JP2012154875A - Magnetic field measuring device and container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the possibility that an atom is deposited on a cell during a period in which measurement is not performed.SOLUTION: A magnetic field measuring device comprises: a cell 1 sealing a substance including an atom that rotates a polarization plane of linear polarized light according to a magnetic field upon being excited by light inside thereof so as to transmit the linear polarized light therethrough, with which the substance in a gaseous state is irradiated; a reservoir having an on-off valve 61 and an interior space communicating with an interior space of the cell 1 through the on-off valve 61 being opened; a measuring section for measuring a rotational angle of the polarization plane of the linear polarized light having been transmitted through the cell 1 when the on-off valve 61 is opened; a temperature adjusting section for adjusting temperature of the cell 1 or temperature of the reservoir such that a temperature of the reservoir is lower than that of the cell 1 after measurement by the measuring section has been completed; and a blocking section for blocking between the interior space of the cell 1 and the interior space of the reservoir by closing the on-off valve 61 after the temperature of the cell 1 or the temperature of the reservoir has been adjusted by the temperature adjusting section.

Description

  The present invention relates to a technique for measuring a magnetic field.

Magnetic sensors using optical pumping are used in MRI (magnetic resonance imaging) devices and the like. In this magnetic sensor, the pump light having the circularly polarized light component and the probe light having the linearly polarized light component are irradiated to the cell so as to intersect (preferably orthogonally), and further in the irradiation direction of these lights. A magnetic field in a direction perpendicular to the magnetic field is applied (see, for example, Patent Document 1).

In the cell irradiated with the pump light and the probe light, atoms such as alkali metals are sealed in a gas state. When excited by pump light, this atom rotates the plane of polarization of linearly polarized light contained in the probe light in accordance with a magnetic field applied from the outside. The magnetic sensor measures the magnetic field by measuring the rotation angle of the polarization plane of the probe light transmitted through the cell.

By the way, prior to the measurement of the magnetic field, the cell is heated so that the atoms described above remain in a gaseous state, but there is a period during which the temperature of the cell is not controlled during the measurement or after the measurement is completed. In addition, atoms in the cell may be cooled below the dew point and deposited on the wall surface (condensation). At this time, if an atom is deposited on a region of the cell wall where the light for measuring the magnetic field (pump light or probe light) is irradiated, the deposited atom absorbs the light and hinders measurement. In order to reduce the precipitation of atoms in such a region, for example, Patent Document 2 discloses a plurality of protrusions having recesses toward the inside of the container in parts other than the window part of the container (particularly in the vicinity of the window part). And providing a heater for heating the container. The technique described in Patent Document 2 generates a temperature difference in which the temperature of the window is higher than that of the protrusion by cooling the protrusion and heating the window portion of the container with a heater. Gather.

JP 2009-14708 A JP 2010-205875 A

However, in order to suppress the deposition of atoms in the region where light is transmitted, even if atoms are collected in other regions, the collected atoms are stored during the period when the magnetic field measurement device is not used. May be diffused and deposited in a region where light is transmitted. This deposition becomes an obstacle when the stored magnetic field measuring apparatus is used again.

An object of the present invention is to reduce the possibility that atoms are deposited in a cell during a period in which no measurement is performed.

The present invention includes a cell containing an atom containing an atom that rotates a polarization plane of linearly polarized light according to a magnetic field when excited by light, and transmitting the linearly polarized light irradiated to the substance in a gaseous state. A reservoir having an open / close valve and having an internal space communicating with the internal space of the cell via the open open / close valve; and polarization of the linearly polarized light transmitted through the cell when the open / close valve is open A measuring unit that measures the rotation angle of the surface, a temperature adjusting unit that adjusts the temperature of the cell or the reservoir so that the temperature of the reservoir is lower than the cell after the measurement by the measuring unit is completed, and After the temperature of the cell or the reservoir is adjusted by the temperature adjusting unit, the shut-off unit is provided to close the on-off valve and shut off the internal space of the cell and the internal space of the reservoir. Providing a magnetic field measurement apparatus according to claim. According to this configuration, it is possible to reduce the possibility that atoms are deposited in the cell during a period in which measurement is not performed.

In the magnetic field measurement device, before the blocking unit blocks the internal space of the cell and the internal space of the reservoir, the cell has the induced light that is light different from the linearly polarized light, and the cell has It is preferable to provide an induced light irradiation unit that desorbs atoms from a film that absorbs atoms. According to this configuration, it is possible to reduce the possibility that atoms absorbed in the film formed in the cell are deposited in a period in which measurement is not performed.

In the magnetic field measuring apparatus, the internal space of the reservoir may communicate with the internal spaces of the plurality of cells through the open on-off valves. According to this configuration, the manufacturing cost can be reduced as compared with the case where one reservoir is connected to one cell.

Further, according to the present invention, when excited by light, a substance containing atoms that rotate the plane of polarization of linearly polarized light according to a magnetic field is enclosed in an internal space, and the linearly polarized light irradiated to the substance in a gaseous state is transmitted. A cell, a reservoir having an internal space communicating with the internal space of the cell, an open / close valve provided between the cell and the reservoir, and shuts off the internal space of the cell and the internal space of the reservoir when closed. A container is provided. According to this configuration, it is possible to reduce the possibility that atoms are deposited in the cell during a period in which measurement is not performed.

It is a figure which shows the structure of the magnetic field measuring apparatus which concerns on this invention. It is a perspective view which shows the structure of a cell. It is a figure which shows a mode that the cell was covered with the coating layer. It is sectional drawing which looked at the cell etc. from arrow IV-IV in FIG. It is sectional drawing which looked at the cell etc. from arrow VV in FIG. It is a block diagram which shows the structure regarding control of a magnetic field measuring apparatus. It is a flowchart which shows the flow of control of the magnetic field measuring apparatus by a control part.

1. Embodiment 1-1. Configuration FIG. 1 is a diagram showing a configuration of a magnetic field measurement apparatus 100 according to the present invention. Magnetic field measuring apparatus 100
Is used for measuring a weak magnetic field generated from a living body such as a magnetocardiogram (magnetism from the heart) and a brain magnetism (magnetism from the brain). The magnetic field measuring apparatus 100 includes a cell 1, a coating layer 2, a pump light irradiation unit 3, a probe light irradiation unit 4, a probe light measurement unit 5, a reservoir 6, a temperature adjustment unit 7, and an induced light irradiation unit. 8.

In order to explain the arrangement of each component of the magnetic field measuring apparatus 100, the space where each component is arranged is represented by xyz.
Expressed as a right-handed coordinate space. Among the coordinate symbols shown in FIG. 1A, a symbol in which a black circle is drawn in a circle with a white inside represents an arrow from the back side to the near side. In addition, among the coordinate symbols shown in FIG. 1B, a symbol depicting two line segments intersecting inside a white circle represents an arrow heading from the front side to the back side of the page. The direction in which the x component increases in space is referred to as the + x direction, and the direction in which the x component decreases is referred to as the −x direction. Similarly, for the y and z components, + y direction, -y direction, + z direction, and -z direction are defined.

As shown in FIG. 1A, the cell 1 is covered with a coating layer 2, and in the −x direction of the cell 1,
A pump light irradiation unit 3 is installed. The pump light irradiation unit 3 generates pump light having a circularly polarized component, +
The cell 1 is irradiated along the arrow D1 direction parallel to the x direction.

The probe light irradiation unit 4 is installed in the −y direction of the cell 1 and irradiates the cell 1 with the probe light having a linearly polarized light component along the arrow D2 direction parallel to the + y direction. The probe light measurement unit 5 is installed in the + y direction of the cell 1. The probe light measurement unit 5 receives the probe light irradiated from the probe light irradiation unit 4 along the direction of the arrow D <b> 2 and transmitted through the cell 1. The magnetic field measuring apparatus 100 is arranged so that the cell 1 is positioned in the magnetic field to be measured. Specifically, the magnetic field measurement apparatus 100 is arranged so that the measurement target is positioned in the −z direction when viewed from the cell 1.
The pump light irradiation unit 3, the probe light irradiation unit 4, and the probe light measurement unit 5 are configured to measure the magnetic field by irradiating light. Hereinafter, these are collectively referred to as a magnetic field measurement unit.

After the measurement of the magnetic field is completed, the induced light irradiation unit 8 is installed in the −z direction of the cell 1 as shown in FIG. The induced light irradiation unit 8 is a laser or LED (Light Emitting Dio).
The cell 1 is irradiated with induced light that is light such as de) along the arrow D3 direction parallel to the + z direction. The induced light irradiation unit 8 is installed in the −z direction of the cell 1 and irradiates the induced light toward the + z direction. The installation position of the induced light irradiation unit 8 and the irradiation direction of the induced light by this are described above. It is not limited to things. In short, it is sufficient that these are set so that the cell 1 is irradiated with the induced light.

FIG. 2 is a perspective view showing the configuration of the cell 1. The cell 1 has a shape in which a tube having an open end extends from one surface of a hollow cube, and is formed of a material that transmits light, such as glass. Cell 1
The above-mentioned hollow cube has at least four members that partition the outside and the inside and transmit pump light or probe light, that is, light used for measuring a magnetic field (hereinafter referred to as measurement light). The four members that transmit the measurement light are members facing the + x direction, the −x direction, the + y direction, and the −y direction of the cell 1, and the members in the −x direction are the wall surfaces 11 a (in FIG. 2). The member in the + x direction is referred to as a wall surface 11b. Wall surface 11a for transmitting these measurement lights,
11b, 12a, and 12b are collectively referred to as a light transmitting wall surface. Of the members of cell 1, -y
The member in the direction is referred to as a wall surface 12a, and the member in the + y direction is referred to as a wall surface 12b (not shown in FIG. 2). Further, among the members constituting the cell 1, a member in the + z direction that is not irradiated with measurement light is a wall surface 13.
The member in the −z direction is referred to as a wall surface 13a (not shown in FIG. 2). A cylindrical member having an open end that extends in the + z direction from the wall surface 13 b and further bends in the −x direction is referred to as a cylindrical portion 14. The shape of the cell 1 may be another three-dimensional shape.

Inside the cell 1, for example, a substance containing atoms such as alkali metal (hereinafter referred to as a polarization plane rotating substance) is sealed in a gas state (that is, a gas state). The polarization plane rotating material is, for example, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), or francium (Fr). The atoms in the cell 1 are excited by circularly polarized light, and the spins of the outer electrons of the atoms are polarized, so that the polarization plane of linearly polarized light is rotated according to the magnetic field. That is, the polarization plane rotating material is an example of a material containing atoms that rotate the polarization plane of linearly polarized light in response to a magnetic field when excited by light. When the cell 1 is excited by light, the cell 1 encloses a substance containing atoms that rotate the polarization plane of linearly polarized light in accordance with a magnetic field, and transmits the linearly polarized light irradiated to the substance in a gaseous state. It is an example of a cell. The cell 1 typically contains a single type of polarization plane rotating material, but may contain a plurality of types of polarization plane rotating materials. In addition, the atoms in the cell 1 do not need to be in a gas state at all times,
What is necessary is just to be a gaseous state when measuring a magnetic field. Further, the inside of the cell 1 may contain helium (He), nitrogen (N), or the like as a buffer gas in order to moderate relaxation of the polarization plane rotating material due to collision with the wall of the cell 1 or the like. Good.

The reservoir 6 includes a container 62 in which one surface of a hollow rectangular parallelepiped (a surface in the + x direction shown in FIG. 2) is opened, and an opening / closing valve 61 provided on the opening surface of the container 62. The open / close valve 61 of the reservoir 6 is connected to the opening of the cylindrical portion 14 of the cell 1. Therefore, when the on-off valve 61 is in the open state, the internal space of the cell 1 is connected to the internal space of the reservoir 6, and the polarization plane rotating material enclosed in the internal space of the cell 1 enters the internal space of the container 62. Inflow. That is, the reservoir 6 is an example of a reservoir having an open / close valve and having an internal space that communicates with the internal space of the cell via the open open / close valve. Then, this “container” in which the opening of the cylindrical portion 14 of the cell 1 is connected to the opening / closing valve 61 of the reservoir 6 to seal the inner space is a polarization plane of linearly polarized light according to the magnetic field when excited by light. A cell containing an atom for rotating the gas, encapsulated in an internal space, transmitting the linearly polarized light irradiated to the material in a gaseous state, a reservoir having an internal space communicating with the internal space of the cell, the cell, and the cell It is an example of a container provided between the reservoir and an open / close valve that shuts off the internal space of the cell and the internal space of the reservoir when closed.

The opening / closing valve 61 of the reservoir 6 is controlled to open / close by a drive unit 610 (see FIG. 4) such as a solenoid. When the opening / closing valve 61 is closed by the drive unit 610, the internal space of the container 62 of the reservoir 6 is blocked from the internal space of the cell 1. That is, the drive unit 610 is an example of a blocking unit that closes the on-off valve to block the internal space of the cell and the internal space of the reservoir.

The temperature adjustment unit 7 includes a heating unit 7 h that heats the cell 1 and a cooling unit 7 c that cools the reservoir 6.
And have. The cooling unit 7c is, for example, a Peltier element, and the container 62 of the reservoir 6 is −
The gas enclosed in the reservoir 6 is cooled by contacting from the X direction and absorbing heat from the contact surface. The heating unit 7h is, for example, an electric heater, and is in contact with the cell 1 and the wall surface 13a.
The gas sealed inside the cell 1 is heated through the contact surface. The heating unit 7h has a hole through which the induced light passes so that the induced light irradiated from the induced light irradiation unit 8 reaches the cell 1 when the measurement of the magnetic field is completed and the magnetic field measurement unit is stopped. Is provided.

The covering layer 2 is a quadrangular prism-shaped member having square openings in the + z direction and the −z direction, respectively. By moving the cell 1 in the −z direction and fitting into the openings, the wall surface 11 a and the wall surface 11 b are formed. , Contacts the wall surface 12a and the wall surface 12b and covers them from the outside.

FIG. 3 is a diagram illustrating a state in which the cell 1 is covered with the covering layer 2. 4 is a cross-sectional view of the cell 1, the coating layer 2, the reservoir 6, and the temperature adjustment unit 7 as seen from the direction of arrows IV-IV in FIG. 5 is a cross-sectional view of the cell 1, the coating layer 2, the reservoir 6, and the temperature adjusting unit 7 as seen from the direction of arrows V-V in FIG. The covering layer 2 has a hole 2 for transmitting the pump light.
1a (not shown in FIG. 2) and a hole 21b, and a hole 22 for transmitting probe light
a and a hole 22b (not shown in FIG. 2) are provided.

The covering layer 2 includes, for example, silicon carbide as a material, and is heated together with the cell 1 when the temperature adjusting unit 7 heats the cell 1 in order to make atoms enclosed in the cell 1 into a gas state. .

The pump light irradiation unit 3 includes a light source, a half-wave plate, a polarization beam splitter, and a quarter-wave plate. The light source irradiates non-polarized laser light in the direction of arrow D1 shown in FIG. The half-wave plate rotates the polarization plane of the light emitted from the light source. The deflecting beam splitter transmits the p-polarized component (component parallel to the incident surface) of the light transmitted through the half-wave plate and transmits the s-polarized component (
The component perpendicular to the incident surface is reflected. This s-polarized component may be used for monitoring the output of laser light, for example, or may be absorbed by a member that absorbs light. The quarter-wave plate changes the light transmitted through the deflecting beam splitter into circularly polarized light. Thereby, the light transmitted through the quarter-wave plate becomes pump light having a circularly polarized component.

The probe light irradiation unit 4 includes a light source, a half-wave plate, a deflection beam splitter, and a polarizing plate. The light source irradiates non-polarized laser light in the direction of arrow D2 shown in FIG. The half-wave plate rotates the polarization plane of the light emitted from the light source. The deflecting beam splitter transmits the p-polarized component of the light transmitted through the half-wave plate and reflects the s-polarized component. The polarizing plate transmits only light polarized in a specific direction out of the light transmitted through the deflecting beam splitter. Thereby, the light transmitted through the polarizing plate becomes probe light having a linearly polarized light component. Note that the pump light and the probe light are preferably orthogonal to each other, but may not be completely orthogonal as long as they intersect.

The probe light measurement unit 5 detects the probe light irradiated from the probe light irradiation unit 4 and transmitted through the cell 1 and measures the rotation angle of the polarization plane of linearly polarized light included in the detected probe light. That is, the probe light measurement unit 5 is an example of a measurement unit that measures the rotation angle of the polarization plane of linearly polarized light that has passed through the cell when the on-off valve is open. The probe light measurement unit 5 includes a half-wave plate, a liquid crystal panel, an optical sensor, an A / D converter, a memory, and a calculation unit. Half-wave plate
The polarization plane of the probe light transmitted through the cell 1 is rotated. The liquid crystal panel transmits a p-polarized component or an s-polarized component of the probe light that has passed through the half-wave plate using a liquid crystal called a nematic liquid crystal. Here, since the liquid crystal panel is time-division controlled, the above-described p-polarized component and s-polarized component are transmitted and separated for each time-division period.

The optical sensor is, for example, a photodiode, which converts probe light transmitted through the liquid crystal panel into an electrical signal and outputs the electrical signal. The A / D converter converts the electrical signal output from the optical sensor into digital data and outputs the digital data. The memory stores data output from the A / D converter. The calculation unit calculates the difference between the p-polarized component and the s-polarized component of the probe light detected by the optical sensor, using the data stored in the memory. The probe light measuring unit 5 is
A polarization beam splitter may be used to separate the probe light transmitted through the cell 1 into a p-polarized component and an s-polarized component, and calculate the difference between them.

When the measurement of the magnetic field ends and the magnetic field measurement unit stops, the induced light irradiation unit 8
It irradiates toward the hole provided in the heating part 7h. The irradiated induced light passes through this hole and is irradiated to the cell 1. A compound such as paraffin is applied to the inner wall of the cell 1 in order to maintain the energy state by the magnetic field of the polarization plane rotating material, thereby forming a coating film on the inner wall surface.

The induced light irradiation unit 8 irradiates the cell 1 with induced light that is light having a predetermined wavelength (for example, 850 nm). When this induced light reaches the coating film formed on the inner wall surface of the cell 1, the light detachment material that has been taken into the coating film is detached from the coating film and released into the internal space of the cell 1. A separation phenomenon occurs. Thereby, the density | concentration of the polarization plane rotating material taken in by the coating film falls. And even when the induced light is irradiated to only a part of the coating film, the decrease in the concentration of the polarization plane rotating material in the region irradiated with the induced light diffuses throughout the coating film, The total concentration of the polarization plane rotating material incorporated in the entire coating film also decreases with the passage of time. That is, the induced light irradiation unit 8 is configured so that the internal space of the cell and the internal space of the reservoir are blocked by the blocking unit.
It is an example of the induced light irradiation part which irradiates the induced light which is light different from linearly polarized light, and desorbs the atoms from the film that absorbs the atoms of the cell.

Note that the wavelength of the induced light is desirably set to a wavelength different from that of the pump light and the probe light (that is, measurement light). Further, it is desirable that the irradiation intensity of the induced light is set to an intensity that does not change the chemical structure of the coating film itself as much as possible.

FIG. 6 is a block diagram illustrating a configuration related to the control of the magnetic field measurement apparatus 100. The control unit 9 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random
Access memory), a hard disk drive, and other storage units. By reading and executing a computer program stored in the storage unit or ROM, the pump light irradiation unit 3, the probe light irradiation unit 4, and the probe light measurement unit 5. Control the reservoir 6, the temperature adjustment unit 7, and the induced light irradiation unit 8. Specifically, the control unit 9 includes an operation unit that receives an operation from the user, a communication interface that communicates with an external device, and the like, through which an instruction from the user or an abnormality is detected. Various instruction signals indicating instructions from other than the user, such as emergency stop instructions at the time, are acquired. That is, the operation unit, the communication interface, and the like are examples of an acquisition unit that acquires an instruction signal indicating an instruction. And the control part 9 controls each structure of the magnetic field measuring apparatus 100 by having acquired these instruction | indication signals.

In addition to these configurations, the magnetic field measuring apparatus 100 may include, for example, a magnetic shield for shielding a magnetic field other than the measurement target, a coil for applying a magnetic field for correcting an external magnetic field, and the like. Moreover, the coating layer 2 may also serve as a magnetic shield.

1-2. Operation Next, the operation of the magnetic field measurement apparatus 100 will be described. FIG. 7 shows a magnetic field measuring apparatus 1 by the control unit 9.
It is a flowchart which shows the flow of control of 00. The control unit 9 determines whether or not the instruction signal acquired from the above-described operation unit or communication interface is a measurement stop instruction signal indicating an instruction to stop measurement (step S101). If the acquired instruction signal does not output the measurement stop instruction signal (NO in step S101), this determination is repeated for the next acquired instruction signal. On the other hand, when the acquired instruction signal is a measurement stop instruction signal (step S
In step S102, the control unit 9 stops the magnetic field measurement unit (pump light irradiation unit 3, probe light irradiation unit 4, and probe light measurement unit 5). The magnetic field measurement unit may be stopped immediately after the control unit 9 receives the measurement stop instruction signal. However, after receiving the measurement stop instruction signal, the magnetic field measurement unit is stopped after a predetermined time has elapsed for each device. May be.

Then, the control unit 9 starts a “push-in process” for pushing the polarization plane rotating substance from the internal space of the cell 1 into the internal space of the reservoir 6 (step S103). Specifically, the control unit 9
Irradiates induced light to the wall surface 13a and the wall surface 13b of the cell 1 by the induced light irradiation unit 8.
Thereby, the polarization plane rotating substance is detached from the coating film formed on the inner wall surfaces of the wall surface 13a and the wall surface 13b. Then, the control unit 9 continues to heat the cell 1 by the heating unit 7 h of the temperature adjusting unit 7 and starts cooling the reservoir 6 by the cooling unit 7 c of the temperature adjusting unit 7. As a result, a temperature difference occurs between the internal space of the cell 1 and the internal space of the reservoir 6 connected thereto. That is, the internal space of the reservoir 6 has a lower temperature than the internal space of the cell 1. That is, the temperature adjustment unit 7 is an example of a temperature adjustment unit that adjusts the temperature of the cell or the reservoir so that the temperature of the reservoir becomes lower than that of the cell after the measurement by the measurement unit is completed.

When the temperature of the internal space of the reservoir 6 is lowered locally below the dew point of the polarization plane rotation material, the polarization plane rotation material is condensed in the reservoir 6, so that the polarization plane rotation material enclosed in these internal spaces Is driven from the cell 1 to the reservoir 6.

Next, the control unit 9 determines whether or not the follow-up process is completed (step S104).
Completion of the follow-up process is determined based on whether or not a predetermined condition is satisfied. This condition is, for example, that the temperature of each component measured by a temperature measurement unit (not shown) exceeds a threshold, or that the elapsed time from the start of the chasing process exceeds a threshold. When it is determined that the driving process is not completed (NO in step S104), the control unit 9 continues this determination. On the other hand, when it is determined that the driving process is completed (step S10).
4), the control unit 9 drives the opening / closing valve 61 of the reservoir 6 by the driving unit 610,
The internal space of the reservoir 6 and the internal space of the cell 1 are blocked (step S105). Specifically, as shown in FIG. 4, this blocking is performed by moving the valve body 611 of the on-off valve 61 in the −z direction by the driving unit 610 so as to be in close contact with the valve seat 612. And the control part 9 stops the chasing process started in step S104 (step S106). That is, the control unit 9 stops the irradiation of the induced light by the induced light irradiation unit 8 and the heating and cooling by the temperature adjusting unit 7 and ends the process.

As described above, the control unit 9 of the magnetic field measurement apparatus 100 detaches the polarization plane rotating material from the coating film of the cell 1 by irradiating the induced light irradiation unit 8 with the induced light when the magnetic field measurement unit is stopped. In addition, a temperature difference is generated in the temperature adjusting unit 7 so that the reservoir 6 has a lower temperature than the cell 1. As a result, among the polarization plane rotating substances that are taken into the coating film inside the cell 1 or are in a gas state, those that may cause condensation are collected in the cooled reservoir 6. Condensation is prevented.

2. Modifications The present invention is not limited to the above-described embodiment, and may be carried out by being modified as follows. Further, the following modifications may be combined.

2-1. The pump light and the probe light irradiated on the cell 1 do not need to have a constant traveling direction from when the light is emitted until it enters the cell 1. That is, the pump light and the probe light are generated in the cell 1
It is only necessary to be in a predetermined direction when it is incident on the beam, and the traveling direction may be changed by being reflected by a mirror or the like on the way. Therefore, for example, it is possible to concentrate the light irradiation position and the detection position in one place.

The probe light may also serve as pump light. In this case, the polarization plane rotating material enclosed in the cell 1 is excited by the light irradiated by the probe light irradiation unit 4, and the polarization of the linearly polarized light component contained in the light is excited by the excited polarization plane rotating material. The surface only needs to rotate. In this modification, the pump light irradiation unit 3 may not be provided.

2-2. The magnetic field measurement apparatus 100 may detect the pump light that has passed through the cell 1. In addition, the magnetic field measuring apparatus 100 may be provided with a member that absorbs pump light transmitted through the cell 1. This member is more preferably in the form of a sheet.

2-3. The magnetic field measurement apparatus 100 may include a means for visualizing a signal corresponding to the light detected by the probe light measurement unit 5 and displaying the signal. The magnetic field measurement apparatus 100 may be configured to generate a signal corresponding to the light detected by the probe light measurement unit 5 and output the signal to an external device (display device, computer device, etc.).

2-4. When the covering layer 2 is made of a transparent material or is made of a material that absorbs light to the extent that it does not affect the magnetic field measurement, the hole 21a or the like may not be provided in the covering layer 2. Further, the coating layer 2 may be omitted.

2-5. In the above-described embodiment, the heating unit 7h of the temperature adjusting unit 7 is heating the wall surface 13a of the cell 1, but may heat another wall surface, for example, a light transmitting wall surface. In this case, the heating unit 7 h may be provided on the coating layer 2.

2-6. In the above-described embodiment, the induced light irradiation unit 8 irradiates the cell 1 with the induced light to cause the photodetachment phenomenon, but the induced light irradiation unit 8 may not be provided. Even in this case, the temperature adjustment unit 7 performs the driving process after the magnetic field measurement unit is stopped, and the reservoir 6 is disconnected from the cell 1 after the driving process is completed.
Even if it is placed in a storage state, the possibility of condensation of the polarization plane rotating material on the light transmitting wall surface is reduced.

2-7. In the above-described embodiment, one reservoir 6 is connected to one cell 1, but one reservoir 6 may be connected to a plurality of cells 1. In this case, the cylindrical part 14 provided in each of the plurality of cells 1 may be connected by a pipe, and the pipe may be connected to the on-off valve 61 of the reservoir 6. By configuring in this way, the number of reservoirs 6 is reduced as compared with the above-described embodiment, and thus the manufacturing cost may be reduced. In this case, the magnetic field measurement device 100 is an example of a magnetic field measurement device in which the internal space of the reservoir communicates with the internal spaces of a plurality of cells via open on-off valves.

DESCRIPTION OF SYMBOLS 1 ... Cell, 11a, 11b, 12a, 12b, 13a, 13b ... Wall surface, 14 ... Cylindrical part, 2
... coating layer, 21a, 21b, 22a, 22b ... hole, 3 ... pump light irradiation unit, 4 ... probe light irradiation unit, 5 ... probe light measurement unit, 6 ... reservoir, 61 ... open / close valve, 611 ... valve body, 612
DESCRIPTION OF SYMBOLS ... Valve seat, 62 ... Container, 7 ... Temperature adjustment part, 7c ... Cooling part, 7h ... Heating part, 8 ... Induction light irradiation part, 9 ... Control part, 100 ... Magnetic field measuring apparatus.

Claims (4)

A cell containing an atom containing an atom that rotates a polarization plane of linearly polarized light according to a magnetic field when excited by light, and transmitting the linearly polarized light irradiated to the substance in a gaseous state;
A reservoir having an open / close valve and having an internal space communicating with the internal space of the cell through the open open / close valve;
A measuring unit for measuring a rotation angle of a polarization plane of the linearly polarized light transmitted through the cell when the on-off valve is open;
A temperature adjusting unit that adjusts the temperature of the cell or the reservoir so that the temperature of the reservoir is lower than that of the cell after measurement by the measuring unit is completed;
And a shut-off unit that closes the open / close valve and shuts off the internal space of the cell and the internal space of the reservoir after the temperature of the cell or the reservoir is adjusted by the temperature adjusting unit. Magnetic field measuring device. Before the blocking part cuts off the internal space of the cell and the internal space of the reservoir, the induced light, which is light different from the linearly polarized light, is irradiated to absorb the atoms of the cell. The magnetic field measurement apparatus according to claim 1, further comprising an induced light irradiation unit that desorbs the atoms. The magnetic field measurement apparatus according to claim 1, wherein the internal space of the reservoir communicates with the internal spaces of the plurality of cells via the open on-off valve. A cell containing an atom containing an atom that rotates a polarization plane of linearly polarized light according to a magnetic field when excited by light, and transmitting the linearly polarized light irradiated to the substance in a gaseous state;
A reservoir having an internal space communicating with the internal space of the cell;
A container provided between the cell and the reservoir, and an on-off valve that shuts off the internal space of the cell and the internal space of the reservoir when closed.

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