QUANTUM SENSOR

Abstract

A sensor apparatus for determining and/or monitoring a process variable of a medium in a containment includes: a crystal body including at least one defect; a magnetic field system for producing a magnetic field in the region of the crystal body and in the region of the medium within the containment, wherein the crystal body and the magnetic field system are arrangeable from the outside at a wall of the containment; a detection unit for detecting a magnetic field-dependent, fluorescent signal from the crystal body, wherein the detection unit has an excitation unit for optical exciting of the defect and a detector for detecting the fluorescent signal; and an evaluation unit for ascertaining at least one piece of information concerning the process variable based on the fluorescent signal.

Claims

1-13. (canceled)

14. A sensor apparatus for determining and/or monitoring a process variable of a medium in a containment, the sensor apparatus comprising: a crystal body including at least one defect; a magnetic field system configured to generate a magnetic field in a region of the crystal body and in a region of the medium within the containment, wherein the crystal body and the magnetic field system are respectively configured as to be arranged at a wall of the containment from the outside; a detection unit configured to detect a magnetic field-dependent fluorescence signal emitted from the crystal body, wherein the detection unit comprises an excitation unit configured to optical excite the at least one defect of the crystal and comprises a detector configured to detect the fluorescence signal; and an evaluation unit configured to determine at least one piece of information about the process variable based on the fluorescence signal.

15. The sensor apparatus of claim 14, wherein the crystal body is: diamond, wherein the at least on defect is at least one nitrogen defect; silicon carbide, wherein the at least on defect is at least one silicon defect; or hexagonal boron, wherein the at least on defect is at least one color center defect.

16. The sensor apparatus of claim 14, wherein the magnetic field system comprises at least one coil.

17. The sensor apparatus of claim 16, wherein the coil surrounds the crystal body, at least partially, when the crystal body and the magnetic field system are arranged at the wall of the containment.

18. The sensor apparatus of claim 14, further comprising an optical fiber configured to guide the fluorescence signal from the crystal body to the detection unit.

19. The sensor apparatus of claim 14, further comprising a frame configured to enable introduction of at least one component of the sensor apparatus into the wall of the containment.

20. A method for determining and/or monitoring a process variable of a medium in a containment using the sensor apparatus according to claim 14, the method comprising: generating a magnetic field in the region of the crystal body and in the region of the medium within the containment using the magnetic field system; exciting the at least defect in the crystal body to fluoresce via the magnetic field; detecting the magnetic field-dependent fluorescence signal from the crystal body; and determining the at least one piece of information about the process variable based on the fluorescence signal.

21. The method of claim 20, wherein based on the fluorescence signal at least one variable characteristic for the magnetic field is determined.

22. The method of claim 21, wherein the at least one variable characteristic for the magnetic field is the magnetic susceptibility or the magnetic permeability.

23. The method of claim 21, wherein at least one physical and/or chemical, characteristic variable of the medium is determined based on the at least one variable characteristic for the magnetic field.

24. The method of claim 21, wherein based on the at least one variable characteristic for the magnetic field a state monitoring of a process running in the containment is performed.

25. The method of claim 21, wherein a predeterminable limit level of the medium in the containment is monitored.

26. The method of claim 25, wherein a limit value for the at least one variable characteristic for the magnetic field is predetermined, and wherein upon exceeding or falling below the limit value a crossing of the predeterminable limit level is signaled.

27. The method of claim 21, wherein the magnetic field generated in the region of the crystal body and in the region of the medium within the containment is generated as an alternating field, wherein the frequency of the alternating field is varied.

Description

[0044] The invention will now be explained in greater detail based on the appended drawing, the figures of which show as follows:

[0045] FIG. 1 a simplified energy level diagram for negative NV centers in diamond,

[0046] FIG. 2 a first embodiment of a sensor apparatus of the invention, and

[0047] FIG. 3 a second embodiment of a sensor apparatus of the invention.

[0048] In the figures, equal elements are provided with equal reference characters.

[0049] With reference to FIG. 1, firstly, the exciting of a fluorescence of a defect in a crystal body will be explained, by way of example, for the case of an NV center in diamond. The considerations can be applied to other crystal bodies with corresponding defects.

[0050] Diamond as one of the elementary forms of carbon has a cubic, face-centered crystal structure with two atoms per primitive cell. Referred to as an NV center is a vacant carbon atom (V) at a lattice site having a nitrogen atom (N) as one of the four nearest neighbors. Important for the exciting and evaluation of fluorescent signals are, especially, the negative NV centers, which have an extra electron from the diamond lattice associated with them.

[0051] Diamond structures with embedded, negative NV centers are assigned to the symmetry group C.sub.3v, which determines the possible spatial eigenstates of the NV center. As evident based on the energy level diagram without resonant excitation and without external magnetic field in FIG. 1, a triplet ground state .sup.3A.sup.2 and an excited triplet state .sup.3E result, between which lie two metastable singlet states .sup.1E and .sup.1A. The triplet ground state .sup.3A.sub.2 has three magnetic substrates m.sub.s=0, ±1. Also in the case of the excited .sup.3E state, there is a splitting of the energy levels.

[0052] By excitation 1 with light of wavelength λ=532 nm, for example, an excitation of a vibration state of the excited .sup.3E state occurs, with following Frank-Condon transition to the ground state .sup.3A.sub.2, in the case of which a fluorescence photon 2 with a wavelength of λ=630 nm is emitted. Upon applying an external magnetic field, additionally, a Zeeman splitting of the energy level occurs, and, associated therewith, two fluorescence minima are emitted, whose separation is, for example, proportional to the applied magnetic field strength B.

[0053] The evaluation of the fluorescent light can occur according to the invention in many different ways. Besides the above mentioned evaluation of the energy difference between the two energy levels, which allows an ascertaining of the magnetic field based on the Zeeman formula, in an alternative optical evaluation method, also the intensity of the radiated light can be considered, such likewise being proportional to the magnetic field. An electrical evaluation is, in turn, an option, for example, via a Photocurrent Detection of Magnetic Resonance (PDMR). Besides these examples of evaluation of the fluorescent signal, other options are available, which likewise fall within the scope of the invention.

[0054] FIG. 2 shows possible examples of embodiments of a sensor apparatus 3 of the invention, as mounted on an outer surface of a containment 4 in the form of a container, which is filled partially with a medium 5. Sensor apparatus 3 includes a crystal body 6 having at least one defect 7, and a magnetic field system 8 having at least one con, which at least partially surrounds the crystal body 6. In the case of the embodiment illustrated here, the crystal body 6 is arranged within the coil 8. The magnetic field system 8 serves for producing a magnetic field B in the region of the crystal body 6 and in the region of an internal volume of the containment 4.

[0055] Additionally, the sensor apparatus includes a detection unit 9 having an excitation unit 10 and a detector 11 for detecting the fluorescent signal 2, as well as an evaluation unit 12 for additional evaluation of the signal 2 and for ascertaining the at least one piece of information concerning the process variable.

[0056] While FIG. 2a shows a non-invasive sensor apparatus 3 securable from the outside on the wall of the containment 4, FIG. 2b shows an apparatus 3 terminating flushly with the wall of the container 4. The apparatus 3 of FIG. 2b includes a frame 13, by means of which at least one component of the sensor apparatus 3 (here, the crystal body 6 and the coil) is securable in an opening of the wall of the container 4.

[0057] FIG. 3 shows another possible embodiment of a system having two apparatuses 3 and 3′ of the invention. In contrast with the embodiments of FIG. 2, in the case of FIG. 3, a compact construction is not used, but, instead, the detection units 9, 9′ and the evaluation units 12, 12′ are arranged spatially removed from the remaining components of the sensor apparatuses 3 and 3′ and therefore not shown. In order, in each case, to be able to lead the fluorescent signal 2 to a detection unit 9, 9′, the two displayed sensor apparatuses 3, 3′ include, in each case, an optical fiber 14, 14′ for bringing the light from the crystal bodies 6, 6′ to the respective detection units 9, 9′. It is even an option to use one detection unit 9 for the two crystal bodies 6, 6′, instead of two separate detection units 9, 9′. The excitation unit 11 can be arranged in the region of the container 4 or with the evaluation unit 12. Also, a shared excitation unit 11 can be used for the excitation, instead of two separate units.

[0058] The sensor apparatus 3 of the invention and the method of the invention permit a comprehensive process monitoring expanding the capabilities of reassuring methods known from the state of the art for process automation. On the one hand, process variables such as a predeterminable fill level of medium in the containment can be monitored. Moreover, however, also a comprehensive characterizing of the medium 5, or of processes transpiring within the containment 5, can be performed. Additionally, the apparatus 3 of the invention is advantageously a non-invasive sensor, which, thus, requires no invasion of the ongoing process and which enables, in simple manner, a miniaturization of a sensor apparatus while at the same time widening the field of application.

REFERENCE CHARACTERS

[0059] 1 excitation light [0060] 2 fluorescent light [0061] 3 sensor apparatus [0062] 4 medium [0063] 5 containment [0064] 6 crystal body [0065] 7 defect [0066] 8 magnetic field system [0067] 9 detection unit [0068] 10 exciter unit [0069] 11 detector [0070] 12 evaluation unit [0071] 13 frame [0072] 14 optical fiber