Messsonde

Abstract

Method for manufacturing a measuring probe (14), comprising the following steps: Insertion of two optical fibers (24, 26) and two electrical conductors (30, 32) into a sleeve (36); Filling the sleeve (36) with a carrier material, wherein the carrier material surrounds the glass fibers (24, 26) and / or electrical conductors (30, 32) at least partially; Curing of the carrier material in the sleeve (36); Polishing one end of the glass fibers (24, 26), electrical conductors (30, 32) and / or the carrier material contained in the sleeve (36); Arranging an RF antenna (34) on the top; and Transferring a quantum emitter (28) to the tip; Laser writing of a first and second optical fiber structure (42, 44) for optical connection of the quantum emitter (28) to the first optical fiber (24) and to the second optical fiber (26), wherein the first optical fiber (24) is optically decoupled from the second optical fiber (26).

Description

[0001] The present invention relates to a method for manufacturing a measuring probe, a corresponding measuring probe and a system with a corresponding measuring probe.

[0002] Quantum emitters, such as nitrogen-vacancy centers in diamonds, are promising candidates for sensors because they exhibit high magnetic sensitivity per unit volume and, among other things, enable measurements at room temperature. It is also known that measurements at cryogenic temperatures can be performed with quantum emitters. Furthermore, electric fields, temperatures, and vectorial measurements of magnetic fields can be achieved using quantum emitters.

[0003] Previous systems with such quantum emitters are mostly built in a microscope-like manner and are therefore more complicated to handle and less flexible in their application; one such system is disclosed, for example, at https: / / doi.org / 10.1515 / nanoph-2019-0209.

[0004] Fiber-optic systems are known to improve handling. However, a disadvantage of these systems is that while a certain reduction in size can be achieved, they cannot be sufficiently miniaturized to a size of a few millimeters or less. In particular, a deterministic method for fixing and connecting nanoscopically small quantum emitters is lacking. Furthermore, the effects of intrinsic fluorescence increase with decreasing scale, thus limiting the possibilities for simple size reduction.

[0005] From patent application US 2021 / 0196177A1, a magnetoencephalography device with a first magnetic field sensor attached to a conductor is known.

[0006] The present invention aims to create a stable, movable, and / or flexible measuring platform with minimal dimensions. In particular, a measuring probe is to be created that includes all the necessary elements for measurement. Preferably, a measuring probe and a method for manufacturing a measuring probe are to be specified, wherein deterministic positioning of the quantum emitter on the measuring probe and subsequent fixation are possible.

[0007] This problem is solved by a method for manufacturing a measuring probe according to claim 1, comprising the following steps: Inserting at least two optical fibers and at least two electrical conductors into a sleeve; Filling the sleeve with a carrier material, preferably comprising an epoxy resin, wherein the carrier material surrounds the glass fibers and / or the electrical conductors at least partially; Hardening of the carrier material in the sleeve; Polishing one end of the glass fibers, electrical conductors and / or the carrier material contained in the sleeve; Arranging a high-frequency antenna, RF antenna, on the polished tip; Transferring a quantum emitter to the tip so that the quantum emitter can be excited by the RF antenna and fixed to the tip of an optical fiber; Laser writing of a first and second optical fiber structure for optical and, in particular, physical connection of the quantum emitter to the first optical fiber and to the second optical fiber, wherein the first optical fiber is optically decoupled from the second optical fiber.

[0008] Furthermore, the task is solved by a measuring probe, in particular manufactured according to the method described above, with: a quantum emitter; an RF antenna; two optical fibers and two electrical wires; a laser-written first optical fiber structure for optical connection and in particular for the physical connection of the quantum emitter to the first optical fiber, to form an optical feed line; a laser-written second optical fiber structure for optical connection and in particular for the physical connection of the quantum emitter to the second optical fiber, to form a signal line, wherein the feed line and the signal line are optically decoupled; the signal line is designed to carry a measurement signal away from the quantum emitter; and the feed line is designed to carry an excitation signal towards the quantum emitter.

[0009] Finally, the above problem is solved by a system for measuring temperature, a magnetic field and / or an electric field comprising: a measuring probe, as previously described; an optical excitation unit for exciting a quantum emitter of the measuring probe; an RF excitation unit for generating an RF magnetic field using the RF antenna of the measuring probe; and an evaluation unit for receiving and / or evaluating a measurement signal from the measuring probe in response to excitation of the quantum emitter of the measuring probe by means of an optical excitation signal and by means of an RF magnetic field; wherein The evaluation unit is designed to determine a temperature, a magnetic field and / or an electric field at the tip of the measuring probe, in particular at the quantum emitter, based on the measurement signal.

[0010] The insertion of at least two optical fibers and at least two electrical conductors into a sleeve allows for advantageous alignment of the optical fibers and electrical conductors. In particular, the use of two optical fibers minimizes disruptive autofluorescence effects, especially those of the optical fibers themselves. A higher degree of miniaturization and increased sensitivity can be achieved. A sleeve facilitates safe handling of the individual components during the manufacturing steps of the measuring probe. The sleeve is preferably designed as a cylindrical tube. Ideally, the sleeve can be removed after completion of the manufacturing process. It is understood that the sleeve can also remain attached to the measuring probe.

[0011] Using a substrate material, particularly an epoxy resin, can increase the stability of the individual components and the measuring probe. Specifically, a cured substrate material can fix the alignment and position of the individual components relative to each other. Subsequent polishing of one end of the mixture consisting of the cured substrate material, the two optical fibers, and / or the electrical conductors creates a base for bonding the optical fibers and electrical conductors. Polishing can also significantly improve signal transmission with the measuring probe.

[0012] Positioning the RF antenna on the polished tip allows for the creation of a comparatively small RF antenna that is stable and precisely aligned with the other components of the measuring probe. The RF antenna can preferably be produced using an additive manufacturing process; more preferably, it is written onto the tip using a laser writing process. The quantum emitter can then be transferred onto the prepared tip.

[0013] Preferably, the quantum emitter can be moved under the tip using an XYZ table, precisely aligned, and then transferred to the tip. Laser writing of an optical fiber structure enables precise connection of the quantum emitter to the first and second optical fibers.

[0014] Preferably, the optical decoupling is achieved such that excitation light can be directed into the quantum emitter through the first laser-etched optical guide structure in a first direction that differs from the direction caused by the second laser-etched optical guide structure to the second optical fiber. It is understood that a multitude of possible directions are conceivable. Particularly preferably, the laser-etched optical connections are configured such that the direction of the excitation light forms an angle of approximately 90 degrees with the direction of the light emitted and detected by the quantum emitter.

[0015] Preferred embodiments of the invention are described in the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. In particular, the measuring probe and the system can be configured according to the embodiments described for the method in the dependent claims.

[0016] In its preferred embodiment, the method comprises the following steps: Creating a suspension from a photoresist and the quantum emitter; Positioning the suspension, preferably as drops, on a carrier plate; Positioning the carrier plate in a predefined position relative to the polished end. The aforementioned steps are performed before the step "transferring the quantum emitter to the tip".

[0017] By introducing the quantum emitter into a photoresist suspension and transferring this droplet to the polished tip, the quantum emitter can be transferred together with a means that allows laser writing of the optical fiber structure. No additional transfer and retention structures are required, as the quantum emitter can be fixed in the photoresist by laser writing. Furthermore, optical links can be created directly via the photoresist by laser writing. Preferably, the quantum emitter in the photoresist suspension is transferred to a substrate, wherein the substrate is moved and aligned under the polished tip using an XYZ stage and then transferred onto the tip by moving the stage in the direction of the tip.

[0018] It goes without saying that more than two optical fibers can also be used. In this case, at least one of the optical fibers, which serves primarily as a feed line, is connected to the quantum emitter by means of a light guide structure consisting of a polymer. Furthermore, at least one of the optical fibers, which serves as a signal line, is connected to the quantum emitter by means of a light guide structure.

[0019] The optical fibers that serve as feed lines direct light to the quantum emitter. The optical fibers that serve as signal lines direct light from the quantum emitter to a detector unit.

[0020] Preferably, the laser writing of a first and second optical fiber structure comprises laser writing using a polymer resist of a first optical fiber structure between a core of the first optical fiber and the quantum emitter, and of a second optical fiber structure between a core of the second optical fiber and the quantum emitter. The first optical fiber structure preferably includes an optical connection to the quantum emitter that is perpendicular to an optical connection between the second optical fiber structure and the quantum emitter. This allows for the creation of a stable physical structure that fixes the quantum emitter with respect to the two optical fibers. Furthermore, the laser writing process reliably achieves optical decoupling of the first and second optical fibers at the connection point of the quantum emitter.

[0021] The RF antenna is preferably arranged at the tip using an additive manufacturing process, particularly laser writing. Additionally, the RF antenna material comprises a material compatible with that of the electrical conductors. Furthermore, the electrical conductors and the RF antenna material comprise, in particular, silver, copper, and / or gold. Laser writing of an RF antenna enables the creation of a high-precision, small-scale RF antenna. In particular, laser writing of the RF antenna allows for advantageous integration of the RF antenna with the electrical conductors. The functionality can be improved by selecting a compatible material. The quality of the obtained data can be enhanced. In particular, the reliability of the measuring probe can be increased. The method used can, in principle, produce free antenna geometries that selectively direct the field to the quantum emitter.to form homogeneous shapes in the near field and to generate the highest possible RF field intensity at the quantum emitter.

[0022] Advantageously, the method of direct laser writing of the RF antenna allows the homogeneity of the radiated near field to be optimized, thus achieving better sensitivity.

[0023] Advantageously, the method includes the step of matching the impedance of the RF antenna by measuring reflections and adjusting the length of the electrical conductors. This advantageous matching method allows a preferred impedance of the RF antenna to be set without having to make any changes to the antenna itself. In particular, the impedance of the RF antenna can also be easily changed later, if necessary.

[0024] In a preferred embodiment, the method comprises the step of attaching a static magnetic field source, in particular a permanent magnet or a coil, in the vicinity of the tip to generate a static background magnetic field. A static background magnetic field is particularly advantageous for measuring very weak magnetic or electric fields. A permanent magnet can be used to create a passive component that does not require separate control. By establishing a permanent magnetic field using a coil, a controllable background magnetic field can be created, the strength of which can be adjusted, in particular, to the area to be measured. A static magnetic field is understood to be, in particular, a magnetic field that maintains a constant magnetic field strength over a predefined period of time.

[0025] In a preferred embodiment of the measuring probe, it has at least two additional electrical conductors and an additional laser-etched RF antenna. This allows for more precise excitation of the quantum emitter by means of the two RF antennas. Particularly preferably, a superposition of different excitation modes and / or a phase of the microwave field can be implemented.

[0026] In a further preferred embodiment, the measuring probe comprises at least one additional optical fiber, which forms at least one additional feed line and / or one additional signal line. This allows the quantum emitter to be preferably superimposed with several light frequencies and optically excited more homogeneously from different directions. The additional signal line can improve the data quality of the received signal from the quantum emitter.

[0027] In a preferred embodiment of the system, the system comprises an optical interconnect unit arranged between the optical excitation unit and the measuring probe, as well as between the evaluation unit and the measuring probe. The optical interconnect unit has a first input interface, a second input interface, an optional third input interface, an output interface, and a combined input / output interface.

[0028] The interfaces are preferably designed as fiber couplers and are preferably used to connect optical fibers to the optical connection unit.

[0029] The first input interface is designed to couple in a first excitation signal in the form of laser light of a first wavelength. The second input interface is designed to couple in a second excitation signal in the form of laser light of a second wavelength. Therefore, both the first and second input interfaces can be connected to laser light sources.

[0030] The third input interface is designed for coupling in a measurement signal. Consequently, the third input interface is intended for connection to the measuring probe, in particular a signal line of the measuring probe.

[0031] The output interface is designed to extract the measurement signal. Consequently, the output interface is connected to a detector.

[0032] The combined input / output interface is designed to extract the first excitation signal, the second excitation signal, and / or to couple in the measurement signal. Consequently, the combined input / output interface is preferably connected to the signal line of the measuring probe and / or the probe's supply line.

[0033] A first light path is formed between the first input interface and the combined input / output interface by a first mirror, a second mirror, and a first beam-superimposing element, in particular a first dichroic mirror. The first light path preferably further comprises a first wave plate, a first polarizing beam splitter, and a first filter.

[0034] A second light path is formed between the second input interface and the combined input / output interface by a third mirror, a fourth mirror, and a second beam-superimposing element, in particular a second dichroic mirror. The second light path preferably comprises a second waveplate, a second polarizing beam splitter, and a second filter, and in particular passes through the first beam-superimposing element.

[0035] A third light path is formed between the combined input / output interface and the output interface by a fifth mirror and a sixth mirror. This third light path passes through the first beam-superimposing element and the second beam-superimposing element and preferably includes a third filter and a fourth filter.

[0036] A fourth optical path is formed between the third input interface and the output interface by an optional seventh mirror, the fifth mirror, and the sixth mirror. The fourth optical path preferably includes the third filter and the fourth filter.

[0037] The optical link unit further includes an optional optical separator that interrupts the third light path and shields the first and second light paths from the fourth light path. The first, second, and third light paths each feature an optional additional wave plate.

[0038] Preferably, the optical interconnect is designed as a compact box with a width of approximately 24 centimeters. The first wavelength is preferably in the range of 515 to 532 nanometers. The second wavelength covers the range of 580 to 640 nanometers.

[0039] Preferably, several wavelengths in a preferred wavelength range can also be superimposed in the first light guide path and / or in the second light guide path.

[0040] The invention is based on the measurement principle of exciting a quantum emitter, for example a diamond, with a nitrogen-vacancy center in the diamond lattice and obtaining information about magnetic and electric fields or temperatures based on brightness differences of this diamond. These brightness differences are guided to a detector via the optical fiber structure and a fiber optic cable. The basic measurement principles, such as optically detected magnetic resonance, the Zeeman effect, etc., are known to those skilled in the art and are described, for example, at https: / / doi.org / 10.48550 / arXiv.2108.06060.

[0041] HF is specifically understood as high frequency. In electrical engineering, the frequency range from 9 kHz to the THz range is referred to as high frequency.

[0042] An XYZ table is a three-axis system, preferably consisting of three single-axis linear guide systems, that allows an object to be moved in three spatial directions. An XY table enables movement within a plane.

[0043] Laser writing, particularly direct laser writing, is preferably a generic term for additive, subtractive, and modifying manufacturing processes in which relative motion is generated between a laser beam and a material, thereby causing ablation, transfer, or modification of the material. Besides laser-induced chemical vapor deposition and selective laser sintering, stereolithography and multiphoton lithography are established as standard processes.

[0044] The invention is described and explained in more detail below with reference to some selected embodiments in conjunction with the accompanying drawings. These show: Fig. 1 a schematic system according to the invention comprising a measuring probe, an optical excitation unit, an RF excitation unit, an optional static magnetic field source and an evaluation unit; Fig. 2 a schematic representation of the head of a measuring probe; Fig. 3a to 3f schematic representations of individual steps for manufacturing a measuring probe; Fig. 4 a schematic representation of the setup of a measuring apparatus using the measuring probe; Fig. 5 a schematic representation of an optical connecting unit; Fig. 6 a schematic-perspective representation of a coaxial setup of a measuring probe; and Fig. 7 a schematic-perspective representation of another measuring probe.

[0045] In Fig. Figure 1 schematically depicts a system 10 for measuring a magnetic field, a temperature and / or an electric field.

[0046] System 10 comprises an evaluation and excitation device 12 and a measuring probe 14. The evaluation and excitation device 12 includes an optional optical connection unit 16, an optical excitation unit 18, an evaluation unit 20 and an RF excitation unit 22.

[0047] The measuring probe 14 comprises a first optical fiber 24 and a second optical fiber 26, both of which are optically decoupled from each other and connected to a quantum emitter 28.

[0048] The first optical fiber 24 and the second optical fiber 26 are connected to the optical excitation unit 18 and the evaluation unit 20 by means of the optional optical connection unit 16.

[0049] The RF excitation unit 22 is connected to an RF antenna 34 by means of a first electrical line 30 and a second electrical line 32. The RF antenna 34 is located in the vicinity of the quantum emitter 28 and can excite it by RF radiation.

[0050] Furthermore, an optional static magnetic field source 35 is arranged near the quantum emitter 28. It is understood that the representation of the static magnetic field source 35 is only symbolic and any known static magnetic field source, such as a permanent magnet or a coil, can be used.

[0051] In this context, "static" means, in particular, that a constant background magnetic field can be created for a specific period of time. A person skilled in the art recognizes that a coil can generate magnetic fields of varying strengths. These are also considered static if they maintain a constant magnetic field strength over a predefined period.

[0052] In the example shown, the quantum emitter 28 is designed as a diamond with nitrogen-vacancy centers.

[0053] In Fig. Figure 2 schematically shows a more detailed representation of the head of a measuring probe 14. The head has a preferably laser-etched optical guidance structure between the first optical fiber 24 and the quantum emitter 28. Optically decoupled from this, the head has a second optical guidance structure from the second optical fiber 26 to the quantum emitter 28. In the illustrated embodiment, the two optical guidance structures are perpendicular to each other at the quantum emitter 28. It is understood that other geometries are also conceivable.

[0054] The connections created by the optical fiber structures optically link the quantum emitter 28 to the two optical fibers 24, 26. At the same time, the quantum emitter 28 is also physically fixed upside down.

[0055] In the illustrated embodiment, the RF antenna 34 is designed as a so-called microstripline. It essentially comprises a flat, rectangular cross-section that connects the two electrical conductors 30 and 32. The two electrical conductors 30 and 32 are, for example, made of silver cables or silver wires.

[0056] In the Fig. Figures 3a to 3f schematically illustrate the individual steps for manufacturing a measuring probe 14, with a side view of the components shown on the left and a top view of the components shown on the right.

[0057] In Fig. 3a In a first step to manufacture a measuring probe, at least two optical fibers 24, 26 and at least two electrical conductors 30, 32 are inserted into a sleeve 36. The sleeve 36 can preferably be a hollow ceramic sleeve, i.e., a hollow ceramic tube.

[0058] As in Fig. As shown in Figure 3b, the sleeve 36 is filled with a carrier material in a further step. The carrier material can, for example, be an epoxy resin. The carrier material surrounds the glass fibers 24, 26 and / or the electrical conductors 30, 32, at least partially. It is understood that an adhesive or other filler material can also be used instead of an epoxy resin. The filler material is then cured. Preferably, the filling and curing take place in a mold (not shown).

[0059] In Fig. Figure 3c schematically shows a further step in which one end of the glass fibers 24, 26, electrical conductors 30, 32 and / or the carrier material contained in the sleeve 36 is polished. Preferably, at least a partially flat surface can be created to allow the attachment of further components to the measuring probe 14.

[0060] In Fig. Figure 3d schematically shows the attachment of an RF antenna 34 to the measuring probe 14, wherein the RF antenna 34 is conductively connected to the two electrical lines 30 and 32. The arrangement of the RF antenna 34 on the polished tip is shown in the Fig. The embodiment shown in 3d is achieved by laser writing using a laser writing device 38. It is understood that other application methods are also conceivable, such as vapor deposition and / or mechanical application. In principle, any other process, preferably additive, is suitable.

[0061] In Fig. Figure 3e schematically illustrates the step of transferring a quantum emitter 28 onto the polished tip. The quantum emitter 28 is positioned at the tip such that it can be excited by the RF antenna 34. Preferably, a droplet 40 of a photoresist emulsion is prepared for this purpose, and the quantum emitter 28, along with the droplet 40, is transferred to the tip.

[0062] Preferably, the drop 40 can first be transferred onto a glass support plate, which is then aligned relative to the tip of the measuring probe 14 using an XYZ table. This allows for precise positioning of the quantum emitter 28. The transfer can be carried out, for example, by moving the XYZ table towards the tip of the measuring probe 14. Alternatively, the tip can be moved towards an XY table, which serves to position the drop and quantum emitter relative to the tip.

[0063] Photoresist is understood to be, in particular, a transparent polymeric varnish with minimal fluorescent properties. Furthermore, the photoresist is preferably suitable for additive direct laser writing processes or similar methods.

[0064] In Fig. Figure 3f schematically depicts the process of writing a first optical guide structure for the optical and physical connection of the quantum emitter 28 to the first optical fiber 24 and a second optical guide structure for the optical and physical connection of the quantum emitter 28 to the second optical fiber 26. The first optical fiber 24 is optically decoupled from the second optical fiber 26. Furthermore, the first optical guide structure is also optically decoupled from the second optical guide structure.

[0065] Optical decoupling means that preferably no or very little light is transferred from the first optical fiber and the first light guide structure to the second optical fiber and / or second light guide structure and vice versa.

[0066] In Fig. Figure 4 schematically shows a measurement setup for measuring with a measuring probe 14. The measuring probe 14 is in the Fig. Figure 4 on the left shows the assembly and comprises two optical fibers 24, 26, which in the illustrated embodiment are arranged around the two electrical conductors 30, 32. The first optical fiber 24 is optically connected to the quantum emitter 28 by means of a first optical guide structure 42. The second optical fiber 26 is optically connected to the quantum emitter 28 by means of a second optical guide structure 44. The two optical fibers 24, 26 and the two optical guide structures 42, 44 are optically decoupled from each other.

[0067] The RF antenna 34 is arranged between the light guide structures 42, 44 and electrically connected to the electrical lines 30, 32. An object 45 to be measured is positioned in front of the measuring probe 14.

[0068] The object 45 to be measured can, for example, be a magnetic and / or electrical source or a hot / cold object, in particular a hot / cold liquid or fluid. The electric and / or magnetic fields and / or thermal radiation / conduction or temperature can be measured at the location of the quantum emitter 28, so that ultimately the object 45 to be measured can be measured.

[0069] The first optical fiber 24 is connected via a first interface 46a to a light sensor 20b and a data acquisition unit 20a, which together form a detector. Furthermore, the first optical fiber 24 is optically connected via the first interface 46a to a first laser light source 18a.

[0070] The second optical fiber 26 is connected to a second laser light source 18b via a second interface 46b.

[0071] The first electrical line 30 and the second electrical line 32 are connected by means of electrical connections 48 to an RF excitation unit 22, in particular a microwave source preferably for the range of 2.4 GHz to 3.5 GHz.

[0072] The light sources 18a, 18b, the RF excitation unit 22 and the data acquisition unit 20a are connected to a computer 49. In this respect, part of the computer 49 together with the data acquisition unit 20a and the light sensor 20b forms an evaluation unit.

[0073] Another part of the computer 49 is designed to control the laser light sources 18a, 18b and the RF excitation unit 22. It is understood that the data acquisition unit 20a is designed and configured to transmit the fluorescence of the quantum emitter 28, detected by the light sensor 20b, to the computer 49 as a suitable data format.

[0074] The second optical fiber 26 and the second optical guide structure 44 form a second optical connection, which is preferably designed to direct excitation light only to the quantum emitter 28, but not to the first optical guide structure 42 and the first optical fiber 24.

[0075] The first optical fiber 24 preferably comprises a so-called multimode fiber, which on the one hand directs excitation light via a conductive / transparent, low fluorescent structure, for example a polymer structure, to the quantum emitter 28 and collects fluorescence light from the optically excited quantum emitter 28 as efficiently as possible and forwards it to the light sensor 20b.

[0076] Consequently, excitation can occur via both the first optical fiber 24 and the second optical fiber 26, but detection preferably occurs only via the first optical fiber 24.

[0077] The RF antenna 34 is connected to the electrical lines 30, 32 and is designed to emit a high magnetic microwave field in the near field in the direction of the quantum emitter 28.

[0078] The tips of the electrical conductors 30, 32 and the optical fibers 24, 26, as well as the RF antenna and the optical connections created by means of the light guide structures 42, 44, form a measuring probe.

[0079] To obtain sufficient mechanical stability, the tips of the electrical conductors 30, 32 and the glass fibers 24, 26 are, for example, embedded in a ceramic sleeve and fixed with a filler material, in particular an epoxy resin.

[0080] To protect the structure and increase stability, a protective cap, not shown for clarity, can surround the RF antenna 34, the light guide structures 42, 44 and the quantum emitter 28.

[0081] In Fig. Figure 5 schematically depicts an optical connecting unit.

[0082] The optional optical connection unit 16 has three input interfaces 46.1-46.3, one output interface 46.4 and one combined input / output interface 46.5.

[0083] The first input interface 46.1 is configured for coupling in a first excitation signal in the form of laser light of a first wavelength or a first wavelength range. The first wavelength preferably comprises light in a range from 515 nanometers to 532 nanometers.

[0084] The second input interface 46.2 is designed to couple in a second excitation signal in the form of laser light of a second wavelength or a second wavelength range. The second wavelength is preferably in the range of 580 nanometers to 640 nanometers.

[0085] The third input interface 46.3 is optional. It is therefore not mandatory. The third input interface 46.3 is designed for coupling a measurement signal into the optional optical connection unit 16. It can thus be coupled to the first optical fiber 24.

[0086] Output interface 46.4 is designed to extract the measurement signal. Output interface 46.4 is therefore preferably optically connected to a light sensor or an evaluation unit.

[0087] The combined input / output interface 46.5 is designed for coupling out the first excitation signal, the second excitation signal, and / or for coupling in the measurement signal. The combined input / output interface 46.5 can therefore be optically connected to the first optical fiber 24 or to the second optical fiber 26.

[0088] A first light path runs between the first input interface 46.1 and the combined input / output interface 46.5. This path is shown as a dashed line in the figure. The first light path is formed by a first mirror 50.1, a second mirror 50.2, and a first beam-intersecting element 51.1, which in the illustrated embodiment comprises a first dichroic mirror. A first optional waveplate 54.1 and a first optional polarizing beam splitter 56.1 are also arranged in the first light path between the first mirror 50.1 and the first input interface 46.1. A further optional waveplate 55 is arranged between the first dichroic mirror and the combined input / output interface 46.5. A first optional filter 52.1 is arranged between the second mirror 50.2 and the first dichroic mirror.

[0089] A second light path is formed between the second input interface 46.2 and the combined input / output interface 46.5. This second light path includes a third mirror 50.3, a fourth mirror 50.4, and a second beam-overlaying element 51.2, which is also configured as a second dichroic mirror. A second optional waveplate 54.2 and a second optional polarizing beam splitter 56.2 are arranged in the second light path between the second input interface 46.2 and the third mirror 50.3. The first dichroic mirror and the additional optional waveplate 55 are arranged between the second dichroic mirror and the combined input / output interface 46.5. A second optional filter 52.2 is arranged between the fourth mirror 50.4 and the second dichroic mirror.

[0090] A third light path is formed between the combined input / output interface 46.5 and the output interface 46.4. This third light path includes a fifth mirror 50.5 and a sixth mirror 50.6. Between the fifth mirror 50.5 and the combined input / output interface 46.5, the first and second dichroic mirrors, as well as the additional optional waveplate 55, are arranged in the third light path. A third optional filter 52.3 is arranged between the sixth mirror 50.6 and the output interface 46.4. A fourth optional filter 52.4 is arranged between the fifth mirror 50.5 and the sixth mirror 50.6.

[0091] A fourth optical path is formed between the optional third input interface 46.3 and the output interface 46.4. The fourth optical path includes an optional seventh mirror 50.7, the fifth mirror 50.5, and the sixth mirror 50.6. The fourth optical path preferably includes the third optional filter 52.3 and the fourth optional filter 52.4.

[0092] To improve the shielding of the individual light paths from each other, an optional optical separator 58 can be provided. The optional optical separator 58 interrupts the third light path and shields the first and second light paths from the fourth light path.

[0093] In the figure, the individual light guide paths are shown as dashed lines. Optional elements are also shown as dashed lines.

[0094] The excitation light, i.e., light that is introduced into the optional optical connection unit 16 via the first input interface 46.1 and / or the second input interface 46.2, is preferably polarized by a wave plate, in particular a lambda / 2 plate, so that maximum transmission through the respective polarizing beam splitter 56.1 and 56.2 is achieved.

[0095] The beam splitters 56.1 and 56.2 ensure that, as far as possible, only linearly polarized light is transmitted in one direction of oscillation. The first to fourth mirrors 50.1 to 50.4 optimize and adjust the respective beam position and angle so that maximum coupling efficiency into the connected optical fiber (either the first fiber 24 or the second fiber 26) can be achieved at the combined input / output interface 46.5. The first and second filters 52.1 and 52.2 perform wavelength-selective filtering of the excitation light.

[0096] Dichroic mirrors are mirrors that transmit light above a certain cutoff wavelength and reflect light below a certain cutoff wavelength. This means that, with appropriate selection, laser beams of different wavelengths can be superimposed, and fluorescence light can be transmitted almost unimpeded through dichroic mirrors to a detector above a certain wavelength.

[0097] In the embodiment shown, the cutoff wavelength of the first dichroic mirror is 550 nanometers, and that of the second dichroic mirror is 660 nanometers.

[0098] Thus, light with a wavelength smaller than 550 nanometers can be directed via the first dichroic mirror, and light with a wavelength smaller than 660 nanometers via the second dichroic mirror, to the combined input / output interface 46.5, i.e., to the measuring probe. Light with a wavelength greater than 660 nanometers, on the other hand, is transmitted through the mirrors to the output interface 46.4, i.e., to the detector.

[0099] The additional wave plate 55 can be installed between the combined input / output interface 46.5 and the first and second light guide paths, i.e. the excitation light, in order to change the polarization of the excitation light towards the measuring probe and thereby further increase the sensitivity.

[0100] The combined input / output interface 46.5 can be used as a connection for a multimode or single-mode fiber optic cable of the sensor; therefore, either the first fiber optic cable 24 or the second fiber optic cable 26 can be connected to the combined input / output interface 46.5.

[0101] If the single-mode fiber, i.e., the second fiber 26, is connected to the combined input / output interface 46.5, then the multi-mode fiber, i.e., the first fiber 24 of the measuring probe 14, must be connected to the optional third input interface 46.3 for the detection of the fluorescence of the quantum emitter 28. The fluorescence is then forwarded to the output interface 46.4 via the optional seventh mirror 50.7. At this output interface 46.4, the fluorescence is again coupled into a preferably commercially available fiber and forwarded, for example, to a fiber-coupled photodetector. Alternatively, the photodetector can also be installed directly at the output interface 46.4.

[0102] In this measurement method, the optional optical separator 58 can be used to further reduce stray light. This element divides the optional optical connecting unit 16 into two optically separate areas, so that only excitation light is directed into one area and only detection light into the other. This minimizes stray light, particularly on the detection side.

[0103] Alternatively, the multimode fiber of the measuring probe, i.e., the first fiber 24, can be connected to the combined input / output interface 46.5. In this configuration, excitation and detection are performed by the first fiber 24. The fluorescence light then travels along the third optical path. It is understood that the optional optical separator 58 and the optional seventh mirror 50.7 are not installed for this purpose. The single-mode fiber of the measuring probe, i.e., the second fiber 26, is not required.

[0104] Mirrors 50.5 and 50.6, the fifth and sixth, couple the fluorescence light into the optical fiber connected to output interface 46.4, which then directs the fluorescence light to the detector. Alternatively, the detector can be connected directly to output interface 46.4.

[0105] The optional third filter 52.3 preferably represents a long-pass filter which filters out the excitation light that is also directed to the detector due to reflection or similar.

[0106] The fourth filter, 52.4, represents, for example, a gray filter or the like.

[0107] In Fig. Figure 6 schematically shows an alternative embodiment of the first optical fiber 24. This is a so-called coaxial design in which the first electrical conductor 30 coaxially encases the first optical fiber 24. The first optical fiber 24 is encased by an electrical insulation structure 60, which in turn is encased by the second electrical conductor 32. This allows the possible overall size of the measuring probe 14 to be further reduced.

[0108] In Fig. Figure 7 schematically shows a further structure of a measuring probe 14. The measuring probe 14 has the two electrical conductors 30, 32 and the two optical fibers 24, 26, which protrude from the sleeve 36 and are used for connection to measuring electronics, such as for measuring parameters. Fig. 4 and / or 5 described, can be used. Furthermore, an elongated measuring head 62 is shown on the opposite side of the sleeve 36, which, for example, can be used as described with respect to Fig.2 can be structured as described.

[0109] The invention has been described in detail. A person skilled in the art will recognize that the disclosed teaching allows for the achievement of one or more of the following advantages in particular.

[0110] The design of a miniaturized, fully integrated, fiber-based sensor or measuring probe based on quantum effects is presented. In particular, a manufacturing process for creating such a measuring probe is disclosed. The complete integration of a glass fiber-based approach is especially advantageous.

[0111] In particular, the method according to the invention enables improved deterministic positioning and fixation of nanoscopic quantum emitters on a suitable measuring platform using an additive manufacturing method, which is advantageous compared to simple adhesive bonds. The light, i.e., both excitation and detection light, can be selectively directed within the connection structure, and the quantum emitter can be precisely positioned and fixed on a measuring platform.

[0112] Furthermore, the required RF field strength can be reduced by minimizing the distance between the quantum emitter and the RF antenna, as well as by selectively shaping the emitted field through the geometry of the RF antenna. This is preferably achieved using additive manufacturing methods, in particular direct metallic laser writing with silver lacquer.

[0113] Furthermore, sensitivity can be increased by optically separating the excitation and detection beam paths. This leads, in particular, to an improvement in the signal-to-noise ratio by reducing autofluorescence. Moreover, the disclosed system is stable against temperature fluctuations, since thermal expansions can be essentially compensated for by the connection at the light-guiding structures.

[0114] By minimizing and combining all the components required for the described sensor, such a sensor can be flexibly positioned and used as a measuring probe even in confined spaces.

[0115] The remote access to the measuring probe via a fiber optic cable for optical signals and an electrical antenna feed line for generating locally intense RF field strengths directly at the measuring probe or quantum emitter allows the use of a central measuring and computing unit, which can be positioned at various measuring points of a device or similar. Reference symbol list 10 System 12 Evaluation and excitation device 14 measuring probe 16 Optical connection unit 18 Optical excitation unit 18a First laser light source 18b Second laser light source 20 evaluation units 20a Data Acquisition Unit 20b Light sensor 22 RF excitation unit 24 First fiber optic cable 26 Second fiber optic cable 28 quantum emitters 30 First electrical line 32 Second electrical line 34 HF antenna 35 Static magnetic field source 36 Sleeve 38 Laser writing device 40 drops 42 First light guide structure 44 Second light guide structure 45 Object to be measured 46a first interface 46b second interface 46.1 to 46.3 Input interfaces 46.4 Output interface 46.5 Combined input / output interface 48 Electrical connections 49 computers 50.1 to 50.7 mirrors 51.1 to 51.2 Beam-overlapping element 52.1 to 52.4 Filters 54.1 to 54.2 Corrugated plates 55 More wave plates 56.1 to 56.2 Polarizing beam splitter 58 Optical separator 60 Insulation structure 62 Measuring head

Claims

[1] Method for manufacturing a measuring probe (14) comprising the following steps: Insertion of two optical fibers (24, 26) and two electrical conductors (30, 32) into a sleeve (36); Filling the sleeve (36) with a carrier material, wherein the carrier material surrounds the glass fibers (24, 26) and / or electrical conductors (30, 32) at least partially; Curing of the carrier material in the sleeve (36); Polishing one end of the glass fibers (24, 26), electrical conductors (30, 32) and / or the carrier material contained in the sleeve (36); Arranging an RF antenna (34) on the top; and Transferring a quantum emitter (28) to the tip; Laser writing of a first and second optical fiber structure (42, 44) for optical connection of the quantum emitter (28) to the first optical fiber (24) and to the second optical fiber (26), wherein the first optical fiber (24) is optically decoupled from the second optical fiber (26). [2] Method according to claim 1 comprising the steps: Generating a suspension from a photoresist and the quantum emitter (28); Positioning the suspension on a support plate; and Positioning the support plate in a predefined position with respect to the polished end, wherein the aforementioned steps are performed prior to the step of transferring the quantum emitter (28) to the tip. [3] Method according to any one of the preceding claims, wherein the laser writing of a first and second optical fiber structure (42, 44) comprises laser writing using a polymer varnish of a first optical fiber structure (42) between a glass fiber core of the first glass fiber (24) and the quantum emitter (28) and of a second optical fiber structure (44) between a glass fiber core of the second glass fiber (26) and the quantum emitter (28), and the first optical fiber structure (42) preferably comprises an optical connection to the quantum emitter (28) which is perpendicular to an optical connection of the second optical fiber structure (44) to the quantum emitter (28). [4] Method according to any one of the preceding claims, wherein The RF antenna (34) is arranged at the tip by means of an additive process, in particular by means of laser writing, and a material of the RF antenna (34) comprises a material compatible with the material of the electrical conductors (30, 32); and the electrical conductors (30, 32) and the material of the RF antenna (34) include in particular silver, copper and / or gold. [5] Method according to any one of the preceding claims comprising the steps: Adjusting the impedance of the RF antenna (34) by measuring reflection and adapting the length of the electrical lines (30, 32). [6] Method according to one of the preceding claims comprising the step: attaching a static magnetic field source (35), in particular a permanent magnet or a coil, in a vicinity of the tip to generate a static background magnetic field. [7] Measuring probe (14), preferably manufactured according to a method according to one of the preceding claims, comprising: a quantum emitter (28); an RF antenna (34); two optical fibers (24, 26); two electrical lines (30, 32), and a laser-written first optical guidance structure (42) for optically connecting the quantum emitter (28) to the first optical fiber (24), to form an optical feed line, and a laser-written second optical guidance structure (44) for optically connecting the quantum emitter (28) to the second optical fiber (26) to form a signal line; wherein the supply line and the signal line are optically decoupled; the signal line is designed to direct a measurement signal away from the quantum emitter (28); and the lead is designed to direct an excitation signal to the quantum emitter (28). [8] Measuring probe (14) according to claim 7, wherein the measuring probe (14) comprises at least two further electrical conductors and a further laser-printed RF antenna. [9] Measuring probe (14) according to claim 7 or 8, wherein the measuring probe (14) comprises at least one further optical fiber which forms at least one further feed line and / or one further signal line. [10] System (10) for measuring a temperature, a magnetic field and / or an electric field comprising: a measuring probe (14) according to one of claims 7 to 9; an optical excitation unit (18) for exciting a quantum emitter (28) of the measuring probe (14), an RF excitation unit (22) for generating an RF magnetic field by means of the RF antenna (34) of the measuring probe (14); an optional static magnetic field source (35) in the form of a permanent magnet or a coil; and an evaluation unit (20) for receiving and evaluating a measurement signal from the measuring probe (14) in response to excitation of the quantum emitter (28) of the measuring probe (14) by means of an optical excitation signal and by means of an RF magnetic field, wherein the evaluation unit (20) is designed to determine a temperature, a magnetic field and / or an electric field at a tip of the measuring probe (14), in particular at the quantum emitter (28), based on the measurement signal. [11] System (10) according to the preceding claim, comprising an optical connection unit (16) arranged between the optical excitation unit (18) and the measuring probe (14) and between the evaluation unit (20) and the measuring probe (14), wherein the optical interconnect unit (16) has a first input interface (46.1), a second input interface (46.2), an optional third input interface (46.3), an output interface (46.4) and a combined input / output interface (46.5); the first input interface (46.1) is designed to couple in a first excitation signal in the form of laser light of a first wavelength; the second input interface (46.2) is designed to couple in a second excitation signal in the form of laser light of a second wavelength; the third input interface (46.3) is designed for coupling in a measurement signal; the output interface (46.4) is designed to extract the measurement signal; the combined input / output interface (46.5) is designed for coupling out the first excitation signal, the second excitation signal and / or for coupling in the measurement signal; a first light guide path is formed between the first input interface (46.1) and the combined input / output interface (46.5) by a first mirror (50.1), a second mirror (50.2) and a first beam-overlaying element (51.2), which preferably comprises a first wave plate (54.1), a first polarizing beam splitter (56.1) and a first filter (52.1); a second light guide path is formed between the second input interface (46.2) and the combined input / output interface (46.5) by a third mirror (50.3), a fourth mirror (50.4) and a second beam-overlaying element (51.2), which preferably comprises a second wave plate (54.2), a second polarizing beam splitter (56.2) and a second filter (52.2); a third light guide path is formed between the combined input / output interface (46.5) and the output interface (46.4) by a fifth mirror (50.5) and a sixth mirror (50.6), which passes through the first beam-overlaying element (51.1) and the second beam-overlaying element (51.2) and preferably has a third filter (52.3) and a fourth filter (52.4); a fourth light path is formed between the third input interface (46.3) and the output interface (46.4) by an optional seventh mirror (50.7), the fifth mirror (50.5) and the sixth mirror (50.6), which preferably includes the third filter (52.3) and the fourth filter (52.4); an optional optical separator (58) interrupts the third light path and shields the first and second light paths from the fourth light path; and the first light guide path, the second light guide path and the third light guide path have an optional additional wave plate (55).

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