JP2011203133A - Cell unit, cell unit group, and magnetic field measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply pump light and probe light to each of a plurality of cells without disposing a light source for each cell.SOLUTION: A cell layer 12 has the plurality of cells containing an atom of alkali metal. An optical distribution layer 11 branches incoming pump light with a branching coupler 111A, and guides the branched pump light with an optical fiber 112 so that the branched pump light is radiated to each cell. The optical distribution layer 11 branches incoming probe light with a branching coupler 111B, and guides the branched probe light with the optical fiber 112 so that the branched probe light is radiated to each cell. The pump light and probe light guided with the optical fiber 112 are radiated to each cell, and the pump light crosses the probe light in the cells.

Description

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

As an invention for measuring a magnetic field, for example, there is an optical pumping magnetometer disclosed in Patent Document 1. This optical pumping magnetometer intersects circularly polarized pump light and linearly polarized probe light in a cell filled with an alkali metal gas, and measures the polarization rotation angle of the probe light that has passed through the cell. Measure the magnetic field.

JP 2009-236599 A

By the way, since one cell can measure only a certain part of the magnetic field, a plurality of cells are required to measure the magnetic field in a wide range. However, when a plurality of cells are arranged, the optical pumping magnetometer disclosed in Patent Document 1 requires a pump light source or a probe light source for each cell, which increases the scale of the apparatus.
The present invention has been made in view of the above-described circumstances, and one of its purposes is to be able to supply pump light and probe light to each cell without providing a light source for each of the plurality of cells. .

In order to achieve the above object, a cell unit according to the present invention includes a cell layer including a plurality of cells having atoms excited by light therein, and the incident first light is branched and branched. A distribution layer for guiding one light to each of the plurality of cells.
According to the present invention, light is branched and guided to a plurality of cells. Since light is branched in the distribution layer and guided to a plurality of cells, light can be supplied to each cell without providing a plurality of light sources for each cell.

In the present invention, the distribution layer branches the incident second light, and splits the second light so that the second light intersects the first light in each of the plurality of cells. It is good also as a structure led to the plurality of cells. According to the present invention, when the first light is irradiated to the cell unit,
When the first light is branched and guided to each of the plurality of cells and the second light is applied to the cell unit,
The light is branched and guided to a plurality of cells. Since light is branched in the distribution layer and guided to a plurality of cells, the first light and the second light can be supplied to each cell without providing a plurality of light sources for each cell.
In the present invention, the cell layer may be stacked on one of the distribution layers, and the first light and the second light may be incident on the cell layer from the one distribution layer. According to this configuration, since the first light and the second light are irradiated from one surface side of the cell layer, the thickness of the cell unit can be suppressed.
In the present invention, the distribution layer includes a first distribution layer that guides the first light and a second distribution layer that guides the second light, and the first distribution layer is stacked on the cell layer. The second layer may be provided in contact with a surface of the cell layer that intersects the surface facing the first distribution layer. According to this configuration, one distribution layer branches and guides one type of light and does not branch and guide the other types of light. Therefore, the configuration of one distribution layer can be simplified.
Moreover, in this invention, it is good also as a structure which has a detection part which detects the said 2nd light which permeate | transmitted the said cell. Moreover, in this invention, it is good also as a structure which has a detection part which detects the said 1st light which permeate | transmitted the said cell. According to these configurations, since light can be detected by the cell unit, it is not necessary to provide a separate detection unit in the device including the cell unit, and the configuration of the device can be simplified.

In the present invention, the distribution layer includes a plurality of films that reflect and transmit incident light, the films are arranged in a direction in which the incident light travels, and the light reflected by the plurality of films is The plurality of cells may be irradiated. According to this configuration, since the light can be branched by the film and guided to the cell, the configuration of the cell unit can be simplified as compared with the configuration in which the optical component branches and guides the light.
In the present invention, the distribution layer has a diffraction grating on the side facing the cell layer that transmits a part of incident light and reflects the remaining light, and the light that has passed through the diffraction grating is the plurality of light beams. It is good also as a structure irradiated to this cell.
In the present invention, the distribution layer has a diffraction grating that reflects incident light in the first direction and the second direction on a surface opposite to the surface facing the cell layer, and extends in the first direction. The reflected light may be applied to the plurality of cells.
According to these configurations, light can be branched by the diffraction grating and guided to the cell.
The configuration of the cell unit can be simplified as compared with the configuration in which light is branched or guided by optical components.

Moreover, the cell unit group according to the present invention has a configuration in which the cell units having any one of the above configurations are arranged in multiple stages. According to this configuration, the magnetic field gradient in the direction in which the cell units are arranged in multiple stages can be measured by measuring the light that has passed through the cells in each stage.

In order to achieve the above object, a magnetic field measurement apparatus according to the present invention branches a cell layer including a plurality of cells having therein atoms excited by light, and the incident first light, A cell unit having a distribution layer for guiding the first light branched into each of the cells, a first irradiation unit for irradiating the cell unit with the first light, and the first light transmitted through the cell. And a detecting unit for detecting.
According to the present invention, when the first light is irradiated to the cell unit from the first irradiation unit, the first light is branched and guided to each of the plurality of cells. For this reason, in the magnetic field measurement apparatus, it is possible to supply the first light to each cell and measure the first light that has passed through the cell without providing a plurality of light sources for each cell.
In addition, the magnetic field measurement apparatus according to the present invention includes a cell layer including a plurality of cells having atoms excited by light therein, and the incident first light that excites the atoms to branch the plurality of cells. The first light that is branched into each of the first light, the incident second light is branched, and the second light is branched so that the second light intersects the first light in each of the plurality of cells. A cell unit having a distribution layer that guides the plurality of cells, a first irradiation unit that irradiates the cell unit with the first light, and a second irradiation unit that irradiates the cell unit with the second light, A detection unit that detects the second light transmitted through the cell.
According to the present invention, when the first light is irradiated from the first irradiation unit to the cell unit, the first light is branched and guided to each of the plurality of cells, and when the second light is irradiated to the cell unit, The second light is branched and guided to each of the plurality of cells. Since light is branched in the distribution layer and guided to a plurality of cells, the magnetic field measurement apparatus can supply the first light and the second light to each cell without providing a plurality of light sources for each cell.

The figure which showed the structure of the magnetic field measuring apparatus 1 which concerns on one Embodiment of this invention. The figure which showed the external appearance of the cell unit 10. FIG. 3 is a schematic cross-sectional view of the cell unit 10. FIG. The figure which showed the external appearance of 10A of cell units which concern on a modification. The schematic diagram of 11C of light distribution layers which concern on a modification. The schematic diagram of light distribution layer 11D which concerns on a modification. The schematic diagram of the light distribution layer 11E which concerns on a modification. The figure explaining the inclination of the cell 121 which concerns on a modification.

[Embodiment]
FIG. 1 is a diagram showing a configuration of a magnetic field measurement apparatus 1 according to an embodiment of the present invention. The magnetic field measurement apparatus 1 is an apparatus that measures a magnetic field using an optical pumping method. The magnetic field measuring apparatus 1 is the first
The irradiation unit 20, the second irradiation unit 30, the detection unit 40, and the cell unit 10 to which a magnetic field generated by a living body (for example, a magnetic field generated by the heart 2) is applied.
In addition, in FIG. 1, the structure of the part which concerns on an optical pumping method is shown, and about well-known structures, such as a magnetic shield which reduces magnetism, such as geomagnetism, and a plurality of Helmholtz coils which reduce a residual magnetic field in a magnetic shield Is omitted, and the description thereof is also omitted below.

The first irradiation unit 20 is an example of a unit that outputs circularly polarized pump light, and includes a light source 21 and a conversion unit 22. The light source 21 is a device that outputs laser light. The non-polarized laser light output from the light source 21 is preferably an external resonator type laser or a distributed feedback type laser having a narrow spectrum width.
The converter 22 is an example of means for converting non-polarized laser light into circularly polarized laser light. The conversion unit 22 includes optical components such as a beam expander, a collimator lens, a polarizing plate, and a quarter wave plate. The laser light incident on the conversion unit 22 is spread by a beam expander and converted into parallel light by a collimator lens. The parallel light emitted from the collimating lens is linearly polarized by the polarizing plate and circularly polarized by the quarter wavelength plate. The circularly polarized light is applied to the cell unit 10 as pump light in the optical pumping method.
The pump light may contain other polarization components as long as it has a circular polarization component.

The second irradiation unit 30 is an example of a unit that outputs linearly polarized probe light.
A conversion unit 32 is included. The light source 31 is a device that outputs laser light in the same manner as the light source 21.
The converter 32 is an example of means for converting non-polarized laser light into linearly polarized laser light. The conversion unit 32 includes optical components such as a beam expander, a collimator lens, a polarizing plate, and a half-wave plate. The laser light incident on the conversion unit 32 is spread by a beam expander and is converted into parallel light by a collimator lens. The parallel light emitted from the collimating lens is linearly polarized by the polarizing plate, and the polarization plane is rotated by the half-wave plate. The linearly polarized light whose polarization plane is rotated by the half-wave plate is applied to the cell unit 10 as probe light in the optical pumping method.
The probe light may contain other polarization components as long as it has linear polarization components.

The detection unit 40 is an example of a unit that detects probe light that has passed through a cell 121 of the cell unit 10 described later. The detection unit 40 includes a half-wave plate 41, a polarization beam splitter 42, and sensors 43A and 43B.
The half-wave plate 41 is an optical component that rotates the polarization plane of the probe light that has passed through the cell 121. The light whose polarization plane is rotated by the half-wave plate 41 enters the polarization beam splitter 42.
The polarization beam splitter 42 is an optical component that branches the probe light into P-polarized light and S-polarized light. The P-polarized light separated by the polarization beam splitter travels straight and enters the sensor 43A. On the other hand, the S-polarized light separated by the polarization beam splitter proceeds in a direction orthogonal to the P-polarized light,
It enters the sensor 43B.
The sensor 43A and the sensor 43B have an element such as a photodiode that outputs an electrical signal corresponding to incident light. The sensor 43 </ b> A detects the P-polarized light branched by the polarization beam splitter 42 and outputs an electrical signal corresponding to the detected light to the calculation unit 50. The sensor 43 </ b> B detects the S-polarized light branched by the polarization beam splitter 42 and outputs an electrical signal corresponding to the detected light to the calculation unit 50.
The calculation unit 50 includes a differential amplifier, and outputs a signal obtained by amplifying the difference between the signal output from the sensor 43A and the signal output from the sensor 43B. By analyzing the signal output from the calculation unit 50, it is possible to know information on the magnetic field generated by the living body.

Next, the cell unit 10 will be described. FIG. 2A is a plan view of the cell unit 10, and FIG. 2B is a front view of the cell unit 10. FIG. 3 is a diagram schematically showing a cross section of the cell unit 10. In FIG. 3, the arrows indicate the traveling direction of the laser light. For convenience of explanation, in the figure, directions are indicated by orthogonal X-axis, Y-axis, and Z-axis. When the cell unit 10 is viewed from the front, the left-right direction is the X-axis direction, and the depth direction is the Y-axis. The direction of height and the height direction are the Z-axis direction. The dimensions of each component in the figure are
The dimensions of the components are different from the actual dimensions so that the shapes of the components can be easily understood.
The cell unit 10 includes a light distribution layer 11, a cell layer 12, and a light receiving layer 13. The cell layer 12 is stacked on the light distribution layer 11, and the light receiving layer 13 is stacked on the cell layer 12. Yes.
Each layer has a square shape when viewed from the Z-axis direction, but the shape viewed from the Z-axis direction may be a rectangle or a shape other than a rectangle.

The cell layer 12 is formed of a material that transmits light such as glass. The cell layer 12 has hollow cells 121-1 to 121-9. The cells 121-1 to 121-9 have a cubic shape and are sealed. These cells 121-1 to 121-9 are arranged in three columns in the X-axis direction and in three rows in the Y-axis direction. In addition, since the structure of each cell is the same, description of the branch number of a code | symbol is abbreviate | omitted about a cell below, when it is not necessary to distinguish each cell.
The cell 121 is located in the cell layer 12 in a tilted state. Specifically, cell 12
1. Cell layer in a state where the upper surface and the lower surface are parallel to the XY plane and the side surfaces are parallel to the XZ plane and the YZ plane, and rotated at a predetermined angle about the central axis in the Y-axis direction. 12
Is arranged. That is, in the cell 121, two orthogonal surfaces are obliquely directed to the light distribution layer 11, and a surface opposite to the surface directed to the light distribution layer 11 is obliquely directed to the light receiving layer 13. .

The cell 121 has a predetermined atom inside. Here, the predetermined atom is
An atom that is excited by circularly polarized light and spin-polarized, for example, an element of group 1 element excluding hydrogen (H), that is, an alkali metal atom. Elements corresponding to alkali metals are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). The alkali metal sealed in the cell 121 is typically one type, but it does not preclude multiple types. In the cell 121, such alkali metal atoms are enclosed in a gaseous state (that is, in a gas state). The alkali metal atoms enclosed in the cell 121 need only be in a gaseous state when the detection unit 40 obtains magnetic field information, and need not always exist as a gas. The cell 121 may contain helium (He), nitrogen (N), or the like as a buffer gas.

Note that the number of cells 121 is not limited to the above-described number, and is 10 or more or 8
Or less. Further, the cell arrangement is not limited to 3 rows and 3 columns, and may be another arrangement. The shape of the cell 121 is not limited to a cubic shape, and may be a rectangular parallelepiped shape. The shape of the cell 121 may be a shape obtained by chamfering a cube or a rectangular parallelepiped.

The light distribution layer 11 is made of transparent glass or resin, and the branch couplers 111A and 111B for branching light and the light branched by the branch couplers 111A and 111B for the cell 12 are used.
1 to the inside.
Pump light is incident on the branch coupler 111A. This pump light is branched coupler 11
1A branches into nine pump lights. The branching coupler 111A includes nine optical fibers 1
12 is connected. One of the branched pump lights is incident on one optical fiber 112. In the optical fiber 112, one optical fiber is one cell 121.
It arrange | positions so that pump light may be guided to. In optical fiber 112, branch coupler 1
The end opposite to the side connected to 11A is directed to one surface of the cell 121 facing the light distribution layer 11 side. The pump light branched by the branch coupler 111A is guided by the optical fiber 112, enters the cell layer 12 from the end of the optical fiber 112, and enters the cell 12
1 is irradiated.

On the other hand, the probe light is incident on the branch coupler 111B. This probe light is branched into nine probe lights by the branch coupler 111B. Nine optical fibers 112 are connected to the branch coupler 111B. One probe light out of the branched probe lights enters one optical fiber 112. The optical fiber 112 is arranged so that one optical fiber guides the probe light to one cell 121. In the optical fiber 112,
The end opposite to the side connected to the branching coupler 111B is a surface facing the light distribution layer 11 side in the cell 121, and is directed to be orthogonal to the surface on the pump light incident side. . The probe light branched by the branch coupler 111B is guided by the optical fiber 112,
The cell layer 12 is entered from the end of the optical fiber 112 and irradiated to the cell 121.
Note that the position and orientation of the end of the optical fiber 112 are set so that the pump light and the probe light to be output intersect inside the cell 121.

The light receiving layer 13 is formed of transparent glass or resin, and is a layer that guides the probe light that has passed through the cell 121 and reached the light receiving layer 13 to the detection unit 40. The light receiving layer 13 includes nine optical fibers 131 that guide the probe light to the detection unit 40. The optical fiber 131 is arranged so that one optical fiber 131 receives and guides one probe light, and one end of the optical fiber 131 is directed to the cell 121. The other end of the optical fiber 131 faces the half-wave plate 41.

The configuration of each part of the magnetic field measurement apparatus 1 according to the present embodiment is as described above. Under this configuration, the magnetic field measurement apparatus 1 measures a magnetic field generated by a living body. Note that the cell unit 10 of the magnetic field measurement apparatus 1 is positioned above the measurement target when performing measurement. For example, when measuring the magnetic field generated by the heart 2, the person is on his back and the cell unit 10 is located above the heart 2.
When the magnetic field measuring apparatus 1 starts measurement, laser light is output from the light source 21 and the light source 31. The laser light output from the light source 21 is circularly polarized by the conversion unit 22 and reaches the cell unit 10 as pump light. The pump light is emitted from the cell unit 1 from the negative direction of the X axis.
Reach 0. On the other hand, the laser light output from the light source 31 is linearly polarized by the conversion unit 32 and reaches the cell unit 10 as probe light. The probe light reaches the cell unit 10 from the plus direction of the X axis.

The pump light reaching the cell unit 10 enters the branching coupler 111A. The pump light entering the branch coupler 111A is branched into nine pump lights. The branched pump light is guided below the cell 121 by the optical fiber 112 so that one pump light reaches one cell. The pump light guided below the cell 121 is transmitted from the end of the optical fiber 112 to the cell 1.
21 is irradiated.
On the other hand, the probe light reaching the cell unit 10 enters the branch coupler 111B. The probe light entering the branching coupler 111B is branched into nine probe lights. The branched probe light is guided below the cell 121 by the optical fiber 112 so that one probe light reaches one cell. The probe light guided below the cell 121 is the optical fiber 11.
The cell 121 is irradiated from the end of 2.
The probe light applied to the cell 121 passes through the cell 121 and intersects with the pump light, and then exits the cell 121 and reaches the light receiving layer 13. Note that the polarization plane of the linearly polarized light rotates in response to the magnetic field generated by the heart 2.

The nine probe lights reaching the light receiving layer 13 are guided by the optical fiber 131 and reach the half-wave plate 41. The probe light that has reached the half-wave plate 41 has its polarization plane rotated and enters the polarization beam splitter 42. The P-polarized light separated by the polarization beam splitter 42 travels straight and enters the sensor 43A, and the separated S-polarized light enters the sensor 43B.
Since nine probe lights enter the polarization beam splitter 42, the sensor 43
N P-polarized light enters A, and nine S-polarized light enters the sensor 43B. The sensor 43A generates an electrical signal for each of the nine incident P-polarized lights and outputs the electrical signal to the computing unit 50. Further, the sensor 43B has nine S polarizations with respect to nine incident S polarizations.
An electrical signal is generated for each polarized light and output to the calculation unit 50.

The computing unit 50 outputs a signal obtained by amplifying the difference between the electric signal corresponding to the P-polarized light separated from the one probe light and the electric signal corresponding to the S-polarized light separated from the probe light.
For example, a signal obtained by amplifying the difference between the electric signal corresponding to the P-polarized light separated from the probe light that has passed through the cell 121-1 and the electric signal corresponding to the S-polarized light separated from the probe light is output. Further, a signal obtained by amplifying the difference between the electric signal corresponding to the P-polarized light separated from the probe light that has passed through the cell 121-2 and the electric signal corresponding to the S-polarized light separated from the probe light is output. Note that a signal obtained by amplifying the difference between the electrical signals is also output for the electrical signal obtained from the probe light that has passed through the other cell 121.
By analyzing the signal output from the calculation unit 50, the magnetic field can be measured in a wider range than in the case of using one cell.

According to this embodiment, since the pump light is branched into a plurality of light distribution layers 11, one light source 2 is used.
1 can supply pump light to a plurality of cells 121. Further, according to the present embodiment, the light distribution layer 1
1, the probe light is branched into a plurality of light sources, so that the single light source 31 can supply the probe light to the plurality of cells 121.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows. In addition, you may combine each of embodiment mentioned above and the following modifications.

In the embodiment described above, the pump light is incident on the cell layer 12 from the lower surface side of the cell layer 12, but the configuration for irradiating the cell layer 12 with the pump light is not limited to this configuration.
For example, the light distribution layer 11 may also be provided on the side surface of the cell unit 10, the probe light may be irradiated to the cell layer 12 from the lower surface side of the cell unit 10, and the pump light may be irradiated from the side surface of the cell unit 10.

FIG. 4A is a plan view of a cell unit 10A according to this modification, and FIG.
It is a front view of cell unit 10A. In FIG. 4A and FIG. 4B, the arrows indicate the traveling direction of the laser light. The cell unit 10A includes three cells 121-
1 to 121-3. Unlike the above-described embodiment, the upper surface and the lower surface of the cell 121 are parallel to the XY plane, and two of the side surfaces of the cell 121 are parallel to the ZY plane. The cell unit 10 </ b> A has a light distribution layer 11 </ b> A on the lower surface side of the cell layer 12 and a light distribution layer 11 </ b> B on the side surface of the cell layer 12.
The light distribution layer 11 </ b> A includes the branch coupler 111 </ b> B and the optical fiber 112 similarly to the light distribution layer 11 described above. The light distribution layer 11A does not include the branch coupler 111A. The light distribution layer 11B includes a branch coupler 111A and an optical fiber 112.

The branch coupler 111B on which the probe light is incident is located at the end in the Y-axis direction, and branches the incident probe light into three. Three optical fibers 112 are connected to the branch coupler 111B. The optical fiber 112 is arranged so that one optical fiber guides the probe light to one cell 121. The probe light branched into three is an optical fiber 11.
2 and irradiated to the lower surfaces of the cells 121-1 to 121-3.
Further, the branch coupler 111A into which the pump light is incident branches the incident pump light into three. Three optical fibers 112 are connected to the branch coupler 111A. The optical fiber 112 is arranged so that one optical fiber guides the pump light to one cell 121. The pump light branched into three is guided by the optical fiber 112 and the cell 121-1.
Irradiated to the side surface of ~ 121-3.
Also in this configuration, pump light can be supplied to the plurality of cells 121 with one light source 21. In addition, probe light can be supplied to the plurality of cells 121 with one light source 31. In FIG. 4, the cells 121 are only one row, but the cell units 10 </ b> A according to this modification may be arranged in a plurality of rows.

In the above-described configuration, the light distribution layers 11, 11 </ b> A, and 11 </ b> B branch light with a branch coupler, but the configuration for branching light is not limited to the branch coupler.
FIG. 5 is a schematic diagram of a light distribution layer 11C according to this modification. In FIG. 5, the arrow indicates the traveling direction of the laser beam. 11C of light distribution layers are the light guide 113 formed with the material which laser light permeate | transmits, such as transparent glass and resin, and the film | membrane 114-1-1 which branches a laser beam
14-N.
The films 114-1 to 114-N are dielectric multilayer films that reflect a part of incident light and transmit the remaining light to split the light. The reflectances of the films 114-1 to 114-N are adjusted so that the light beams reflected and branched by the films 114-1 to 114-N are uniform. Further, the angle and position of the film are set so that the cell 121 is irradiated.
Incidentally, the optical power of the laser beam incident on the N-th layer Pin N, Pout the optical power of the _N-th laser beam reflected by the film N, the reflectivity of the _N-th layer as R _N, in film Assuming that there is no absorption, the transmittance is represented by 1- _RN , and the following equations 1 to 4 are established.

Expression of the following Equation 5 from these equations is obtained, the inverse of R _N is found to be arithmetically. As a result, R _N can be represented by the formula 6.

R ₀ is the reflectance of the film on which the laser beam is reflected first, and is set according to the number of branches of the laser beam. Note that the films 114-1 to 114 -N may be provided along the Y-axis direction. In the case of this configuration, the laser light may be spread by a beam expander so that the laser light is incident on the entire end surface in the X-axis direction of the light distribution layer 11B. In this configuration, a film that reflects the pump light and a film that reflects the probe light may be provided, and both the pump light and the probe light may be branched by a single distribution layer.

In the modification described above, the light distribution layer 11C uses a film to split the laser light, but the configuration for branching the laser light is not limited to the film.
FIG. 6 is a schematic diagram of a light distribution layer 11D according to a modification. In FIG. 6, the arrows indicate the traveling direction of the laser light. The light distribution layer 11D includes a light guide 113 formed of a material that transmits laser light, such as transparent glass or resin, and a diffraction grating 115. Note that a triangular prism 116 on which laser light is incident is provided at the end of the upper surface of the light guide 113. In this configuration, the laser light passes through the triangular prism 116 and enters the light guide 113. The laser light entering the light guide 113 is totally reflected by the lower surface of the light guide 113 and reaches the diffraction grating 115.
A part of the light that reaches the diffraction grating 115 passes through the diffraction grating 115, and the remaining light is reflected by the diffraction grating 115. The light reflected by the diffraction grating 115 is again totally reflected by the lower surface of the light guide 113 and reaches the diffraction grating 115 again. As described above, the laser light travels through the light guide 113 while being branched by the diffraction grating 115, so that the laser light is branched into a plurality of parts and outputted to the outside of the light distribution layer 11D. The diffraction grating 115 is set so that the passed light is irradiated to the cell 121.

The diffraction grating 115 may be provided not on the upper surface side of the light distribution layer 11D but on the lower surface side as shown in FIG. In FIG. 7, the arrows indicate the traveling direction of the laser light. In this case, a part of the laser light is branched by the diffraction grating 115 and reflected in the Z-axis direction. Further, the remaining light travels in a direction different from the Z-axis direction, is totally reflected by the upper surface of the light guide 113, and reaches the diffraction grating 115 again. In this way, the laser light travels inside the light guide 113 while being branched by the diffraction grating 115, so that the laser light is branched into a plurality of light distribution layers 1.
1E is output outside.

In the present invention, the inclination angle of the cells 121-1 to 121-9 in the cell layer 12 is
It is not limited to what was mentioned above.
FIG. 8 is a diagram illustrating an example of the cell 121 tilted at a different angle from the above-described configuration.
In this configuration, a Z axis passing through the center of the cell 121 and extending along the vertical direction is assumed. Then, the cell 121 may be tilted so that the angles θ formed by the Z axis and the three laser beams L1 to L3 orthogonal to each other through the center of the cell 121 are the same angle.
In this configuration, the laser beams L1 to L3 can be switched between the pump beam and the probe beam, and the laser beams L1 to L3 that have passed through the cell 121 are switched.
You may make it provide the detection part 40 for every.
In this configuration, for example, after measuring the magnetic field using the laser light L1 as pump light and the laser light L2 as probe light, the magnetic field may be measured using the laser light L1 as pump light and the laser light L3 as probe light. After this, the laser light L2 is pumped and the laser light L
After measuring the magnetic field with 1 as the probe light, the laser light L2 is the pump light, the laser light L3
The probe may be used to measure the magnetic field. In this modification, the magnetic field may be measured by sequentially switching the directions of the pump light and the probe light in this way.

In the present invention, a polarization beam splitter may be disposed at a position where the probe light is incident on the light receiving layer 13, and the probe light may be branched into P-polarized light and S-polarized light by the light receiving layer 13. Also,
A photodiode may be arranged in the light receiving layer 13 to detect P-polarized light and S-polarized light branched by the polarizing beam splitter in the light receiving layer 13. Further, in the light receiving layer 13, a half-wave plate may be disposed, and the light that has passed through the half-wave plate may be branched by a polarization beam splitter. That is, the light receiving layer 13 may have the configuration of the detection unit 40 described above.
In the above-described embodiment, the optical fiber 13 that guides the probe light to the detection unit 40.
1 is disposed on the upper surface of the cell layer 12, and the upper surface of the cell layer 12 may not be provided with a layer formed of transparent glass or resin.
In the present invention, a polarizing plate, a half-wave plate, a quarter-wave plate, or the like is arranged in the cell unit 10 so that the state of circularly polarized light or linearly polarized light is adjusted before the laser light enters the cell 121. May be.

In the embodiment described above, the magnetic field is measured by irradiating the cell 121 with two types of light, pump light and probe light, but the method of measuring the magnetic field is not limited to the embodiment described above.
For example, when measuring a magnetic field using a non-linear magneto-optical effect (NMOR), one cell is irradiated with a linearly polarized laser beam,
Excites atoms in the cell. Further, the magnetic field is measured by guiding the laser beam that has passed through the cell to the analyzer and measuring the light branched by the analyzer.
For this reason, when measuring a magnetic field using a nonlinear magneto-optical effect, a magnetic field measuring apparatus is 1
A light distribution layer that divides the two laser beams into a plurality of laser beams, that is, the light distribution layer 11 described above.
A magnetic field is measured using a cell unit provided with any of A-11E.
In the present modification, the above-described analyzer and a photodiode that detects light that has passed through the analyzer may be disposed in the light receiving layer 13.

In the embodiment described above, the magnetic field measuring apparatus 1 measures the magnetic field using one cell unit 10, but the cell units are arranged so that the light distribution layer 11 is directed in the same direction and overlapped when viewed from the Z-axis direction. A cell unit group in which a plurality of cell units 10 are arranged (that is, a cell unit group in which the cell units 10 are arranged in multiple stages) is arranged, and a laser beam passing through the cell 121 of each cell unit 10 is measured to measure a magnetic field. Good. Also in this modification, the light passing through the cell 121 may be measured by a photodiode disposed in the light receiving layer 13 of the cell unit 10.
According to this configuration, the magnetic field gradient can be measured by the cell units 10 arranged in multiple stages. Specifically, the cell unit 10 close to the heart 2 has a magnetic field from the heart 2 and
The environmental magnetic field other than the magnetic field from the heart 2 is measured, and the cell unit 10 far from the heart 2 measures the environmental magnetic field. Measuring the magnetic field generated by the heart 2 excluding the influence of the environmental magnetic field by taking the difference between the measurement result obtained by the cell unit 10 close to the heart 2 and the measurement result obtained by the cell unit 10 far from the heart 2 Can do.
In addition, according to the cell unit according to the present embodiment, since the cell 121 and the light distribution layer 11 are integrated, the cell is different from the case where the cell and the light distribution structure are provided separately. The height in the direction of multi-stage arrangement can be suppressed, and the configuration of the apparatus can be made compact.

DESCRIPTION OF SYMBOLS 1 ... Magnetic field measuring apparatus, 10 ... Cell unit, 11, 11A, 11B, 11C, 11
D, 11E ... light distribution layer, 12 ... cell layer, 13 ... light receiving layer, 20 ... first irradiation part, 21 ... light source, 22 ... conversion part, 30 ... 2nd irradiation part, 31 ... Light source, 32
... Conversion unit, 40 ... Detection unit, 41 ... Half-wave plate, 42 ... Polarizing beam splitter, 43A, 43B ... Sensor, 111A, 111B ... Branch coupler, 112
... Optical fiber, 113 ... Light guide, 114-1 to 114-N ... Membrane, 115.
..Diffraction grating, 121, 121-1 to 121-9 ... cell, 131 ... optical fiber

Claims (12)

A cell layer comprising a plurality of cells having atoms excited by light therein;
A cell unit comprising: a distribution layer for branching incident first light and guiding the branched first light to each of the plurality of cells. The distribution layer branches the incident second light, and splits the second light into the plurality of cells so that the second light intersects the first light in each of the plurality of cells. The cell unit according to claim 1, wherein the cell unit is guided. 3. The cell according to claim 2, wherein the cell layer is stacked on one of the distribution layers, and the first light and the second light are incident on the cell layer from the one distribution layer. unit. The distribution layer has a first distribution layer that guides the first light and a second distribution layer that guides the second light,
The first distribution layer is stacked on the cell layer, and the second layer is the first layer in the cell layer.
The cell unit according to claim 2, wherein the cell unit is provided in contact with a surface intersecting with a surface facing the distribution layer. 5. The cell unit according to claim 2, further comprising a detection unit configured to detect the second light transmitted through the cell. The cell unit according to claim 1, further comprising a detection unit configured to detect the first light transmitted through the cell. The distribution layer includes a plurality of films that reflect and transmit incident light, the films are arranged in a direction in which the incident light travels, and the light reflected by the plurality of films is irradiated to the plurality of cells. The cell unit according to any one of claims 1 to 6, wherein: The distribution layer has a diffraction grating that transmits a part of incident light and reflects the rest on the side facing the cell layer, and the light that has passed through the diffraction grating is irradiated to the plurality of cells. The cell unit according to any one of claims 1 to 6. The distribution layer has a diffraction grating that reflects incident light in a first direction and a second direction on a surface opposite to the surface facing the cell layer, and the light reflected in the first direction is the plurality of light beams. The cell unit according to claim 1, wherein the cell unit is irradiated with the cell unit. A cell unit group in which the cell units according to any one of claims 1 to 9 are arranged in multiple stages. A cell layer including a plurality of cells having atoms excited therein by light; and a distribution layer for branching the incident first light and guiding the branched first light to each of the plurality of cells. A cell unit,
A first irradiation unit that irradiates the cell unit with the first light;
A magnetic field measurement apparatus comprising: a detection unit that detects the first light transmitted through the cell. A cell layer including a plurality of cells having atoms excited by light therein, and the incident first light for exciting the atoms are branched to guide the first light branched to each of the plurality of cells. A distribution layer that branches the incident second light and guides the second light branched so that the second light intersects the first light in each of the plurality of cells to the plurality of cells. A cell unit having
A first irradiation unit that irradiates the cell unit with the first light;
A second irradiation unit that irradiates the second light to the cell unit;
A magnetic field measurement apparatus comprising: a detection unit that detects the second light transmitted through the cell.

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