"quantum sensor microscopy devices"

Abstract

Embodiments relate to quantum microscopy devices and quantum microscopes. In one embodiment, a quantum microscopy device includes a substrate comprising a first surface and a second reverse surface, wherein at least one aperture is disposed through the substrate from the first surface to the second reverse surface, and a frame extending from the first surface of the substrate, the frame including at least one connecting segment having a first end attached to the substrate and a mounting segment attached to a second end of the at least one connecting segment, the mounting segment configured to receive at least part of an objective to mount the frame on the objective, wherein the substrate is configured to accommodate a quantum sensor to be positioned at least partially over the at least one aperture of the substrate.

Description

"Quantum Sensor Microscopy Devices"Technical Field

[0001] Embodiments generally relate to devices for quantum sensor microscopy, and in some embodiments, devices for mounting a quantum sensor to a microscope to enable microscopic imaging of magnetic fields.Background

[0002] Quantum systems have unique properties which allow for the precise measurement of magnetic fields at the nanoscale. Quantum sensors can therefore be used to perform imaging of these magnetic fields. One technique in this regard is based on the use of Nitrogen- Vacancy (NV) centres in diamond. These defects in the diamond lattice can be manipulated to function as highly sensitive magnetometers. By measuring the spin state of the NV centres, it is possible to map out the magnetic field with high spatial resolution. This information can then be used to construct a map of the source quantity (magnetisation or current density) in a sample.

[0003] In the field of quantum- sensor-enabled magnetic field imaging, there exist several platforms that use quantum sensors to image magnetic fields. These fall into two broad categories: scanning quantum sensors and widefield quantum sensors. The scanning approach involves a single or small ensemble of quantum sensors that are scanned across a sample usually via attachment to an atomic force microscope. While this offers better spatial resolution (typically ~50 nm at best) it is slow in comparison to the widefield approach and offers a much smaller field of view (~10 um), which is limited by scanning stages. The widefield approach uses a larger excitation beam to control and read out a large region of the sample without any scanning. This addresses a large ensemble of sensors in parallel, which ultimately leads to a greater sensitivity, a faster measurement time, and a larger field of view, but at the cost of worse spatial resolution (generally limited by optical diffraction).

[0004] Traditionally, in wide field imaging approaches, a diamond sensor is manually placed onto the sample to be imaged. This is a tedious and time-consuming task, requires specialist expertise, and is costly. Another approach is to fabricate the sample directly onto the quantum sensor which is difficult in the sample preparation process and limits applications as not allsamples can be made in this fashion. Another approach is to attach the diamond sensor to a mechanical arm and bring it into alignment with the focal plane between the imaging optics and the sample. However, this involves a completely separate stage to allow for positioning of the diamond sensor with respect to the sample. This approach is unstable, disrupts the imaging optics, is cumbersome, and limits the application of higher magnification objectives with small work distances and oil objectives. Further, it is not a generalised technique which can be used with an existing optical microscope.

[0005] It is desired to address or ameliorate one or more shortcomings or disadvantages associated with prior quantum microscopy devices, or to at least provide a useful alternative thereto.

[0006] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.Summary

[0007] Some embodiments relate to a quantum microscopy device, including: a substrate comprising a first surface and a second reverse surface, wherein at least one aperture is disposed through the substrate from the first surface to the second reverse surface; and a frame extending from the first surface of the substrate, the frame including: at least one connecting segment having a first end attached to the substrate; and a mounting segment attached to a second end of the at least one connecting segment, the mounting segment configured to receive at least part of an objective to mount the frame on the objective; wherein the substrate is configured to accommodate a quantum sensor to be positioned at least partially over the at least one aperture of the substrate.

[0008] In some embodiments, the device may include a quantum sensor disposed at least partially over the at least one aperture of the substrate. The quantum sensor may be disposed on the first surface or the second reverse surface of the substrate.

[0009] A transparent substrate may be positioned over, or disposed within, the at least one aperture, and the quantum sensor may be attached to the transparent substrate in some embodiments. The transparent substrate may be glass. The quantum sensor may be adhered to the transparent substrate with a glue.

[0010] In some embodiments, the mounting segment may be configured to receive the objective such that the frame extends along the length of the objective. In some embodiments, the substrate may be a printed circuit board (PCB). The substrate may be configured such that a generated electromagnetic field is incident on the aperture. An electromagnetic antenna or waveguide may be disposed on the substrate and configured to generate an electromagnetic field incident on the aperture. In some embodiments, the electromagnetic antenna may be a loop antenna.

[0011] In some embodiments, the frame may be configured to at least partially encase the objective. The frame may include a plurality of connecting segments, each having a first end attached to the substrate, and a second end attached to the mounting segment. The frame may be substantially rectilinear in shape. In some embodiments, the frame may be substantially cylindrical in shape.

[0012] The at least one connecting segment may be an elongate structural member. In some embodiments, the at least one connecting segment may be a wall. The at least one connecting segment may define a sleeve configured to encase the objective.

[0013] In some embodiments, the mounting segment may define an opening configured to receive at least part of the objective therethrough. The mounting segment may be configured to abut at least part of the objective. The mounting segment may include an attachment mechanism for attaching the mounting segment to an objective.

[0014] The mounting segment may include an attachment mechanism for attaching the mounting segment to a secondary component, wherein the secondary component may bemounted on the objective. In some embodiments, the attachment mechanism may include a cylindrical aperture with a screw thread, configured to threadingly engage with a screw thread of the objective. The attachment mechanism may be a screw mount adapter.

[0015] In some embodiments, the substrate may include an embedded waveguide. The substrate may include at least one connector, disposed on the first surface. In some embodiments, the substrate may include a pair of connectors, disposed on the first surface.

[0016] In some embodiments, the at least one connecting segment may include a threaded portion, and may be attached to the substrate by an adjustable screw mount. The adjustable screw mount may be configured to change the vertical distance between the objective and the quantum sensor upon rotation of the substrate.

[0017] In some embodiments, the quantum sensor may be a solid-state quantum sensor. The quantum sensor may be a diamond having nitrogen- vacancy centres.

[0018] Some embodiments relate to a quantum microscopy device, including: an objective; a substrate comprising a first surface and a second reverse surface, wherein at least one aperture is disposed through the substrate from the first surface to the second reverse surface; and a frame extending from the first surface of the substrate, the frame including: at least one connecting segment having a first end attached to the substrate; and a mounting segment attached to a second end of the at least one connecting segment, the objective extending at least partially through the mounting segment; wherein the substrate is configured to accommodate a quantum sensor to be positioned at least partially over the at least one aperture of the substrate.

[0019] Some embodiments relate to a quantum microscopy device, including: an objective; a substrate comprising a first surface and a second reverse surface, wherein at least one aperture is disposed through the substrate from the first surface to the second reverse surface; anda frame extending from the first surface of the substrate, the frame including: at least one connecting segment having a first end attached to the substrate; and a mounting segment attached to a second end of the at least one connecting segment, the objective extending at least partially through the mounting segment; wherein the substrate is configured to accommodate a quantum sensor to be positioned at least partially over the at least one aperture of the substrate; and a mechanical stage mounted to an upper portion of the objective, and attached to the mounting segment such that the frame is mounted to the mechanical stage and the objective extends through the mechanical stage and into the frame; wherein the mechanical stage is adjustable such that the position of the quantum sensor relative to the objective may be adjusted.

[0020] In some embodiments, the mechanical stage may be adjustable in at least one of a vertical position, a lateral position, a pitch tilt and a yaw tilt.

[0021] Some embodiments relate to a method of imaging magnetic fields, including performing magnetic field imaging using any of the devices disclosed herein.

[0022] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.Brief Description of Drawings

[0023] Various ones of the appended drawings merely illustrate example embodiments of the present disclosure and cannot be considered as limiting its scope.

[0024] Figure 1 is an illustrative schematic diagram of a quantum microscopy device, according to some embodiments;

[0025] Figure 2A is a schematic diagram of a bottom view of a substrate in the form of a printed circuit board (PCB), according to some embodiments;

[0026] Figure 2B is a schematic diagram of a top view of the PCB of Figure 2A, according to some embodiments;

[0027] Figures 3A to 3D are cross sectional diagrams showing various example configurations in which a quantum sensor and / or a transparent substrate are attached to a substrate, according to some embodiments;

[0028] Figure 4A is a diagram of a connecting segment being attachable to a substrate through a screw mount, according to some embodiments;

[0029] Figure 4B is a top view diagram of a substrate showing an adjustable screw mount, according to some embodiments;

[0030] Figure 5 is a diagram showing a screw mount configuration attached and mounted to an objective, according to some embodiments;

[0031] Figures 6A and 6B are schematic diagrams of a quantum microscopy device with an integrated illumination source, according to some embodiments;

[0032] Figure 7 is a schematic diagram of a quantum microscopy device integrated into a microscope, according to some embodiments;

[0033] Figure 8 shows an example magnetic image obtained by the quantum microscope of Figure 7, according to some embodiments;

[0034] Figure 9 is a partially exploded- view diagram of a high precision quantum sensing microscope, according to some embodiments;

[0035] Figure 10 is a schematic diagram of a second quantum microscopy device integrated into a microscope, according to some embodiments

[0036] Figure 11A is an example image obtained by a high precision quantum sensing microscope, according to some embodiments; and

[0037] Figure 11B is a graph of the linecut through a magnetic bead, having the same magnetic nanoparticles of the sample in Figure 11 A.Description of Embodiments

[0038] Embodiments generally relate to devices for quantum microscopy, and in some embodiments devices for mounting a quantum sensor to an optical microscope to enable microscopic imaging of magnetic fields. Some embodiments relate to devices for mounting a quantum sensor to an objective of an optical microscope. Some embodiments relate to devices that include quantum sensors to enable microscopic imaging of magnetic fields. Some embodiments relate to specialised quantum sensor microscopy devices capable of imaging magnetic fields.

[0039] Some embodiments of the quantum microscopy devices disclosed herein may also be referred to as a quantum microscopy sleeve or a Quantum Sensor Microscopy Sleeve (QSMS). In some embodiments, the quantum microscopy device is a device for mounting a quantum sensor to an objective of an optical microscope, effectively enabling the transformation of a traditional optical microscope into a quantum microscope capable of imaging the magnetic field emanating from a sample.

[0040] Figure 1 is an illustrative schematic diagram of a quantum microscopy device 100, according to some embodiments. The device 100 includes a substrate 102, for example, a printed circuit board (PCB), having a first surface 105 and a reverse, or opposite surface 107. An aperture 104 is disposed in the substrate 102 and extends from the first surface 105 through to the reverse surface 107. As illustrated in Figure 1, the aperture 104 may be positioned at or toward a centre of the surface(s) 105, 107 of the substrate 102.The aperture 104 of the substrate 102 is provided such that light may pass through unimpeded. In some embodiments, the aperture 104 of the substrate 102 may include a filter configured to block all or some light.

[0041] The substrate 102 is configured to accommodate a quantum sensor 108 to be positioned at least partially over the at least one aperture 104 of the substrate 102. In some embodiments, the substrate is configured such that an electromagnetic field generated by an electromagnetic antenna (not shown) is incident on the aperture 104 and / or the quantum sensor 108.

[0042] The device 100 includes a quantum sensor 108 disposed at least partially over the aperture 104 of the substrate 102. In some examples, the dimensions of the quantum sensor 108 are similar to or smaller than those of the aperture 104 such that when centrally aligned with the aperture 104, the quantum sensor 108 does not overlap with the reverse surface 107 of the substrate 102. The quantum sensor 108 may be coupled or attached to (directly or indirectly) the reverse surface 107 of the substrate 102. In some embodiments, the quantum sensor 108 may be illuminated below the substrate 102, and the aperture 104 may include a long pass filter to block the excitation light but allow transmission of the photoluminescence.

[0043] In some embodiments, as depicted in Figure 1, a transparent substrate 116 is disposed over the aperture 104 of the substrate 102, on the first surface 105 of the substrate 102. The transparent substrate 116 may extend across the extent of the aperture 104 and in some examples, may have an upper surface flush with the first surface 105 of the substrate 102. In such embodiments, the quantum sensor 108 may be indirectly attached to the substrate 102 by coupling or adhering the quantum sensor 108 to the transparent substrate 116 such that the quantum sensor 108 at least partially covers the aperture 104. In some embodiments, the quantum sensor 108 may be adhered directly to the reverse surface 107 of substrate 102 to at least partially cover the aperture 104.

[0044] In Figure 1, the substrate 102 has a pair of connectors 110 and 112, although in some embodiments the substrate 102 may have only one connector, or may have more than two connectors. The connectors 110 and 112 may be microwave (MW) connectors.

[0045] In some embodiments, a waveguide 114 may be embedded in the substrate 102. In some embodiments, the waveguide 114 may be disposed along a portion of or the entire reverse surface 107 of the substrate 102. The waveguide 114 may comprise a first segment and a second segment, with one of the segments disposed on or embedded in the reverse surface 107 of the substrate 102 on either side of the quantum sensor 108. The waveguide 114 may be a microwave waveguide.

[0046] The quantum microscopy device 100 comprises a frame 106 extending upwards from the first surface 105 of the substrate 102. The frame 106 includes a connecting segment 118 having one end attached to the first surface 105 of the substrate 102, and a mounting segment120 attached to the other end of the connecting segment 118. The mounting segment 120 is configured to receive at least part of an objective 122, such that the frame 106 can be mounted onto the objective 122.

[0047] In some embodiments, the device 100 enables the integration of the quantum sensor 108 with the objective 122 by using the mounting frame 106. A commercial microscope objective may be adapted to hold the frame 106 by attaching a mounting segment 120 in the form of a screw mount adaptor to the objective screw 124, which does not interfere with the objective 122 being mounted to an objective receptacle 126. In some embodiments, the objective receptacle 126 may be larger, smaller or the same size as the frame 106. The frame 106 is then attached to the screw mount adaptor 120 and surrounds the objective 122. In some embodiments, the mounting frame 106 is in the form of a sleeve which houses the objective 122 and can be retroactively attached to existing optical microscope designs. As shown in the embodiment of Figure 1, the mounting frame 106 is attached to the top of the objective 122 via a mounting segment 120 which directly screws onto the objective screw mount 124. In other embodiments, the frame 106 may be attached to an additional structure to convert from the objective screw 124 to the mounting frame 106. The frame 106 allows for the mounting of additional components that house the quantum sensor 108. In some embodiments, the frame 106 allows for the mounting of additional components (not shown) to deliver the electromagnetic frequency, such as radio frequency (RF) or microwaves (MW) required for driving the spin- states of the quantum sensor 108.

[0048] The quantum sensor 108 is positioned in the appropriate location for magnetic imaging of a sample 127 placed on a stage 128. As mentioned above, the quantum sensor 108 may be held in place by being coupled or adhered to the transparent (or appropriately milled) substrate 116 disposed over the aperture 104 of the substrate 102. The frame 106 enables the quantum sensor 108 to be spaced apart from the bottom or distal end of the objective 122 and held in place with respect to or relative to the objective 122. As the quantum sensor 108 may be larger than the optical field of view of the imaging system, it is not necessary to have fine control over the lateral positioning of the quantum sensor 108 with respect to the objective 122 or the sample 127 being imaged.

[0049] Reference to an objective herein may refer to any optical lens-based system that can focus light to form an image. An objective may refer to a microscope objective which relays an image of the object to the eyepiece of a microscope. In embodiments described herein, an objective may be an air objective or an oil objective. In some embodiments, objectives may have a magnification in the range of lx to lOOx. An objective may have a 4x, lOx, 20x, 40x, and 50x, magnification. An objective may also refer to a singular lens optical system. In some embodiments, the objective may be an achromatic objective, a plan achromatic objective, a fluorite objective, a plan fluorite objective, and / or a plan apochromat objective.

[0050] In some embodiments, the substrate 102 may be a PCB. In some embodiments, the PCB may be formed from a single layer of substrate material. The substrate material of the PCB may be a phenolic resin or epoxy, or a fiberglass -reinforced epoxy laminate. The substrate material of the PCB may have at least one side coated with a thin layer of conducting material that may be etched to create a circuit pattern. The substrate material of the PCB may have both sides coated with a thin layer of conducting material. In some embodiments, the PCB may include one or more apertures that allow circuits on one side to connect to circuits on the other side. In some embodiments, the PCB may be formed from a plurality of layers of substrate material, for example the plurality of layers may be laminated together. Each of the plurality of layers may be separated by insulation to prevent the circuits from interfering with one another.

[0051] In some embodiments, the PCB may be formed from a flexible substrate material to enable the PCB to be bent during use. For example, this may include, but is not limited to, polyimide, LCP (liquid crystal polymer), polyester and / or polyethylene naphthalate (PEN). The PCB may be made from materials that do not absorb or reflect high-frequency signals, such as high frequency electromagnetic waves. In some embodiments, the PCB may be made from, for example, aluminium in order to efficiently dissipate heat, copper to enable high power distribution, or high glass transition temperature materials to withstand high temperatures. The PCB may be a single layer PCB, a double-layer PCB, a multi-layer PCB, a flexible PCB, a rigid PCB or a rigid-flex PCB.

[0052] The substrate 102 may be substantially planar. In some embodiments, it may be of any suitable shape, including rectangular, polygonal or rounded. The shape of the substrate 102 may be chosen based on the shape of the frame 106, and / or the connecting segments which attach tothe substrate 102. In some embodiments, the substrate 102 may form a base portion of the frame 106. In some embodiments, the substrate 102 may not have an aperture, and may instead be formed from a transparent material. The quantum sensor 108 may be attached directly to the first surface 105 or the reverse surface 107 of the substrate 102 made from the transparent material in a position that aligns with the focal plane of the objective 122.

[0053] The substrate 102 defines the aperture 104. The aperture 104 may be disposed proximate to the centre of the substrate 102, or it may be disposed proximate to an integrated element of the substrate 102. For example, the aperture 104 may be disposed in the centre of a loop antenna integrated into the substrate 102. The aperture 104 may be of any shape. In some embodiments, the aperture 104 is substantially circular. In some embodiments, the aperture 104 may have a diameter in the range of 1 mm to 15 mm. The aperture 104 may have a diameter of about 12 mm. In some embodiments, the aperture 104 may have a diameter in the range of about 1 mm to 5mm. The aperture 104 may have a diameter of about 3 mm. The aperture 104 may be positioned on the substrate 102 such that it is substantially in line with focal plane of the objective when the frame 106 is mounted to the objective. In some embodiments, a transparent substrate 116 may at least partially cover the aperture 104 of the substrate 102. The transparent substrate 116 may provide a cover over the aperture 104 by being placed upon the first or upper surface 105 of the substrate 102. Alternatively, the transparent substrate 116 may cover the aperture 104 by being attached to the reverse surface 107 of the substrate 102. In some embodiments, the transparent substrate 116 is dimensioned to fit entirely within the bounds of the aperture 104. The transparent substrate 116 may be fixedly attached or removably attached to the substrate 102. For example, the transparent substrate 116 may be glued to the first or upper surface 105 or the second reverse or lower surface 107 of the substrate 102, or it may be glued to the side wall(s) of the aperture 104.

[0054] The transparent substrate 116 may be made of a suitable transparent material for example, glass, polymers, crystal, gemstones, acrylic, polycarbonate, resin, or quartz. In some embodiments, the transparent substrate 116 is made of glass, and embedded within the aperture of the substrate 102 to entirely cover the aperture whilst enabling light to pass through. In some embodiments, the transparent substrate 116 may be attached to the electromagnetic frequency delivery system. The transparent substrate 116 may have a thickness in the range of about 0.1 mm to about 1 mm. In some embodiments the transparent substrate 116 may have a thickness ofabout 0.15 mm. In some embodiments, the transparent substrate 116 may have a thickness of about 0.17 mm.

[0055] Figure 2A is a schematic diagram of a bottom view of a substrate in the form of a PCB 200, according to some embodiments. The bottom view of the PCB 200 shows an underside or second reverse surface 203 of the PCB 200. In this example, the PCB 200 includes an integrated antenna 202, such as a loop antenna. An aperture 204 is disposed at or toward the center of the loop antenna 202. The aperture 204 is entirely covered by a transparent substrate 206, such as a glass substrate, adhered to the PCB 200 in this example. A quantum sensor 208, for example, a diamond sensor, is coupled or adhered, for example, glued, to the bottom surface of the transparent substrate 206. Although in this embodiment the quantum sensor 208 is only partially covering the aperture, in some embodiments the quantum sensor 208 may entirely cover the aperture 204.

[0056] Figure 2B is a schematic diagram of a top view of the PCB 200, having a frame 201 attached, according to some embodiments. The top view of the PCB 200 shows a first surface 205 or an upper surface of the PCB 200. The first surface 205 of the PCB 200 includes a frame 201 attached to the first surface 205, the frame 201 including a connecting segment (not shown) attached at a first end to the PCB 200, and a mounting segment 212 attached to the second end of the connecting segment, the mounting segment 212 defining an opening 214 configured to receive at least part of an objective. The PCB 200 also includes a connector 216, such as a microwave connector, configured to receive a cable or lead (not shown) to feed electromagnetic radiation into the antenna 202.

[0057] The quantum sensor 208 may be attached directly to the PCB 200, or it may be attached to the transparent substrate 206 attached to the PCB. In some embodiments, the quantum sensor 208 is attached to a first surface 205 or a reverse surface 203 of the PCB 200 proximate to the aperture 204, such that the quantum sensor 208 at least partially covers the aperture 204. For example, the quantum sensor 208 may be attached to the first surface 205 or the reverse surface 205 of the PCB 200 to overlap and cover the aperture 204, or it may be attached to the periphery of the aperture 204 such that it sits within, and entirely covers, the aperture 204. The quantum sensor 208 may be attached to the transparent substrate 206 which covers the aperture 204, such that the quantum sensor 208 is centred on the aperture 204 and / or aligns with the centre of theaperture 204 to at least partially cover the aperture 204. In some embodiments, the quantum sensor 208 may be larger than the aperture 204, and the quantum sensor 208 may substantially cover the aperture 204. In some embodiments, the quantum sensor 208 may be smaller than the aperture 204, and the quantum sensor 208 may partially cover the aperture 204. The quantum sensor 208 may be attached to the transparent substrate 206 using an adhesive material, such as a low fluorescence glue. When the frame 201 is mounted on an objective (not shown), the quantum sensor 208, disposed over the aperture 204 of the PCB 200, is brought into alignment with the focal plane of the objective.

[0058] Figures 3A to 3D are cross sectional diagrams showing example configurations in which the quantum sensor and / or the transparent substrate are attached to a substrate 300, according to some embodiments. Figure 3A shows a substrate 300 defining an aperture 304, and a transparent substrate 306 attached to the reverse surface 302 of the substrate 300. The quantum sensor 308 is adhered to the reverse surface 302 of the transparent substrate 306, centrally aligned with the aperture 304. Figure 3B shows the substrate 300 defining an aperture 304, with the quantum sensor 308 attached directly to reverse surface 302 of the substrate 300, entirely covering the aperture 304 and overlapping the reverse surface. In this example, the quantum sensor 208 is larger than the aperture 304 defined by the substrate. Figure 3C shows the substrate 300 defining an aperture 304, with the quantum sensor 308 disposed within the aperture 304 and attached directly to at least part of the wall 303 defined by the aperture 304. The quantum sensor 308 extends through the aperture 304 from the first surface 301 to the reverse surface 302. Figure 3D shows the substrate 300 defining an aperture 304, and the transparent substrate 306 attached to the wall 303 defined by the aperture 304. The quantum sensor 308 is attached or adhered to the transparent substrate 306 such that it is centrally aligned with the aperture 304, and disposed partially within the aperture 304, extending above the reverse surface 302 of the substrate 300.

[0059] The quantum sensor 308 may be a quantum magnetic field sensor. The quantum sensor 308 may be a solid-state quantum sensor (SSQS). The quantum sensor 308 may be a diamondbased quantum sensor, such as a diamond. The quantum sensor 308 may include a diamond containing nitrogen- vacancy centres. The diamond containing nitrogen- vacancy (NV) centres can act as a magnetic field sensor whose sensing method involves optical excitation and readout of the spin-state. The diamond may be a high -pressure high-temperature diamond. In someembodiments, the diamond may be { 100} oriented. In other embodiments, the diamond may be { 111 } oriented or { 110} oriented. The diamond may have a thickness in the range of about 1 to 500 |im. In some embodiments the diamond may have a thickness of about 400 |am.

[0060] For a diamond-based quantum sensor, an illumination source is used to excite the NV center(s) of the diamond quantum sensor and the photoluminescence may be imaged using a camera. In some embodiments, electromagnetic radiation, for example, microwave radiation, may be generated by an antenna, such as a loop antenna, which surrounds the quantum sensor. The microwave radiation may be generated by a control box which feeds microwaves into a microwave connector integrated into the substrate. By generating microwave radiation incident on the quantum sensor, the microwave field can be used to probe the electron spin resonances of the NV center quantum sensor owing to spin-dependent photoluminescence. That is, the stray magnetic fields produced by a sample can be imaged by the quantum sensor through its photoluminescence (PL) response. This may be referred to herein as optically detected magnetic resonance (ODMR). In some embodiments, an externally applied bias magnetic field may be used to shift the spin resonances.

[0061] In some embodiments, the quantum sensor may be formed from any material suitable for an optically addressable quantum sensor. In some embodiments, the quantum sensor may be formed from materials other than diamond, for example, silicon carbide, boron nitride or an organic semiconductor such as, but not limited to, super yellow poly(p-phenylene-vinylene) (PPV) copolymer (SY-PPV). In some embodiments, the quantum sensor may comprise or further include graphene(s), mxenes, quantum dots, films of quantum dots, semiconductors, organic films, magneto-optical sensors or electro-optical sensors (transducers).

[0062] Referring back to Figures 2A and 2B, the PCB 200 may include an electromagnetic antenna 202 configured to generate an electromagnetic field incident on the aperture 204. The electromagnetic antenna 202 may be a radio frequency (RF) antenna. In some embodiments, the electromagnetic antenna 202 may be a microwave antenna. The antenna 202 may be a loop antenna, disposed around the aperture 204 of the PCB 200. In some embodiments, the antenna 202 is a microwave loop antenna, substantially centred around the aperture 204. The antenna 202 may be configured to generate an electromagnetic field incident on the aperture 204 using microwave radiation.

[0063] In some embodiments, electromagnetic radiation, such as microwaves, is generated by the antenna 202 which is in close proximity to the quantum sensor 208 located within or around the aperture 204. The electromagnetic field, such as a microwave field, may be directed towards, or incident on, the quantum sensor 208. In some embodiments, the electromagnetic radiation may be generated using connecting leads or cables (not shown) attached to the first surface 205 and / or the reverse surface 203 of the PCB 200.

[0064] The PCB 200 may include at least one connector 216 to enable connection of a cable (not shown) to the PCB 200. The connector 216 may be configured to facilitate delivery of electromagnetic radiation to the PCB 200. In some embodiments, the connector 216 may be a microwave connector, configured to receive a microwave cable for inputting microwaves to the PCB 200. The connector 216 may be coupled to the antenna 202. The connector 216 may be a SubMiniature version A (SMA) connector or a SubMiniature version B (SMB) connector. In some embodiments, the PCB 200 may include a pair of connectors. The pair of connectors may be disposed on opposing edges of the first surface 203 of the PCB. Two connectors may be beneficial to ensure that at least one connector is accessible at any given position in which the PCB 200 is mounted.

[0065] As shown in the device 100 of Figure 1, the substrate 102 may include an embedded waveguide 114. In some embodiments, the embedded waveguide 114 is a microwave waveguide, configured to guide microwaves from the input connector 112 toward the antenna. Microwaves may be supplied by a microwave cable (not shown) attached to the connector 112. In some embodiments, the waveguide 114 may deliver the microwaves to the quantum sensor 108 directly, without an antenna. The waveguide 114 may be disposed on the reverse surface 107 of the substrate 102. In some embodiments, the waveguide 114 may be coupled to the antenna (not shown), such that the waveguide 114 couples energy into the antenna. In some embodiments, the electromagnetic antenna may not be integrated in the substrate 102, but instead may be included on the transparent substrate 116. In some embodiments, the waveguide 114 may be configured to act as an antenna. In other embodiments, an electromagnetic antenna may not be provided on the substrate 102, and electromagnetic radiation may instead be provided by an external source configured to generate electromagnetic radiation.

[0066] Referring back to Figure 1, the device 100 includes a frame 106 attached to, and extending upwards from, the first surface 105 of the substrate 102. The frame 106 includes at least one connecting segment 118 and a mounting segment 120. The at least one connecting segment 118 has a first end attached to the substrate 102, and a second end attached to the mounting segment 120. The frame 106 is configured to be mounted to the objective 122, thereby holding the substrate 102 in place under the objective 122 such that the focal plane of the objective and the aperture 104 of the substrate 102 are aligned. The frame 106 may be configured to be removably attachable to the objective 122, or it may be fixedly attached. In some embodiments, the frame 106 may be integrally formed with the objective 122. The frame 106 may be substantially rectilinear in shape, or it may be rounded. For example, the frame 106 may be substantially cylindrical. In some embodiments, the shape of the frame 106 defines a sleeve. The frame 106 may receive the objective 122 such that the focal plane of the objective and the aperture 104 of the substrate 102 are aligned. The frame 106 may be configured to at least partially encompass the objective 122, or entirely encompass the objective 122. The frame 106 may be of any appropriate shape to receive the objective, for example, the frame 106 may be substantially rectilinear or substantially cylindrical. The frame 106 may be formed from injection molding or by 3D printing.

[0067] The at least one connecting segment 118 extends upwards from the substrate 102, being configured to join the substrate 102 to the mounting segment 120. In some embodiments, the connecting segment 118 extends between the substrate 102 and the mounting segment 120 to allow appropriate separation between the mounting segment 120 and the substrate 102. For example, to enable the substrate 102 to sit below, and be spaced apart from, the objective 122. The connecting segment 118 may define the sides of the frame 106. In some embodiments, the length of the connecting segment 118 may be determined based on the dimensions of the objective 122.

[0068] The at least one connecting segment 118 may be of varying shapes and forms. In some embodiments, the connecting segment 118 may include at least one elongate structural member, such as a beam extending substantially vertically between the mounting segment 120 and the substrate 102. In some embodiments, there may be a plurality of connecting segments 118, such as elongate structural members, extending from the substrate 102 to the mounting segment 120. In some embodiments, the connecting segment 118 may be in the form of a surface, for example,a wall. The surface may be substantially planar or may be substantially curved. In some embodiments, the connecting segment 118 may be tubular, for example, forming a substantially cylindrical shape. The connecting segment 118 may form a cylindrical sleeve, where one end of the sleeve is attached to the substrate 102, and the other end of the sleeve is attached to the mounting segment 120, and the sleeve is configured to encompass the objective 122, as shown in the configuration of Figure 1. Where the connecting segment 118 forms a sleeve, the dimensions of the sleeve may be determined by the dimensions of the objective 122 encompassed by the connecting segment 118. For example, the diameter of such a cylindrical connecting segment may be determined on the basis of the diameter of the objective 122.

[0069] In some embodiments, all or part of the connecting segment 118 may be solid and / or continuous. In some embodiments, all or part of the connecting segment 118 may be flexible and / or include one or more flexible and / or adjustable components. In some embodiments, the connecting segment 118 may form a mesh-type or cage-type structure configured to connect the substrate 102 and the mounting segment 120.

[0070] The connecting segment 118 may be attached directly or indirectly to the substrate 102. The connecting segment 118 may be removably attachable to the substrate 102, such that the substrate 102 is able to be swapped out without removing the frame 106 from its mounted position on the objective 122. For example, the connecting segment 118 may be attached to the substrate 102 by mating with a detachable snap fit protrusion extending from the substrate 102. The connecting segment 118 may be attached to the substrate 102 by, for example, a screw fastener, snap fastener, hook-and-loop fastener, magnetic attachments, clips, bayonet mounts, quick-release buckles, latches, catches, spring clip and pins, slide rails and tracks, threads and / or twist locks. In other embodiments, the connecting segment 118 may be fixedly attached to the substrate 102. For example, the first end of the connecting segment 118 may be fixedly attached to the substrate 102 by adhesive or chemical bonding (such as glue), welding, soldering, rivets, nails and / or fixed joints between the connecting segment 118 and the substrate 102 or a component of the substrate 102.

[0071] The connecting segment 118 may be attached proximate to one or more edges or corners of the substrate 102. This may reduce interference with any circuitry integrated on the substrate 102. In other embodiments, the connecting segment 118 may be attached to thesubstrate 102 within the boundaries of an antenna and / or waveguide 114, and / or proximate to the aperture 104. In embodiments where a plurality of connecting segments are used, the plurality of connecting segments may be equally spaced apart from one another. The plurality of connecting segments may be equally spaced apart from the aperture 104 of the substrate 102. Alternatively, the plurality of connecting segments may be clustered in groups, for example, they may be disposed on opposing ends of the first surface 105 of the substrate 102.

[0072] In some embodiments, the connecting segment 118 may include an adjustable component, for example to vary the length or height of the connecting segment 118. In some embodiments, the connecting segment 118 may be attached indirectly to the substrate 102 through an adjustable component, such as a mount adjuster.

[0073] Figure 4A is a diagram of a connecting segment 400 in the form of a sleeve being attachable to the substrate 402 through a screw mount 405, according to some embodiments. The screw mount 405 includes a threaded protrusion 407 extending from a first surface 401 of the substrate 402. The threaded protrusion 407 may be substantially circular in shape, having a thread on the outer surface of the protrusion, and has a diameter less than the diameter of the connecting segment 400. The threaded protrusion 407 is disposed around the aperture, and within the bounds of the diameter of the connecting segment 400. The threaded protrusion 407 may be spaced apart from any connectors 404 disposed on first surface 401 of the substrate 402 to enable the connectors to be in use when the connecting segment 400 engages with the screw mount 405. The lower end of the connecting segment 400 includes a corresponding thread 406, configured to threadingly engage with the thread of the threaded protrusion 407. It will be appreciated that the threaded protrusion 407 may be of any appropriate shape to engage with the shape of the connecting segment 400. Once engaged, the connecting segment 400 is attached to the substrate 402 via the screw mount 405. The screw mount 405 may be adjustable, such that rotation of the substrate 402 with respect to the connecting segment 400 may increase and / or decrease the vertical distance Az, between the objective 410 and the quantum sensor 408 disposed on the substrate 402.

[0074] In some embodiments, the connecting segment 400 may engage with a threaded portion on an adjustable component (not shown) attached to the first surface 401 of the substrate 402. The connecting segment 400 may be attached to the adjustable component, such as an adjustablescrew mount, and the adjustable component may be rotated to increase or decrease the length and / or height of the adjustable component to increase and / or decrease the vertical distance Az between the objective 410 and the quantum sensor 408 disposed on the substrate 402, without disengaging the connecting segment 400 from the adjustable component or the adjustable component from the substrate 402.

[0075] Figure 4B is a top view diagram of a substrate 450 showing an adjustable screw mount 452 attached to the first surface 451 of the substrate 450, according to some embodiments. The adjustable screw mount 452 is disposed within the boundary of an antenna 454, and spaced apart from a connector 456, such as a microwave connector, also disposed on the first surface 451 of the substrate 450. The adjustable screw mount 452 surrounds an aperture (not shown), disposed through the substrate 450 from the first surface 451 to the second reverse surface (not shown), which contains a quantum sensor (not shown).

[0076] Figure 5 is a diagram showing a screw mount 502 attached to a frame 501, and the frame 501 mounted on an objective 500, according to some embodiments. The screw mount 502 is threadingly engaged with a first end of the connecting segment 504 in the form of a sleeve. The screw mount 502 is shown fully engaged in Figure 5, where the vertical distance between the objective 500 and a quantum sensor 506 is at its lower limit. Upon rotation of the substrate 508, the screw mount 502 partially disengages the screw thread 510 of the connecting segment 504 such that the substrate 508 remains attached to the connecting segment 504 by the screw mount 502, but the substrate 508 moves away from the objective 500 as the screw mount 502 is disengaged, or unscrewed, from the connecting segment 504, thereby increasing the vertical distance between the objective 500 and the quantum sensor 506. The sample 512 may be moved independently relative to the quantum sensor 506 and / or the objective 500. For example, the sample 512 may be placed on a mechanical stage with adjustable lateral position, vertical position, pitch tilt and yaw tilt.

[0077] The adjustable screw mount 502 enables control of the placement of the quantum sensor 506 with respect to the focal plane of the objective 500. In some embodiments, the screw mount 502 provides a generalised approach to control the placement of the quantum sensor 506 with respect to the focal plane of the objective 500. This makes it suitable to enable mounting of the quantum microscopy device shown in Figure 5 onto a commercial microscope. As high precisionis not required in the case of a lower magnification objective (for example, a 4x magnification objective), the screw mount 502 between the substrate 508 and the connecting segment 504 can be used to adjust the distance from the quantum sensor 506 to the objective 500. In some embodiments, the lateral movements and tilt of the quantum sensor 506 are fixed. By rotating the substrate 508, the distance between the objective 500 and the quantum sensor 506 may be changed. The rotation may be used to fine tune the position of the quantum sensor 506 along the optical axis for optimised focus. In some embodiments, locking screw rings (not shown) may be used to fix the screw mount 502 at a specific position.

[0078] Referring again to Figure 1, a mounting segment 120 may define a top portion of the frame 106. The mounting segment 120 is attached to the second end of the connecting segment 118, for example, the opposing end to that connected to the substrate 102. In some embodiments, the mounting segment 120 may be fixedly attached to the at least one connecting segment 118, or it may be removably attachable to the at least one connecting segment 118. In some embodiments, the frame 106 may be integrally formed such that the mounting segment 120 and the connecting segment 118 are formed in a single piece. The mounting segment 120 may be substantially planar and / or flat, configured to abut a surface of the objective 122. The mounting segment 120 may be polygonal or circular in shape, and the dimensions of the mounting segment 120 may depend on the dimensions of the connecting segment 118 and the dimensions of the objective 122. For example, the mounting segment 120 may be of any appropriate shape, and may be shaped to attach to the at least one connecting segment 118 and to receive at least part of the objective 122. In some embodiments, the mounting segment 120 may not be planar, but instead may be configured to encircle or surround at least part of the objective 122. For example, the mounting segment 120 may be substantially annulus-shaped, rectangularly annulus-shaped, torus-shaped or flat torus-shaped. In some embodiments, the mounting segment 120 may be configured to encompass at least part of the body of the objective 122. In further embodiments, the mounting segment 120 may be defined by a flange that extends substantially perpendicular from the at least one connecting segment 118.

[0079] The mounting segment 120 is configured to receive at least part of an objective 122 to mount the frame 106 on the objective 122. In some embodiments, the mounting segment 120 defines an opening that is configured to receive at least part of the objective 122. For example, part of the objective may be the objective screw 124. In some embodiments, the mountingsegment 120 may include an aperture (not shown) that is designed to receive an objective screw 124. The aperture may be big enough to receive the screw 124, but not big enough to receive the body of the objective 122. This configuration enables a surface of the mounting segment 120 to abut a surface of the objective 122, whilst allowing the objective screw 124 to be received by an objective receptacle 126 in a microscope. Once the objective 122 is engaged with the objective receptable 126, the mounting segment 120 is kept in place by a clamping force applied to the mountain segment 120 between the objective 122 and the receptacle 126.

[0080] In some embodiments, the mounting segment 120 may include an attachment mechanism for attaching the mounting segment 120 to the objective 122. For example, the attachment mechanism may include a screw mount adapter, where the screw mount adapter is configured to threadingly engage with the objective screw 124 and the objective receptacle 126, or configured to threadingly engage with at least part of the objective screw 124, before the objective screw 124 is engaged with the objective receptable 126. In some embodiments, the attachment mechanism may be a screw clamp, configured to apply a clamping force to opposing sides of the objective 122 to hold the frame 106 in a fixed position with respect to the objective 122. In some embodiments, the mounting segment 120 may be integrally formed with the objective 122. For example, the mounting segment 120 may be integrally formed with the case of the objective 122 and include means for engaging the at least one connecting segment 118.

[0081] In some embodiments, the mounting segment 120 includes an attachment mechanism configured to attach the mounting segment 120 to a secondary component, wherein the secondary component is mounted on the objective 122. For example, the mounting segment 120 may include a screw mount configured to be received by a corresponding thread of a secondary component attached to the objective. The secondary component may include means for adjusting the position of the frame 106 and / or the substrate 102 with respect to the objective, and may include, for example, a thread mount adjuster or a mechanical stage.

[0082] The quantum microscopy devices disclosed herein may further include an illumination source. Figures 6A and 6B are schematic diagrams of a quantum microscopy device 600 mounted on an objective 602 showing an integrated illumination source 604, according to some embodiments. Figure 6A illustrates the illumination source 604 disposed on the reverse surface 603 of the substrate 606, configured to transmit light to the quantum sensor 608 from an adjacentposition. Figure 6B illustrates the illumination source 604 disposed within the frame 610, directing light through the transparent substrate 612 and towards the quantum sensor 608 at a position which maintains enough separation to still allow the imaging optics of the objective 602 to function.

[0083] The illumination source 604 may be configured to provide light excitation to the sensor 608. The illumination source 604 may be integrated directly into the frame 610. In some embodiments, the illumination source 604 may be incorporated into the substrate 606 through an embedded photonic waveguide (not shown). In some embodiments, the illumination source 604 may be attached directly or indirectly to the substrate 606. For example, an illumination source 604 in the form of a light-emitting diode (LED) may be attached directly to the substrate 606. In some embodiments, the illumination source 604 is configured such that it can transmit light onto the sensor 608 without the need to pass through imaging optics in the objective 602. The illumination source 604 may include on-chip integration of photonics. In some embodiments, the illumination source 604 may include coupling to an external light source through optical fibres and / or waveguides. In further embodiments, the illumination source 604 may include light emitting elements, such as rings, disposed in the frame 610. In some embodiments, the illumination source 604 may be an LED. The inclusion of an illumination source 604 into the quantum microscopy device 600 removes the requirement for external light illumination which is advantageous in cases where the device 600 is fitted to a commercial optical microscope which may not be equipped with a suitable light source for the quantum sensor readout.

[0084] In some embodiments, the quantum microscopy devices described herein may be mounted on an existing microscope, such as a commercially available microscope. As shown in Figure 1, the quantum microscopy device 100 can be mounted on an existing commercial optical microscope by mounting the device 100 on an objective configured to attach to the microscope. Some embodiments provide a method for converting an optical microscope into a quantum microscope, including providing a quantum microscopy device as described herein, and mounting the quantum microscopy device to the objective (or a secondary component mounted on the objective), such that the quantum sensor of the quantum microscopy device is disposed beneath and sufficiently spaced apart from the objective, and is aligned with the focal plane of the objective to allow magnetic field imaging.

[0085] In some embodiments, a method for mounting the quantum microscopy device to an optical microscope may include removing an objective from the microscope, screwing the objective into the device, for example, by screwing the objective into a screw adaptor, and then screwing the objective and / or the device into an objective receptacle within the microscope. In some embodiments, a method for mounting the quantum microscopy device to an optical microscopy may include mounting the device to an objective by bringing two or more parts together. For example, this may include placing the mounting segment of the frame of the device over an objective attached to the microscope and attaching a first end of the connecting segment of the frame to the mounting segment, wherein the second end of the connecting segment is attached to a substrate configured to accommodate a quantum sensor. In another example, the frame may be configured to be placed over the objective attached to a microscope, and the mounting segment may be configured to lock, tighten or otherwise attach to the objective once in position such that the frame is mounted to the objective without removing the objective from the microscope. In some embodiments, a method for mounting the quantum microscopy device to an optical microscope may include removing an objective from the microscope, placing the frame over the objective such that the objective is received within the frame, and then screwing the objective back into an objective receptable within the microscope, such that at least a part of the frame is clamped between the objective and the objective receptable to mount the frame to the objective.

[0086] Some embodiments provide a method for magnetic field imaging using the device(s) described herein. In some embodiments, there is provided a method of magnetic field imaging including using any of the quantum microscopy devices disclosed herein to perform magnetic field imaging. In some embodiments, a method of magnetic field imaging using the devices disclosed herein may include the use of a control box, wherein the control box includes a microwave generator, or an RF generator, software, and a camera attached to a microscope camera port. The control box may be used to control the illumination source and the frequency. For example, the microwave generator may be used to sweep through a range of frequencies during the imaging process. The method may include obtaining one or more camera frames corresponding to one or more microwave frequencies and performing signal processing on the frames corresponding to the frequencies to obtain a magnetic field image.

[0087] In some embodiments, the quantum microscopy devices described herein may be integrated into a microscope. In some embodiments, there is provided a microscope including the quantum microscopy device described herein. Figure 7 is a schematic diagram of a quantum microscopy device 700 integrated into a microscope 701, according to some embodiments. The microscope includes a 4x magnification objective 702, lenses 715, a dichroic mirror 703 and an illumination source 704 in the form of a light emitting diode (LED) for illumination of the quantum sensor 705. The quantum microscopy device 700 may be, for example, similar to devices 100 and 600. The device 700 includes a frame 706 having a connecting segment 707 in the form of a sleeve, a mounting segment 708 to mount the frame 706 to the body of the microscope 701, and a substrate 710, such as a PCB, attached to the connecting segment 707. The substrate 710 comprises a first surface 713 and a second reverse surface 711, wherein at least one aperture 712 is disposed through the substrate 710 from the first surface 713 to the second reverse surface 711. The substrate 710 is configured to accommodate a quantum sensor 705 to be positioned at least partially over the at least one aperture of the substrate 710. A quantum sensor 705 is disposed on a transparent substrate 709 attached to the substrate 710. The quantum sensor 705 is aligned with the focal plane of the objective 702. The microscope 701 is configured to perform magnetic imaging of the sample 714 placed beneath the quantum sensor 705.

[0088] The microscope 701 may also include a camera 716 for sensor readout. In some embodiments, the microscope 701 includes additional electronics and software such as a control box (not shown) configured to provide control of the input electromagnetic radiation, such as microwaves, and provide optical readout of the quantum sensor 705 to produce a magnetic field image. In some embodiments, the control box may include a microwave generator and an amplifier.

[0089] Figure 8 shows an example magnetic image obtained by the quantum microscope of Figure 7, according to some embodiments. As a test sample, a magnetic patterned CoFeB thin film, placed in proximity to the quantum sensor 705 was used. The example magnetic image shows a spatial resolution of about 10 micrometers.

[0090] To obtain a higher spatial resolution, an additional fine control configured to control the distance between the quantum sensor 705 and the objective 702 may be added. It is beneficial tohave an additional axis of motion for the quantum sensor 705 including at least one of lateral position, pitch, and yaw tilting. This additional axis of motion is enabled by placing the quantum microscopy device 700 on an adjustable mount with the desired degrees of freedom, which enables the fine control. In some embodiments, the fine control may be performed by having an adjustable mount on the objective 702. In some embodiments, the control of the axis of motion may be implemented with mechanical hand-controlled stages and / or electrically controlled stages for greater precision.

[0091] Figure 9 is a partially exploded- view diagram of a high precision quantum sensing microscope 900, according to some embodiments. A quantum sensor 902 is attached to a substrate 904, such as a PCB. The quantum sensor 902 may be a diamond-based SSQS that contains nitrogen-vacancy centres. The substrate 904 may be similar to the substrate configurations shown in Figures 2A, 2B, or 4B. The frame 906 has been 3D printed, and is made up of four connecting segments 908 in the form of substantially elongate structural members, integrally formed with a mounting segment 910 that receives at least part of an objective 912. The mounting segment 910 is configured to attach to a mechanical stage 914 that is configured to enable fine control of the vertical and lateral position, as well as pitch and yaw tilting of the quantum sensor 902. The mechanical stage 914 is mounted on the objective 912. In some embodiments, the mechanical stage 914 may be mounted on another part of the microscope 900, such as the microscope body. The sample 916 is located on a stage 918, which may also be configured to control the vertical and lateral position, and the pitch and yaw tilting of the sample, to enable precise positioning of the sample in close proximity to the quantum sensor 902. Figure 9 provides a complete quantum microscope, able to perform microscopic imaging of magnetic fields. The microscope 900 additionally includes an illumination source 920 in the form of an LED, and a camera 922 for imaging. The microscope may further include the required electronics and software (not shown) to enable the acquisition of magnetic field images of the sample 916. In some embodiments, the quantum microscope 900 may include an objective 912 with a magnification of 4x, lOx, 20x, 40x and / or 50x. The objective 912 may be an air and / or oil objective.

[0092] Figure 10 is a schematic diagram of another quantum microscopy device 1000 integrated into a microscope 1002, according to some embodiments. In this embodiment, quantum microscopy device 1000 includes a substrate, for example, a PCB 1004, having a firstsurface and a reverse, or opposite, surface (not shown). An aperture 1006 is disposed in the PCB 1004 and extends from the first surface through to the reverse surface. The PCB 1004 is configured to accommodate a quantum sensor 1008, for example, a diamond sensor. The quantum sensor 1008 may be coupled or adhered to the PCB 1004 or coupled to or adhered to a transparent substrate or coverslip (not shown), with the coverslip attached and / or adhered to the PCB 1004. In some embodiments, the quantum sensor 1008 may be a diamond sensor with dimensions of about 4 mm x 4 mm x 400 pm.

[0093] Quantum microscopy device 1000 includes a frame comprising a connecting segment 1012. The connecting segment 1012 is attached at a first end to the first surface of the PCB 1004. The PCB 1004 may include an 8 mm microwave (MW) loop antenna.

[0094] The frame further comprises a mounting segment 1014 attached to a second end of the connecting segment 1012. The mounting segment 1014 includes a mounting plate 1016 with an aperture (not shown) configured to receive at least part of an objective 1018 therethrough. The objective 1018 may be, for example, a Plan Achromatic 4x / 0.10 NA objective. The mounting plate 1016 has external threading (not shown) which is used to mount the plate 1016 to the objective 1018. The mounting plate 1016 includes a first arm 1010 and a second arm 1011. In some embodiments, the mounting plate 1016 may have more or less arms. The first arm 1010 extends from the mounting plate 1016 and may be hingedly or rotatably attached to the mounting plate 1016 such that the position of the arm 1010 may be adjustable. The first arm 1010 may be configured to hold a lens 1015 for collimation of a fibre coupled laser light from an illumination source 1017, for example, to provide side illumination of the quantum sensor 1008. In some embodiments, the illumination source 1017 may include a laser. For example, the laser may be a Laser Quantum Opus 2 W (532 nm). The second arm 1011 extends from the mounting plate and may be hingedly or rotatably attached to the mounting plate 1016 such that the position of the arm 1011 may be adjustable. The second arm 1011 includes a slot (not shown) for mounting and / or adjusting the angle of a magnet 1019 configured to be held by the arm 1011. The magnet 1019 may be a bias magnet.

[0095] The mounting segment 1014 further includes a body 1022 attached to and extending in a downward direction from the underneath of the mounting plate 1016. In some embodiments, the body 1022 may be directly or indirectly connected to the mounting plate 1016. In theembodiment shown in Figure 10, the mounting segment 1014 further includes an adjustable screw mount in the form of a rotating collar 1020 configured to connect the underneath of the mounting plate 1016 and the first end of the body 1022. That is, the rotating collar 1020 may be at least partially engaged with the mounting plate 1016, and at least partially engaged with a first end of the body 1022, for example, via a threading engagement.

[0096] The rotating collar 1020 may be an internally threaded rotating collar, which, when rotated, is configured to increase or decrease the amount of separation between the underneath of the mounting plate 1016 and the first end of the body 1022. The internally threaded rotating collar may therefore be used for tuning the vertical height (z) to bring the quantum sensor 1008 into optical focus with respect to the objective 1018.

[0097] The second end of the connecting segment 1012 may include a slider mechanism to enable the second end of the connecting segment 1012 to engage with a second end of the body 1022 of mounting segment 1014. For example, the slider mechanism may include at least one dovetail joint 1024 to hold the second end of the connecting segment 1012 to attach to the mounting segment 1014. In some embodiments, the slider mechanism may include two, three or four dovetail joints to attach the connecting segment 1012 to the mounting segment 1014. The at least one dovetail joint enables the PCB 1004 to be held in place with reference to the body 1022 of the mounting segment 1014. The connecting segment 1012 may further include one or more gaps between and / or aligned with dovetail joints and / or parts of the connecting segment 1012 which are attached to the PCB 1004, so as to allow enough space for side illumination of the quantum sensor 1008 by illumination source 1017, for example, a laser. In some embodiments, the connecting segment 1012 may be made partially or entirely of a transparent material, so as to allow side illumination of the quantum sensor 1008 by an illumination source.

[0098] In some embodiments, attaching the connecting segment 1012 to the mounting segment 1014 of the device 1000 may complete the installation of the device 1000 onto the microscope 1002. For example, the second end of the connecting segment 1012 may be slotted into the second end of the body 1022 of the mounting segment 1014, where the mounting segment 1014 is already attached to the objective 1018 of a microscope 1002. The microscope 1002 may be a commercial microscope system for example, the OXJS304, Biology research microscope, trinocular, 3 W LED, 110-240 V. The quantum microscopy device 1000, on being attached to themicroscope 1002, enables the microscope 1002 to perform NV centre based widefield magnetic imaging.

[0099] Figure 11A is an example image obtained by the high precision quantum sensing microscope 900, according to some embodiments. The quantum microscope 900 of Figure 9 was used to image magnetic FC2O3 nanoparticles having diameters of about 5 nm to 50 nm as a test sample. The image shows that the quantum microscope 900 which integrates the frame 906 and substrate 904 arrangement is able to get near, or reach, diffraction limited magnetic imaging with the objective 912. Additionally, Figure 11B is a graph of the linecut through a magnetic bead, having the same magnetic nanoparticles of the sample in Figure 11 A, which demonstrates a magnetic spatial resolution of 930 nm, which is similar to the theoretical diffraction limit of 740 nm.

[0100] The quantum microscopy devices disclosed herein provide a number of technical advantages to the field of quantum microscopy. The design of the quantum microscopy devices is small, compact and robust, making it an efficient and practical device to retrofit existing microscope systems to enable quantum sensing.

[0101] As the device is configured to be mounted on the microscope objective, a single quantum sensor can be easily removed and attached to other objectives. Additionally, this removes the requirement to place the sample directly onto the quantum sensor, making interfacing the microscope with any sample significantly easier and more efficient. Additionally, the device provides a straightforward way to enable the imaging of magnetic fields. By mounting the quantum sensor to a microscope objective, the usability of techniques to image magnetic fields is improved. Thus, such a device could be used by someone with little to no training.

[0102] The device affords flexibility on implementation. Due to the minimal design and the ability to retrofit existing microscope systems with the device, there is a significant cost benefit over designs which would require an entirely new microscope to be purchased just to image magnetic fields. Further, sample universality is achieved with this device, as the devices described herein address a significant deficiency of existing technologies in which potential samples need to meet strict geometric requirements in order to be properly imaged.

[0103] The quantum microscopy device can be used to integrate the sensing chip into the imaging optics. That is, the physical connection of mounting the quantum sensor to the objective provides an interface between the sensor and the objective to create a single imaging optics component. This allows for an inverted geometry, like a traditional microscope, where the sample sits on a stage and the objective is brought down on top of the sample to image. This enables precise positioning of the sample and sensor for measurement just like in a normal microscope. Thus, this approach is generalisable to most microscope systems and is simple enough for a non-expert to use.

[0104] In addition to the advantages described above, the device can be used for a wide range of applications. The device may be used as a magnetic inspection solution for R&D, production, and quality control, across various industries involving magnets and electric currents, such as in the automotive, energy generation, medical devices, and consumer electronics sectors. Imaging magnetic fields has various applications across a wide range of sectors, including: a. Geological sector - Applications may include finding and identifying the type and concentration of magnetic deposits in rock and ore samples. While there are various techniques that can measure if a sample is magnetic, they often fail to provide an image of what that magnetism looks like. This is important for identifying the type of material that is contained within the rocks and is also important in the scientific community for various techniques including dating of rocks. Additionally, geological exploration companies that work in gold or rare earth minerals have issues in identifying the purity of new veins. This is because a lot of mineral and ore veins are associated with volcanic / igneous intrusion. Imaging of these often-magnetic impurities can be difficult. Imaging these defects using the quantum microscopy devices disclosed herein and may help to improve the allocation of resources to higher quality deposits. b. Medical sector -Markers are often used in medical research to track and identify various interactions and transport. Some of these markers can be invasive and perturb the results of the research. In some processes, magnetic beads are attached to cells and are used as tracker, but current methods for imaging these beads are complex and require expertise that is not common in the field. The quantum microscopy device disclosed herein is intrinsically biocompatible and can image these magnetic markets with significant sampleto sensor standoff. This facilitates a non-invasive magnetic imaging technique for biological systems. c. Electronics sector - Integrated circuits can involve many processes that can fail, which can be difficult to track and identify, both during manufacturing and operation. For instance, a fault in a single embedded track may impair the entire circuit. Locating the source of the defect is crucial. Current methods for identifying where the fault lies are built around layer-by-layer destruction of the circuit and visual inspection of the layer quality. This has many issues but mainly it is expensive, invasive, and is prone to errors. The techniques for magnetic imaging enabled by the quantum microscopy devices disclosed herein are nondestructive and offer an alternative approach to imaging the current flow through the circuit in order to identify the source of the fault without damaging the circuit. This also allows for additional testing to be performed after the initial magnetic images are taken. d. Material development - Magnetic materials are becoming more relevant in technology as memory and electronics becomes smaller and smaller. Part of this development involves the use of various methods to determine the qualities of new materials. Magnetic imaging of these materials is not commonplace as the expertise for such operations is often done in research at universities rather than easy to use equipment for general use. The devices disclosed herein, and their capability to convert an optical microscope to a quantum microscope, may facilitate high-throughput analysis of new materials, greatly improving material development.

[0105] It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A quantum microscopy device, including: a substrate comprising a first surface and a second reverse surface, wherein at least one aperture is disposed through the substrate from the first surface to the second reverse surface; and a frame extending from the first surface of the substrate, the frame including: at least one connecting segment having a first end attached to the substrate; and a mounting segment attached to a second end of the at least one connecting segment, the mounting segment configured to receive at least part of an objective to mount the frame on the objective; wherein the substrate is configured to accommodate a quantum sensor to be positioned at least partially over the at least one aperture of the substrate.

2. The device according to claim 1, including a quantum sensor disposed at least partially over the at least one aperture of the substrate.

3. The device according to claim 2, wherein the quantum sensor is disposed on the first surface or the second reverse surface of the substrate.

4. The device according to claim 2 or 3, wherein a transparent substrate is positioned over, or disposed within, the at least one aperture, and wherein the quantum sensor is attached to the transparent substrate.

5. The device according to claim 4, wherein the transparent substrate is glass.

6. The device according to claim 4 or 5, wherein the quantum sensor is adhered to the transparent substrate with a glue.

7. The device according to any one of claims 1 to 6, wherein the mounting segment is configured to receive the objective such that the frame extends along the length of the objective.

8. The device according to any one of claims 1 to 7, wherein the substrate is a printed circuit board (PCB).

9. The device according to any one of claims 1 to 8, wherein the substrate is configured such that a generated electromagnetic field is incident on the aperture.

10. The device according to any one of claims 1 to 9, further including an electromagnetic antenna or waveguide disposed on the substrate and configured to generate an electromagnetic field incident on the aperture.

11. The device according to claim 10, wherein the electromagnetic antenna is a loop antenna.

12. The device according to any one of claims 1 to 11, wherein the frame is configured to at least partially encase the objective.

13. The device according to any one of claims 1 to 12, wherein the frame includes a plurality of connecting segments, each having a first end attached to the substrate, and a second end attached to the mounting segment.

14. The device according to any one of claims 1 to 13, wherein the frame is substantially rectilinear in shape.

15. The device according to any one of claims 1 to 13, wherein the frame is substantially cylindrical in shape.

16. The device according to any one of claims 1 to 15, wherein the at least one connecting segment is an elongate structural member.

17. The device according to any one of claims 1 to 15, wherein the at least one connecting segment is a wall.

18. The device according to any one of claims 1 to 12, wherein the at least one connecting segment defines a sleeve configured to encase the objective.

19. The device according to any one of claims 1 to 18, wherein the mounting segment defines an opening configured to receive at least part of the objective therethrough.

20. The device according to any one of claims 1 to 19, wherein the mounting segment is configured to abut at least part of the objective.

21. The device according to any one of claims 1 to 20, wherein the mounting segment includes an attachment mechanism for attaching the mounting segment to an objective.

22. The device according to any one of claims 1 to 21, wherein the mounting segment includes an attachment mechanism for attaching the mounting segment to a secondary component, wherein the secondary component is mounted on the objective.

23. The device according to claim 21 or 22, wherein the attachment mechanism includes a cylindrical aperture with a screw thread, configured to threadingly engage with a screw thread of the objective.

24. The device according to any one of claims 21 to 23, wherein the attachment mechanism is a screw mount adapter.

25. The device according to any one of claims 1 to 24, wherein the substrate includes an embedded waveguide.

26. The device according to claim any one of claims 1 to 25, wherein the substrate includes at least one connector, disposed on the first surface.

27. The device according any one of claims 1 to 25, wherein the substrate includes a pair of connectors, disposed on the first surface.

28. The device according to any one of claims 1 to 27, wherein the at least one connecting segment includes a threaded portion, and is attached to the substrate by an adjustable screw mount.

29. The device according to claim 28, wherein the adjustable screw mount is configured to change the vertical distance between the objective and the quantum sensor upon rotation of the substrate.

30. The device according to any one of claims 1 to 29, wherein the quantum sensor is a solid state quantum sensor.

31. The device according to any one of claims 1 to 30, wherein the quantum sensor is a diamond having nitrogen- vacancy centres.

32. A quantum microscopy device, including: an objective; a substrate comprising a first surface and a second reverse surface, wherein at least one aperture is disposed through the substrate from the first surface to the second reverse surface; and a frame extending from the first surface of the substrate, the frame including: at least one connecting segment having a first end attached to the substrate; and a mounting segment attached to a second end of the at least one connecting segment, the objective extending at least partially through the mounting segment; wherein the substrate is configured to accommodate a quantum sensor to be positioned at least partially over the at least one aperture of the substrate.

33. A quantum microscopy device, including:an objective; a substrate comprising a first surface and a second reverse surface, wherein at least one aperture is disposed through the substrate from the first surface to the second reverse surface; and a frame extending from the first surface of the substrate, the frame including: at least one connecting segment having a first end attached to the substrate; and a mounting segment attached to a second end of the at least one connecting segment, the objective extending at least partially through the mounting segment; wherein the substrate is configured to accommodate a quantum sensor to be positioned at least partially over the at least one aperture of the substrate; and a mechanical stage mounted to an upper portion of the objective, and attached to the mounting segment such that the frame is mounted to the mechanical stage and the objective extends through the mechanical stage and into the frame; wherein the mechanical stage is adjustable such that the position of the quantum sensor relative to the objective is adjusted.

34. The device according to claim 33, wherein the mechanical stage is adjustable in at least one of a vertical position, a lateral position, a pitch tilt and a yaw tilt.

35. A method of imaging magnetic fields, including performing magnetic field imaging using the device of any one of claims 1 to 34.

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