DE102021202416A1 - NMR vapor cell assembly, method of making the NMR vapor cell assembly, NMR gyroscope and method of operating the NMR gyroscope - Google Patents

Abstract

The invention relates to an NMR vapor cell arrangement, - with a first medium being arranged in a first chamber (101), - with a second medium (1020) being arranged in a second chamber (102), and - with between the first chamber (101 ) and the second chamber (102) a passage arrangement (103) is formed, wherein the passage arrangement (103) comprises a duct (1030) for conducting the second medium (1020) from the second chamber (102) into the first chamber (101). , wherein- the NMR vapor cell assembly (100) comprises a heater (104) for setting a first temperature in the first chamber (101), and- the port assembly (103) comprises a connection structure (1031) for providing thermal coupling between the first chamber (101) and the second chamber (102),• wherein a second temperature can be generated by setting the first temperature in the first chamber (101) due to the thermal coupling in the second chamber (102), and• wherein ei n temperature difference between the first temperature and the second temperature is determined by a dimensioning of the connection structure (1031). The invention also relates to a method for producing the NMR vapor cell arrangement (100), an NMR gyroscope and a method for operating the NMR gyroscope.

Description

State of the art

In "Microfabricated alkaline vapor cell with anti-relaxation wall coating" (Straessle et al., Applied Physics Letters, 105, issue 4, 043502/1-4, 2014) a microstructured alkaline vapor cell is described, which includes a reservoir chamber, in which liquid alkali droplets are arranged, and which comprises a measuring chamber, wherein alkali vapor can get from the reservoir chamber into the measuring chamber via a channel connecting the chambers.

essence and advantages of the invention

Today's rotation rate sensors based on MEMS allow vehicles to stay in lane for a period of around 40 seconds as a backup for radar, video-assisted and GPS positioning. At a cruising speed of 100 km/h, this enables an emergency stop function if all other driver assistance systems fail.

In order to improve the safety and comfort of autonomously driving vehicles, a significant increase in drift stability and a significant reduction in the noise of yaw rate sensors would be desirable in order to enable purely inertial navigation even for longer distances, such as in tunnels or in urban canyons.

Gyroscopes known from basic research, which evaluate nuclear magnetic resonance signals from atomic nuclei with a non-vanishing magnetic moment (spin 1/2 nuclei, spin 3/2 nuclei, spin ((2n+1)/2) nuclei, where n is a natural number), show a 100-fold increase in drift stability and a 50-fold increase in accuracy compared to the MEMS angular rate sensors currently used in the automotive industry (see Neul, et al., IEEE Sensors Journal, Vol. 7, No. 2 (2007)).

Compared to other high-precision yaw rate sensors, which are used for example in the field of aircraft navigation and which are based on the optical Sagnac effect (laser gyro), miniaturized nuclear spin gyroscopes (= NMR gyroscope) are significantly lower production costs than the Sagnac Gyroscopes that are used in aviation have.

Another advantage of NMR gyroscopes compared to Sagnac gyroscopes is that NMR gyroscopes have a high potential for miniaturization with a very high sensitivity, whereas Sagnac gyroscopes require a significantly larger structure due to their operating principle.

Diese äußere Rotation ω_rot kann folglich mittels eines NMR-Gyroskops ermittelt werden.In nuclear magnetic resonance gyroscopes, also known as spin-based gyroscopes or NMR gyroscopes (NMR=nuclear magnetic resonance), which are based on a vapor cell, the resulting spin-larmor precession ω _larmor is read out in a vapor cell. An outer rotation ω _rot represents an additional rotation, which can be determined by reading out the rotation frequency ω _mess as follows: $${\mathrm{\omega }}_{\text{mess}}={\mathrm{\omega }}_{\text{larmor}}\pm {\mathrm{\omega }}_{\text{red}}$$

This outer rotation ω _rot can consequently be determined using an NMR gyroscope.

An exemplary structure of an NMR gyroscope and its mode of operation are shown, for example, in "MEMS Components for NMR Atomic Sensors" (R. M. Noor and A. M. Shkel; Journal of Microelectromechanical Systems, 27(6):1148-1159, Dec. 2018).

The invention relates to an NMR vapor cell assembly, a method for manufacturing the NMR vapor cell assembly, an NMR gyroscope and a method for operating the NMR gyroscope.

An advantage of the invention with the features of the independent patent claims is that the drift stability is increased and the noise is significantly reduced compared to known NMR gyroscopes, and measurement errors or functional failures can be reduced or avoided.

This is achieved with an NMR vapor cell assembly comprising a first medium, a second medium, a first chamber and a second chamber. In this case, the first medium is arranged in the first chamber, and the second medium is arranged in the second chamber. A passage arrangement is formed between the first chamber and the second chamber, the passage arrangement comprising a duct for conducting the second medium from the second chamber into the first chamber. The NMR vapor cell assembly is characterized in that the NMR vapor cell assembly includes a heater for setting a first temperature in the first chamber, and the port assembly includes a connection structure for providing thermal coupling between the first chamber and the second chamber. The connection structure between the first chamber and the second chamber is dimensioned such that a second temperature is generated in the second chamber due to the thermal coupling by setting the first temperature in the first chamber, the first temperature differing from the second temperature. By setting the first temperature in Consequently, a second temperature is generated in the first chamber due to the thermal coupling in the second chamber, with a temperature difference between the first temperature and the second temperature being determined in particular by a dimensioning of the connection structure.

The realization of a two-chamber MEMS (= microelectromechanical system) chip (i.e. the NMR vapor cell arrangement) filled with two media, such as rubidium as the second medium and xenon as the first medium, with defined thermal coupling of the two chambers, advantageously enables the to keep the heated measuring chamber (first chamber) a few degrees warmer than the reservoir chamber (second chamber), whereby the condensation of the second medium in the measuring chamber, which reaches the measuring chamber through the at least one duct from the reservoir chamber, can be permanently avoided. Thus, advantageously, measurement errors or functional failures in an NMR-based gyroscope, which includes the NMR vapor cell arrangement, or in an atomic clock, which includes the NMR vapor cell arrangement, can be sustainably avoided.

An NMR vapor cell arrangement is understood to mean, in particular, a vapor cell arrangement which is designed for use in an NMR gyroscope.

The NMR vapor cell assembly may include two chambers (also called vapor cells) or more than two chambers. A vapor cell is designed here, for example, as a hollow body made of glass, silicon, etc., with the first chamber and the second chamber being connected by the duct, so that gas exchange can take place between the two vapor cells. The two vapor cells and the duct can be hermetically sealed from the environment of the NMR vapor cell arrangement, so that gases in particular cannot escape from the interior of the vapor cells during operation and pressures can be generated inside the vapor cells which can deviate from the ambient pressure of the NMR vapor cell arrangement.

To set a pressure and/or to generate a gas in the chambers, a heating element can be arranged on the first chamber or in an environment of the first chamber, which is thermally connected to the first chamber. An embodiment of a heating element for heating the first chamber comprises at least one laser, i. H. a heating laser, in particular an infrared laser, the laser light of which is directed onto a region of the first chamber or the environment thermally connected to the first chamber. For example, the laser power can be 50 mW (milliwatts). The laser light is absorbed by the material of the first chamber, in particular the silicon or glass, and thus heats the vapor cell.

In particular, the at least one vapor cell can be made of glass and/or silicon and can be round, cylindrical, cube-shaped, oval, etc., for example, or have any desired polygonal contour. An advantage of this embodiment of the heating element is that the magnetic field configuration required for the measuring principle of the NMR gyroscope is not disturbed by this heating method, and the sensitivity and reliability of a measurement can therefore be increased when using the NMR vapor cell arrangement in an NMR gyroscope.

A further embodiment for heating the steam cell or steam cells comprises, for example, electrically conductive wires as heating elements, with a temperature of the media located in the steam cell being adjustable via the electric current flowing through the wires.

The first temperature can be set in the first chamber by heating. The first chamber and the second chamber are thermally coupled to one another via the connection structure. Therefore, when the first chamber is heated, there is a flow of heat towards the second chamber, which is consequently also heated or passively heated via the connection structure. Because of the thermal resistance of the connection structure, the second chamber heats up to the second temperature, which is in particular lower than the first temperature. In equilibrium, a temperature difference thus arises between the first chamber and the second chamber. In particular, a temperature difference of greater than or equal to 3° Celsius, in particular greater than or equal to 5° Celsius (C), can thus be achieved, with the reservoir chamber being able to be kept at the temperature of approximately 90°-100° C. required for operating the NMR gyroscope. The temperature difference can advantageously permanently prevent condensation of the second medium, in particular rubidium, in the first chamber, as a result of which measurement errors and functional failures of the NMR gyroscope can be avoided.

For example, a noble gas such as xenon (Xe), neon (Ne), krypton (Kr) or helium-3 ( ³ He) can be used as the first medium. For example, an alkali metal such as rubidium (Rb), in particular rubidium 87 ( ⁸⁷ Rb) or rubidium 85 ( ⁸⁵ Rb), cesium (Cs), potassium (K), etc. or mercury (Hg) can be used as the second medium. The first medium and the second medium can in particular be gaseous or by heating in one gaseous state can be converted. In particular, the second medium can be introduced into the second chamber in a liquid state of aggregation during the production of the NMR vapor cell arrangement.

In particular, the second medium is introduced into the second chamber in a solid or liquid state during the manufacture of the vapor cell arrangement.

In particular, the second medium in the first chamber is only in a gaseous state when the NMR gyroscope is in operation, but not in a solid or liquid state.

The passage arrangement comprises the connection structure and at least one duct.

A dimensioning of the connection structure includes both the description of a material from which the connection structure is made and the shape, dimensions and cross-sectional area of the connection structure.

In one embodiment, the connection structure extends in the form of one or more webs or bridges between the first chamber and the second chamber. In particular, it can be made of the same material as the chambers--i.e. H. Glass, silicon, etc. - or be made of a material different from the chambers. In particular, the connection structure can be curvilinear, angular, meandering and/or straight, at least in sections. In particular, the connection structure can have a square, trapezoidal, rectangular, round or any shaped cross section.

The connection structure acts as a thermal coupling (coupling structure) between the first chamber and the second chamber. It has a thermal resistance which depends on the dimensioning of the connection structure. Thermal resistance is a measure of the temperature difference that occurs in an object when a heat flow (heat per unit time or heat output) passes through it. For example, the thermal resistance of this coupling structure and thus the temperature difference between the heated first chamber and the passively heated second chamber can be adjusted in a targeted manner via the length and the cross-sectional area of the connecting structure. The first chamber serves as a measuring chamber in the NMR gyroscope. The second chamber, which is heated passively via the connection structure as a function of the thermal resistance of the connection structure, serves as a reservoir chamber in the NMR gyroscope. An advantage of also heating the second chamber indirectly via the connection structure, with a temperature difference being established between the first and second chambers, is that advantageously a condensation of the second medium, in particular rubidium, can be permanently prevented in the first chamber and thus the function and reliability of the NMR vapor cell arrangement can be ensured.

The first chamber and the second chamber are in particular arranged at a distance from one another, with a medium or material being arranged in the space between the first chamber and the second chamber, which thermally decouples the first chamber and the second chamber from one another, so that the thermal coupling is preferably exclusively through the connection structure. In particular, this medium/material differs from the material from which the first chamber, the second chamber and the connecting structure are formed. In particular, a gaseous medium such as air can be located in the intermediate space. In one embodiment, there may be a vacuum in the gap.

The connection structure connects the first chamber and the second chamber across the gap. In particular, the connecting structure extends in the form of a bar in the intermediate space between the first chamber and the second chamber, from the first chamber to the second chamber.

In order to enable the second medium to be conducted from the reservoir chamber, into which the second medium is introduced during the manufacture of the NMR vapor cell arrangement, into the first chamber, the thermal coupling web, i. H. the connection structure - provided with a channel which is about half as wide as the web and a few 10 to a few 100 microns deep - preferably on the top or the bottom. The line channel can be understood in particular as a structure which is suitable for enabling gas exchange between the first chamber and the second chamber. For example, the duct can extend in the form of a tube or tunnel between the first chamber and the second chamber. In particular, the duct can have a round, rectangular, square or any shape cross-section. In particular, the duct can be applied to the connection structure, embedded at least partially or completely in the connection structure. In particular, a first line channel can run on a first side of the connection structure from the first chamber to the second chamber. Alternatively or additionally, a second line channel, which runs from the first chamber to the second chamber, can be arranged on a second side of the connecting structure opposite the first side.

In particular, the second medium can only get into the first chamber through the duct in a vapor phase.

In one embodiment, the connection structure comprises at least one, but in particular greater than or equal to two coupling webs, all of which, more than one or only one are each provided with at least one exchange channel (line channel) for the first and second medium (e.g. Xe and Rb gas). are. One advantage is that the first chamber and the second chamber can thus advantageously be arranged closer together with the same thermal resistance of the connection structure.

• • Strukturieren einer Grundplatte zum Erzeugen der ersten Kammer, der zweiten Kammer und der Durchlassanordnung, wobei die Durchlassanordnung den mindestens einen Leitungskanal und die mindestens eine Verbindungsstruktur umfasst;
• • Einbringen des zweiten Mediums in die zweite Kammer, wobei das Medium in einem festen oder flüssigen Aggregatzustand vorliegt;
• • Aufbringen einer Deckplatte auf die strukturierte Grundplatte zum Verschließen der ersten Kammer, der zweiten Kammer und/oder des mindestens einen Leitungskanals.

A method for manufacturing the NMR vapor cell assembly comprises the steps:

• • structuring a base plate to create the first chamber, the second chamber and the passage arrangement, wherein the passage arrangement comprises the at least one duct and the at least one connection structure;
• • introducing the second medium into the second chamber, the medium being present in a solid or liquid state of aggregation;
• • Applying a cover plate to the structured base plate to close the first chamber, the second chamber and/or the at least one duct.

The advantages are that the NMR vapor cell configurations using MEMS technology can be manufactured in large numbers, at low cost and with high precision. In particular, several NMR vapor cell arrangements can be produced according to the above methods by producing several, in particular at least two, first chambers and several, in particular at least two, second chambers and several, in particular at least two passage arrangements when structuring a base plate, with each of the passage arrangements having at least one Includes duct and at least one connection structure. The NMR vapor cell assemblies can then be separated. For this purpose, the stack of layers of structured base plate and cover plate can be divided in a dicing step.

The connection between the base plate and the cover plate is preferably produced by means of anodic bonding. Alternatively or in addition, the connection can also be made by direct wafer bonding, thermocompression bonding, or similar bonding methods and by connecting with seal glass.

A thickness of the base plate is in particular one millimeter (1 mm) or more than one millimeter or less than one millimeter.

In one embodiment, the first chamber, the second chamber and the connection structure as well as the duct are produced by structuring the base plate (also called wafer or substrate), the base plate being made of silicon, for example.

Alternatively or additionally, the base plate can be made of glass. One advantage of production in glass, due to the lower thermal conductivity of glass, is that the setting of the temperature difference of greater than or equal to 3° Celsius, in particular greater than or equal to 5° Celsius, can already be achieved with very small chamber distances of a few 100 μm, for example 200 μm can, which leads to a smaller size of the entire NMR vapor cell assembly and thus advantageously allows miniaturization of the NMR vapor cell assembly.

According to one embodiment, the NMR vapor cell arrangement is produced with a defined thermal coupling of the chambers, ie, one that is fixed by the dimensioning of the connection structure, using MEMS technology. In particular, the NMR vapor cell assembly includes a triple stack of a bottom wafer (bottom plate), a patterned wafer (base plate), and a top wafer (top plate), with the patterned wafer sandwiched between the bottom wafer and the top wafer. In particular, the structured wafer can be made of silicon, glass or the like. The lower wafer and the upper wafer can each be designed as a glass wafer, for example. The connection between the three wafers is preferably established by means of anodic bonding. Alternatively or in addition, the connection can also be made by direct wafer bonding, thermocompression bonding, or similar bonding methods and by connecting with seal glass. The middle wafer (base plate) is structured in such a way that two separate chambers—the measuring chamber and the reservoir chamber—are created as openings that go through the entire thickness of the structured wafer (e.g. silicon wafer). The surrounding material surfaces (in particular Si surfaces) of these openings are connected by the thermal coupling structure (connection structure) as a straight or meandering ridge that extends from the upper to the lower surface of the silicon wafer. The thermal resistance of this coupling structure and thus the temperature difference between the laser-heated measuring chamber and the passively heated reservoir can be adjusted by selecting the dimensions, such as the length, the cross-sectional area, etc chamber in order to permanently prevent Rb from condensing in the measuring chamber. In order to enable an exchange of the second medium from the reservoir chamber, into which it is introduced during production of the chip, into the measuring chamber, the thermal coupling web is provided with at least one channel on the top and/or the bottom, which extends from the first chamber extends to the second chamber. This channel is about half as wide as the web and a few 10 μm to a few 100 μm, greater than or equal to 10 μm and less than or equal to 200 μm deep.

• • Aufbringen einer ersten Fotomaske, insbesondere umfassend einen Positivlack, auf die Grundplatte zur fotolithografischen Strukturierung des mindestens einen Leitungskanals;
• • Anwenden eines Ätzprozesses, insbesondere reaktives Ionentiefenätzen (DRIE-Prozess), zum Erzeugen des mindestens einen Leitungskanals in der Grundplatte. Die Ätztiefe liegt insbesondere in einem Bereich von größer gleich 10 µm bis kleiner gleich 200 µm, beispielsweise 50 µm, sodass der mindestens eine Leitungskanal folglich eine Tiefe im Bereich von größer gleich 10 µm bis kleiner gleich 200, beispielsweise 50 µm, aufweist.
• • Entfernen der ersten Fotomaske.

In one embodiment, the structuring of the base plate to create the at least one duct can include at least one of the following steps:

• • Application of a first photomask, in particular comprising a positive resist, to the base plate for photolithographic structuring of the at least one duct;
• • Applying an etching process, in particular deep reactive ion etching (DRIE process), to produce the at least one line channel in the base plate. The etching depth is in particular in a range from greater than or equal to 10 μm to less than or equal to 200 μm, for example 50 μm, so that the at least one line channel consequently has a depth in the range from greater than or equal to 10 μm to less than or equal to 200, for example 50 μm.
• • Removal of the first photomask.

In one embodiment, after structuring the base plate to create the at least one duct, the base plate, the base plate (if present) and/or the cover plate are wet-chemically cleaned, for example by an RCA cleaning step.

• • Aufbringen einer Maske auf die Grundplatte, wobei das Aufbringen der Maske insbesondere die nachfolgenden Schritte umfassen kann:
  • ◯ Thermisches Oxidieren der Grundplatte, insbesondere kann das Oxid auf einer Unterseite der Grundplatte entfernt werden und eine Bodenplatte (beispielsweise ein Glaswafer) auf der Unterseite der Grundplatte angeordnet werden. Die Grundplatte und die Bodenplatte können beispielsweise durch anodisches Bonden miteinander verbunden werden;
  • ◯ Aufbringen einer zweiten Fotomaske auf die thermisch oxidierte Grundplatte, insbesondere auf eine der Unterseite gegenüberliegende Oberseite der thermisch oxidierten Grundplatte, zur fotolithografischen Strukturierung der ersten Kammer und der zweiten Kammer, wobei die zweite Fotomaske insbesondere einen Positivlack umfasst;
  • ◯ Anwenden eines Ätzprozesses, insbesondere eines Trockenätzprozesse, bei dem die Strukturierung der Fotomaske auf die Oxidschicht der Grundplatte übertragen wird, d. h. die Oxidschicht wird durch den Ätzprozess in den Bereichen entfernt, in denen die erste Kammer, die zweite Kammer und die Verbindungsstruktur erzeugt werden sollen;
  • ◯ Entfernen der zweiten Fotomaske;
    • • Aufbringen einer metallischen Schicht, insbesondere einer Aluminium-Schicht, auf eine Unterseite der Bodenplatte, welche einer Oberseite der Bodenplatte, die mit der Grundplatte verbunden ist, gegenüberliegt;
    • • Anwenden eines Ätzprozesses, insbesondere eines Tiefenätzprozesses, bei dem die Strukturierung der Oxidschicht auf die Grundplatte übertragen wird und somit die erste Kammer, die zweite Kammer und die Verbindungsstruktur ausgebildet werden;
    • • Entfernen der Maske, insbesondere der strukturierten Oxidschicht, dieser Schritt erfolgt beispielsweise durch einen Nassätzprozess

In one embodiment, the structuring of the base plate to create the first chamber, the second chamber and the connection structure comprises at least one of the following steps:

• • Applying a mask to the base plate, whereby the application of the mask can include the following steps in particular:
  • ◯ Thermal oxidation of the base plate, in particular the oxide on a bottom side of the base plate can be removed and a bottom plate (e.g. a glass wafer) can be arranged on the bottom side of the base plate. The base plate and the bottom plate can be connected to one another, for example, by anodic bonding;
  • ◯ Application of a second photomask to the thermally oxidized base plate, in particular to an upper side of the thermally oxidized base plate opposite the underside, for photolithographic structuring of the first chamber and the second chamber, the second photomask comprising in particular a positive resist;
  • ◯ Applying an etching process, in particular a dry etching process, in which the structure of the photomask is transferred to the oxide layer of the base plate, i.e. the oxide layer is removed by the etching process in the areas in which the first chamber, the second chamber and the connection structure are to be created ;
  • ◯ removing the second photomask;
    • • Application of a metallic layer, in particular an aluminum layer, to an underside of the base plate which is opposite an upper side of the base plate which is connected to the base plate;
    • • Applying an etching process, in particular a deep etching process, in which the structuring of the oxide layer is transferred to the base plate and the first chamber, the second chamber and the connection structure are thus formed;
    • • Removal of the mask, in particular the structured oxide layer, this step is carried out, for example, by a wet etching process

In one embodiment - for example by atomic layer deposition (ALD) - a thin layer of aluminum oxide (Al ₂ O ₃ ) on the structured upper side of the base plate and / or the surface of the cover plate, which is to be connected to the structured base plate, be raised.

• • Einbringen des zweiten Mediums in die zweite Kammer in Form einer wässrigen Lösung, wobei als zweites Medium beispielsweise Rubidiumazid (RbN₃) verwendet wird;
• • Trocknen des zweiten Mediums, wobei als zweites Medium beispielsweise Rubidiumazid (RbN₃) als wässrige Lösung vorliegt.

In one embodiment, the step of introducing the second medium into the second chamber comprises at least one of the following steps:

• • introducing the second medium into the second chamber in the form of an aqueous solution, rubidium azide (RbN ₃ ), for example, being used as the second medium;
• • Drying of the second medium, rubidium azide (RbN ₃ ), for example, being present as an aqueous solution as the second medium.

The first medium can, for example, be introduced from the cover plate to the base plate directly before the anodic bonding. This happens in particular in the bond tool itself.

In one embodiment, the second medium in the second chamber is activated by irradiating it with ultraviolet radiation (UV radiation), in particular UV activation takes place by exposing the second medium to UV radiation for twenty-four hours. The second medium can also be activated, in particular, by irradiation with a UV laser.

In one embodiment, the NMR vapor cell assembly includes the base plate, the top plate, and a bottom plate.

In one embodiment, the base plate, the cover plate and/or the base plate can be multi-layered. Thus, the NMR vapor cell assembly may include two wafers, three wafers, or more than three wafers.

Advantages of an NMR gyroscope including the NMR vapor cell arrangement result from the aforementioned advantages of the NMR vapor cell arrangement according to the respective embodiment.

• • Einstellen der ersten Temperatur in der ersten Kammer durch Heizen, wobei die Verbindungsstruktur zwischen der ersten Kammer und der zweiten Kammer derart dimensioniert ist, dass durch Einstellen der ersten Temperatur in der ersten Kammer aufgrund der thermischen Kopplung eine zweite Temperatur in der zweiten Kammer erzeugt wird, wobei die erste Temperatur von der zweiten Temperatur abweicht;
• • Erzeugen einer synchronisierten Präzessionsbewegung polarisierter Kernspins des ersten Mediums in der ersten Kammer;
• • Optisches Auslesen der synchronisierten Präzessionsbewegung der polarisierten Kernspins in der ersten Kammer, welches einen Schritt Erfassen eines Messsignals umfasst;
• • Bestimmen einer Drehmessgröße der Drehung des NMR-Gyroskops aus dem Messsignal.

A method of operating the NMR gyroscope includes the steps:

• • Setting the first temperature in the first chamber by heating, wherein the connection structure between the first chamber and the second chamber is dimensioned such that a second temperature is generated in the second chamber by setting the first temperature in the first chamber due to the thermal coupling , wherein the first temperature differs from the second temperature;
• • generating a synchronized precession motion of polarized nuclear spins of the first medium in the first chamber;
• • Optical readout of the synchronized precession movement of the polarized nuclear spins in the first chamber, which includes a step of acquiring a measurement signal;
• • Determination of a rotational variable of the rotation of the NMR gyroscope from the measurement signal.

This means that the second chamber is thus heated, in particular passively, due to the thermal coupling by means of the connection structure.

A temperature difference between the first temperature and the second temperature is determined in particular by a dimensioning of the connection structure.

One advantage is that due to the temperature difference between the first and the second chamber, condensation of the second medium in the measuring chamber (first chamber), which enters the measuring chamber through the at least one duct from the reservoir chamber (second chamber), can be permanently avoided , and thus measurement errors or functional failures in an NMR-based gyroscope, which includes the NMR vapor cell arrangement, can be avoided in the long term.

Examples of rotation quantities are the rotation rate or the rotation frequency of the rotation of the NMR gyroscope.

When detecting the measurement signal, for example, a readout light beam can first radiate through the first chamber of the NMR vapor cell arrangement, in which case the readout light beam can be recorded, for example, by a detection arrangement after passing through the first chamber. The read-out light beam is converted there into a measurement signal, for example in the form of an electrical signal, as described below.

The operating principle of the NMR gyroscope is based on the following steps: The electron spin of an alkali metal vapor such as rubidium (Rb) is polarized in a vapor cell by optical pumping. Specifically, as the alkali metal, rubidium 87 ( ⁸⁷ Rb) or rubidium 85 ( ⁸⁵ Rb), cesium (Cs), potassium (K), etc. can be used. An inert gas such as xenon (Xe), neon (Ne), krypton (Kr) or helium-3 ( ³ He) is also arranged in the vapor cell.

Due to a strong electron-nuclear spin interaction between the noble gas and the alkali metal, the electron spin polarization leads to a polarization of the nuclear spins of the noble gas. A bias field to which the vapor cell is subjected dictates a direction about which the polarized nuclear spins of the noble gas precess. By applying an oscillating magnetic field (AC magnetic field), which has at least one component orthogonal to the direction of the bias field, the precession motion of the polarized nuclear spins around the direction of the bias field is synchronized, so that all polarized nuclear spins are in phase with each other at the Larmor frequency (if no external rotation rate applied to the NMR gyro) precess around the direction of the bias field, ie perform a collectively coherent precession motion, resulting in a harmonically oscillating macroscopic magnetization. The frequency of the oscillating magnetic field preferably matches the Larmor frequency of the polarized nuclear spins. The electron spins of the alkali metal are sensitive to the periodic magnetic field change caused by the in-phase nuclear spin precession. So it is possible lich to transfer the in-phase nuclear spin precession to the electron spins of the alkali metal. The precession movement of the polarized nuclear spins can thus be converted into a readable electrical signal. For this purpose, the vapor cell can be illuminated with a linearly polarized readout light beam, for example. When passing through the vapor cell, the polarization of the readout light beam is rotated periodically, which is caused by the precession movement of the polarized nuclear spins (Faraday effect). The Faraday effect describes the rotation of the plane of polarization of a linearly polarized electromagnetic wave in a medium when there is a magnetic field parallel to the direction of propagation of the wave. The periodic rotation of the polarization of the read-out light beam can be converted into an electrical signal by a detection arrangement, for example. For example, a polarization filter can be arranged in front of the photodiode, which leads to an attenuation of the read-out light beam as a function of this polarization rotation, so that an intensity fluctuation can be observed at the photodiode, which is modulated with the Larmor frequency of the nuclear spins of the first medium. This intensity fluctuation can be detected, for example, in the form of an electrical signal and used as a measurement signal, which is a measure of the periodically changing radiation intensity. In the case of a measuring system at rest, this Larmor frequency is equal to the product of the gyromagnetic ratio of the nuclei of the second medium and the bias field. In the case of a uniformly rotating measuring system, a Larmor frequency that is higher or lower by this rotational frequency of the measuring system is measured, which is used to determine the rotational frequency (angular rate) of the measuring system.

During operation of the NMR gyroscope, the second medium should be present as vapor with constant pressure in the measuring cell, i.e. the first chamber. This requires active heating of the first chamber to approx. 115° Celsius. This can be done, for example, as described above, using an infrared laser.

character list

Embodiments of the invention are shown in the drawings and are explained in more detail in the following description. The same reference symbols in the figures denote the same or equivalent elements.

• 1a bis 1d eine Darstellung des Wirkprinzips eines NMR-Gyroskops,
• 2 eine dreidimensionale Ansicht einer NMR-Dampfzellenanordnung gemäß einem Ausführungsbeispiel,
• 3 eine dreidimensionale Ansicht einer strukturierten Grundplatte einer NMR-Dampfzellenanordnung gemäß einem Ausführungsbeispiel,
• 4 einen Querschnitt durch die Durchlassanordnung der 2,
• 5 einen Querschnitt durch die erste Kammer und die zweite Kammer der 2,
• 6 eine Temperaturverteilungsfunktion in einer NMR-Dampfzellenanordung gemäß einem Ausführungsbeispiel,
• 7 einen Aufbau eines NMR-Gyroskops, umfassend eine NMR-Dampfzellenanordnung, gemäß einem Ausführungsbeispiel,
• 8 ein Flussdiagramm eines Verfahrens zur Herstellung einer NMR-Dampfzellenanordnung gemäß einem Ausführungsbeispiel,
• 9 eine Aufsicht einer strukturierten Grundplatte einer NMR-Dampfzellenanordnung gemäß einem Ausführungsbeispiel
• 10 bis 27 jeweils einen Querschnitt der in 9 gezeigten NMR-Dampfzellenanordnung während der verschiedenen Herstellungsschritte und
• 28 ein Verfahren zur Verwendung eines NMR-Gyroskops gemäß einem Ausführungsbeispiel.

Show it

• 1a until 1d a representation of the operating principle of an NMR gyroscope,
• 2 a three-dimensional view of an NMR vapor cell arrangement according to an embodiment,
• 3 a three-dimensional view of a structured base plate of an NMR vapor cell arrangement according to an embodiment,
• 4 a cross section through the passage arrangement of 2 ,
• 5 a cross section through the first chamber and the second chamber of 2 ,
• 6 a temperature distribution function in an NMR vapor cell arrangement according to an embodiment,
• 7 a structure of an NMR gyroscope, comprising an NMR vapor cell arrangement, according to an embodiment,
• 8th a flowchart of a method for producing an NMR vapor cell arrangement according to an embodiment,
• 9 a top view of a structured base plate of an NMR vapor cell arrangement according to an embodiment
• 10 until 27 each a cross-section of the in 9 shown NMR vapor cell arrangement during the various manufacturing steps and
• 28 a method of using an NMR gyroscope according to an embodiment.

Embodiments of the invention

In the 1a until 1d the operating principle of an NMR gyroscope is shown using principle sketches. A first medium and a second medium are arranged in a vapor cell 101 or a first chamber of an NMR vapor cell arrangement, which are symbolized by circles which represent atoms, with each circle being provided with an arrow which represents the respective spin of the respective atom (for the first medium the nuclear spin 2011, for the second medium the electron spin 2012). Xenon is used here as the first medium and rubidium is used as the second medium here by way of example.

In 1a the electron spins 2012 of the second medium are polarized by optical pumping. The vapor cell 101 is exposed to a bias field 2010, which is shown here in the z-direction as an example. In particular, the bias field 2010 may include a static magnetic field. The electron spins 2012 of the second medium precess around the direction (here z-direction) that is predetermined by the bias field 2010 . i.e. 1a shows an alignment ten of the electron spins 2012 of the second medium as a result of the polarization and the application of the bias magnetic field 2010 and exciting the electron spins 2012 to a precession motion, which in 1a is represented by a dashed ellipse at the end of the arrow of the electron spins 2012.

The electron spin polarization caused by optical pumping leads to a polarization of the nuclear spins 2011 of the first medium due to a strong electron-nuclear spin interaction between the second medium and the first medium. This is done like this in 1b an alignment of the nuclear spins 2011 is shown, which are excited to a precession movement due to the presence of the bias magnetic field 2010, which is shown in 1b is indicated by a dashed ellipse at the end of the arrow of the nuclear spins 2011. Due to the alignment of the electron spins 2012 and the nuclear spins 2011, there is a resulting magnetization 2014, which here shows in the z-direction.

wobei $\overrightarrow{B_{AC}}$

das magnetische Wechselfeld 2015, $\overrightarrow{B_0}$

die Amplitude des magnetischen Wechselfelds 2015 und ω_L eine Frequenz, welche vorzugsweise der Larmorfrequenz des ersten Mediums entspricht, bezeichnet.
Durch das Anlegen des mangetischen Wechselfeldes 2015 werden die Präzessionsbewegungen der Kernspins 2011 synchronisiert, sodass sie gleichphasig zueinander präzedieren. Diese gleichphasige Kernspin-Präzessionsbewegung sorgt dafür, dass die resultierende Magnetisierung 2014 präzediert und somit eine periodische Magnetfeldänderung bewirkt, wie dies in 1c durch eine gestrichelte Ellipse an dem Pfeil der die Magnetisierung 2014 repräsentiert, angedeutet ist.In 1c an alternating magnetic field 2015 is applied antiparallel to the y-direction, which can be described, for example, as follows: $$\overrightarrow{B_{AC}}=\overrightarrow{{\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="DE102021202416A1\_0009.png"\; state="\{\{state\}\}">B</figure-callout>}}_0}\cdot \text{cos}\left({\omega }_{L}t\right)$$

whereby $\overrightarrow{B_{AC}}$

the alternating magnetic field 2015, $\overrightarrow{{\mathrm{<figure-callout\; id="0"\; label="B"\; filenames="DE102021202416A1\_0009.png"\; state="\{\{state\}\}">B</figure-callout>}}_0}$

denotes the amplitude of the alternating magnetic field 2015 and ω _L denotes a frequency which preferably corresponds to the Larmor frequency of the first medium.
By applying the alternating magnetic field 2015, the precession movements of the nuclear spins 2011 are synchronized so that they precess in phase with one another. This in-phase nuclear spin precession movement ensures that the resulting magnetization 2014 precesses and thus causes a periodic magnetic field change, as shown in 1c indicated by a dashed ellipse on the arrow representing the 2014 magnetization.

This periodic magnetic field change acts back on the electron spins 2012 and can be detected by the Faraday effect in the second medium with a readout laser, as shown in 1d is sketched. For this purpose, a read-out light beam 2000 (here anti-parallel to the y-direction) is directed onto the vapor cell 101 . When passing through the vapor cell 101, the polarization of the readout light beam 2000 is rotated periodically, which is caused by the synchronized precession movement of the polarized nuclear spins 2011 (Faraday effect). The Faraday effect describes the rotation of the plane of polarization of a linearly polarized electromagnetic wave - here the read-out light beam 2000 - in a medium (here the first medium and the second medium) when there is a magnetic field parallel to the propagation direction of the wave. Due to the periodic magnetic field rotation in the xy plane, the magnetic field changes periodically in the y direction, ie in the propagation direction of the readout light beam 2000 . The periodic rotation of the polarization of the read-out light beam 2000 can be converted into an electrical signal by a detection unit 2080, for example. For example, the detection unit 2080 can include a photodiode and a polarization filter, the polarization filter being arranged in the beam path in front of the photodiode. The polarization filter leads to an attenuation of the read-out light beam after passing through the vapor cell 101 depending on the polarization rotation, so that an intensity fluctuation can be observed at the photodiode, which is modulated with the Larmor frequency of the nuclear spins 2011 of the first medium. This intensity fluctuation can be detected, for example, in the form of an electrical signal and used as a measurement signal, which is a measure of the periodically changing radiation intensity. As an alternative to using a polarization filter, a polarization beam splitter can be used, which splits the incident light into two partial beams with polarization directions perpendicular to one another. The two partial beams leaving the polarization filter are each detected with a photo detector. From the difference in the signals from the photodetectors, the Faraday rotation can be determined and intensity fluctuations in the read-out light beam can be suppressed. In the case of a stationary measurement system (NMR gyroscope), this Larmor frequency is equal to the product of the gyromagnetic ratio of the nuclei of the second medium and the bias field. In the case of a uniformly rotating measuring system, a Larmor frequency that is higher or lower by this rotational frequency of the measuring system is measured, which is used to determine the rotational frequency (angular rate) of the measuring system.

2 shows a three-dimensional view of an NMR vapor cell arrangement 100. The NMR vapor cell arrangement 100 comprises a base plate 105, a structured base plate 106 and a cover plate 107, the structured base plate being arranged between the base plate 105 and the cover plate 107 in this exemplary embodiment. The bottom plate 105, the structured base plate 106 and/or the cover plate 107 can be made of glass, for example. The structured base plate 106 can alternatively or additionally include silicon or be made of silicon. The structured base plate 106 includes a first chamber 101, a second chamber 102 and a Passage arrangement 103. The structured base plate 106 is in this case divided into a first partial plate 1010 and a second partial plate 1021, the first partial plate 1010 and the second partial plate 1021 being separated from one another by an intermediate space 1000. The gap 1000 can be filled with a gas, such as air, for example. Alternatively, a vacuum can be created in the gap 1000 . The first chamber 101 extends as a cylindrical opening (hole) between the top plate 107 and the bottom plate 105 through the base plate 106 and the second chamber 102 extends as a cylindrical opening (hole) between the top plate 107 and the bottom plate 105 through the base plate 106 through. The openings in the base plate 106 are open towards the cover plate 107 and the base plate 105, so that the respective partial plate 1010, 1021 together with the base plate 105 and the cover plate form the boundary surfaces of the closed, cylindrical chambers 101, 102. The passage arrangement 103 extends through the intermediate space 1000 between the first chamber 101 and the second chamber 102. This arrangement connects the first partial plate 1010 and the second partial plate 1021, in particular the first chamber 101 and the second chamber 102, to one another.

The passage arrangement 103 comprises a line channel 1030 and a connection structure 1031. These can be formed in particular by structuring the base plate from the material of the base plate. In this exemplary embodiment, the connection structure 1031 has a meandering shape. On its top, i. H. On one side of the connection structure facing cover plate 107, a channel-shaped depression is embedded in connection structure 1031, which extends from first chamber 101 to second chamber 102 and is open to chambers 101, 102, so that gaseous media in particular can flow between the chambers 101, 102 can be exchanged. The cover plate 107 and the connecting structure 1031 form the boundary surfaces of the channel-shaped depression, which is designed as a line channel 1030 between the chambers 101, 102. In an exemplary embodiment not shown here, the line channel 1030 can alternatively or additionally be formed on a side of the connection structure 1031 facing the base plate. In particular, a plurality of connection structures 1031 can also be arranged between the partial plates 1010, 1021, with at least one of the connection structures 1031 having one or more line channels 1030.

The second medium 1020 is arranged in the second chamber 102 and was introduced into the second chamber 102 during production, for example in an aqueous solution or in a solid form. In particular, the second medium is selected in such a way that the electron spins of the second medium 1020 can be polarized by optical pumping. Therefore, for example, alkali metals such as rubidium (Rb), in particular rubidium 87 ( ⁸⁷ Rb) or rubidium 85 ( ⁸⁵ Rb), cesium (Cs), potassium (K), etc. or mercury (Hg) are suitable as the second medium 1020. In the In the first chamber 101, the first medium is introduced, in particular in a gaseous state. In particular, the first medium is chosen in such a way that the nuclear spins of the first medium, as described above, can be polarized by the electron-nuclear spin interaction. Noble metals such as xenon (Xe), neon (Ne), krypton (Kr) or helium-3 ( ³ He) are particularly suitable for this purpose as the first medium. The gaseous first medium can also spread to the second chamber along the connecting structure.

The NMR vapor cell assembly 100 further includes a heater 104 directed toward an environment 1011 thermally connected to the first chamber. In particular, this environment is heated by the heating device to a temperature, with the first partial plate 1010 and the cover plate, in particular in the area 1011 of the first chamber 101, heat up. The first partial plate 1010 forms the lateral boundary surfaces of the first chamber 101 and the cover plate 107 forms the upper boundary surface, so that heating of the surroundings 1011 causes the first chamber 101 to heat up. In particular, the environment 1011 is heated in such a way that a first temperature is established in the first chamber 101, the first temperature being in particular in the range between approximately 95° Celsius and approximately 105° Celsius. In particular, the heating device can comprise a heating laser. In particular, the power of the heating laser can be about 50 mW. Alternatively or additionally, the heating device 104 can be arranged on the first chamber 101 .

The connection structure 1031 represents a thermal coupling between the first chamber 101 and the second chamber 102. D. h. a temperature change in the first chamber leads to a temperature change in the second chamber 102, in other words the second chamber 102 is passively heated by the first chamber, with the heat flow flowing via the connection structure 1031. This means that when the first chamber 101 is heated to the first temperature, a second temperature is automatically set in the second chamber 102, the second temperature being in particular in the range between approximately 90° Celsius and approximately 100° Celsius. The temperature difference between the first chamber 101 and the second chamber 102 depends on the dimensioning of the connection structure 1031. In the second chamber 102, at least part of the second medium 1020, which is present in a solid or aqueous solution, is converted into a gaseous state of aggregation. The gaseous second medium 1020 can then reach the first chamber 101 via the at least one line channel 1030 . There, the electron spins of the second medium can be polarized by optical pumping as described above, and the nuclear spins of the first medium in the first chamber 101 can be polarized by the strong electron-nuclear spin interaction. The first chamber 101 can, for example, as in 1d shown to be read out in order to obtain a measurement signal from which the rotational measurement variable can be determined. For this purpose, an NMR gyroscope 200 is used, as is the case, for example, in 7 is shown and which, for example, the in 2 NMR vapor cell assembly 100 shown includes.

In particular, a temperature difference of greater than or equal to 3° Celsius, in particular greater than or equal to 5° Celsius, between the first chamber 101 and the second chamber 102 is advantageous in order to prevent condensation of the second medium 1020 in the first chamber 101. The thermal resistance of this connecting structure 1031 and thus the temperature difference between the measuring chamber heated by the laser and the passive reservoir chamber can be set in a targeted manner by dimensioning the connecting structure 1031, for example via the length and the cross-sectional area of the connecting structure. The temperature difference achieved increases approximately linearly with the length of the connecting structure and decreases approximately inversely proportional to the cross-sectional area of the connecting structure.

3 10 shows a three-dimensional view of the NMR vapor cell assembly 100 according to an exemplary embodiment. The chambers 101, 102 have, for example, a rectangular cross section. The connection structure 1031 is embodied as a straight web which mechanically and thermally connects the first partial plate 1010 and the second partial plate to one another. For the sake of clarity, the heating arrangement 104, the base plate 105 and the cover plate 107 are not shown. The latter can, for example, be analogous to 2 be arranged on opposite sides of the structured base plate 106 . The heating arrangement 104 can also be analogous to 2 be executed.

4 Figure 12 shows a sectional view of the three-dimensional view 3 along the section line AB, ie a sectional view of the passage arrangement 103. Here, the base plate 105 and the cover plate 107 were also shown. The line channel 1030 is let into the connection structure 1031 as a rectangular depression. The duct 1030 is open to the chambers 101, 102. The lateral boundary surfaces and the lower boundary surface are formed by the connecting structure 1031, the upper boundary surface is formed by the cover plate 107.

5 Figure 12 shows a sectional view of the three-dimensional view 3 along the section line CD, ie a sectional view of the partial plates 1010, 1021 and the two chambers 101, 102. The bottom plate 105 and the cover plate 107 were also shown, which form the upper and lower boundary surfaces of the chambers 101, 102 respectively.

6 shows a sketch of a temperature distribution function 110 in the NMR vapor cell arrangement 100 from FIG 3 shown exemplary embodiment, ie for a straight web as connecting structure 1031. On the x-axis 109 is the length along the path of the connecting line CD from 3 plotted in millimeters and the temperature in ° Celsius is plotted on the y-axis 108 . The sections of the temperature distribution function in the first chamber 101, along the connection structure 1031 and in the second chamber 102 are highlighted by double arrows. This was analogous to 2 the surroundings 1011 of the first chamber 101 are heated with a heating laser with a heating power of 50 mW.

7 shows an exemplary structure of an NMR gyroscope 200, comprising an NMR vapor cell arrangement 100, for example one of the 2 or 3 NMR vapor cell arrangements 100 shown. The NMR gyroscope 200 comprises the NMR vapor cell arrangement 100, the first chamber 101 being heated by a heating device 104, here a heating laser.

The NMR vapor cell arrangement 100 is surrounded by a magnetic field generating device 206, which provides the static magnetic field, which serves as the bias field 2010, and an oscillating magnetic field 2015, which has at least one component orthogonal to the bias field 2010, at the location of the NMR vapor cell arrangement 100. in the in 7 In the NMR gyroscope 200 shown, the magnetic field generating device 206 comprises a two-axis pair of Helmholtz coils. Alternatively, the second chamber 102 can also be arranged outside the magnetic field generating device 206 or lie outside the center of the magnetic field generating device. A magnetic shield 207 is here placed around the NMR vapor cell assembly 100, around the NMR vapor cells shield arrangement 100 from surrounding magnetic fields, such as the earth's magnetic field. The geometry of the magnetic shielding 207, the number of shielding layers and the positions provided for the coils 206 can be varied as desired. Instead of Helmholtz coil pairs, cylindrical coils, saddle coils or other free-form coils can also be used in the magnetic field generation device, as well as any combinations thereof.

Furthermore, the NMR gyroscope 200 includes a pump illumination source 2052, a polarizer 2051, in particular a circular polarizer, being arranged in the beam path between the pump illumination source 2052 and the NMR vapor cell arrangement 100. The pump illumination source 2052 and the polarizer 2051 are part of an illumination device 205. The pump illumination source 2052 emits electromagnetic radiation 2001 to provide the pump light beams for the vapor cell arrangement 201 in order to polarize the electron spins 2012 of the second medium 1020 by optical pumping, where the nuclear spins 2011 of the first medium can be polarized by means of this electron spin polarization through a strong electron-nuclear spin interaction between the second medium and the first medium. The bias field 2010 defines a direction of a precession movement of the polarizable nuclear spins 2011 of the first medium and the oscillating magnetic field 2015 enables the precession movements of the polarizable nuclear spins 2011 of the first medium to be synchronized.

The NMR gyroscope 200 includes a detection arrangement 208 which is set up to detect a rotation of the NMR gyroscope 200 about a direction of the bias field 2010 from a change in the precession movement of the polarizable nuclear spins 2011 . In this exemplary embodiment, the detection arrangement 208 comprises a linear polarizer 2081 and a readout illumination source 2084, the linear polarizer 2081 being arranged in the beam path between the readout illumination source 2084 and the NMR vapor cell arrangement 100, so that electromagnetic radiation emitted by the readout illumination source 2084 after passing through of the linear polarizer 2081 as a linearly polarized light beam 2000 on the NMR vapor cell arrangement 100, in particular the first chamber 101, and is transmitted 2002 by this. Furthermore, the detection arrangement 208 includes a polarizer 2083 and a detector element 2082, so that using the magneto-optical Faraday effect, the precession movements of the polarized nuclear spins 2011 of the first medium in the NMR vapor cell arrangement 100 as a measurement signal 2003, for example in the form of an electrical signal, which a Is a measure of the periodically changing radiation intensity, can be detected. The measurement signal 2003 is transmitted to a signal processing device 2085 which determines a detection signal 2086 (for example a rotation rate) of the NMR gyroscope 200 from the measurement signal 2003 . The signal processing device 2085 can be embodied as part of the NMR gyroscope 200 or can be arranged outside of the NMR gyroscope 200, with the NMR gyroscope 200 having communication interfaces in this case, which in particular enable the measurement signals 2003 of the NMR gyroscope 200 to be transmitted to the Signal processing device 2085 allows.

• • Strukturieren einer Grundplatte 1060 zum Erzeugen 301 der ersten Kammer 101, der zweiten Kammer 102 und der Durchlassanordnung 103, wobei letztere den mindestens einen Leitungskanal 1030 und die mindestens eine Verbindungsstruktur 1031 umfasst;
• • Aufbringen der Grundplatte auf die Bodenplatte
• • Einbringen 302 des zweiten Mediums 1020 in die zweite Kammer 102, wobei das zweite Medium 1020 in einem festen oder flüssigen Aggregatzustand vorliegt
• • Einbringen des gasförmigen ersten Mediums in die erste Kammer vorzugsweise in der Einrichtung zum Aufbringen der Deckplatte
• • Aufbringen 303 der Deckplatte 107 auf die strukturierte Grundplatte 106 zum Verschließen der ersten Kammer 101, der zweiten Kammer 106 und des mindestens einen Leitungskanals 1030.

8th shows a flowchart of a method 300 for manufacturing the NMR vapor cell assembly 100. It includes the steps:

• • Structuring a base plate 1060 for generating 301 the first chamber 101, the second chamber 102 and the passage arrangement 103, the latter comprising the at least one duct 1030 and the at least one connection structure 1031;
• • Applying the base plate to the floor plate
• • Introducing 302 the second medium 1020 into the second chamber 102, the second medium 1020 being present in a solid or liquid state of aggregation
• • Introduction of the gaseous first medium into the first chamber, preferably in the device for applying the cover plate
• • Applying 303 the cover plate 107 to the structured base plate 106 to close the first chamber 101, the second chamber 106 and the at least one duct 1030.

• • Einbringen 3020 des zweiten Mediums 10200, insbesondere Rubidiumazid (RbN3), in die zweite Kammer 102 in Form einer wässrigen Lösung;
• • Trocknen 3021 des zweiten Mediums 10200, welches in Form einer wässrigen Lösung eingebracht wurde.

In this exemplary embodiment, the step of introducing 302 the second medium 1020 into the second chamber 102 also comprises the steps:

• • introducing 3020 the second medium 10200, in particular rubidium azide (RbN3), into the second chamber 102 in the form of an aqueous solution;
• • Drying 3021 of the second medium 10200 introduced in the form of an aqueous solution.

9 shows a top view of the structured base plate 106 of the NMR vapor cell arrangement 100 according to an exemplary embodiment, the production of which is shown in FIGS 10 until 27 in a cross sectional view along the section line EF is illustrated. In this case, the chambers 101, 102 have a rectangular outline, for example. Alternatively or additionally, the chambers 101, 102 can also have shapes that differ from one another; in particular, at least one of the chambers 101, 102 can be cylindrical, cube-shaped, etc., or have any desired polygonal contour. The dimensioning of the passage arrangement 103 is also only selected as an example; in particular, the passage arrangement can be straight, curvilinear, curved, meandering, etc. In this exemplary embodiment, the passage arrangement 103 has a stepped top view.

the 10 until 27 each show a cross-section of the in 9 NMR vapor cell assembly 100 shown during the various manufacturing steps.

10 shows the cross-section of a base plate 1060, which will be structured in the following steps. In particular, this can be a silicon wafer. The unstructured base plate 1060 is preferably polished on both sides, ie a top side 1061 and a bottom side 1062 of the unstructured base plate 1060 facing away from the top side 1061 have a polished surface. In this exemplary embodiment, the unstructured base plate is 1 mm thick, for example.

11 shows the cross section of the base plate 1060, wherein a first photomask 3011, in particular comprising a positive resist, was applied to the upper side 1061 of the base plate 1060. This is done in order to subsequently produce the at least one line channel 1030, preferably by photolithographic structuring.

12 shows the cross section of the base plate 1060 after applying an etching process, in particular deep reactive ion etching (DRIE process), to produce the at least one duct 1030 in the base plate 1060. The base plate 1060 has a U-shaped depression on the upper side 1061. The etching depth is in particular in a range from greater than or equal to 10 μm to less than or equal to 200 μm, for example 50 μm, so that the at least one line channel 1030 consequently has a depth in the range from greater than or equal to 10 μm to less than or equal to 200 μm, for example 50 μm.

13 shows the cross-section of the base plate 1060 with the u-shaped trench after removing the first photomask 3011.

14 shows the cross section of the base plate 1060 with the U-shaped trench after removing the first photomask 3011 and cross sections of the bottom plate 105 and the top plate 107. The bottom plate 105 and the top plate 107 are made of glass, for example. In this step, the base plate 1060, the cover plate 107 and/or the base plate 105 are wet-chemically cleaned, for example by an RCA cleaning step.

the 15 until 19 show steps for applying a mask 3010 to the base plate 1060 to produce the connection structure 1031, the first chamber 101 and the second chamber 102 by structuring the base plate 1060.

15 10 shows the cross section of the base plate 1060 with the u-shaped trench, the base plate 1060 being thermally oxidized so that a surface of the base plate 1060 with the u-shaped trench is provided with an oxide layer 3010.

As in 16 shown, the oxide layer can be removed in particular on the underside 1062 of the base plate 1060 .

In 17 the base plate 105 is applied to the underside of the base plate 1060. The connection between the bottom plate 105 and the base plate 1060 can be produced, for example, by anodic bonding or other suitable connection methods.

In 18 a second photomask 3012 was applied to the thermally oxidized base plate 1060 or to the oxide layer 3010 which is formed on the upper side 1061 of the base plate 1060. The second photomask 3012 has a structure which defines the outlines of the connection structure 1031 and the geometry of the chambers 101, 102. The second photomask 3010 includes, in particular, a positive resist. The structuring of the second photomask 3010 can be transferred to the oxide layer 3010 of the base plate 1060 by applying an etching process, in particular a dry etching process, ie the oxide layer 3010 is removed by the etching process in the areas in which the first chamber, the second chamber and the Connection structure 1031 are to be generated. The second photomask 3012 can then be removed (see FIG 19 ).

As in 20 shown, a metallic layer 111, in particular an aluminum layer, is applied to an underside of the base plate 105. The underside of the base plate 105 is in this case a side of the base plate 105 which is a side of the base plate 105 which is connected to the base plate 1060 opposite.

In the next, in 21 illustrated step is applied an etching process, in particular Deep etching process in which the structuring of the oxide layer 3010 is transferred to the base plate. Through the etching step, the first chamber 101, the second chamber 102 and the connection structure 1031 are formed. This results in the structured base plate 106 of the NMR vapor cell arrangement 100.

Subsequently, the metallic layer 111 and the mask 3010 (see 22 ) to be removed. The mask 3010 and the metallic layer 111 can each be removed by wet etching, for example.

In 23 was formed on a side of the cover plate 107 facing the structured base plate 106, which side is to be connected to the structured base plate 106 in the following, and on the upper side of the structured base plate 106 facing the cover plate 107, including the boundary surfaces of the depressions, which later form the first chamber 101 , The second chamber 102 and the at least one line channel form - for example by atomic layer deposition (ALD) - each have a thin layer 3013, for example an aluminum oxide layer (Al ₂ O ₃ ), applied.

In the 24 until 27 the introduction of the second medium 1020 into the second chamber 102 is shown.

In 24 the second medium 10200 is introduced into the second chamber 102 in the form of an aqueous solution, rubidium azide (RbN ₃ ), for example, being used as the second medium. This is then dried so that it is in a solid form 10201 (see 25 ).

As in 26 shown, the cover plate 107 is applied to the structured base plate 106 . As a result, the first chamber 101, the second chamber 102 and the at least one line channel 1030 are closed.

In particular, the first medium can be introduced into the first chamber 101 immediately before the cover plate 107 is applied.

The second medium in the second chamber can then be activated by irradiating it with ultraviolet radiation (UV radiation) (see 27 ). In particular, the UV activation takes place by exposing the second medium to UV radiation for twenty-four hours or by exposing it to a UV laser. Thus, a uv-activated second medium 10202 is present in the second chamber 102 at the end of this step.

• • Einstellen 401 der ersten Temperatur in der ersten Kammer 101 durch Heizen, ◯ wobei durch das Einstellen 401 der ersten Temperatur in der ersten Kammer 101 aufgrund der thermischen Kopplung in der zweiten Kammer 102 die zweite Temperatur erzeugt wird 402, und
  • ◯ wobei der Temperaturunterschied zwischen der ersten Temperatur und der zweiten Temperatur durch die Dimensionierung der Verbindungsstruktur 1031 festgelegt ist;
• • Erzeugen 403 einer synchronisierten Präzessionsbewegung polarisierter Kernspins des ersten Mediums in der ersten Kammer 101;
• • Optisches Auslesen 404 der synchronisierten Präzessionsbewegung der polarisierten Kernspins in der ersten Kammer 101, welches einen Schritt Erfassen 4040 eines Messsignals 4041 umfasst;
• • Bestimmen 405 einer Drehmessgröße 4050 der Drehung des NMR-Gyroskops 200 aus dem Messsignal 4041.

In 28 A flow chart of a method 400 for operating the NMR gyroscope 200 is shown. It includes the steps:

• • Setting 401 the first temperature in the first chamber 101 by heating, ◯ the second temperature being generated 402 by the setting 401 of the first temperature in the first chamber 101 due to the thermal coupling in the second chamber 102, and
  • ◯ wherein the temperature difference between the first temperature and the second temperature is determined by the dimensioning of the connection structure 1031;
• • generating 403 a synchronized precession movement of polarized nuclear spins of the first medium in the first chamber 101;
• • Optical readout 404 of the synchronized precession movement of the polarized nuclear spins in the first chamber 101, which comprises a step of detecting 4040 a measurement signal 4041;
• • Determining 405 a rotational measurement variable 4050 of the rotation of the NMR gyroscope 200 from the measurement signal 4041.

Claims (14)

NMR vapor cell arrangement (100) comprising a first medium, a second medium (1020), a first chamber (101) and a second chamber (102), - wherein the first medium is arranged in the first chamber (101), - wherein the second medium (1020) is arranged in the second chamber (102), and - a passage arrangement (103) being formed between the first chamber (101) and the second chamber (102), the passage arrangement (103) having a duct ( 1030) for conducting the second medium (1020) from the second chamber (102) into the first chamber (101), characterized in that - the NMR vapor cell arrangement (100) has a heating device (104) for setting a first temperature in the first chamber (101), and - the passage arrangement (103) comprises a connection structure (1031) for providing a thermal coupling between the first chamber (101) and the second chamber (102), the connection structure (1031) between the first chamber (101) and d he second chamber (102) is dimensioned such that by setting the first temperature in the first chamber (101) a second temperature is generated in the second chamber (102) due to the thermal coupling, the first temperature differing from the second temperature. NMR vapor cell arrangement (100) after claim 1 , characterized in that the first temperature is greater than the second temperature. NMR vapor cell arrangement (100) according to one of the preceding claims, characterized in that the temperature difference between the first chamber (101) and the second chamber (102) is greater than or equal to 3° Celsius, in particular greater than or equal to 5° Celsius. NMR vapor cell arrangement (100) according to one of the preceding claims, characterized in that the connecting structure (1031) extends in the form of a web between the first chamber (101) and the second chamber (102). NMR vapor cell arrangement (100) according to one of the preceding claims, characterized in that the connecting structure (1031) is curvilinear, meandering and/or straight, at least in sections. NMR vapor cell arrangement (100) according to one of the preceding claims, characterized in that the dimensioning of the connection structure (1031), by which the thermal resistance of the connection structure (1031) and thus the temperature difference can be determined, a length and/or a cross-sectional area of the connection structure (1031). NMR vapor cell arrangement (100) according to one of the preceding claims, characterized in that the duct (1030) is formed on or at least partially in the connecting structure (1031). NMR vapor cell arrangement (100) according to one of the preceding claims, characterized in that the passage arrangement (103) comprises two or more than two ducts (1031). NMR vapor cell arrangement (100) according to one of the preceding claims, characterized in that the at least one duct (1030) extends from the first chamber (101) to the second chamber (102), a depth in the range of greater than or equal to 10 µm to less equal to 200 µm and/or is half as wide as the connection structure (1031). NMR vapor cell arrangement (100) according to any one of the preceding claims, characterized in that the NMR vapor cell arrangement (100) comprises two, three or more than three layers (105, 106, 107), the first chamber (101) and the second Chamber (102) are formed in at least one of the layers (105, 106, 107). Method (300) for producing an NMR vapor cell arrangement (100) according to any one of the preceding claims, comprising the steps of: • Structuring a base plate (1060) to create (301) the first chamber (101), the second chamber (102) and the passage arrangement (103), the passage arrangement (103) having the at least one duct (1030) and the at least one connection structure (1031) includes; • Introduction (302) of the second medium (1020) into the second chamber (102), wherein the second medium (1020) is in a solid or liquid state of aggregation when it is introduced (302). • Applying (303) a cover plate (107) to the structured base plate (106) to close the first chamber (101), the second chamber (102) and the at least one duct (1030). Method (300) according to claim 11 , characterized in that the step of introducing (302) the second medium (1020) into the second chamber (102) comprises at least one of the following steps: • introducing (3020) the second medium (10200), in particular rubidium azide (RbN3), into the second chamber (102) in the form of an aqueous solution; • drying (3021) the second medium (10200). NMR gyroscope (200) comprising the NMR vapor cell assembly (100) according to any one of Claims 1 until 10 . Method (400) for operating the NMR gyroscope (200). Claim 13 , comprising the steps of: • adjusting (401) the first temperature in the first chamber (101) by heating, wherein the connecting structure (1031) between the first chamber (101) and the second chamber (102) is dimensioned such that by adjusting the first temperature in the first chamber (101) generates a second temperature in the second chamber (102) due to the thermal coupling, the first temperature differing from the second temperature; • generating (403) a synchronized precession motion of polarized nuclear spins of the first medium in the first chamber (101); • Optical readout (404) of the synchronized precession movement of the polarized nuclear spins in the first chamber (101), which comprises a step of detecting (4040) a measurement signal (4041); • Determination (405) of a rotation quantity (4050) of the Rotation of the NMR gyroscope (200) from the measurement signal (4041).

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