements may be stored in storage system 6 and may be loaded from storage system 6 into memory 4 where it may be processed by processor or controller 2. In some embodiments, some of the components shown in Fig. 2 may be omitted. For example, memory 4 may be a non-volatile memory having the storage capacity of storage system 6. Accordingly, although shown as a separate component, storage system 6 may be embedded or included in memory 4.

[0069] Input devices 7 may be or may include any suitable input devices, components, or systems, e.g., a detachable keyboard or keypad, a mouse and the like. Output devices 8 may include one or more (possibly detachable) displays or monitors, speakers and/or any other suitable output devices. Any applicable input/output (RO) devices may be connected to Computing device 1 as shown by blocks 7 and 8. For example, a wired or wireless network interface card (NIC), a universal serial bus (USB) device or external hard drive may be included in input devices 7 and/or output devices 8. It will be recognized that any suitable number of input devices 7 and output device 8 may be operatively connected to Computing device 1 as shown by blocks 7 and 8.

[0070] A system according to some embodiments of the invention may include components such as, but not limited to, a plurality of central processing units (CPU) or any other suitable multi-purpose or specific processors or controllers (e.g., similar to element 2), a plurality of input units, a plurality of output units, a plurality of memory units, and a plurality of storage units. [0071] The term neural network (NN) or artificial neural network (ANN), e.g., a neural network implementing a machine learning (ML) or artificial intelligence (Al) function, may be used herein to refer to an information processing paradigm that may include nodes, referred to as neurons, organized into layers, with links between the neurons. The links may transfer signals between neurons and may be associated with weights. A NN may be configured or trained for a specific task, e.g., pattern recognition or classification. Training a NN for the specific task may involve adjusting these weights based on examples. Each neuron of an intermediate or last layer may receive an input signal, e.g., a weighted sum of output signals from other neurons, and may process the input signal using a linear or nonlinear function (e.g., an activation function). The results of the input and intermediate layers may be transferred to other neurons and the results of the output layer may be provided as the output of the NN. Typically, the neurons and links within a NN are represented by mathematical constructs, such as activation functions and matrices of data elements and weights. At least one processor (e.g., processor 2 of Fig. 2) such as one or more CPUs or graphics processing units (GPUs), or a dedicated hardware device may perform the relevant calculations.

[0072] Reference is now made to Fig. 3, which depicts a system 100 for contactless measurement and/or calculation of values of properties of an inspected sample, according to some embodiments.

[0073] As explained herein, system 100 may employ an OHE configuration (e.g., as elaborated in Fig. 1C), and may provide a variety of improvements over currently available measurement systems that employ MOKE-based (e.g., Fig. ID) configurations.

[0074] According to some embodiments of the invention, system 100 may be implemented as a combination of software modules and hardware modules. For example, system may include a computing device 50 such as element 1 of Fig. 2. Computing device 50 may be configured to control other modules (e.g., 30, 40, 60 , 70) of system 100 as elaborated herein, to obtain therefore information indicative of material properties 50MP of a sample 20 of interest.

[0075] Computing device 50 may subsequently execute one or more modules of executable code (e.g., element 5 of Fig. 2) to calculate a value of the material properties 50MP at one or more locations of interest, as further described herein. [0076] Additionally, computing device 50 may control the configuration of modules 30, 40, 60 , 70 of system 100, so as to implement a microscope configuration, thereby producing an image 50MPI of a material property of interest across the inspected sample 20, as elaborated herein.

[0077] As shown in Fig. 3, thin arrows may represent flow of one or more data elements to and from system 100 and/or among modules or elements of system 100. Additionally, thick arrows in Fig. 3 may represent physical effects (e.g., movement, illumination, application of a magnetic field, etc.) of one entity in system 100 upon another. Some arrows have been omitted in Fig. 3 for the purpose of clarity.

[0078] Reference is also made to Fig. 4, which is a schematic diagram depicting an example of a microscope configuration based on the system 100 for contactless sensing of material properties in a sample, according to some embodiments of the invention. Modules and elements of Fig. 4 may be the same as their respectively enumerated counterparts of Fig. 3. [0079] As shown in Figs. 3 and 4, system 100 may include a light source component 70 configured to direct a first ray of light 10A to interact with a sample of interest 20 in a predetermined location 210. The term “interact” may indicate for example reflection of ray 10A from sample 20, transmission of ray 10A through sample 20, and any combination thereof.

[0080] Sample 20 may include, for example, one or more Ferromagnetic (FM, e.g., Iron, Cobalt, Nickel, etc.) elements of interest, one or more normal metal (NM, e.g., Copper, Gold, Aluminum, etc.) elements of interest, one or more semiconductor (SC, e.g., Silicon, GaAs, etc.) elements or devices (e.g., transistors, diodes, striplines, etc.) of interest, one or more insulating materials (e.g., plastic, SiO2) of interest, and the like.

[0081] According to some embodiments, light source component 70 may include a first illuminant 720, configured to generate first light ray 10A. illuminant 720 may include, for example a Light Emitting Diode (LED), a Laser diode, an Xray radiation source, a microwave radiation source, and the like. Choice of an appropriate illuminant may depend on the material of sample 20 and/or specific material properties of interest.

[0082] Additionally, or alternatively, illuminant 720 may be configured or controlled, e.g., by at least one processor, to generate light ray 10A in a predetermined wavelength.

[0083] Light source component 70 may further include a polarization element 730, adapted to apply a predetermined polarization to the first light ray. For example, polarization element 730 may include a linear polarization filter, adapted to apply linear polarization of ray 10A along a predetermined polarization axis. In such embodiments, computing device 50 may control polarization element 730 to apply the linear polarization axis at a predetermined angle in relation to the plane of propagation of ray 10A.

[0084] In another example, polarization element 730 may apply circular polarization to ray 10A. In such embodiments, computing device 50 may control polarization element 730 to apply the circular polarization at a predetermined revolution rate and direction.

[0085] As explained herein, computing device 50 may measure, and/or calculate a value of morphological properties (e.g., pertaining to shape), mechanical properties (e.g., pertaining to size and structure) chemical properties (e.g., pertaining to composition, doping, etc.), electrical and/or magnetic properties of sample 20 based on a change in polarization of light ray 10A. This measurement may be referred to as “contactless” in a sense that it may not require physical connection of measurement instruments to sample 20. In other words, embodiments of the invention may facilitate quick, and accurate measurement of samples of interest (e.g., electric circuits during activation) without the overhead and inaccuracies inherent in the connection of samples to measurement and testing equipment.

[0086] As shown in Figs. 3 and 4, system 100 may include a magnetic field generator 30, adapted to apply a modulated magnetic field 30MF to sample 20.

[0087] For example, magnetic field generator 30 may include a movable platform 310 such as a rotatable platform, such as a disk 310, and one or more permanent magnets 330 mounted on the movable platform (e.g., the rotatable disk) 310. Additionally, magnetic field generator 30 may include at least one motor or actuator 320 that may be configured to apply a modulating movement to platform 310. For example motor 320 may rotate platform (e.g., disk) 310 about a rotational axis that is perpendicular to a plane of platform 310. Motor or actuator 320 may thereby change a distance between the one or more permanent magnets 330 and the predetermined location 210 of sample 20, and consequently modulate the magnetic field 30MF at a frequency that corresponds to the applied movement (e.g., rotation of platform 310).

[0088] The movement of motor or actuator 320 may thus be referred to as a “modulating movement”, in a sense that it may affect modulation of magnetic field 30MF as experienced at location 210 of sample 20. [0089] It may be appreciated that additional forms and configurations of modulating movements may also be applicable for modulating magnetic field 30MF. Such modulating movements may include, for example, translational movements (e.g., to-and-from sample 20) and lateral movements (e.g., at a perpendicular direction to that of sample 20).

[0090] As shown in Figs. 3 and 4, system 100 may include a detector module 40, configured to receive a second ray of light 10B from the predetermined location 210 of sample 20. As explained herein, detector 40 may be configured to detect a change in polarization between the first ray 10A and the second ray 10B, thereby sensing material properties in the predetermined location.

[0091] The inventors have selected to use permanent magnets 330, rather than using electromagnets, for a number of benefits. For example, in order to use an electromagnet for generating a large magnetic field, high electrical currents may be required. Switching an electrical current of a few tens of amperes on and off, at a useful rate (e.g., in excess of 500 Hz) is difficult due to large inductance of the electromagnet.

[0092] According to some embodiments, detector module 40 may include a second polarization element 430, adapted to apply a second polarization to the second light ray 10B, thereby producing a third light ray 10C. Detector module 40 may further include at least one first photodetector 420, adapted to produce at least one respective electric signal 420ES representing measured intensity of the third light ray 10C. Polarization element 430 may be configured such that the intensity of light ray 10C (and hence, electric signal 420ES) may be indicative of a change in polarization between the first ray 10A and the second ray 10B. [0093] For example, computing device 50 may control polarization element 730 to apply a first, linear polarization of ray 10A, along a first polarization axis. Computing device 50 may further control polarization element 430 to apply a second linear polarization on ray 10B, along a second polarization axis, thereby producing ray 10C. The first and second polarization axes may be substantially perpendicular axes. It may be appreciated that in such configuration, and in lack of any change to a polarization of the light beam, electric signal 420ES of detector 420 may be substantially nullified. In other words, in such configuration, detector 420 may be tuned to detect a change in polarization between the first ray 10A and the second ray 10B, following the light beam’s interaction with sample 20.

[0094] As known in the art, demodulating detector devices such as phase- sensitive detectors and lock-in amplifier devices may be used to extract the component of a signal that fluctuates at the same frequency as that of a modulated reference signal, thereby effectively isolating the desired signal from noise and interference.

[0095] According to some embodiments, detector module 40 may receive a reference signal, corresponding to a frequency of modulation of the magnetic field 30MF.

[0096] For example, system 100 may include a scanning module 60, adapted to move or locate sample 20. Scanning module 60 may include a magnetic field sensor 610, adapted to produce a measurement of magnetic field in the vicinity of sample 20, substantially at predefined location 210. In such embodiments, a reference signal 610R may be produced by magnetic field sensor 610, positioned at the vicinity of sample 20. In other words, magnetic field sensor 610 may be configured to: (i) measure the magnetic field substantially at the predetermined location 210 and (ii) produce reference signal 610R based on the measurement, to indicate a rate of movement of the movable platform 310.

[0097] In another example, the reference signal may be produced by magnetic field generator 30. For example, magnetic field generator 30 may include a second illuminant 350, such as a laser diode, and a second photodetector 360. Movable platform (e.g., rotating disk) 310 may include one or more elements 370, such as mirrors or holes. Illuminant 350 may be configured to direct a second light beam 350L to the movable platform, e.g., to the location of elements 370 on movable platform (e.g., rotating disk) 310. Photodetector 360 may receive light beam 350L following interaction of beam 350L with elements 370. For example, photodetector 360 may receive reflection of light beam 350L from one or more reflecting elements 370 on the rotating platform 310. Additionally, or alternatively, photodetector 360 may receive transmission of light beam 350L through one or more apertures or holes 370 in platform (e.g., rotating disk) 310. Photodetector 360 may subsequently produce reference signal 360R based on the reception (or lack thereof), to indicate a rate of movement of the movable platform (e.g., rotation of the disk) 310.

[0098] Detector module 40 may include a demodulation module 410, configured to receive reference signal 360R/610R. Based on the reference signal 360R/610R, demodulation module 410 may demodulate at least one electric signal 420ES of the at least one photodetector 420, to produce at least one respective demodulated, electrical signal 410DS. [0099] For example, demodulation module 410 may be, or may include a demodulating detector device, phase-sensitive detector device, a homodyne detector device, a lock-in amplifier device, a heterodyne detector device, and the like, that may extract demodulated signal 410DS from photodetector signal 420ES.

[00100] As shown in Fig. 4, system 100 may include at least one motor or actuator 340 that is configured to apply another, translational movement (also referred to herein as “amplitude movement”) to the movable platform, so as to change a distance between the one or more permanent magnets 330 and the predetermined location 210 of sample 20. Motor 340 may thereby change an amplitude of the modulated magnetic field 30MF at predetermined location 210.

[00101] Reference is also made to Fig. 5, which is a graph showing examples of modulated magnetic fields, according to some embodiments of the invention. As shown in the example of Fig. 5, a modulation movement, such as rotation of permanent magnets 330 on rotating platform 310 may produce a sinusoidal modulation that may be sensed (e.g., by magnetic field sensor 610) at location 210. The frequency of that modulation may be defined by the rate of rotation of platform 310, and the number of embedded or mounted magnets 330.

[00102] The three graphs show an effect of an amplitude movement, e.g., translation of platform 310 in relation to sample 20, on the amplitude, or maximal modulation value. The maximal amplitude in this example was obtained when the distance between platform 310 and sample 20 was 1mm. The minimal amplitude in this example was obtained when the distance between platform 310 and sample 20 was 5mm.

[00103] As elaborated herein, computing device 50 may obtain one or more readings (e.g., digitized, sampled values) of at least one demodulated signal 410, and analyze these readings, to calculate a value of at least one material property 50MP of sample 20 at predetermined location 210.

[00104] Figs. 6 A and 6B are graphs showing examples of experimental measurements using embodiments of the present invention. These measurements show relations between an amplitude of an applied modulated magnetic field (e.g., a maximal magnetic field intensity value) and corresponding measurements of voltage, emitted by a photodetector of the present invention. Specifically, the examples of Figs. 6A and 6B show measurements of voltage signal 420ES, originating from photodetector 420, as functions of measured or precalibrated maximal magnetic field intensity values 610 are presented. The graphs pertain to measurements that were applied to gold (Au) and copper (Cu) samples 20. [00105] It has been experimentally obtained that a square root of a voltage signal 420ES (here denoted VPD) of photodetector 420 is indicative of a change in electrical (E) component of light ray 10B (here denoted E_ref). In other words, voltage signal 420ES (VPD), may represent a change in polarization between light ray 10A and light ray 10B, following interaction of the light with sample 20.

[00106] Fig. 6A presents the dependence of voltage signal 420ES (here denoted VPD) on the amplitude of applied modulated magnetic field 30MF (here denoted B_z). Fig. 6B presents the dependence of a square root of voltage signal 420ES (here denoted VPD) on the amplitude of applied modulated magnetic field 30MF (here denoted B_z). By observing Fig. 6B, it may be appreciated that a linear relation exists between the square root of voltage signal 420ES (VPD) and the amplitude of applied modulated magnetic field 30MF (B_z).

[00107] This linear relation is provided by equation Eq. 1, below:

[00108] In Eq. 1, Co represents a constant calibration factor identical for all samples 20. Co may be system 100-specific, and may calibrated based on a on a variety of system 100 parameters including, for example light ray 10A intensity, attenuation of polarization elements 430, 730, responsivity of illuminant 720, and the electrical characteristics of detector 420.

[00109] Additionally, m represents carrier density in the material of sample 20; m* represents an effective mass of an electron; q represents an electron charge; B_z represents the maximal amplitude of applied, modulated magnetic field 30MF, e.g., as measured by sensor 610. Additionally, w_p represents a plasma frequency of sample 20, which, as known in the art is a natural, material-dependent resonance frequency, and w_opt is an optical frequency of light ray 10A.

[00110] As elaborated herein, computing device 50 may analyze readings of demodulated signal 410DS, to calculate a value of the at least one material property 50MP of the sample at the predetermined location, according to Eq. 1.

[00111] For example, at least one processor (e.g., processor 2 of Fig. 2) of computing device 50 may obtain a plurality of readings of the at least one demodulated signal 410DS, corresponding to a plurality of translation positions of the platform. Additionally, processor 2 may obtain, from magnetic field sensor 610 a corresponding plurality of measurements of maximal magnetic field values at the plurality of translation positions.

[00112] Processor 2 may calculate a mathematical relation between the readings of the at least one demodulated signal 410DS and the corresponding maximal values 610R of modulated magnetic field 30MF. Such relation between demodulated signal 410DS readings and the corresponding readings of magnetic field sensor 610 may be demonstrated, for example as a slope between a square root of demodulated signal 410DS and corresponding maximal magnetic field values 610, e.g., similar to that of graph 6B.

[00113] Based on Eq. 1, it may be appreciated that such a relationship (e.g., the slope of square root of demodulated signal 410DS to magnetic field 30MF amplitude) may provide indication of carrier density m in the material of sample 20. In other words, computing device 50 may calculate a material property 50MP such as carrier density value m based on readings of demodulated signal 410DS and corresponding maximal magnetic field values 610.

[00114] Additionally, or alternatively, computing device 50 may receive a value of Co and/or a value of a material property 50MP such as carrier density value m, and calculate a value of another material property 50MP such as effective mass m* according to Eq. 1, based on the received values (e.g., m ,Co). Other computational combinations are also possible.

[00115] According to some embodiments, computing device 50 may proceed to calculate a conductivity of material at the predetermined location based on carrier density value m, e.g., according to equation Eq. 2 below:

Eq. 2 o = q- nr p where G represents material conductivity, m is the carrier density (e.g., calculated via Eq. 1), q represents an electron charge, and p represents electron mobility in the sampled material. [00116] It may be appreciated that computing device 50 may calculate values of various additional material properties 50MP, based on Eq. 1.

[00117] For example, computing device 50 may be configured to utilize Eq. 1 to calculate an effective mass m* of material at predetermined location 210.

[00118] In another example, as may be observed by the differentiation between gold and copper in Figs. 6A and 6B, a calculated material property 50MP may include a type of material of sample 20 at the predetermined location 210, or a level of doping of material at the predetermined location. [00119] In another example, as carrier planar density value m may be affected by a thickness of sample 20, computing device may use Eq. 1 to calculate a thickness, or morphology of sample 20 around location 210.

[00120] In another example, computing device may use Eq. 1 to compute an optical Hall coefficient value: - - - ^4 - characterizing the material of sample 20 at the

predetermined location.

[00121] Additionally, or alternatively, computing device 50 may calculate a magnetic texture of sample material 20 at predetermined location 210. For example, as elaborated herein (e.g., in relation to Figs. 9C and 9D), embodiments of the invention using the OHE configuration (e.g., Fig. 1C) may provide improved SNR for measuring photodetector voltage signal (e.g., demodulated signal 410DS) in relation to currently available MOKE configurations (e.g., Fig. ID). As explained above, in FM materials, the photodetector voltage signal (e.g., 410DS) may be indicative of a change in polarization of ray 10A, due to local magnetization properties (e.g., direction of magnetization vectors). Embodiments of the invention may therefore provide an accurate magnetization map, showing a texture of magnetization in sample 20.

[00122] As shown in Fig. 4, system 100 may include a first lens 740, positioned along a trace of the first ray 10A, to focus it onto predetermined location 210. Additionally, or alternatively, system 100 may include a second lens 440, positioned along a trace of the second ray 10B to focus it onto the at least one photodetector 420 (e.g., via polarizer 430). It may be appreciated that such lens configuration may allow system 100 to provide microscopic capabilities for inspecting sample 20. In such embodiments, each photodetector 420 may provide pixel-level information, representing localized material property values 50MP.

[00123] Additionally, or alternatively, illuminator 720 may be, or may include a laser source, enabling direction of a focused beam 10A to location 210 of sample 20. In such embodiments, lenses 740 and 440 may not be required as part of system 4.

[00124] As known in the art, a confocal microscope is an advanced optical imaging tool used in microscopy to obtain high-resolution, three-dimensional images of specimens. Confocal microscopes employ a specific optical configuration that enhances image quality and provides optical sectioning capabilities. The term "confocal" refers to the use of a confocal pinhole to eliminate out-of-focus light and improve image sharpness. [00125] Confocal microscopes typically include a pinhole which acts as a spatial filter, allowing only the light from the focal plane to reach the detector while rejecting out-of-focus light. The confocal microscope may thereby eliminate out-of-focus light, improve resolution, and enhance the clarity of images. Another advantage of confocal microscopy is its ability to optically section the specimen. In other words, a confocal microscope may be configured to capture thin optical sections of the observed specimen, corresponding to the focal plane, one at a time. By acquiring such optical sections at different depths within the examined specimen, a confocal microscope may allow reconstruction of three-dimensional images.

[00126] Additionally, or alternatively, element 740 may include a configuration of optical elements, allowing sampling of specimen 20 with super resolution, as known in the art.

[00127] Reference is now made to Fig. 7, which is a schematic diagram depicting another example for implementation of system 100. In this example, system 100 may provide a configuration of a scanning, confocal microscope based on contactless sensing of material properties in a sample, according to some embodiments of the invention. The configuration depicted in the example of Fig. 7 may allow system 100 to operate as a reflectance microscope.

[00128] As shown in the example of Fig. 7, the first ray 10A and the second ray 10B may be substantially collinear. System 100 may include a beam splitter 760, positioned along a trace of the second ray 10B, thereby splitting the second ray to a first portion (denoted 10B- 1) and a second portion (denoted 10B-2). The second portion of the second ray 10B-2 may be directed toward detector module 40. In such configuration, embodiments of the invention may function as a reflectance microscope, allowing the first lens 740 and second lens 440 to be the same, single lens, denoted here as lens 740’.

[00129] In other words, In the configuration example of Fig. 4, lens 740 may focus light ray 10A onto sample 20, and lens 440 may collect and focuses light ray 10B from the sample 20 onto detector 40 (photodetector 420). In the reflectance microscope configuration example of Fig. 7, lenses 440 and 740 may be the same lens 740’, in a sense that the functions of first lens 740 and second lens 440 of Fig. 4 may be united into a single entity.

[00130] Additionally, and as also shown in the example of Fig. 7, system 100 may further include at least one pinhole 450/750. In this example, at least one pinhole 750 may be positioned along a trace of the firstray 10A (denoted 10A-1). Additionally, or alternatively, at least one pinhole 450 may be positioned along a trace of the second ray 10B (denoted 10B-2). In such embodiments, the first lens 740/740’, second lens 440/740’ and at least one pinhole 450/750 may be arranged in a confocal microscope configuration.

[00131] In other words, inclusion of beam splitter 760 and the at least one pinhole 450/750 may allow (a) elimination of out-of-focus light, to enhance the clarity of images, (b) capturing of thin optical sections of sample 20 one at a time, and (c) construction of three dimensional models of sample 20, as provided by confocal microscopy systems.

[00132] According to some embodiments, scanning module 60 may further include at least one scan motor 620 (e.g., a step motor) or actuator, adapted to move, or locate sample 20 in a set of predetermined locations 210.

[00133] In other words, computing device 50 may control the at least one scan motor 620 to move the sample through a plurality of positions 210, to receive a plurality of readings of demodulated signals 410DS, respectively originating from the plurality of positions 210. Computing device 50 may subsequently calculate a plurality material property values 50MP, respectively based on the plurality of readings 410DS.

[00134] Additionally, or alternatively, computing device 50 may produce at least one image 50MPI of the material property values 50MP, corresponding to the plurality of positions 210. Image 50MPI may represent a two-dimensional scan of sample 20 through the set of predetermined locations 210. Computing device 50 may subsequently present two- dimensional scan 50MPI of sample 20 e.g., via output device (e.g., monitor) 8 of Fig. 2.

[00135] Additionally, or alternatively, computing device 50 may aggregate a plurality of two-dimensional scans (images 50MPI) of sample 20, to produce a layered, three- dimensional model 50MPM of sample 20. Computing device 50 may subsequently present three-dimensional model 50MPM of sample 20 e.g., via output device (e.g., monitor) 8 of Fig. 2.

[00136] Reference is now made to Fig. 8, which is a schematic diagram depicting another example for implementation of system 100. In this example, system 100 may provide a configuration of an array-based, confocal microscope, based on contactless sensing of material properties in a sample, according to some embodiments of the invention.

[00137] As shown in Fig. 8, the at least one photodetector 420 may include a plurality of photodetectors 420 that may be arranged in a detector array 425. In such embodiments, the plurality of photodetectors 420 may provide two-dimensional images 50MPI of sample 20, thereby replacing need for scanning of the inspected sample 20.

[00138] In other words, at least one processor 2 of computing device 50 may receive a plurality of readings of demodulated signals 410DS, respectively originating from the plurality of photodetectors 420 of array 425. The at least one processor 2 may calculate a respective plurality material property values 50MP corresponding to respective demodulated signals 410DS readings. The at least one processor 2 may then produce a two-dimensional image 50MPI of material property values 50MP in sample 20, where pixels or portions of image 50MPI may correspond to specific photodetectors 420 in the array of photodetectors 425. Computing device 50 may subsequently present two-dimensional image 50MPI of sample 20 e.g., via output device (e.g., monitor) 8 of Fig. 2.

[00139] Additionally, or alternatively, computing device 50 may aggregate a plurality of two-dimensional images 50MPI of sample 20, to produce a layered, three-dimensional model 50MPM of sample 20. Computing device 50 may subsequently present three- dimensional model 50MPM of sample 20 e.g., via output device (e.g., monitor) 8 of Fig. 2. [00140] Reference is now made to Figs. 9A-9D, which are graphs showing examples of experimental measurements, where modulation of a light source (L) is compared with modulation of a magnetic field (B), according to some embodiments of the invention.

[00141] As known in the art, currently available methods of determining material parameter values may rely on a MOKE configuration, as explained herein with relation to Fig. ID. Such methods may apply a static magnetic field (BDC) to a sample of interest, and analyze a change in an incident light ray’ s polarization to determine properties of the sample. The incident light ray is typically modulated (e.g., on-off modulation) to enhance a signal- to-noise ratio of a photodetector, thereby sensing the material properties of interest. Measurements of such VPD demodulated photodetector signal 410D according to currently available, MOKE - based configuration (e.g., constant magnetic field BDC with a modulated incident light ray L (10A)) is shown in Figs. 9B and 9D: Fig. 9B shows MOKE based measurement of NM materials (Bi, Pt, and Ta), whereas Fig. 9D shows MOKE based measurement of an FM material, in this case Permalloy (Py), a ferromagnetic alloy of nickel and iron.

[00142] In contrast, embodiments of the invention may employ an (OHE) configuration, as explained herein with relation to Fig. 1C. In this configuration, system 100 may apply a modulated magnetic field (BAC) rather than a static one (BDC). System 100 may thereby boost its sensitivity to the underlying physical phenomena by which the magnetic field affects the change in the incident light beam’s polarization.

[00143] Measurements of such VPD demodulated photodetector signal 410D in an OHE configuration, according to embodiments of the invention (e.g., amplitude Bz of modulated magnetic field BAC) is shown in Figs. 9A and 9C. Fig. 9A shows OHE based measurement of NM materials (Bi, Pt, and Ta), whereas Fig. 9C shows OHE based measurement of an FM material (e.g., Py).

[00144] It may be appreciated that system 100 may employ dual modulation, e.g., for both illuminator 720 and magnetic field 30MF. In other words, system 100 may apply modulation (e.g., on-off modulation) to incident light ray 10A, in a predefined light-modulation frequency, and may subsequently apply demodulation of light ray 10C according to the same light-modulation frequency.

[00145] By comparing Figs. 9A and 9B, it may be observed that the OHE configuration may allow embodiments of the invention to clearly identify a NM material of sample 20, whereas currently available MOKE configurations may not provide such distinction among NM materials.

[00146] By comparing Figs. 9C and 9D, it may be observed that the OHE configuration may allow embodiments of the invention, using the OHE configuration to provide improved Signal to Noise Ratio (SNR) ratio for demodulated signal 410DS (VPD) in relation to currently available MOKE configurations, in FM materials. It may be appreciated that such improved SNR may facilitate accurate evaluation of material properties of sample 20 based on demodulated signal 410DS.

[00147] The inventors have studied the enhancement in sensitivity by comparing an OHE measurement of a thin film of Py (Fig. 9C) and a MOKE measurement having a static external magnetic field, B_DC, and an on-off modulated laser beam (Fig. 9D). Both experiments were carried out with the same optical alignment and lock-in amplifier settings. [00148] The film was 15nm thick, and was magnetized in the sample plane. All samples of these experimental measurements were grown by DC magnetron sputtering at a base pressure of 8 X 10^-10 T orr on a Si/SiO2 substrate. A parabolic dependence of V_PD on B_AC and B_DC was measured in both cases. It is readily seen that V_{PD B}

benefits from a higher signal to noise ratio (SNR). Additionally, the conventional MOKE signal is offset by a large background DC level of ~ 215 V whereas in the OHE configuration it is only ~ 2.5 V. Interestingly, the variation of V_PD with the applied magnetic field is of the same order of magnitude with V_{PD Bmod} = 0.02 mV and V_{PD Lmod} = 0.012 mV. The higher DC level of the conventional MOKE originates from stray laser field and imperfections of the polarizers which are eliminated in the OHE configuration. The SNR was evaluated from the ratio between the root mean square error (RMSE) and V_PD by fitting the signals to a quadratic function. Accordingly, RMSE_Bmod = 8.76 • 10^-6 mV and RMSE_Lmod = 1.43 • 10^-4 mV were measured so that the SNRs were

2154

88 illustrating an improvement of 14 dB.

[00149] As shown in Fig. 3, system 100 may include, or may be associated with a machine learning (ML) model 90, configured to predict 90PR a value of at least one material property 50MP. For example ML model 90 may be implemented as a software module, e.g., as part of executable code 5 of Fig. 1. Additionally, or alternatively, ML model 90 may be included or integrated into an online application and may be implemented or executed by a remote computing device such as an online, or cloud server.

[00150] According to some embodiments, computing device 50 may provide ML model 90 with readings of demodulated signal 410DS, as measured in at least one specific location 210 of interest, computing device 50 may further provide ML model 90 with one or more measurement parameters 90P representing the measurement by which demodulated signal 410DS was obtained. Measurement parameters 90P may include, for example a wavelength of ray 10A, a distance of sample 20 from magnetic field generator 30, an orientation of sample 20 in relation to magnetic field generator 30, and the like.

[00151] During an inference stage, ML model 90 may be pretrained to receive the demodulated signal 410DS reading and/or measurement parameters 90P, and predict 90PR a value of at least one material property 50MP based on the received data (e.g., 410DS, 90P). [00152] During a training stage, ML model 90 may receive a training dataset 90DS. Training dataset 90DS that may include a plurality of data tuples, where each data tuple may include a demodulated signal reading 410DS, adjoint with one or more measurement parameters 90P and respective material property annotations 90AN. Material property annotations 90AN may be regarded as ground-truth information, indicating a value of at least one material property 50MP at a specific region 210 and/or specific samples 20 of material. As known in the art, system 100 may subsequently utilize a training scheme (e.g., a backward propagation scheme), to train ML model 90 to predict 90PR a value of at least one material property 50MP, while using training dataset 90DS as supervisory information. [00153] For example, ML model 90 may be pretrained using a known effect in the material, e.g., effect of oxidation on magnetization properties of a metal. Subsequent to this training, system 100 may be applied to a sample 20 that includes an unknown level of oxidation, to produce readings of signal 410DS. ML model 90 may subsequently be inferred on these readings, to predict 90PR the material property 50MP (oxidation).

[00154] Reference is now made to Fig. 10, which is a flow diagram depicting a method of contactless sensing of material properties in a sample, according to some embodiments of the invention.

[00155] As shown in step S1005, embodiments of the method may include configuring a light source component (e.g., light source 70 of Fig. 4) to direct a first ray of light (e.g.,10A of Fig. 4) to interact with the sample (e.g., 20 of Fig. 4) in a predetermined location (e.g., 210). As elaborated herein, light source 70 may emit light ray 10A having a first, predetermined polarization, such as a linear polarization along a predetermined axis.

[00156] According to some embodiments, scanning module 60 may allow changing the orientation of light ray 10A in relation to a plane of sample 20. Additionally, or alternatively, scanning module 60 may allow changing the orientation of modulated magnetic field 30F in relation to the plane of sample 20.

[00157] It may be appreciated that by selecting such predetermined orientations of modulated magnetic field 30F and/or light ray 10A, scanning module 60 may facilitate scanning of surfaces in different orientations of sample 20. For example, scanning module 60 may allow ray 10A to be sent in different orientations, and thereby probe perpendicular or in-plane motions of charge carriers (e.g., electrons) in sample 20.

[00158] Additionally, by selecting such predetermined orientations, scanning module 60 may be configured to determine sample material properties (e.g., charge carrier density) and/or morphological parameters (e.g., thickness), in relation to different axes of sample 20. [00159] As shown in step S1010, embodiments of the method may include adapting a magnetic field generator (e.g., 30 of Fig. 4) to apply a modulated magnetic field (e.g., 30MF of Fig. 3) to sample 20. As elaborated herein (e.g., in relation to Figs. 4,5), modulated magnetic field 30MF may be produced by moving one or more permanent magnets (e.g., 330 of Fig. 4) in the vicinity of sample 20. The term “vicinity” may be used herein to describe a distance that may allow effective application of magnetic field 30MF to sample 20, typically being less than 1 centimeter.

[00160] As shown in step S1015, embodiments of the method may include configuring a detector module (e.g., 30 of Fig. 4) to receive a second ray (e.g., 10B of Fig. 4) of light from the predetermined location 210. As elaborated herein, detector 30 may be configured to produce at least one electric signal (e.g., 420ES of Fig. 3), indicative of a change in polarization between the first ray 10A and the second ray 10B.

[00161] As shown in step S1020, embodiments of the method may include receiving a reference signal (e.g., 610R/360R of Fig. 4), corresponding to a frequency of the modulation of magnetic field 30MF.

[00162] As shown in step S1025, embodiments of the method may include using a demodulation detector (e.g., 410 of Fig. 4, such as a phase-sensitive detector device) to demodulate the at least one electric signal 420ES based on the reference signal 610R/360R, to produce at least one respective demodulated signal (e.g., 410DS of Fig. 3).

[00163] As shown in step S 1025, embodiments of the method may include analyzing the at least one demodulated signal by at least one processor (e.g., 2 of Fig. 2) of a computing device (e.g., 50 of Fig. 4). As elaborated herein, based on said analysis the at least one processor may calculate a value (e.g., 50MP of Fig. 4) of a material property of sample 20 at predetermined location 210.

[00164] The OHE setup may be based on the polar MOKE geometry as illustrated in system 100 of Fig. 4. It may include two polarizers (430, 730) which may be cross-polarized and may be operated in a polar geometry as presented in Fig. 4 using a 445 nm CW laser as an illuminator 720.

[00165] A high extinction ratio analyzer and polarizer may be carefully cross-aligned so that the orthogonal polarization component relative to the incident beam polarization axis may be probed. A large amplitude, mechanically modulated magnetic field H_o may be applied by a modulator that may be positioned on a motorized translation stage 340 capable, for example to modulate up to 0.5 T at the laser spot 210.

[00166] The inventors have achieved high sensitivity using a large amplitude magnetic field modulator, suitable for thin films. The setup is based on a polar cross polarized MOKE configuration for which the detected photocurrent has the general form as in equation Eq. 3 below: Eq. 3 l_y oc P_y ² = q² ■ N² ■ q ■ El_ff ■ B² , where P_y, q, N,j , E_e^ and B_z are the orthogonal component of the polarization, electron charge, total number of interacting electrons, optical mobility, effective polarizing field, and the perpendicular applied magnetic field, respectively.

[00167] The total number of interacting electrons N may be calculated according to equation Eq. 4 below:

Eq. 4

where A_beam, d_pen, and zq being the optical beam area, optical penetration depth and the carrier density, respectively.

[00168] Accordingly, the voltage drop on the photodetector, V_{Photo Det} , should follow a quadratic parabolic dependence on B_z as presented in Fig. 11A for Pt, Ta, and Bi films of thicknesses of 50 nm, 50 nm, and 2 um, respectively, indicating that indeed the orthogonal component is sensed.

[00169] The traces differ in the coefficient of their quadratic term. When -^Vphoto.Det (e.g., square root of 410DS) is taken (Fig. 11B), a linear dependence on B_z is obtained as expected for

. The Pt sample exhibits the strongest dependence on B_z while the Ta sample has the weakest.

[00170] The inventors performed DC Hall measurements on the same samples, in the Van der Pauw configuration (e.g., Fig. 1A). From these measurements the inventors have extracted the DC Hall resistivity from which the carrier density was extracted.

[00171] The electrical Hall voltage is given by equation Eq. 5, below:

Eq. 5

= I_Qx ■ B_z/(q • n_r d) where I_Ox is the applied current, m is the charge carrier (electron) density, d is the sample 20 thickness, and q is the electron charge.

[00172] Fig. 11C presents the Hall resistance, V_H /I_Ox, measured for Pt, Ta, and Bi.

[00173] Fig. 12 A is a graph depicting normalized measurements of a photodetector signal as a function of a component of the magnetic field (B_z ), where the magnetic field in turn is affected by distance from a source of a modulated magnetic field, according to some embodiments of the invention.

[00174] In the OHE measurements, in order to eliminate the macroscopic geometrical differences between the samples -^Vphoto.Det ^was normalized to the sample thickness d. In the Bi sample, d was taken as the optical penetration depth estimated to be -100 nm. In this manner only electrons that interact with optical field may be accounted for. This data is presented in Fig. 12A.

[00175] In the figure the slope for Pt is largest while the slope of Bi is shallowest. These slopes scale with n and are inversely proportional to the slopes obtained in the DC Hall measurements of Fig. 11C. The effective electrical field, E_e^, and the optical mobility, j , are of the same order of magnitude for all samples since interaction occurs at length scales that are shorter than the Drude length.

[00176] Likewise, in the DC electrical Hall measurements the inventors have accounted for the thickness variation between the samples by examining the quantity d ■ V_H/I_Ox, as plotted in Fig. 12B. As compared to Fig. 11C, the relations between the slopes remained: Bi exhibits the sharpest slope, then Ta, and then Pt. These slopes are proportional to n^-1 explaining the invers relations between the DC Hall measurements and the OHE measurements.

[00177] As shown in Fig. 12A, the ratio (slope, ~^~^) between the normalized optical (OHE) signal and the maximal magnetic amplitude is proportional to charge carrier density ni. Where Pt exhibits the highest density, and Bi has the lowest. This order is maintained through comparison with the standard electrical Hall measurements ("electrical") of Fig. 12B, where the charge carrier density m is inversely proportional to the ratio (slope, ^dB ’ ^ccl^Lia' ^{to n}i/^ between the measured Hall resistance and the applied DC magnetic field.

[00178] By comparing Figs. 12A and 12B, it may be appreciated that the optical measurement (OHE, 12A) may scale in a similar manner to measurements using the electrical Hall effect configuration (12B). Accordingly, the OHE configuration measurements (e.g., as facilitated by system 100 in Fig. 4) may reliably evaluate charge carrier density m in contactless measurements. [00179] Conventional light microscopes provide a magnified image of the morphology of a sample. Embodiments of the invention may include a new type of microscope, capable of providing spatial information such as effective mass and carrier density across the sample. [00180] Embodiments of the microscope may be based on implementing OHE measurements using a focused light beam to provide the spatial resolution in the measurement.

[00181] In one mode of operation (referred to herein as a “basic configuration”), an image may be constructed using a scanning stage as in confocal microscopy. Additionally, or alternatively, a super resolution scheme may be applied as known in the art, to provide enhanced image resolution.

[00182] According to some embodiments, in the basic configuration, a laser beam (e.g., 10A of Fig. 4) may be emitted from a laser source (e.g., Illuminator 720 of Fig. 4) and may be linearly polarized by a polarization module (e.g., 730 of Fig. 4). An objective lens (e.g., 740 of Fig. 4) may be placed in the trace of beam 10A following polarization module 730 and may focus beam 10A to a spot (e.g., 210 of Fig. 4) on an examined sample (e.g., 20of Fig. 4).

[00183] After being reflected from sample 20, the beam (e.g., 10B of Fig. 4) may be collected using a second lens (e.g., 440 of Fig. 4), after which the beam enters a second polarization module (e.g., 430 of Fig. 4). Polarization module may be cross polarized with respect to polarization module 730. This way the orthogonal polarization may be transmitted and sensed using a photodetector (e.g., 420 of Fig. 4). It may be appreciated that other means and arrangement of polarization module capable of transferring only orthogonal polarization may be used, including for example orthogonal circular polarization modules.

[00184] In order to obtain an OHE signal at (e.g., 210 of Fig. 4) on an examined sample (e.g., 20 of Fig. 4), a rotating platform such as a magnetic wheel (e.g., 310 of Fig. 4) may be placed by the sample (e.g., behind the sample in the direction of the incident light beam 10A). The rotating magnetic wheel may modulate the magnetic field, H_o, thereby facilitating high sensitivity for measurement of the OHE signal. The magnitude of H_o may be swept by translating the rotating magnetic wheel on a translation stage (e.g., by actuator 340 of Fig. 4) in the +z direction (e.g., substantially in the direction of the incident light beam 10A) as indicated in Fig. 4. [00185] By measuring the signal I_det on a photodiode (e.g., 420 of Fig. 4) as a function of H_o, the OHE signal may be extracted. As elaborated herein, the OHE signal may subsequently be analyzed (e.g., by at least one processor) to calculate properties of the examined sample, including for example the carrier density, and effective mass.

[00186] Embodiments of the invention may include a lock-in detector, also referred to herein as a demodulation module (e.g., element 410 of Fig. 3). Lock-in detector may use a lock-in amplifier operating at the same frequency as modulated magnetic field Ho. A reference signal (e.g., 360R/610R of Fig. 4) of the lock-in may be generated, for example, using a second illuminator such as a laser source (e.g., 350 of Fig. 4) and a second photodetector (e.g., 360 of Fig. 4) adapted to receive light reflected off the rotating wheel (e.g., 310 of Fig. 4). The wheel may be patterned with holes that allow beam (e.g., 350L of Fig. 4) to pass through and generate the reference signal (e.g., 360R).

[00187] Embodiments of the invention may then construct an image of a material property (e.g., carrier density) by scanning over sample 20 in the x — y plane using a scanning stage 60. The process of sweeping over H_o and recording I_det may be repeated at each point that is scanned.

[00188] Embodiments of the invention may include several, alternative implementations of microscope configurations.

[00189] For example, as depicted in Fig. 7, a first alternative may include combining of lenses (e.g., elements 740 and 440 of Fig. 4), using a beam splitter (e.g., 760 of Fig. 7) as in typical reflection microscopes. Pinholes (e.g., 450, 740 of Fig. 7) may be added for increased resolution as in confocal microscopes.

[00190] In another example, as depicted in Fig. 8, embodiments of the invention may implement a single-shot configuration that may not require spatial scanning. An image of a material property (e.g., carrier density) can be constructed without using x-y plane scanning. In such embodiments, photodetectors 420 may be arranged in an array, e.g., as a camera sensor, a charged coupled device (CCD) sensor, and the like. In such embodiments, the spatial information may be recorded simultaneously on all pixels on the camera. In order to record material property (e.g., carrier density) at each pixel of the image, the material property at each pixel may be recorded as a function of modulated magnetic field H_o. Here as well, a lock-in detection algorithm may be applied to extract the data. [00191] Embodiments of the invention may be applied, for example, in the semiconductor industry, for inspecting Very Large Scale Integrated (VLSI) circuits, where an image of the material properties such as carrier density may be used to predict failures in an inspected circuit.

[00192] Embodiments of the invention may not be limited to inspection of metallic samples. For example, microscopic samples of insulators and semiconductors may also be studied and imaged, allowing detection of weak conductive links in any type of a circuit.

[00193] Embodiments of the invention may further provide a scientific tool for research purposes both in academia and in the industry, for development of new devices and discovery of novel materials.

[00194] Embodiments of the invention may be utilized as a microscope for imaging magnetic textures, acting as an ultrasensitive Kerr microscope.

[00195] Unless explicitly stated, the method embodiments described herein are not constrained to a particular order or sequence. Furthermore, all formulas described herein are intended as examples only and other or different formulas may be used. Additionally, some of the described method embodiments or elements thereof may occur or be performed at the same point in time.

[00196] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

[00197] Various embodiments have been presented. Each of these embodiments may of course include features from other embodiments presented, and embodiments not specifically described may include various features described herein.

Claims

1. A system for contactless sensing of material properties in a sample, the system comprising: a light source component, configured to direct a first ray of light to interact with the sample in a predetermined location; a magnetic field generator, adapted to apply a modulated magnetic field to the sample; and a detector module, configured to: (i) receive a second ray of light from the predetermined location, and (ii) detect a change in polarization between the first ray and the second ray, thereby sensing material properties in the predetermined location.

2. The system of claim 1, wherein the light source component comprises: a first illuminant, configured to generate the first light ray; and a first polarization element, adapted to apply a first polarization to the first light ray.

3. The system of claim 2, wherein the detector module comprises: a second polarization element, adapted to apply a second polarization to the second light ray, thereby producing a third light ray; and at least one first photodetector, adapted to produce at least one respective electric signal representing measured intensity of the third light ray, wherein said intensity is indicative of the change in polarization between the first ray and the second ray.

4. The system of claim 3, wherein the first polarization is a linear polarization along a first axis, and wherein the second polarization is a linear polarization along a second, substantially perpendicular axis.

5. The system according to any one of claims 3-4, wherein the detector module further comprises a demodulation module configured to: receive a reference signal, corresponding to a frequency of the modulation of the magnetic field; and based on the reference signal, demodulate the at least one electric signal of the at least one first photodetector, to produce at least one respective demodulated signal.

6. The system of claim 5, wherein said demodulation module is selected from a list consisting of a phase- sensitive detector device, a homodyne detector device, a lock-in amplifier device and a heterodyne detector device.

7. The system according to any one of claims 1-6, wherein the magnetic field generator comprises: a movable platform; one or more permanent magnets, mounted on the movable platform; and at least one motor or actuator configured to apply a first movement to the platform, wherein the first movement is configured to change a distance between the one or more permanent magnets and the predetermined location, thereby modulating the magnetic field at a frequency that corresponds to said movement.

8. The system of claim 7, wherein the movable platform comprises a rotatable platform, and wherein the at least one motor is configured to rotate the rotatable platform about a rotational axis that is perpendicular to the rotatable platform, thereby modulating the magnetic field at a frequency that corresponds to the rotatable platform’s rotation rate.

9. The system according to any one of claims 5-8 further comprising: a movable platform; one or more permanent magnets, mounted on the movable platform; at least one motor or actuator configured to move the platform in relation to the predetermined location; and a magnetic field sensor, configured to: (i) measure the magnetic field substantially at the predetermined location, and (ii) produce the reference signal based on said measurement, to indicate a rate of movement of the movable platform.

10. The system according to any one of claims 5-9 further comprising: a rotatable platform; one or more permanent magnets, mounted on the rotatable platform; at least one motor configured to rotate the rotatable platform; a second illuminant, adapted to direct a second light beam to the rotatable platform; and a second photodetector, adapted to: receive (a) reflection of the second light beam from one or more reflecting elements on the rotatable platform, or (b) transmission of the second light through one or more apertures in the rotatable platform; and produce the reference signal based on said reception, to indicate a rate of rotation of the rotatable platform.

11. The system according to any one of claims 1-10, wherein said material property is selected from a list consisting of: a charge carrier density at the predetermined location, a type of material at the predetermined location, a level of doping at the predetermined location, a thickness of the sample at the predetermined location, an optical Hall coefficient value characterizing the material at the predetermined location, a conductivity of material at the predetermined location, and a magnetic texture of the material at the predetermined location, an effective mass of a charge carrier in the predetermined location of the sample, and any combination thereof.

12. The system according to any one of claims 5-11 further comprising a non-transitory memory device, wherein modules of instruction code are stored, and at least one processor associated with the memory device, and configured to execute the modules of instruction code, whereupon execution of said modules of instruction code, the at least one processor is configured to: obtain one or more readings of the at least one demodulated signal; and analyze said readings, to calculate a value of the at least one material property of the sample at the predetermined location.

13. The system of claim 12, wherein the at least one motor or actuator is further configured to apply a second, translation movement to the platform, so as to change a distance between the one or more permanent magnets and the predetermined location, thereby changing an amplitude of the modulated magnetic field at the predetermined location.

14. The system according to any one of claims 12-13, wherein the at least one processor is further configured to: obtain a plurality of readings of the at least one demodulated signal, corresponding to a plurality of translation positions of the platform; obtain, from a magnetic field sensor, a corresponding plurality of measurements of maximal magnetic field values at the plurality of translation positions; calculate a mathematical relation between the readings of the at least one demodulated signal and the corresponding maximal magnetic field values; and calculate the material property value based on said relation.

15. The system according to any one of claims 1-14, further comprising: a first lens, positioned along a trace of the first ray, to focus the first ray onto the predetermined location; and a second lens, positioned along a trace of the second ray, to focus the second ray onto the at least one photodetector.

16. The system of claim 15, further comprising at least one pinhole, positioned along a trace of at least one of the first ray and second ray, and wherein the first lens, second lens and at least one pinhole are arranged in a confocal microscope configuration.

17. The system according to any one of claims 15-16, wherein the second ray and the first ray are substantially collinear, and wherein the system further comprises a beam splitter, positioned along a trace of the second ray, thereby splitting the second ray to a first portion and a second portion, directed toward the detector module, and wherein the first lens and the second lens are the same lens.

18. The system according to any one of claims 12-17, wherein the at least one processor is configured to: control at least one scan motor, to move the sample through a plurality of positions; receive a plurality of readings of demodulated signals, respectively originating from the plurality of positions; calculate a plurality material property values, respectively based on the plurality of readings; and produce an image of the material property values, corresponding to the plurality of positions.

19. The system according to any one of claims 12-18, wherein the at least one first photodetector comprises a plurality of the first photodetectors, arranged in an array, and wherein the at least one processor is configured to: receive a plurality of readings of demodulated signals, respectively originating from the plurality of first photodetectors of the array; calculate a plurality material property values, respectively based on the plurality of readings; and produce an image of the material property values, corresponding to the array of the first photodetectors.

20. A method of contactless sensing of material properties in a sample, the method comprising: configuring a light source component to direct a first ray of light to interact with the sample in a predetermined location; adapting a magnetic field generator to apply a modulated magnetic field to the sample; configuring a detector module to receive a second ray of light from the predetermined location, and produce at least one electric signal, indicative of a change in polarization between the first ray and the second ray; receiving a reference signal, corresponding to a frequency of the modulation of the magnetic field; demodulating the at least one electric signal based on the reference signal, to produce at least one respective demodulated signal; and analyzing the at least one demodulated signal, by at least one processor, to calculate a value of a material property of the sample at the predetermined location.

21. The method of claim 20, wherein the light source component comprises a first illuminant, configured to generate the first light ray; and a first polarization element, adapted to apply a first polarization to the first light ray.

22. The method of claim 21 , wherein the detector module comprises a second polarization element, and at least one first photodetector, and wherein the method further comprises: adapting the second polarization element to apply a second polarization to the second light ray, thereby producing a third light ray; and adapting the at least one first photodetector to produce at least one respective electric signal representing measured intensity of the third light ray, wherein said intensity is indicative of the change in polarization between the first ray and the second ray.

23. The method of claim 22, wherein the first polarization is a linear polarization along a first axis, and wherein the second polarization is a linear polarization along a second, substantially perpendicular axis.

24. The method according to any one of claims 22-23 , wherein the detector module further comprises a demodulation module, and wherein the method further comprises: obtaining a reference signal, corresponding to a frequency of the modulation of the magnetic field; and configuring the demodulation module to demodulate the at least one electric signal of the at least one first photodetector, based on the reference signal, to produce at least one respective demodulated signal.

25. The method of claim 24, wherein said demodulation module is selected from a list consisting of a phase- sensitive detector device, a homodyne detector device, a lock-in amplifier device and a heterodyne detector device.

26. The method according to any one of claims 20-25, wherein the magnetic field generator comprises: a movable platform; one or more permanent magnets, mounted on the movable platform; and at least one motor or actuator configured to apply a first movement to the platform, and wherein the first movement is configured to change a distance between the one or more permanent magnets and the predetermined location, thereby modulating the magnetic field at a frequency that corresponds to said movement.

27. The method of claim 26, wherein the movable platform comprises a rotatable platform, and wherein the method further comprises configuring the at least one motor to rotate the rotatable platform about a rotational axis that is perpendicular to the rotatable platform, thereby modulating the magnetic field at a frequency that corresponds to the rotatable platform’s rotation rate.

28. The method according to any one of claims 24-27, wherein the magnetic field generator further comprises: a movable platform; one or more permanent magnets, mounted on the movable platform; at least one motor or actuator configured to move the platform in relation to the predetermined location; and a magnetic field sensor, and wherein the method further comprises configuring the magnetic field sensor to: (i) measure the magnetic field substantially at the predetermined location, and (ii) produce the reference signal based on said measurement, to indicate a rate of movement of the movable platform.

29. The method according to any one of claims 24-28, wherein the magnetic field generator further comprises: a rotatable platform; one or more permanent magnets, mounted on the rotatable platform; at least one motor configured to rotate the rotatable platform; a second illuminant, adapted to direct a second light beam to the rotatable platform; and a second photodetector, and wherein the method further comprises adapting the second photodetector to: receive (a) reflection of the second light beam from one or more reflecting elements on the rotatable platform, or (b) transmission of the second light through one or more apertures in the rotatable platform; and produce the reference signal based on said reception, to indicate a rate of rotation of the rotatable platform.

30. The method according to any one of claims 20-29, wherein said material property is selected from a list consisting of: a charge carrier density at the predetermined location, a type of material at the predetermined location, a level of doping at the predetermined location, a thickness of the sample at the predetermined location, an optical Hall coefficient value characterizing the material at the predetermined location, a conductivity of material at the predetermined location, and a magnetic texture of the material at the predetermined location, an effective mass of a charge carrier in the predetermined location of the sample, and any combination thereof.

31. The method according to any one of claims 24-30 further comprising providing a non- transitory memory device, wherein modules of instruction code are stored, and at least one processor associated with the memory device, and configured to execute the modules of instruction code, and configuring the at least one processor, upon execution of said modules of instruction code, to: obtain one or more readings of the at least one demodulated signal; and analyze said readings, to calculate a value of the at least one material property of the sample at the predetermined location.

32. The method of claim 31, further comprising configuring the at least one motor or actuator to apply a second, translation movement to the platform, so as to change a distance between the one or more permanent magnets and the predetermined location, thereby changing an amplitude of the modulated magnetic field at the predetermined location.

33. The method according to any one of claims 31-32, further comprising configuring the at least one processor to: obtain a plurality of readings of the at least one demodulated signal, corresponding to a plurality of translation positions of the platform; obtain, from a magnetic field sensor, a corresponding plurality of measurements of maximal magnetic field values at the plurality of translation positions; calculate a mathematical relation between the readings of the at least one demodulated signal and the corresponding maximal magnetic field values; and calculate the material property value based on said relation.

34. The method according to any one of claims 20-33, further comprising: positioning a first lens along a trace of the first ray, to focus the first ray onto the predetermined location; and positioning a second lens along a trace of the second ray, to focus the second ray onto the at least one photodetector.

35. The method of claim 34, further comprising positioning at least one pinhole along a trace of at least one of the first ray and second ray, to arrange the first lens, second lens and at least one pinhole are arranged in a confocal microscope configuration.

36. The method according to any one of claims 34-35, further comprising: arranging the second ray and the first ray substantially collinearly; positioning a beam splitter along a trace of the second ray, thereby splitting the second ray to a first portion and a second portion, wherein the second portion is directed toward the detector module, wherein the first lens and the second lens are the same lens.

37. The method according to any one of claims 31-36, further comprising configuring the at least one processor to: control at least one scan motor, to move the sample through a plurality of positions; receive a plurality of readings of demodulated signals, respectively originating from the plurality of positions; calculate a plurality material property values, respectively based on the plurality of readings; and produce an image of the material property values, corresponding to the plurality of positions.

38. The method according to any one of claims 31-37, wherein the at least one first photodetector comprises a plurality of the first photodetectors, arranged in an array, and wherein the method further comprises configuring the at least one processor to: receive a plurality of readings of demodulated signals, respectively originating from the plurality of first photodetectors of the array; calculate a plurality material property values, respectively based on the plurality of readings; and produce an image of the material property values, corresponding to the array of the first photodetectors.