Abstract
A current sensor includes a magnetometer. The magnetometer includes a sensor element including at least one paramagnetic center that generates fluorescence radiation, a radiation receiver configured to receive the fluorescence radiation from the sensor element and generate a first electrical signal based on receiving the fluorescence radiation from the sensor element, and an electronic output circuit configured to generate and output a second electrical signal based on the first electrical signal. The value of the fluorescence radiation generated by the sensor element depends in part on a magnetic flux density at the location of the sensor element. The magnetometer is configured to be placed near or in direct contact to a wire carrying a current such that the current in the wire modifies the magnetic flux density at the location of the sensor element.
Claims
1. A current sensor comprising a magnetometer comprising: a sensor element comprising at least one paramagnetic center that generates fluorescence radiation; a radiation receiver configured to receive the fluorescence radiation from the sensor element and generate a first electrical signal based on receiving the fluorescence radiation from the sensor element; and an electronic output circuit configured to generate and output a second electrical signal based on the first electrical signal; wherein: a value of the fluorescence radiation generated by the sensor element depends at least in part on a magnetic flux density at a location of the sensor element; and the magnetometer is configured to be placed near to a wire carrying a current to be measured or in direct contact with the wire carrying the current to be measured such that the current to be measured in the wire modifies the magnetic flux density at the location of the sensor element.
2. The current sensor of claim 1, further comprising: a pump radiation source that emits pump radiation; wherein: the sensor element is arranged to receive a portion of the pump radiation emitted by the pump radiation source; and the sensor element generates the fluorescence radiation in response to receiving the pump radiation.
3. The current sensor of claim 2, wherein the sensor element, the electronic output circuit and the pump radiation source are included in or on a substrate.
4. The current sensor of claim 1, wherein the electronic output circuit includes one or more of: amplifiers, filters, controllers, analog-to-digital converters, and signal processors.
5. The current sensor of claim 1, further comprising a feature vector extraction unit, wherein the feature vector extraction unit is configured to receive the second electrical signal, and extract, from a temporal course of values of the second electrical signal, a feature vector signal, the feature vector signal comprising a temporal sequence of feature vectors.
6. The current sensor of claim 5, further comprising a sub-device configured to execute a neural network model and/or an HMM model to analyze the feature vector signal and generate one or more signalizations and output the one or more signalizations to a higher-level control unit.
7. The current sensor of claim 1, wherein the at least one paramagnetic center is an NV center.
8. The current sensor of claim 7, wherein the NV center is in a diamond crystal.
9. A current measuring system, comprising: a sensor element comprising at least one paramagnetic center that generates fluorescence radiation; a radiation receiver configured to receive the fluorescence radiation from the sensor element and generate a first electrical signal based on receiving the fluorescence radiation from the sensor element; a wire; and an electronic output circuit configured to generate and output a second electrical signal based on the first electrical signal; wherein: a value of the fluorescence radiation generated by the sensor element depends at least in part on a magnetic flux density at a location of the sensor element; the wire is arranged to conduct a current to be measured; and the wire is arranged such that the current to be measured modifies the magnetic flux density at the location of the sensor element.
10. The current measuring system of claim 9, wherein the wire is U-shaped.
11. The current measuring system of claim 10, wherein a bend in the U-shaped wire defines a plane whereby the sensor element is located at a distance of no more than 10 mm from this plane.
12. The current measuring system of claim 11, wherein the bend defines a plane whereby the sensor element is located at a distance of no more than 1 mm from this plane.
13. The current measuring system of claim 9, further comprising: a pump radiation source that emits pump radiation; wherein: the sensor element is arranged to receive a portion of the pump radiation emitted by the pump radiation source; and the sensor element generates the fluorescence radiation in response to receiving the pump radiation.
14. The current measuring system of claim 13, wherein the sensor element, the electronic output circuit and the pump radiation source are included in or on a substrate.
15. The current measuring system of claim 9, wherein the electronic output circuit includes one or more of: amplifiers, filters, controllers, analog-to-digital converters, and signal processors.
16. The current measuring system of claim 9, further comprising a feature vector extraction unit, wherein the feature vector extraction unit is configured to receive the second electrical signal, and extract, from a temporal course of values of the second electrical signal, a feature vector signal, the feature vector signal comprising a temporal sequence of feature vectors.
17. The current measuring system of claim 16, further comprising a sub-device configured to execute a neural network model and/or an HMM model to analyze the feature vector signal and generate one or more signalizations and output the one or more signalizations to a higher-level control unit.
18. The current measuring system of claim 9, wherein the at least one paramagnetic center is an NV center.
19. The current measuring system of claim 18, wherein the NV center is in a diamond crystal.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[1011] The figures explain some, but not all, aspects of the proposal. They are provided for clarification. The applicable claims are decisive for the stressing. The figures are only individual examples that do not limit the claim.
[1012] FIG. 1 shows the basic structure of the magnetometer as a highly simplified block diagram.
[1013] FIG. 2 shows a cross-sectional view of a module whose function corresponds to the basic structure of an exemplary magnetometer shown in FIG. 1.
[1014] FIG. 3 shows a current sensor based on the module of FIG. 2.
[1015] FIG. 4 shows the block diagram of a magnetometer comprising optical feedback compensation.
[1016] FIG. 5 shows the block diagram of a magnetometer comprising a chopper stage.
[1017] FIG. 6 shows a cross-section of a module whose function corresponds to the structure of an exemplary magnetometer shown in FIG. 5.
[1018] FIG. 7 shows a current sensor based on the module of FIG. 6.
[1019] FIG. 8 shows a sensor element in an optical waveguide as the core of an electric coil for current measurement.
[1020] FIG. 9 shows a sensitivity curve for the change in intensity of fluorescence radiation (FL) as a function of magnetic flux density B.
[1021] FIGS. 10 to 18 show a method of manufacturing an optical module using a glass frit paste that is molten.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1
[1022] FIG. 1 shows the basic structure of the magnetometer as a highly simplified block diagram. The signal generator (G) in this simple example is a pump current source (I0), which cannot be modulated in this example. The pump current source (I0) generates the pump current (I.sub.pump) as a transmission signal (S5). The pump current (I.sub.pump) feeds the pump radiation source (PLED). The pump radiation source (PLED) emits pump radiation (LB) into a first transmission path (i1, not drawn). The intensity of the pump radiation (LB) typically depends on the transmission signal (S5). As a result, the pump radiation source (PLED) irradiates at least one area of the sensor element (NVD) using pump radiation (LB). The sensor element (NVD) emits fluorescence radiation (FL) depending on the pump radiation (LB). The intensity of the fluorescence radiation (FL) depends on the intensity of the pump radiation (LB) in the emission area of the fluorescence radiation (FL) and, if necessary, on other parameters, for example the magnitude of the magnetic flux density B, in this area. An optical filter (F1) preferably allows a portion of the fluorescence radiation (FL) sufficient for the measuring system to pass, while it does not allow a portion of the pump radiation (LB) sufficient for the measuring system to pass. As a result, essentially only the fluorescence radiation (FL) reaches the radiation receiver (PD) via a second transmission path (i2, not shown in FIG. 1). The radiation receiver (PD) converts the received intensity of the fluorescence radiation (FL) and possibly further received radiation into a receiver output signal (S0), the value of which represents the amount of radiation intensity received by the radiation receiver (PD). In the example of FIG. 1, a first amplifier (V1) amplifies the receiver output signal (S0) to a demodulated signal (S4). This name demodulated signal is chosen only because modulations will be added later.
[1023] In this example, an analog-to-digital converter (ADC) converts the demodulated signal (S4) into a digitized signal (DS). A data interface (IF) then enables access to this value via a data bus (DB).
FIG. 2
[1024] FIG. 2 shows a cross-sectional view of an exemplary module, the function of which corresponds to the basic structure of an exemplary magnetometer shown in FIG. 1. On an exemplary circuit carrier (GPCB), which is made of optically transparent glass, for example, on the upper side of the circuit carrier (GPCB) lines not shown here are applied, for example in thick-film technology, to which, for example, a microintegrated circuit (IC), the radiation receiver (PD) and the pump radiation source (PLED) are electrically and possibly also mechanically connected. The pump radiation source (PLED) irradiates a sensor element (NVD), which for example includes NV centers in diamond, using pump radiation (LB). Depending on the magnetic flux density B as an exemplary physical quantity, the NV centers of the sensor element (NVD) emit fluorescence radiation (FL). An optical filter (F1) ensures that no pump radiation (LB) enters the radiation receiver (PD). A housing (GH) ensures that potential other optical paths are interrupted. The housing (GH) preferably comprises black thermoset as the housing material. A mirror surface (ML) ensures that as much as possible of the pump radiation (LB) from the pump radiation source (PLED) reaches the sensor element (NVD) and that as much as possible of the fluorescence radiation (FL) reaches the radiation receiver (PD) to maximize the sensitivity of the system.
[1025] The sensor element (NVD) is preferably mounted on the other side of the circuit carrier (GPCB). This means that it is electrically isolated from the microintegrated circuit (IC) and the other electronic components (PLED, PD) on the upper side of the circuit carrier (GPCB).
[1026] A bias magnet (BM), which is typically a permanent magnet, is attached to the top of the circuit carrier (GPCB) here as an example to set the bias magnetic field. In FIG. 9 it can be seen later that, for example, a bias magnetic field of about 10 mA is often very suitable for NV centers.
FIG. 3
[1027] FIG. 3 shows a current sensor based on the module of FIG. 2. The module of FIG. 2 is now supplemented by an electrical conductor (LTG). If a current flow takes place in the electrical conductor (LTG), this generates a magnetic flux density B, which influences the fluorescence radiation (FL) of the sensor element (NVD) and can therefore be measured and converted into a measured value and whose measured values can be passed on via the said data bus (DB), for example.
FIG. 4
[1028] FIG. 4 shows the block diagram of a magnetometer comprising optical feedback compensation. It is similar to FIG. 1, but now a second amplifier (V2) amplifies the demodulated signal (S4). The second amplifier (V2) provides the demodulated signal (S4) if necessary with an offset. The second amplifier (V2) generates the compensation transmission signal (S7) by means of the compensation current source (I1). The compensation transmission signal (S7) feeds the compensation radiation source (CLED) using a compensation transmission current (I.sub.comp). The compensation radiation source (CLED) also radiates into the radiation receiver (PD) via a third transmission path (I3, not shown here). Having a total intensity, the irradiation of the fluorescence radiation (FL) and the compensation radiation (CL) of the compensation radiation source (CLED) is preferably approximately summing. The instantaneous value of the receiver output signal (S0) of the radiation receiver (PD) depends on this instantaneous total intensity. Thus, the instantaneous value of the receiver output signal (S0) of the radiation receiver (PD) is also dependent on the intensity of the fluorescence radiation (FL) and the intensity of the compensation radiation (CL). The gains and signs in this control loop are thereby preferably selected in such a way that stability is achieved. This means that the total intensity is preferably constant, so that the physical conditions in the radiation receiver (PD) do not change even if the intensity of the fluorescence radiation (FL) changes, since a corresponding change in the intensity of the compensation radiation (CL) in the opposite direction compensates for this.
FIG. 5
[1029] FIG. 5 shows the block diagram of an exemplary magnetometer comprising an exemplary chopper stage. As in FIG. 4, the radiation receiver (PD) again receives the total intensity of the radiations, namely the fluorescence radiation (FL) of the sensor element (NVD) and the compensation radiation (CL). An optical filter (F1) again prevents pump radiation (LB) from reaching the radiation receiver (PD). The radiation receiver (PD) converts the value of the total radiation intensity to the instantaneous value of the receiver output signal (S0). A synchronous demodulator (SDM) converts the receiver output signal (S0) to the demodulated signal (S4) using the transmission signal (S5). A signal generator (G) preferably generates the transmission signal (S5). The transmission signal (S5) preferably has a frequency different from 0 Hz. In the example of FIG. 5, the exemplary synchronous demodulator (SDM) comprises a first multiplier (M1) which converts the receiver output signal (S0) into an instantaneous value of the multiplier output signal (S3) by multiplying the instantaneous value of the receiver output signal (S0) by the instantaneous value of the transmission signal (S5). An exemplary low-pass filter (TP) amplifies and filters the multiplier output signal (S3) to the demodulated signal (S4). Thus, the low-pass filter (TP) here has taken over the function of the first amplifier (V1) of FIG. 1 and FIG. 4. Preferably, the low-pass filter (TP) lets through essentially only a DC signal and no frequencies of the transmission signal (S5) and higher. Evaluation means (ADC, IF) which are no longer shown can then process the demodulated signal (S4) as shown in FIG. 4. A second multiplier (M2) multiplies the instantaneous value of the demodulated signal (S4) with the instantaneous value of the transmission signal (S5) to the instantaneous value of the compensation pre-signal (S6). If necessary, a second amplifier (V2) further amplifies the compensation pre-signal (S6) to the compensation transmission signal (S7) and typically provides it with an offset. The intensity of the compensation radiation (CL) emitted by the compensation radiation source (CLED) typically depends on the instantaneous value of the compensation transmission signal (S7). The intensity of the pump radiation (LB) emitted by the pump radiation source (PLED) typically depends on the instantaneous value of the transmission signal (S5). The gains and offsets in the control loop are preferably designed in such a way that stability is achieved essentially apart from control errors and system noise.
FIG. 6
[1030] FIG. 6 shows a cross-sectional view of a module which corresponds in its function to the structure of an exemplary magnetometer of FIG. 5. It corresponds to the module of FIG. 2. In contrast to FIG. 2, it now comprises the additional compensation radiation source (CLED) of FIGS. 4 and 5. A user of the technical teaching disclosed herein will preferably select the compensation radiation wavelength (.sub.ks) of the compensation radiation (CL) such that it can pass the optical filter (F1) in the example of FIG. 6. For example, if the pump radiation (LB) is green and the fluorescent radiation (FL) is red, for example, an infrared radiation may be useful as the compensation radiation (CL).
FIG. 7
[1031] FIG. 7 again shows a current sensor based on the module of FIG. 6. Analogous to FIG. 3, it again comprises the said electrical conductor (LTG).
FIG. 8
[1032] FIG. 8 shows a sensor element in an optical waveguide as the core of an electrical coil (L) for current measurement. The optical transmission paths of the systems shown above can also be designed completely or partially as optical waveguides (OFC). It may then be useful to wind a coil (L) as an electrical conductor (LTG) around the optical waveguide (LWL) and the sensor element (NVD) inserted in the optical waveguide (LWL) in order to maximize the magnetic flux density B.
FIG. 9
[1033] FIG. 9a shows an exemplary fluorescence curve for a sensor element comprising NV centers in diamond. FIG. 9b shows the corresponding sensitivity curve for the change in the intensity of the fluorescence radiation as a function of the magnetic flux density B.
FIGS. 10 to 18
[1034] FIGS. 10 to 18 show a method of manufacturing an optical module. The sequence of individual steps may be modified. Steps may be added to the process. Steps can be omitted if necessary and if it makes sense to do so.
FIG. 10
[1035] The exemplary method begins with the provision of a system carrier (GPCB) in FIG. 10. In the example of FIG. 10, the system carrier (GPCB) is optically opaque. It has a first exemplary optically transparent feedthrough (OV1) and a second exemplary optically transparent feedthrough (OV2) and a third exemplary optically transparent feedthrough (OV3), which allow later functional elements to communicate optically with the other side of the system carrier (GPCB).
FIG. 11
[1036] In the example shown here, the manufacturing device not shown applies a glass frit paste of glass dust and a carrier to the system carrier (GPCB) of FIG. 10. This application can use functionally equivalent materials from other substances (e.g., from salts). In this case, the application of the glass frit paste is carried out using stencil printing, for example. The sections of the glass frit paste printed in this way later form the first transmission path (i1) and the second transmission path (i2) and the third transmission path (i3).
FIG. 12
[1037] The manufacturing device, which is not drawn, applies a glass frit paste comprising ferromagnetic particles to the other side of the system carrier (GPCB), for example by means of stencil printing, onto the system carrier of FIG. 11. This glass frit paste, which comprises ferromagnetic particles, is later to form the bias magnet (BM), for example.
FIG. 13
[1038] On the system carrier (GPCB) of FIG. 12, the manufacturing device, which is not drawn, introduces a glass frit paste, for example by means of stencil printing, into the gap between the glass frit paste section, which will later constitute the second transmission path (i2), and the glass frit paste section, which will later constitute the first transmission path (i1). This glass frit paste may be interspersed with, for example, diamond microcrystals comprising high density NV centers. This new glass frit paste section will then later form the sensor element (NVD).
FIG. 14
[1039] The production device, which is not drawn, applies a glass frit paste, for example by means of stencil printing, to the system carrier (GPCB) of FIG. 13 in the gap between the glass frit paste section, which will later represent the second transmission path (i2), and the glass frit paste section located to the left of it. This glass frit paste can be interspersed with colored glass particles or a coloring salt, for example. This additional material is chosen in such a way that later this section no longer transmits pump radiation (LB) from the pump radiation source (PLED), but does transmit radiation having the fluorescence radiation wavelength (.sub.fl) of the fluorescence radiation (FL) from the sensor element (NVD). This new glass frit paste section will then later form the optical filter (F1).
FIG. 15
[1040] On the system carrier (GPCB) of FIG. 14, the manufacturing device, which is not drawn, introduces a glass frit paste, for example by means of stencil printing, into the gap between the glass frit paste section, which will later represent the third transmission path (i3), and the glass frit paste section located to the right of it. This glass frit paste can, for example, be interspersed with white colored glass particles or with particles of a different refractive index. This additional material then leads, in the exemplary case proposed here, to a scattering of the compensation radiation (CL) and the fluorescence radiation (FL) by these particles, so that this radiation can then later fall through the second exemplary optically transparent feedthrough (OV2) onto the radiation receiver (PD), which is not yet mounted here. This new glass frit paste section will later form an optical diffuser device (STR) in the beam path.
FIG. 16
[1041] Heat treatment of the system carrier (GPCB) of FIG. 15 melts and remelts the glass frit paste sections. They now preferably form a firm mechanical bond with the system carrier (GPCB).
FIG. 17
[1042] A printing technique preferably applies electrical leads (LT) to the system carrier (GPCB) of FIG. 16 using thick-film technology.
FIG. 18
[1043] An undrawn manufacturing device prints solder paste onto the system carrier (GPCB) of FIG. 17. An undrawn assembly device assembles the system carrier (GPCB) of FIG. 17 comprising electronic components (IC, CLED, PD, PLED). The system carrier is soldered, for example, in a soldering device not drawn, for example a reflow oven. The pump radiation source (PLED), for example a green LED, can now feed the pump radiation (LB), which is for example green, via the first exemplary optically transparent feedthrough (OV1) into the first transmission path (i1), which now acts as an optical waveguide (LWL) after melting. The pump radiation (LB) impinges on the sensor element (NVD), which here comprises NV centers as an example. The sensor element (NVD) functions here as a short optical waveguide (LWL) comprising active components, the NV centers. The sensor element (NVD) emits fluorescence radiation (FL) into the second transmission path (i2), into which pump radiation (LB) also enters and which also acts as an optical waveguide (LWL). Here, the optical filter (F1) acts as a wavelength-selective optical waveguide (LWL). Due to its coloring, the optical filter (F1) only allows fluorescence radiation (FL) to pass. The fluorescence radiation (FL) now enters another optical waveguide (LWL). On the other side, the compensating radiation source (CLED) radiates the compensation radiation (CL) into the third transmission link (i3) via the third exemplary optically transparent feedthrough (OV3). The compensation radiation (CL) enters the diffuser device (STR) via the third transmission path (i3), which acts as an optical waveguide (LWL) comprising a highly scattering material. The diffuser device (STR) scatters the compensation radiation (CL) toward the radiation receiver (PD) via the second exemplary optically transparent feedthrough (OV2). The diffuser device (STR) scatters the fluorescence radiation (FL) from the further optical waveguide (LWL) also via the second exemplary optically transparent feedthrough (OV2) towards the radiation receiver (PD), where the fluorescence radiation (FL) and the compensation radiation (CL) overlap. The radiation receiver (PD) receives the total radiation intensity from the intensity of the incident fluorescence radiation (FL) and incident compensation radiation (CL). For the rest, please refer to the description of the control circuits from here on.
