System and method for recording a physical parameter induced by a sample

Abstract

The disclosure relates to a system for recording a physical parameter induced by a sample. The method comprises: a platform assembly for receiving the sample; a solid-state material having an outer layer embedded with colour centres sensitive to the physical parameter; a pump light source for providing pumping light; a beam steering arrangement configured to redirect a plurality of beams of said pumping light among sub-regions of the outer layer to generate fluorescent light signals from said sub-regions; a control unit configured to control the beam steering arrangement such that the plurality of beams are sequentially redirected among said sub-regions to generate fluorescent light signals from said sub-regions; and a processing unit configured to process said fluorescent light signals to establish a spatially resolved output indicative of the physical parameter. The disclosure further relates to a method for recording a time-dependent physical parameter induced by a sample.

Description

[0001] SYSTEM AND METHOD FOR RECORDING A PHYSICAL PARAMETER INDUCED BY A SAMPLE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a system and a method for recording a physical parameter, such as a magnetic field, induced by a sample, for example a biological sample or an integrated circuit.

[0004] BACKGROUND OF THE INVENTION

[0005] Various platforms for recording physical parameters induced by samples, for example recording magnetic fields induced by biological samples or microchips, exist.

[0006] As an example, a diamond embedded with nitrogen-vacancy centres can be combined with a conventional image sensor, such as a CMOS sensor or a charge-coupled device, to provide a system which is capable of providing a spatially and temporally resolved measurement of a physical parameter induced by a sample arranged at the nitrogen-vacancy centres.

[0007] Other examples of measurement systems are superconducting quantum interference devices and spin-exchange relaxation-free sensors.

[0008] However, each of these platforms have limitations with respect to spatial resolution, sensitivity of the physical parameter, and / or temporal resolution. For example, conventional systems based on nitrogen-vacancy centres cannot simultaneously yield high spatial resolution, sensitivity, and temporal resolution.

[0009] Hence, a need exists for systems and methods which are capable of providing measurements which have spatial resolution, high sensitivity of the physical parameter, and a high temporal resolution.

[0010] SUMMARY OF THE INVENTION

[0011] On the above background, it is an object of preferred embodiments of the present disclosure to provide systems and methods which are capable of efficiently providing spatially resolved measurements of physical parameters, such as magnetic fields, induced by samples, such as biological samples or microchips. Preferably, the spatially resolved measurements of physicalparameters further have a high temporal resolution and / or a high sensitivity with respect to the physical parameter.

[0012] A first aspect of the present disclosure relates to a system for recording a physical parameter induced by a sample, the system comprising:

[0013] a platform assembly for receiving the sample;

[0014] a solid-state material having an outer layer embedded with colour centres sensitive to the physical parameter, wherein the outer layer is arranged at the platform assembly;

[0015] a pump light source for providing pumping light;

[0016] a beam steering arrangement configured to redirect a plurality of beams of said pumping light among sub-regions of the outer layer to generate fluorescent light signals from said sub-regions;

[0017] a control unit configured to control the beam steering arrangement such that the plurality of beams are sequentially redirected among said sub-regions and such that separate beams of the plurality of beams are directed to separate regions of said sub-regions to generate fluorescent light signals from said subregions, wherein each respective signal of said fluorescent light signals is indicative of the physical parameter at a respective region of said sub-regions; and

[0018] a processing unit configured to process said fluorescent light signals to establish a spatially resolved output indicative of the physical parameter.

[0019] By controlling a beam steering arrangement to sequentially redirect a plurality of beams of pumping light among sub-regions of an outer layer embedded with colour centres, a physical parameter induced by a sample near that outer layer can be measured and mapped more efficiently. For example, within a given duration of time, two beams can sequentially map twice the number of sub-regions as a single beam of pumping light. As a result, aspects and examples of the present disclosure are capable of providing measurements of physical parameters, such as magnetic fields, induced by samples, such as biological samples or microchips, with these measurements simultaneously having high spatial and temporal resolutions. Further, examples of the present disclosure may also have a high sensitivity withrespect to the physical parameter and a high temporal resolution if, for example, photodetectors are used to record the fluorescent light signals.

[0020] The beam steering arrangement is configured to redirect the plurality of beams of pumping light among sub-regions of the outer layer of the solid-state material. Such redirection may be performed via reflection, diffraction, dispersion, interference, or some combination thereof. As an example, an acousto-optic deflector can be utilized, in which the acousto-optic effect is used to diffract light via sound waves in a material such as quartz. Thereby, different orders of light can be diffracted, and the directionality of these orders depend on the frequency of the sound waves. By adjusting the frequency of the sound waves, the directionality of the beam of light can thereby be rapidly adjusted. The directionality can be adjusted in several directions by applying separate sound waves along different transverse directions, for example by using two quartz crystals arranged in series in which sound waves are applied in the different transverse directions. A beam steering arrangement can generally comprise any means capable of steering one or more beams among sub-regions of the outer layer of the solid-state material, such as a set of galvanometric mirrors, a micromirror device, or a spatial light modulator. A beam steering arrangement may comprise several of such devices, for example several sets of galvanometric mirrors. Further, a beam steering arrangement may further be configured to establish several beams of light from a single beam of light originating from the pump light source. For example, an acousto-optic deflector can be used to establish several beams of light from a single beam of light.

[0021] The beam steering arrangement is generally controlled by a control unit. The control unit may control a beam steering arrangement via one or more drivers. As an example, an acousto-optic modulator or deflector may receive an oscillating electric signal from an AOM / AOD driver, where the oscillating electric signal output by the driver is, in turn, controlled by a control unit which sets, e.g., intensity and / or frequency of this oscillating electric signal.

[0022] One approach for measuring the fluorescent light signals is to use a plurality of photodiodes in which each respective photodiode records a respective signal of the fluorescent light signals. Another approach is to record several fluorescent light signals using, e.g., the same photodetector in combination with applying a modulation to the plurality of beams, such that the fluorescent light signals can processed separately by means of demodulation.

[0023] Alternatively, other measurement means, such as a camera, can also be used, but a camera may generally provide reduced temporal resolution and sensitivity in comparison with, e.g., photodetectors.Examples of the present disclosure comprise a platform assembly. Such a platform assembly can also be referred to as a sample tissue chamber. The platform assembly may be configured to receive a biological sample or microchips. Further, the platform assembly may be configured to facilitate an artificial environment for the biological sample, for example with oxygen, carbon dioxide, glucose, particular salts, etc. The biological sample can be immersed in a solution bath, for example at a set temperature and / or with flow circulation of the solution bath.

[0024] Further, examples according to the present disclosure comprise a solid-state material having an outer layer embedded with colour centres sensitive to the relevant physical parameter. Typical examples employ a diamond as the solid-state material, with the outer layer being an outer diamond layer. Further, typical examples employ colour centres which are nitrogenvacancy centres. However, examples of the present disclosure can, in principle, utilize any solid-state material having any type of colour centres embedded in an outer layer. Many types of various colour centres in different types of materials exist. Yet, diamonds having nitrogen-vacancy centres have been thoroughly studied scientifically and are thereby well-understood, which cause these to be simpler and more straightforward to implement and utilize. Further, such centres are sensitive to relevant physical parameters. Another example of a suitable type of colour centre in a solid-state material is a silicon-vacancy centre in silicon carbide.

[0025] Systems according to the present disclosure may further comprise a means for generating a bias magnetic field at the platform assembly, for example one or more bulk magnets in combination with a set of one or more coils which may, for example, surround the platform assembly. In such cases, one or more bulk magnets may provide the primary contribution to the magnitude of the desired bias field, and coils can then be used for fine tuning such that the desired field can be accurately obtained. Further, systems according to the present disclosure may comprise a means for applying a microwave field at the platform assembly, the microwave field being adjusted to the applied bias magnetic field. The bias magnetic field may for example have a magnitude in the range from 1 mT to 3 mT, and the microwave field may for example have a frequency in the range from 2.5 GHz to 3.4 GHz (suitable for nitrogen vacancy centres). As another example, a three-frequency microwave driving scheme may be used tuned to a spin transition (2.73 GHz for nitrogen vacancy centres) and a hyperfine transition (2.16 MHz for nitrogen vacancy centres).

[0026] The pump light source provided in examples according to the present disclosure may typically be a laser system configured to excite the colour centres, for example while applying a bias magnetic field and a microwave field, to generate fluorescent light from these colour centres. That is, pumping light generate fluorescent light signals from the colour centres of the outerlayer of the solid-state material. The colour centres may be sensitive to a relevant physical parameter in the sense that the amount of fluorescent light generated by these colour centres, when subject to irradiation from the pumping light, depends on the physical parameter. For example, a biological sample may induce a magnetic field from an action potential of that biological sample, and the amount of fluorescent light generated by various sub-regions of the outer layer of the solid-state material then depends on the local magnetic field. The pump light source may simultaneously irradiate all colour centres relevant for recording the relevant physical parameter.

[0027] As an example, the pump light source can be a continuous wave laser generating pumping light having a wavelength of 532 nm. Irradiation of such pumping light onto nitrogen-vacancy centres can provide fluorescent light having a wavelength in a range from 630 nm to 750 nm at room temperature (for example, 20 °C).

[0028] The light emitted by the pump light source can be split into several beams to provide a plurality of beams of light. Such splitting can for example be implemented by conventional beam splitters, via a grating, or by splitting via an acousto-optic deflector. An acousto-optic deflector can also be used as a beam steering arrangement for redirecting the beams, and / or be used to apply a modulation to the beams. Alternatively, multiple lasers can also be used as a pump light source. The beam steering arrangement may also include multiple devices, such as multiple sets of galvanometric mirrors.

[0029] The processing unit can process the fluorescent light signals to thereby establish a spatially resolved output indicative of the physical parameter. The fluorescent light signals may be provided to the processor via detection means, such as one or more photodetectors. The processing unit may process the fluorescent light signals individually or collectively to generate a spatially resolved and, optionally, temporally resolved output. Further, the processing unit may apply processing steps such as demodulation, filtering, or noise removal.

[0030] Preferably, the control unit and the processing unit are operated in synchronization, for example via triggering based on a common clock or a common arbitrary waveform generator.

[0031] The control unit and the processing unit may optionally be integrated together to collectively form a control and processing unit.

[0032] A primary application of systems and methods according to the present disclosure is to study biological systems, such as muscle samples or brain samples. However, systems and methods according to the present disclosure can also be utilized to study systems other thanbiological systems, such as complex and / or microscopic circuits, or exotic solid-state materials.

[0033] According to examples of the present disclosure, at least two different modulations are applied to separate beams of the plurality of beams, for example via the beam steering arrangement,

[0034] wherein the processing unit is configured to apply demodulation to the fluorescent light signals to thereby distinguish the fluorescent light signals generated by the separate beams to which the at least two different modulations are applied.

[0035] By applying different modulations to separate beams and processing the fluorescent light signals accordingly, it is possible to record fluorescent light signals from multiple beams using, e.g., a single photodetector. This may significantly simplify the optical system required to rapidly record a physical parameter induced in a sample.

[0036] It is potentially particularly advantageous to implement modulation into the beam steering arrangement, for example into an acousto-optic deflector / modulator, since such a device may already be present in the system. The beam steering arrangement can thus be utilized to implement several technical features simultaneously (for example, any combination of steering, modulation, and beam-splitting).

[0037] According to examples of the present disclosure, the different modulations are intensity modulations.

[0038] Intensity modulations are potentially particularly simple to implement in the context of the present disclosure. However, other types of modulations may alternatively be utilized, for example frequency modulation or phase modulation.

[0039] According to examples of the present disclosure, the beam steering arrangement comprises any of an acousto-optic modulator, an acousto-optic deflector, an electro-optic deflector, a micromirror device, a spatial light modulator, and a set of galvanometric mirrors.

[0040] In case different modulations are applied to the beams, it is particularly advantageous to utilize a beam steering arrangement through which such different modulations can be applied to the beams, for example one or more acousto-optic deflectors.According to examples of the present disclosure, the system further comprises an activation unit configured to activate a time-dependent process in the sample, the time-dependent process inducing or causing the physical parameter, wherein the spatially resolved output is a spatially resolved time-dependent output.

[0041] An activation unit may be an electrode for providing a current pulse. A neuron signal in a biological sample may for example be induced using a current in a range from 0.2 mA to 0.8 mA. An activation unit may be synchronized with the rest of the control unit via a common clock or an arbitrary waveform generator.

[0042] According to examples of the present disclosure, the beam steering arrangement is controlled to direct the one or more beams to the outer layer according to a scanning pattern, preferably a rectangular scanning pattern, such as a raster scanning pattern,

[0043] wherein the scanning pattern is repeated during the time-dependent process to establish the spatially resolved time-dependent output.

[0044] Generally, the temporal resolution of the output is limited by the number of sub-regions which are to be measured. On the other hand, the temporal resolution is improved by the number of beams of pumping lights used. For example, if 100 sub-regions of the outer layer are to be measured, each of these regions typically has to be probed by a beam of pumping light before the measurement can be repeated to provide temporal resolution. However, by using many beams, for example 5, each beam only has to scan 20 sub-regions, instead of 100, thereby improving temporal resolution.

[0045] Optionally, a scanning pattern may be adapted between repetitions, which may, for example, be relevant in case a region in which the physical parameter changes moves throughout a measurement procedure. For example, sub-regions within a region of interest of the outer layer are repeatedly illuminated by the plurality of beams, wherein the region of interest is moved between these repeated illuminations.

[0046] According to examples of the present disclosure, the system further comprises one or more photodetectors for detecting the fluorescent light signals such that the processing unit can process the fluorescent light signals, for example wherein the one or more photodetectors are a plurality of photodetectors and the plurality of photodetectors are arranged to detect the fluorescent light signals such that respective photodetectors of the plurality of photodetectors receive respective signals of said fluorescent light signals.According to examples of the present disclosure, each respective photodetector of the one or more photodetectors is a PIN diode or a PN diode, wherein each of the respective photodetectors has a linear response to the fluorescent light.

[0047] By providing a plurality of photodetectors to receive respective signals of the fluorescent light signals, i.e., respective signals from the different sub-regions of the outer layer, the systems and methods according to the present disclosure are capable of providing measurements which simultaneously yield a spatial resolution, high sensitivity of the relevant physical parameter, and high temporal resolution. This is particularly in case when employing photodetectors being PN or PIN diodes and having a linear response to the fluorescent light. In a photodetector having a linear response, the leakage current may change linearly with the number of absorbed photons to provide a signal from the photodetector. This behaviour is different from, e.g., single-photon avalanche diodes, in which a single photon can trigger an avalanche current to provide a signal.

[0048] A plurality of photodetectors may provide a sensitivity and a temporal resolution which is greater than that of, e.g., the individual pixels of a charge-coupled device or a complementary metal-oxide-semiconductor sensor array. In practice, photodetectors can have a low electronic noise floor and shot-noise limit, which in turn enables measurement of the physical parameter with improved sensitivity.

[0049] Each of the photodetectors may be configured to provide a parallel and / or simultaneous read-out, in contrast to, e.g., a charge-coupled device in which at least some of the individual pixels based on MOS capacitors are read out sequentially. Further, each of the photodetectors may be configured to simultaneously detect light.

[0050] As an example, the plurality of photodetectors can be arranged in a rectangular array of n x m photodetectors. The processing unit can then assemble a spatially resolved recording of the physical parameter by stacking the measurements from the individual photodetector in the rectangular array. The processing unit may further provide noise or filtering operations. The measurements from the individual photodetector can be arranged according to time to provide a temporally (and spatially) resolved output.

[0051] According to examples of the present disclosure, each of the respective photodetectors is coupled to a respective analogue-to-digital converter or respective subgroups of the plurality of photodetectors are coupled to respective analogue-to-digital converters where each of the respective subgroups includes at most 64 photodetectors.This feature distinguishes examples and aspects of the present disclosure from use of a CMOS sensor, since photodiodes integrated on a CMOS sensor are arranged such that groups of several hundreds or thousands of photodetectors are coupled to analogue-to-digital converters to allow readout of an entire columns of pixels through the same converter.

[0052] According to examples of the present disclosure, each of the respective photodetectors:

[0053] has a temporal resolution of at least 10 kHz, for example of at least 30 kHz, for example at least 100 kHz, for example of at least 300 kHz, such as at least 1.0 MHz; and / or

[0054] is coupled to a respective amplifier and, preferably, a respective analogue-to- digital converter.

[0055] Photodetectors having temporal resolutions as exemplified above are suitable for recording processes in, e.g., biological samples such as an induced action potential, in contrast to typical charge-coupled devices or a complementary metal-oxide-semiconductor sensor arrays.

[0056] The respective amplifier is preferably a respective external amplifier for amplifying the signal generated by the diode of the photodetector outside said diode.

[0057] According to examples of the present disclosure, each of the respective photodetectors in combination with the respective amplifier and the respective analogue-to-digital converter has an electronic noise level below the shot noise level for the fluorescent light when the fluorescent light is in a range from O.lpW and 10 pW, for example when the fluorescent light is at O.lpW, l.OpW, or at lOpW.

[0058] According to examples of the present disclosure, each of the respective photodetectors does not have an internal amplifier.

[0059] An internal amplification is a process occurring inside the photodetector semiconductor structure, for example implemented as additional P and / or N layers built into the diode structure to multiply the signal via impact ionization. An example is an avalanche photodiode operating in Gieger mode.

[0060] According to examples of the present disclosure, the system further comprises an optical system for directing fluorescent light from the sub-regions when the sub-regions areirradiated by the pumping light, wherein the optical system is configured such that respective photodetectors of the one or more photodetectors receive respective signals of said fluorescent light signals.

[0061] According to examples of the present disclosure, the optical system comprises any of:

[0062] one or more lenses;

[0063] an objective lens;

[0064] an array of mirrors for redirecting the fluorescent light signals from the subregions when the sub-regions are irradiated by the plurality of beams, wherein the array of mirrors is configured such that respective subsets of the array of mirrors redirect light from the respective sub-regions of the outer layer to the respective photodetectors of the plurality of photodetectors;

[0065] an array of lenses for directing the fluorescent light signals from the subregions when the sub-regions are irradiated by the plurality of beams, wherein the array of lenses is configured such that respective subsets of the array of lenses direct light from the respective sub-regions of the outer layer to the respective photodetectors of the plurality of photodetectors; and

[0066] any combination thereof.

[0067] An optical system may be used to direct fluorescent light from the colour centres to the respective photodetectors. The light may potentially be more efficiently directed to the individual photodetectors by including an array of mirrors or an array of lenses in which separate subsets of the array direct light to separate photodetectors. However, the optical system may also simply be based on a conventional objective lens and / or a simple lens, for example such that the optical system defines an image plane relative to the outer layer at a plane of the plurality of photodetectors. In such a case, light detection may be improved by providing the plurality of photodetectors in the form of a photodetector array in which the plurality of photodetectors collectively has a large filling factor / fraction.

[0068] An array of mirrors may, for example, be a micromirror array, which is an array of micromirrors, each micromirror having an individually controllable angle. Each mirror of an array of mirrors can be considered to redirect a beamlet of fluorescent light which can be controlled arbitrarily. Generally, micromirror arrays in which the tilt or angle of each mirror is controllable along two independent axes and in which each mirror can be continuouslyadjusted within a span of angles are preferable, since such micromirror arrays provide a greater amount of control of the redirected light. Micromirrors which can be continuously adjusted within a span of angles may also be referred to as analogue micromirrors, in contrast to binary or digital micromirrors which have just two possible angles.

[0069] An array of mirrors or an array of lenses permits light to be more efficiently directed to the individual photodetectors.

[0070] As an example, each respective lens of the array of lenses directs light to a respective photodetector of the plurality photodetectors. The array of lenses may be a microlens array or a metalens array.

[0071] According to examples of the present disclosure, the optical system comprises a lens assembly positioned in an optical path of the fluorescent light between the outer layer and the micromirror array or between the outer layer and the array of lenses, wherein the lens assembly defines an image plane relative to the outer layer, wherein the array of mirrors or the array of lenses is arranged at the image plane.

[0072] Thereby, a projected image of the fluorescent light generated by the colour centres in the outer layer is generated at the array of mirrors or the array of lenses, which allows the fluorescent light to be efficiently redirected. Further, such a lens assembly may adapt the size of the region of the outer layer which has been irradiated by pumping light to the area occupied by the array of mirrors or the array of lenses.

[0073] According to examples of the present disclosure, each of the one or more photodetectors has a bandwidth of at least 0.4 MHz, for example at least 0.6 MHz, for example at least 0.8 MHz, such as at least 1.0 MHz.

[0074] According to examples of the present disclosure, the plurality of photodetectors collectively has a filling factor of at least 40 %, for example of at least 50 %, for example of at least 60 %, such as at least 70 %.

[0075] According to examples of the present disclosure, the sub-regions comprises a first sub-region and a second sub-region different from the first sub-region, wherein the one or more photodetectors comprises a first photodetector and a second photodetector different from the first photodetector,

[0076] wherein the first photodetector detects fluorescent light from the first sub-region, preferably primarily from the first sub-region, such as exclusively from the first sub-region,wherein the second photodetector detects fluorescent light from the second sub-region, preferably primarily from the second sub-region, such as exclusively from the second subregion.

[0077] According to examples of the present disclosure, the solid-state material is a diamond and the outer layer is an outer diamond layer, and / or the colour centres are nitrogen-vacancy centres.

[0078] Colour centres in diamonds have been thoroughly studied scientifically and are thereby well-understood. Similarly, nitrogen-vacancy centres, particularly such centres in diamonds, have also been thoroughly studied scientifically and are thereby well-understood. As a result, such examples are straightforward to implement.

[0079] Further, such colour centres are sensitive to relevant physical parameters, such as magnetic field, electric field, pressure, and temperature. Thereby, such colour centres serve as a versatile platform for measuring a wide variety of different physical parameters.

[0080] As an example, considering nitrogen-vacancy centres in diamond, if an external magnetic field is applied along an axis of a colour centre, the field will not affect the ms= 0 states, but it will perturb the ms= ± 1 states via the Zeeman effect. Thereby, the amplitude and orientation of a magnetic field can be probed. Similarly, the electric field also effects various levels of the colour centre, which can be probed accordingly. Pressure and strain on the solid-state material can also affect the energy levels and can thereby be measured. Furthermore, the temperature also affects the spectrum, allowing this physical parameter to be recorded. Regardless, a colour centre always probes the physical parameter at its local site, which in turn can originate from its surroundings, such as from the sample.

[0081] Generally, the outer layer of the solid-state material may also be referred to as a top layer, an exterior-facing layer, a platform-facing layer, or a sample-facing layer since the top portion of said layer preferably faces the platform assembly to ensure that the embedded colour centres are sensitive to the physical parameter induced by the sample. Regardless, the layer is part of the solid-state material.

[0082] According to examples of the present disclosure, the concentration of the colour centres in the outer layer is from 0.01 to 10 ppm.

[0083] Such a concentration is capable of providing a fluorescent signal which is suitable for, e.g., biological samples, such as a muscle sample or a brain sample.According to examples of the present disclosure, a thickness of the outer layer is at most 100 pm, for example at most 50 pm, preferably in a range from 0.5 pm to 20 pm, for example in a range from 1.0 pm to 10 pm.

[0084] The thickness of the outer layer, in which colour centres are embedded, can influence the eventual spatial resolution of the recorded physical parameter.

[0085] If a colour centre has a large displacement from the sample, the value of the physical parameter at that colour centre is influenced by a larger region of the sample, whereas the value of the physical parameter at a colour centre which has a small displacement from the sample is influenced by a smaller region of the sample.

[0086] By providing a small thickness of the outer layer, the displacement is generally small, and an enhanced resolution of the sample can thereby be acquired.

[0087] The specific thickness ranges exemplified above have been found to provide a resolution which is highly suitable for, e.g., biological samples, such as a muscle sample or a brain sample, in particular in combination with a concentration of the colour centres or the nitrogen-vacancy centres in the outer layer in a range from 1 ppm to 5 ppm.

[0088] Preferably, colour centres are embedded throughout the thickness of the outer layer.

[0089] Preferably, the concentration of colour centres is greater in the outer layer than in a remainder of the solid-state material through which the pumping light and the fluorescent light propagates. For example, the concentration of colour centres in said remainder of the solid-state material may be below 1.0 ppm, for example below 0.5 ppm, for example below 0.2 ppm. In some examples, colour centres are only embedded in the outer layer.

[0090] According to examples of the present disclosure, the platform assembly comprises an insulating layer between the diamond layer and platform surface for receiving the sample, preferably wherein a thickness of the insulating layer is at most 20 pm, for example at most 10 pm, such as at most 5 pm.

[0091] The insulating layer is preferably insulating in terms of optical insulation with respect to pumping light and fluorescent light, and / or insulating in terms of thermal insulation.

[0092] The insulating layer is preferably relatively thin to avoid compromising the spatial resolution of the measurement.A second aspect of the present disclosure relates to a method for recording a physical parameter induced by a sample, the method comprising the steps of:

[0093] arranging the sample at a platform assembly, wherein an outer layer of a solid- state material is arranged at the platform assembly, wherein the outer layer is embedded with colour centres sensitive to the physical parameter;

[0094] providing pumping light from a pump light source;

[0095] directing a plurality of beams of the pumping light to the outer layer of the solid-state material via a beam steering arrangement, wherein the beam steering arrangement is controlled such that the plurality of beams are sequentially redirected among sub-regions of the outer layer and such that separate beams of the plurality of beams are directed to separate regions of said sub-regions to generate fluorescent light signals from the colour centres of said sub-regions, wherein each respective signal of said fluorescent light signals is indicative of the physical parameter at a respective region of said subregions; and

[0096] processing said fluorescent light signals to establish a spatially resolved output indicative of the physical parameter.

[0097] Methods according to the second aspect may have any of the same advantages or effects as systems according to the first aspect of the present disclosure.

[0098] According to examples of the present disclosure, the physical parameter is a time-dependent physical parameter, wherein the method comprises a step of:

[0099] activating a time-dependent process in the sample, the time-dependent process inducing the time-dependent physical parameter,

[0100] wherein the beam steering arrangement is controlled during the time-dependent process such that the plurality of beams is sequentially redirected among said sub-regions of the outer layer.

[0101] According to examples of the present disclosure, the beam steering arrangement is controlled such that said separate beams of the plurality of beams are simultaneously directed to separate regions of said sub-regions.According to examples of the present disclosure, the physical parameter is any of a magnetic field, an electric field, a pressure, a temperature, and combinations thereof.

[0102] According to examples of the present disclosure, the sample is a biological sample, such as a muscle sample or a brain sample, or an electrical circuit, such as an integrated circuit.

[0103] According to examples of the present disclosure, the method according to the second aspect is performed on the system according to any example of the first aspect or on the system according to any example of the fourth aspect.

[0104] A third aspect of the present disclosure relates to a method for recording a time-dependent physical parameter induced by a sample, the method comprising the steps of:

[0105] arranging the sample at a platform assembly, wherein an outer layer of a solid- state material is arranged at the platform assembly, wherein the outer layer is embedded with colour centres;

[0106] providing pumping light from a pump light source;

[0107] activating a time-dependent process in the sample, the time-dependent process inducing the time-dependent physical parameter;

[0108] directing one or more beams of the pumping light to the outer layer of the solid-state material via a beam steering arrangement, wherein the beam steering arrangement is controlled during the time-dependent process such that the one or more beams are sequentially redirected among sub-regions of the outer layer to generate fluorescent light signals from said sub-regions, wherein each respective signal of said fluorescent light signals is indicative of the timedependent physical parameter at a respective region of said sub-regions; and

[0109] processing said fluorescent light signals to establish a spatially resolved timedependent output indicative of the physical parameter induced by the timedependent process.

[0110] By activating a time-dependent process in the sample and controlling the beam steering arrangement during the time-dependent process to sequentially redirect one or more beams among sub-regions of the outer layer, it is possible to obtain a spatially resolved time-dependent output indicative of the physical parameter. Such an output may be obtained with high sensitivity and high temporal resolution.

[0111] According to examples of the present disclosure, the one or more beams of the pumping light is a plurality of beams, wherein the step of directing the plurality of beams to the outer layer comprises directing separate beams of the plurality of beams to separate regions of said subregions of the outer layer to generate the fluorescent light signals.

[0112] According to examples of the present disclosure, the fluorescent light signals generated by plurality of beams are detected simultaneously.

[0113] The fluorescent light signals may be detected simultaneously by one or more photodetectors.

[0114] According to examples of the present disclosure, the method comprises a step of applying at least two different modulations to separate beams of the plurality of beams,

[0115] wherein the step of processing said fluorescent light signals comprises applying demodulation to the fluorescent light signals to thereby distinguish the fluorescent light signals generated by the separate beams to which the at least two different modulations are applied.

[0116] According to examples of the present disclosure, the one or more beams are provided to the respective sub-regions of the outer layer in a pulsed manner such that for each respective region of said sub-regions an initialization pump pulse is provided followed by a readout pump pulse to generate a respective signal of said fluorescent light signals, wherein a microwave pulse is applied between the initialization pump pulse and the readout pump pulse.

[0117] A pulsed scheme in which pumping light is provided to the respective sub-regions of the outer layer in a pulsed manner can improve the fluorescent light signals from said respective sub-regions.

[0118] According to examples of the present disclosure, the fluorescent light signals are processed such that the respective signal of said fluorescent light signal generated by the readout pump pulse provided to the respective region of said sub-regions establishes a respective sub-unit of the spatially resolved time-dependent output, the sub-unit corresponding to one instance of temporal and spatial resolution.According to examples of the present disclosure, the physical parameter is any of a magnetic field, an electric field, a pressure, a temperature, and combinations thereof.

[0119] According to examples of the present disclosure, the physical parameter is a magnetic field, and the system records the magnetic field with a sensitivity of at most 200 pT / (Hz1 / 2), for example a sensitivity of at most 100 pT / (Hz1 / 2), such as a sensitivity of at most 50 pT / (Hz1 / 2).

[0120] According to examples of the present disclosure, the sample is a biological sample, such as a muscle sample or a brain sample, or an electrical circuit, such as an integrated circuit.

[0121] According to examples of the present disclosure, the time-dependent process is an action potential.

[0122] The disclosed method and system are particularly well-suited to measure processes in biological samples. As an example, an action potential can be measured. The aspects disclosed herein offer viable approached for obtaining a sensitive measurement of an action potential which is resolved both temporally and spatially.

[0123] According to examples of the present disclosure, the method according to the second aspect is performed using the system according to any example of the first aspect.

[0124] A fourth aspect of the present disclosure relates to a system for recording a time-dependent physical parameter induced by a sample, the system comprising:

[0125] a platform assembly for receiving the sample;

[0126] a solid-state material having an outer layer embedded with colour centres sensitive to the physical parameter, wherein the outer layer is arranged at the platform assembly;

[0127] a pump light source for providing pumping light;

[0128] a beam steering arrangement configured to redirect one or more beams of said pumping light among sub-regions of the outer layer to generate fluorescent light signals from the colour centres of said sub-regions;an activation unit configured to activate a time-dependent process in the sample, the time-dependent process inducing the time-dependent physical parameter;

[0129] a control unit configured to control the beam steering arrangement during the time-dependent process such that the one or more beams are sequentially redirected among said sub-regions of the outer layer to generate fluorescent light signals from the colour centres of said sub-regions, wherein each respective signal of said fluorescent light signals is indicative of the timedependent physical parameter at a respective region of said sub-regions; and

[0130] a processing unit configured to process said fluorescent light signals to establish a spatially resolved time-dependent output indicative of the physical parameter induced by the timedependent process.

[0131] Systems according to the fourth aspect may have any of the same advantages or effects as methods according to the third aspect of the present disclosure.

[0132] According to examples of the present disclosure, the one or more beams of the pumping light is a plurality of beams, wherein the control unit is configured to control the beam steering arrangement during the time-dependent process such that separate beams of the plurality of beams are directed to separate regions of said sub-regions to generate the fluorescent light signals.

[0133] According to examples of the present disclosure, at least two different modulations are applied to separate beams of the plurality of beams, for example via the beam steering arrangement,

[0134] wherein the processing unit is configured to apply demodulation to the fluorescent light signals to thereby distinguish the fluorescent light signals generated by the separate beams to which the at least two different modulations are applied.

[0135] According to examples of the present disclosure, the system further comprises one or more photodetectors for detecting the fluorescent light signals such that the processing unit can process the fluorescent light signals, for example wherein the one or more photodetectors are a plurality of photodetectors and the plurality of photodetectors are arranged to detect the fluorescent light signals such that respective photodetectors of the plurality of photodetectors receive respective signals of said fluorescent light signals.According to examples of the present disclosure, each respective photodetector of the one or more photodetectors is a PIN diode or a PN diode, wherein each of the respective photodetectors has a linear response to the fluorescent light; and / or

[0136] wherein each of the respective photodetectors is coupled to a respective analogue-to-digital converter or wherein respective subgroups of the plurality of photodetectors are coupled to respective analogue-to-digital converters where each of the respective subgroups includes at most 64 photodetectors.

[0137] According to examples of the present disclosure, the system according to the fourth aspect is arranged to perform the method according to any example of the second aspect or arranged to perform the method according to any example of the third aspect.

[0138] BRIEF DESCRIPTION OF THE DRAWINGS

[0139] Embodiments of the invention will now be further described by reference to the accompanying drawings, in which:

[0140] Fig. 1 illustrates a system for recording a physical parameter of a sample according to the present disclosure,

[0141] Fig. 2 schematically illustrates a system in which different modulations are applied to separate beams of pumping light,

[0142] Fig. 3 schematically illustrates exemplary scanning patterns for a plurality of beams,

[0143] Fig. 4 schematically illustrates the provision of a beam to respective sub-regions of an outer layer in a pulsed manner,

[0144] Fig. 5 schematically illustrates an exemplary system for recording a magnetic field of a biological sample according to the present disclosure,

[0145] Fig. 6 illustrates another system according to the present disclosure in which an optical system comprises an array of mirrors,

[0146] Fig. 7 illustrates an example of redirection of fluorescent light signals onto separate photodetectors,Fig. 8 illustrates another system according to the present disclosure in which an optical system comprises an array of lenses, and

[0147] Fig. 9 illustrates method steps according to an example of the present disclosure.

[0148] DETAILED DESCRIPTION

[0149] Fig. 1 illustrates a system for recording a physical parameter of a sample 1 according to the present disclosure.

[0150] The sample 1 is held in a platform assembly 2. The platform assembly 2 is configured to hold the sample 1 in a fixed position while performing measurements using the system. Further, in examples according to the present disclosure in which the sample 1 is a biological sample, the platform assembly 2 is preferably further configured to facilitate an artificial environment for the biological sample.

[0151] A solid-state material 3 is placed in close proximity to the platform assembly 2, and thereby in close proximity to the sample 1. The solid-state material 3 has an outer layer 4 embedded with colour centres. These colour centres are sensitive to the physical parameter which the system is suitable for recording. For example, the colour centres may be sensitive to magnetic field.

[0152] The system further comprises a pump light source 5 for providing a plurality of beams of pumping light 6aa-ba and a beam steering arrangement 21 configured to redirect the plurality of beams 6aa-ba among sub-regions of the outer layer 4 to generate fluorescent light signals 7 from these sub-regions. In the present example, the beam steering arrangement 21 is an acousto-optic deflector. The plurality of beams 6aa-ba is established by inputting an initial beam of light 6 in the beam steering arrangement 21, which then generates a first beam 6aa and a second beam 6ba.

[0153] The beam steering arrangement 21 is controlled by a control unit 22, which provides a signal to the beam steering arrangement 21, thereby controlling the beam steering arrangement 21 to redirect the beams 6aa, 6ba accordingly.

[0154] Fig. 1 illustrates the first and second beams in first orientations drawn by dotted lines and labelled with reference numerals 6aa and 6ba, and in second orientations drawn by dashed lines and labelled with reference numerals 6ab and 6bb. The first and second orientationscorrespond to two separate instances in time. These orientations of the beams are set by the control unit 22.

[0155] In practice, the control unit 22 controls the beam steering arrangement 21 such that the first and second beams are sequentially redirected among separate orientations as exemplified in the figure by reference numerals 6aa, 6ab and 6ba, 6bb, respectively. Each separate beam at a particular orientation is directed to a particular sub-region of the outer layer 4. The control unit 22 controls the plurality of beams such that they are sequentially redirected among subregions and such that separate beams of the plurality of beams are directed to separate subregions to generate fluorescent light signals from these sub-regions. For example, at a first instance in time, the first beam 6aa is directed to a first sub region and the second beam 6ba is directed to a second sub-region, and at a second instance in time, the first beam 6ab is directed at a third sub-region and the second beam 6bb is directed to a fourth sub-region, the first through fourth sub-regions being different.

[0156] In the present example, the plurality of beams is provided to the solid-state material 3 in an oblique angle relative to the platform assembly 2 and the solid-state material 3. Preferably, the pumping light is coupled into the solid-state material approximately 3 at Brewster's angle to ensure maximum efficiency. For pumping light at 532 nm and a solid-state material 3 of diamond, Brewster's angle is approximately 67° relative to a normal vector of the interface between the diamond and the surrounding atmospheric air.

[0157] As an example, the pumping light 6 may irradiate colour centres in the form of nitrogenvacancy centres with an intensity of 3 kW / cm2. Generally, an intensity in the range from 0.5 kW / cm2to 5 kW / cm2can be applicable to irradiate such colour centres.

[0158] Preferably, a reflective or optically insulating surface is placed between the solid-state material 3 and the sample 1 to ensure that the sample 1 is minimally irradiated and / or heated by the pumping light 6.

[0159] The colour centres embedded in the outer layer 4 emit fluorescent light signals 7 upon irradiation with the pumping light 6. The magnitude of the fluorescent light signals 7 irradiated by a given colour centre depends on the physical parameter locally at that colour centre.

[0160] The system further comprises a detection system 23, for example comprising one or more photodetectors or a camera and optics for directing fluorescent light signals 7 from the solid-state material to the one or more photodetectors or the camera. Thereby, the fluorescent light signals 7 can be provided to a processing unit 14 of the system.The processing unit 14 is configured to process the fluorescent light signals 7 to thereby establish a spatially resolved output 15 indicative of the physical parameter. By repeatedly recording fluorescent light signals 7 from the different sub-regions of the outer layer 4, the spatially resolved output may further be temporally resolved.

[0161] Fig. 2 schematically illustrates a system in which different modulations are applied to separate beams of pumping light.

[0162] The system comprises a pump light source 5 which provides a plurality of beams of pumping light 6a, 6b, ... 6n. Each of these separate beams 6a, 6b, ... 6n is provided to a light modulator 24a, 24b, ... 24n. Thereby, a first modulation is applied to a first beam of light 6a to provide a first modulated beam of light 6a-m, a second modulation is applied to a second beam of light 6b to provide a second modulated beam of light 6b-m, etc. Each of the modulated beams of light 6a-m, 6b-m, ... 6n-m is then provided beam steering means 21a, 21b, ... 21n for redirecting these modulated beams.

[0163] The changing directionality of these beams are indicated in the illustration by different lines, where a dotted line corresponds to directionalities at a first instance in time, a dashed line corresponds to directionalities at a second instance in time, and a solid line corresponds to directionalities at a third instance in time. Thus, the schematic illustration shows the first modulated beam of light 6a-m having three different directionalities which is labelled by 6aa-m, 6ab-m, 6ac-m, the second modulated beam of light 6b-m having three different directionalities which is labelled by 6ba-m, 6bb-m, 6bc-m, etc.

[0164] These beams sequentially having different directionalities are sent to the outer layer 4 of the solid-state material 3, such that each beam having a particular orientation is directed to a separate sub-region of the outer layer 4. This generates fluorescent light signals, which is recorded by a recording system 23. In the present example, the recording system is based on a photodetector which collectively records all the fluorescent light signals and transmits these to a processing unit 14. As a result, the fluorescent light signals generated by all of the beams within a given duration of time are recorded simultaneously. In this particular illustration, the fluorescent signals recorded in a first duration of time are indicated by dotted lines, the fluorescent signals recorded in a second duration of time are indicated by dashed lines, and the fluorescent signals recorded in a third duration of time are indicated by solid lines.

[0165] The processing unit 14 applies demodulation to the fluorescent light signals, which allows the fluorescent light signals generated by the separately modulated beams of light and recorded simultaneously to be separately extracted from the collectively recorded fluorescent lightsignals. Thereby, a spatially resolved output 15 can be generated despite a single photodetector being used.

[0166] The modulation and demodulation may, for example, be based on intensity modulation of the pumping light.

[0167] Even though the present figure illustrates a plurality of light modulators 24a, 24b, ... 24n and a plurality of beam steering means 21a, 21b, ... 21n as separate units, all of these can be implemented by, e.g., a single acousto-optic deflector which is driven by a plurality of oscillating electric signals, each having a separate frequency (for providing the plurality of beams) and a separate modulation (for providing the plurality of modulations).

[0168] Fig. 3 schematically illustrates exemplary scanning patterns 26 for a plurality of beams 6a, 6b. The illustration schematically shows the outer layer 4 of a solid-state material 3, and a plurality (8 x 8) of sub-regions of this outer layer 4. In the present example, four beams (of which only two 6a, 6b are illustrated so as to not obscure the illustration) are provided to separate sub-regions 25. Each beam is scanned across a plurality of sub-regions 25 according to a scanning pattern 26. Each separate beam is scanned across a separate set of subregions, for example such that no sub-region is scanned by more than a single beam. The beams can thereby collectively scan all sub-regions. Each beam may dwell at a sub-region for a duration of time before proceeding to the next sub-region to provide sufficient fluorescent light.

[0169] Fig. 4 schematically illustrates the provision of a beam to respective sub-regions 25 of an outer layer in a pulsed manner. The horizontal axis indicates time.

[0170] For each respective sub-region, an initialization pump pulse of pumping light is provided followed by a readout pump pulse of pumping light to generate a fluorescent light signal. Between the initialization pump pulse and the readout pump pulse, a microwave pulse is applied to prepare a sub-region for the readout pump pulse. In case multiple beams of pumping light are provided to separate sub-regions simultaneously, the microwave pulse can collectively prepare several sub-regions for the readout pump pulse.

[0171] Fig. 5 schematically illustrates an exemplary system for recording a magnetic field of a biological sample according to the present disclosure.

[0172] In the presently illustrated example, the biological sample 1 is a brain sample 12 provided as a brain slice from a mouse.The solid-state material 3 is a diamond, the outer layer 4 is an outer diamond layer, and the colour centres and nitrogen-vacancy centres.

[0173] To dissipate heat, the diamond 3 is mounted in an aluminium nitride heatsink. The diamond 3 and the brain sample 12 is separated by an aluminium layer acting as an additional heatsink and reflecting laser the pumping light (not shown, see Fig. 1) stacked with a Kapton ® layer which electrically insulates the brain sample from the diamond.

[0174] The platform assembly 2 facilitates an artificial environment for the brain sample 12. A solution is continuously circulated through the platform assembly, the solution being a carbogenated artificial cerebrospinal fluid comprising (in mM) 111 NaCI, 11 Glucose, 25 NaHCO3, 3 KCI, 1.1 KH2PO4, 2.5 CaCI2, and 1.3 MgCI2. The solution can be chilled, for example though an ice bath, prior to flowing into the platform assembly 2 to dissipate heat from the aluminium nitride heatsink. Thereby, the brain sample 12 can be held at a temperature of, e.g., 25°C.

[0175] The presently illustrated system comprises a pump light source 5 providing one or more beams of pumping light 6, a beam steering arrangement 21 configured to redirect the one or more beams of pumping light among sub-regions of the outer layer 4 to generate fluorescent light signals from the sub-regions, and a control unit 22 configured to control the beam steering arrangement 21.

[0176] An electrode inserted into a target region of the sample 1 provides a current pulse to induce a current pulse, for example using a current in a range from 0.2 mA to 0.8 mA using an electrode. In other words, a current pulse activates a time-dependent process in the sample, the time-dependent process being an action potential and inducing or causing the physical parameter, the physical parameter being the magnetic field. As this time-dependent process is activated, the control unit 22 controls the beam steering arrangement 21 such that the one or more beams is sequentially redirected among sub-regions of the outer layer to generate fluorescent light signals from the sub-regions, each of the fluorescent light signals being indicative of the time-dependent magnetic field at a respective sub-region.

[0177] The system further comprises a detection system 23 for detecting the fluorescent light signals and providing these to a processing unit 14, which can the process the fluorescent light signals to establish a spatially resolved time-dependent output 15 indicative of the physical parameter.

[0178] Exemplary spatially and temporally resolved measurements 15a-c are illustrated in the figure as three inserts in which a neuron signal propagates through the brain sample 12.Although the present figure illustrates the entire brain sample in the measurements 15a-c, typical measurements according to the present disclosure may be directed towards specific regions of the brain in the millimetre or sub-millimetre range. However, note that the present disclosure is not restricted to any particular size of samples and size of measurement regions.

[0179] The spatial resolution obtained by a measurement may be determined by several factors. One typical limitation is the distance from the colour centres to the sample. Considering a distance of, e.g., 20 pm, the spatial resolution obtained in an eventual measurement will typically also be at least on the order of 20 pm. Another potential limitation is provided by the detection system, and the beam waist of the one or more beams.

[0180] Fig. 6 illustrates another system according to the present disclosure in which an optical system comprises an array of mirrors in the form of a micromirror array 8.

[0181] In comparison to the example illustrated in Fig. 1, the detection system 23 of the example illustrated in Fig. 6 comprises a micromirror array 8 comprising a rectangular array of mirrors 9 for redirecting the fluorescent light signals 7 from the colour centres when the outer layer 4 is irradiated by one or more beams 6 of pumping light. The detection system 23 may further comprise one or more lenses (not shown), for example to define an image plane at the micromirror array 8 relative to the outer layer 4.

[0182] In the present example, the mirrors 9 of the micromirror array 8 are configured to redirect the fluorescent light signals 7, propagating from the solid-state material 3, towards a plurality of photodetectors 11. The mirrors 9 are configured such that separate photodetectors 11 detect fluorescent light from separate sub-regions of the outer layer 4 of the solid-state material 3. The direction of propagation of the redirected fluorescent light 10 is indicated by arrows. Further optical elements, for example one or more lenses (not shown) may be used to ensure that fluorescent light irradiated from a given sub-region of the outer layer 4 reaches, e.g., a specific photodetector 11.

[0183] Each mirror 9 (or, alternatively, each group of mirrors) can be considered to redirect a beamlet, i.e., a sub-region of the fluorescent light 7, separately from other mirrors. This is utilized to steer beamlets of fluorescent light from separate sub-regions of the outer layer towards separate photodetectors 11.

[0184] Each of the photodetectors 11 is a PIN diode and has a linear response to the fluorescent light received. Thus, the respective signals are proportional to the intensity of the fluorescent light 7 from the respective sub-regions.The photodetectors 11 are each connected to a processing unit (not shown), which is configured to receive and process the respective signals received by the photodetectors 11. These signals can then be arranged or stacked according to a spatial distribution of the photodetectors to obtain a recording or measurement in the form of a spatially resolved output.

[0185] Fig. 7 illustrates an example of redirection of fluorescent light signals 7 onto separate photodetectors 11.

[0186] For the sake of simplicity, the incoming beam of fluorescent light 7 is illustrated as a collimated beam of light. However, in practice, this may not be the case, and mirrors of the micromirror array 8 can be adjusted to provide compensation accordingly.

[0187] The direction of propagation of the incoming fluorescent light signals 7 is indicated by a dashed line. This dashed line also corresponds to an optical axis. The mirrors of the micromirror array can be deflected within a span of angles around a resting angle of 0°. The dashed line further indicates the direction in which the fluorescent light is redirected when the mirrors are arranged at this resting angle.

[0188] The exemplary optical system further comprises a lens in the form of a convex lens 16. This lens 16 has a focal length 17 indicated in the illustration, and the photodetectors 11 are arranged behind the lens 16 at a distance corresponding to this focal length 17.

[0189] The angle at which a given mirror is deflected relative to its resting angle determines the direction at which fluorescent light is redirected. Each mirror can be considered to redirect a beamlet 19, i.e., a portion of the fluorescent light 7, separately from other mirrors. The mirror deflection angle 18 can thereby be controlled to control at which photodetector 11 that beamlet arrives.

[0190] In this exemplary setup illustrated in Fig. 7, the position at the focal plane of the lens at which a beamlet from a particular mirror arrives (relative to the optical axis indicated by the dashed line) is determined by f x tan(20), where f is the focal length of the lens, defining the focal plane, and 0 is the deflection angle 18 of that mirror. Thereby, the deflection angle 18 of individual mirrors can be angled to redirect onto a photodetector as desired.

[0191] The illustration provided in Fig. 7 indicates redirection of fluorescent light within a single plane (i.e., the plane of the illustration), but in practice, redirection of light can is not limited to a single plane, and may also be performed, e.g., perpendicular to the plane of the illustration.In case the incoming fluorescent light is not collimated, the angle of mirrors of the micromirror array may be further adjusted as compensation. For example, considering light from a particular region or portion of an outer layer of a solid-state material arriving at a subset of mirrors, the mirrors of this subset can be individually adjusted to correct for divergence. As an example, light from a particular region may arrive at a 10 x 10 array of mirrors, and the mirrors across this subset can then be angled differently to reduce divergence of the redirected fluorescent light. For example, the subset of mirrors may be individually angled to collectively provide a reflection of light which is similar to that of a concave reflective surface. This subset of mirrors can then collectively redirect light from a specific sub-region of the outer layer to a specific photodetector. Even though such compensation requires a significant number of mirrors (e.g., 10 x 10 per region of the outer layer), note that micromirror arrays typically have a very large number of mirrors. For example, a micromirror array may have 512 x 320 mirrors, so even if 10 x 10 mirrors are used per region of the outer layers, this still provides a resolution of the outer layer of the solid-state material, and thereby a resolution of the physical parameter, of 51 x 32.

[0192] Fig. 8 illustrates another system according to the present disclosure in which a detection system 23 comprises an array of lenses 20.

[0193] More specifically, the detection system 23 comprises an array of lenses 20 in which respective subsets of the array of lenses direct light from the respective sub-regions of the outer layer 4 to respective photodetectors 11.

[0194] The propagation of fluorescent light signals from two exemplary sub-regions of the outer layer 4 is indicated in the illustration by dashed lines and dotted lines, respectively. The dashed lines indicate that a first photodetector detects a first fluorescent light signal from a first sub-region of the outer layer 4 via a first respective lens of the array of lenses 20, and the dotted lines indicate that a second photodetector detects a second fluorescent light signal from a second sub-region of the outer layer 4 via a second respective lens of the array of lenses 20.

[0195] In this particular example, the detections system further comprises a lens 16 for gathering the fluorescent light 7 prior to arrival at the array of lenses 20.

[0196] Fig. 9 illustrates method steps S1-S5 according to an example of the present disclosure. The example relates to a method for recording a physical parameter induced by a sample.In a first step SI of the method, a sample is arranged at a platform assembly. An outer layer of a solid-state material is arranged at the platform assembly. The outer layer is embedded with colour centres. The colour centres are sensitive to the physical parameter.

[0197] In another step S2 of the method, pumping light is provided from a pump light source. The pump light source may comprise one or more lasers. Further, one laser may provide several beams of pumping light.

[0198] In another step S3 of the method, a time-dependent process is activated in the sample. The time-dependent process induces the time-dependent physical parameter.

[0199] In another step S4 of the method, one or more beams of the pumping light are directed to the outer layer of the solid-sate material via a beam steering arrangement. The beam steering arrangement is controlled during the time-dependent process such that the one or more beams are sequentially redirected among sub-regions of the outer layer to generate fluorescent light signals from the colour centres of these sub-regions. Each respective signal of these fluorescent light signals is indicative of the time-dependent physical parameter at a respective region of the sub-regions.

[0200] In another step S5 of the method, the fluorescent light signals are processed to establish a spatially resolved time-dependent output indicative of the physical parameter induced by the time-dependent process.

[0201] It is possible to establish a spatially resolved time-dependent output based on a single beam of pumping light.

[0202] Examples according to the present disclosure may comprise additional steps.

[0203] Some examples comprise a step of conditioning the colour centres prior to performing a measurement of the physical parameter. Such conditioning can utilize various operations to redistribute the population in the ground state manifold of the colour centres from a thermal distribution into a target distribution with an increased population in a specific state, such as a target distribution with an increased population in the absolute ground state.

[0204] List of figure references:

[0205] 1 sample

[0206] 2 platform assembly

[0207] 3 solid-state material

[0208] 4 outer layer5 pump light source

[0209] 6 beam of pumping light

[0210] 7 fluorescent light signal

[0211] 8 micromirror array

[0212] 9 mirror

[0213] 10 redirected fluorescent light 11 photodetector

[0214] 12 brain sample

[0215] 14 processing unit

[0216] 15 spatially resolved output 16 lens

[0217] 17 focal length

[0218] 18 mirror deflection angle

[0219] 19 beamlet

[0220] 20 array of lenses

[0221] 21 beam steering arrangement 22 control unit

[0222] 23 detection system

[0223] 24 light modulator

[0224] 25 sub-region

[0225] 26 scanning pattern

[0226] 27 microwave pulse

[0227] S1-S5 method steps

Claims

CLAIMS1. A system for recording a physical parameter induced by a sample, the system comprising:a platform assembly for receiving the sample;a solid-state material having an outer layer embedded with colour centres sensitive to the physical parameter, wherein the outer layer is arranged at the platform assembly;a pump light source for providing pumping light;a beam steering arrangement configured to redirect a plurality of beams of said pumping light among sub-regions of the outer layer to generate fluorescent light signals from the colour centres of said sub-regions;a control unit configured to control the beam steering arrangement such that the plurality of beams are sequentially redirected among said sub-regions and such that separate beams of the plurality of beams are directed to separate regions of said sub-regions to generate fluorescent light signals from the colour centres of said sub-regions, wherein each respective signal of said fluorescent light signals is indicative of the physical parameter at a respective region of said sub-regions; anda processing unit configured to process said fluorescent light signals to establish a spatially resolved output indicative of the physical parameter.

2. A system according to claim 1, wherein at least two different modulations are applied to separate beams of the plurality of beams, for example via the beam steering arrangement,wherein the processing unit is configured to apply demodulation to the fluorescent light signals to thereby distinguish the fluorescent light signals generated by the separate beams to which the at least two different modulations are applied.

3. A system according to claim 2, wherein the different modulations are different intensity modulations.

4. A system according to any of the preceding claims, wherein the beam steering arrangement comprises any of an acousto-optic modulator, an acousto-optic deflector, an electro-optic deflector, a micromirror device, a spatial light modulator, and a set of galvanometric mirrors.

5. A system according to any of the preceding claims, wherein the system further comprises an activation unit configured to activate a time-dependent process in the sample, the timedependent process inducing the physical parameter, wherein the spatially resolved output is a spatially resolved time-dependent output6. A method according to claim 5, wherein the beam steering arrangement is controlled to direct the one or more beams to the outer layer according to a scanning pattern, preferably a rectangular scanning pattern, such as a raster scanning pattern,wherein the scanning pattern is repeated during the time-dependent process to establish the spatially resolved time-dependent output.

7. A system according to any of the preceding claims, wherein the system further comprises one or more photodetectors for detecting the fluorescent light signals such that the processing unit can process the fluorescent light signals, for example wherein the one or more photodetectors are a plurality of photodetectors and the plurality of photodetectors are arranged to detect the fluorescent light signals such that respective photodetectors of the plurality of photodetectors receive respective signals of said fluorescent light signals.

8. A system according to claim 7, wherein each respective photodetector of the one or more photodetectors is a PIN diode or a PN diode, wherein each of the respective photodetectors has a linear response to the fluorescent light; and / orwherein each of the respective photodetectors is coupled to a respective analogue-to-digital converter or wherein respective subgroups of the plurality of photodetectors are coupled to respective analogue-to-digital converters where each of the respective subgroups includes at most 64 photodetectors.

9. A system according to any of claims 7-8, wherein each of the respective photodetectors:has a temporal resolution of at least 10 kHz, for example of at least 30 kHz, for example at least 100 kHz, for example of at least 300 kHz, such as at least 1.0 MHz.

10. A method for recording a physical parameter induced by a sample, the method comprising the steps of:arranging the sample at a platform assembly, wherein an outer layer of a solid- state material is arranged at the platform assembly, wherein the outer layer is embedded with colour centres sensitive to the physical parameter;providing pumping light from a pump light source;directing a plurality of beams of the pumping light to the outer layer of the solid-state material via a beam steering arrangement, wherein the beam steering arrangement is controlled such that the plurality of beams are sequentially redirected among sub-regions of the outer layer and such that separate beams of the plurality of beams are directed to separate regions of said sub-regions to generate fluorescent light signals from the colour centres of said sub-regions, wherein each respective signal of said fluorescent light signals is indicative of the physical parameter at a respective region of said subregions; andprocessing said fluorescent light signals to establish a spatially resolved output indicative of the physical parameter.

11. A method according to claim 10, wherein the physical parameter is a time-dependent physical parameter, wherein the method comprises a step of:activating a time-dependent process in the sample, the time-dependent process inducing the time-dependent physical parameter,wherein the beam steering arrangement is controlled during the time-dependent process such that the plurality of beams is sequentially redirected among said sub-regions of the outer layer.

12. A method according to any of claims 10-11, wherein the beam steering arrangement is controlled such that said separate beams of the plurality of beams are simultaneously directed to separate regions of said sub-regions.

13. A method according to any of claims 10-12, wherein the physical parameter is any of a magnetic field, an electric field, a pressure, a temperature, and combinations thereof.

14. A method according to any of claims 10-13, wherein the sample is a biological sample, such as a muscle sample or a brain sample, or an electrical circuit, such as an integrated circuit.

15. A method according to any of claims 10-14, wherein the method is performed on the system according to any of claims 1-9 or on the system according to any of claims 24-30.

16. A method for recording a time-dependent physical parameter induced by a sample, the method comprising the steps of:arranging the sample at a platform assembly, wherein an outer layer of a solid- state material is arranged at the platform assembly, wherein the outer layer is embedded with colour centres sensitive to the physical parameter;providing pumping light from a pump light source;activating a time-dependent process in the sample, the time-dependent process inducing the time-dependent physical parameter;directing one or more beams of the pumping light to the outer layer of the solid-state material via a beam steering arrangement, wherein the beam steering arrangement is controlled during the time-dependent process such that the one or more beams are sequentially redirected among sub-regions of the outer layer to generate fluorescent light signals from the colour centres of said sub-regions, wherein each respective signal of said fluorescent light signals is indicative of the time-dependent physical parameter at a respective region of said sub-regions; andprocessing said fluorescent light signals to establish a spatially resolved timedependent output indicative of the physical parameter induced by the timedependent process.

17. A method according to claim 16, wherein the one or more beams of the pumping light is a plurality of beams, wherein the step of directing the plurality of beams to the outer layer comprises directing separate beams of the plurality of beams to separate regions of said subregions of the outer layer to generate the fluorescent light signals.

18. A method according to claim 17, wherein the fluorescent light signals generated by plurality of beams are detected simultaneously.

19. A method according to any of claims 17-18, wherein the method comprises a step of applying at least two different modulations to separate beams of the plurality of beams,wherein the step of processing said fluorescent light signals comprises applying demodulation to the fluorescent light signals to thereby distinguish the fluorescent light signals generated by the separate beams to which the at least two different modulations are applied.

20. A method according to any of claims 16-19, wherein the one or more beams are provided to the respective sub-regions of the outer layer in a pulsed manner such that for each respective region of said sub-regions an initialization pump pulse is provided followed by a readout pump pulse to generate a respective signal of said fluorescent light signals, wherein a microwave pulse is applied between the initialization pump pulse and the readout pump pulse.

21. A method according to claim 20, wherein the fluorescent light signals are processed such that the respective signal of said fluorescent light signal generated by the readout pump pulse provided to the respective region of said sub-regions establishes a respective sub-unit of the spatially resolved time-dependent output, the sub-unit corresponding to one instance of temporal and spatial resolution.

22. A method according to any of claims 16-21, wherein the physical parameter is any of a magnetic field, an electric field, a pressure, a temperature, and combinations thereof.

23. A method according to any of claims 16-22, wherein the sample is a biological sample, such as a muscle sample or a brain sample, or an electrical circuit, such as an integrated circuit.

24. A method according to any of claims 16-23, wherein the time-dependent process is an action potential.

25. A system for recording a time-dependent physical parameter induced by a sample, the system comprising:a platform assembly for receiving the sample;a solid-state material having an outer layer embedded with colour centres sensitive to the physical parameter, wherein the outer layer is arranged at the platform assembly;a pump light source for providing pumping light;a beam steering arrangement configured to redirect one or more beams of said pumping light among sub-regions of the outer layer to generate fluorescent light signals from the colour centres of said sub-regions;an activation unit configured to activate a time-dependent process in the sample, the time-dependent process inducing the time-dependent physical parameter;a control unit configured to control the beam steering arrangement during the time-dependent process such that the one or more beams are sequentially redirected among said sub-regions of the outer layer to generate fluorescent light signals from the colour centres of said sub-regions, wherein each respective signal of said fluorescent light signals is indicative of the timedependent physical parameter at a respective region of said sub-regions; anda processing unit configured to process said fluorescent light signals to establish a spatially resolved time-dependent output indicative of the physical parameter induced by the timedependent process.

26. A system according to claim 25, wherein the one or more beams of the pumping light is a plurality of beams, wherein the control unit is configured to control the beam steering arrangement during the time-dependent process such that separate beams of the plurality of beams are directed to separate regions of said sub-regions to generate the fluorescent light signals.

27. A system according to claim 26, wherein at least two different modulations are applied to separate beams of the plurality of beams, for example via the beam steering arrangement,wherein the processing unit is configured to apply demodulation to the fluorescent light signals to thereby distinguish the fluorescent light signals generated by the separate beams to which the at least two different modulations are applied.

28. A system according to any of claims 25-27, wherein the system further comprises one or more photodetectors for detecting the fluorescent light signals such that the processing unit can process the fluorescent light signals, for example wherein the one or more photodetectors are a plurality of photodetectors and the plurality of photodetectors are arranged to detect the fluorescent light signals such that respective photodetectors of the plurality of photodetectors receive respective signals of said fluorescent light signals.

29. A system according to claim 28, wherein each respective photodetector of the one or more photodetectors is a PIN diode or a PN diode, wherein each of the respective photodetectors has a linear response to the fluorescent light; and / orwherein each of the respective photodetectors is coupled to a respective analogue-to-digital converter or wherein respective subgroups of the plurality of photodetectors are coupled to respective analogue-to-digital converters where each of the respective subgroups includes at most 64 photodetectors.

30. A system according to any of claims 25-29, wherein the system is arranged to perform the method according to any of claims 10-15 or arranged to perform the method according to any of claims 16-24.

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