Optically pumped magnetic sensor module

Abstract

An optically pumped magnetic sensor module according to the present invention comprises a cell unit and a housing that accommodates the cell unit. The cell unit has a cell in which an alkali metal is encapsulated, a heater which heats the cell, and a heat insulation member which is disposed on the outside of the cell. Contacting sections, where the cell unit contacts the housing, and separated sections, where the cell unit is separated from the housing and in which an air layer is formed between the cell unit and the housing, are formed on the contact interface between the cell unit and the housing.

Description

Optically excited magnetic sensor module

[0001] One aspect of the present disclosure relates to an optically excited magnetic sensor module.

[0002] As an example of this type of technology, Patent Document 1 describes a magnetic field measuring device that includes a gas cell containing an alkali metal, a heater for heating the gas cell, and a light irradiation means for irradiating a probe light.

[0003] Japanese Patent Application Laid-Open No. 2017-215226

[0004] In an optically excited magnetic sensor module, an alkali metal in a cell is heated by a heater, and when the cell is filled with alkali metal vapor, a change in the magnetic field in the cell is detected using a probe light. In such an optically excited magnetic sensor module, it is sometimes required to reduce the power consumption of the heater and the temperature of the outer surface of the optically excited magnetic sensor module.

[0005] Therefore, an object of one aspect of the present disclosure is to provide an optically excited magnetic sensor module that can reduce power consumption and lower the temperature on the outer surface.

[0006] One aspect of the optically excited magnetic sensor module of the present disclosure is [1] "an optically excited magnetic sensor module comprising: a cell unit; and a housing that houses the cell unit, wherein the cell unit has a cell in which an alkali metal is sealed, a heater that heats the cell, and an insulating member that is arranged outside the cell, and the contact interface between the cell unit and the housing is formed with a contact portion where the cell unit contacts the housing, and a separation portion where the cell unit is separated from the housing to form an air layer between the cell unit and the housing."

[0007] In this photoexcited magnetic sensor module, the contact interface between the cell unit and the housing includes a contact portion where the cell unit contacts the housing and a separation portion where the cell unit is separated from the housing, forming an air gap between the cell unit and the housing. This reduces the contact area (heat conduction area) between the cell unit and the housing, suppressing heat conduction and improving thermal insulation performance. As a result, heat is less likely to escape from the cell, reducing the power consumption of the heater when heating to a target temperature. Furthermore, heat from the cell is less likely to be transmitted to the outer surface of the photoexcited magnetic sensor module, reducing the temperature at the outer surface of the photoexcited magnetic sensor module when the cell is heated to the target temperature. Therefore, this photoexcited magnetic sensor module can reduce power consumption and the temperature at the outer surface.

[0008] The optically excited magnetic sensor module according to one aspect of the present disclosure may be [2] "the optically excited magnetic sensor module according to [1]," in which the thermal conductivity of the material constituting the housing is lower than the thermal conductivity of the material constituting the cell. In this case, heat conduction to the housing can be further suppressed, and thermal insulation performance can be further improved.

[0009] An optically excited magnetic sensor module according to one aspect of the present disclosure may be [3] "the optically excited magnetic sensor module according to [1] or [2], wherein the cell unit further includes a cell case that houses the cell, the heater, and the heat insulating member, and the contact interface between the cell case and the housing includes the contact portion where the cell case contacts the housing and the separation portion where the cell case is separated from the housing to form an air layer between the cell case and the housing." In this case, since the cell unit includes the cell case, it is possible to easily arrange the heat insulating member, etc.

[0010] The photo-excited magnetic sensor module according to one aspect of the present disclosure may be [4] "the photo-excited magnetic sensor module according to [3], wherein the thermal conductivity of the material constituting the cell casing is lower than the thermal conductivity of the material constituting the cell." In this case, heat conduction through the cell casing can be suppressed, and the thermal insulation performance can be further improved.

[0011] An optically excited magnetic sensor module according to one aspect of the present disclosure may be [5] "an optically excited magnetic sensor module according to [3] or [4], in which the contact interface between the heat insulating member and the cell case is formed with an additional contact portion where the heat insulating member contacts the cell case and an additional separation portion where the heat insulating member is separated from the cell case to form an air layer between the heat insulating member and the cell case." In this case, heat conduction can be suppressed not only at the contact interface between the cell case and the housing but also at the contact interface between the heat insulating member and the cell case, thereby further improving heat insulating performance.

[0012] An optically excited magnetic sensor module according to one aspect of the present disclosure may be [6] "the cell unit is disposed in the housing so that the heat insulating member is in direct contact with the housing, and the contact interface between the heat insulating member and the housing is formed with the contact portion where the heat insulating member is in contact with the housing and the separation portion where the heat insulating member is separated from the housing to form an air layer between the heat insulating member and the housing." In this case, the cell case can be omitted, thereby reducing the number of parts.

[0013] An optically excited magnetic sensor module according to one aspect of the present disclosure may be [7] "an optically excited magnetic sensor module according to any one of [1] to [5], in which a concave-convex portion is formed on a contact surface of the housing with the cell unit, and the housing contacts the cell unit at the concave-convex portion to form the contact portion and the separation portion." In this case, the contact portion and the separation portion can be formed by the concave-convex portion formed on the housing.

[0014] The optically excited magnetic sensor module according to one aspect of the present disclosure may be [8] "the optically excited magnetic sensor module according to [5], in which an uneven portion is formed on the contact surface of the cell case with the heat insulating member, and the additional contact portion and the additional separation portion are formed by the cell case contacting the heat insulating member at the uneven portion." In this case, the additional contact portion and the additional separation portion can be configured by the uneven portion formed on the cell case.

[0015] The optically excited magnetic sensor module according to one aspect of the present disclosure may be [9] "the optically excited magnetic sensor module according to any one of [1] to [8], wherein the area of ​​the separating portion is larger than the area of ​​the contact portion." In this case, the proportion of the separating portion can be increased, and the heat insulating performance can be effectively improved.

[0016] The optically excited magnetic sensor module according to one aspect of the present disclosure may be

[10] "the optically excited magnetic sensor module according to [9], in which the ratio of the area of ​​the separating portion to the area of ​​the contact portion is equal to or greater than 9." In this case, the ratio of the separating portion can be increased, and the heat insulating performance can be effectively improved.

[0017] The optically excited magnetic sensor module according to one aspect of the present disclosure may be

[11] "an optically excited magnetic sensor module according to any one of [1] to

[10] , in which the thickness of the air layer is smaller than the thickness of the heat insulating member." In this case, it is possible to suppress the occurrence of air convection, which would increase the thermal conductivity of the air layer, and it is possible to effectively improve the heat insulating performance.

[0018] The optically excited magnetic sensor module according to one aspect of the present disclosure may be

[12] "the optically excited magnetic sensor module according to

[11] , wherein the thickness of the air layer is 1 mm or less." In this case, it is possible to suppress the occurrence of air convection, which would increase the thermal conductivity of the air layer, and it is possible to effectively improve the heat insulating performance.

[0019] The optically excited magnetic sensor module according to one aspect of the present disclosure may be

[13] "the optically excited magnetic sensor module according to any one of [1] to

[12] , wherein the contact portion is formed to extend straight." In this case, the proportion of the separating portion can be increased, and the heat insulating performance can be effectively improved.

[0020] The optically excited magnetic sensor module according to one aspect of the present disclosure may be

[14] "the optically excited magnetic sensor module according to any one of [1] to

[12] , wherein the contact portion is formed in a lattice pattern." In this case, the proportion of the separating portion can be increased, and the heat insulating performance can be effectively improved.

[0021] The photo-excited magnetic sensor module according to one aspect of the present disclosure may be

[15] "an photo-excited magnetic sensor module according to any one of [1] to

[12] , wherein the contact portion is formed in a dotted shape." In this case, the proportion of the separating portion can be increased, effectively improving the heat insulating performance. Furthermore, the contact portion and the separating portion can be easily formed in a planar shape, which facilitates the arrangement of the cell unit relative to the housing.

[0022] An optically excited magnetic sensor module according to one aspect of the present disclosure may be

[16] "an optically excited magnetic sensor module according to any one of [1] to

[12] , in which the contact portion and the separation portion are configured by arranging a plurality of the contact portions or the separation portions having the same shape along two directions perpendicular to each other." In this case, the contact portion and the separation portion can be easily formed in a planar shape, which facilitates the arrangement of the cell unit relative to the housing.

[0023] The optically excited magnetic sensor module according to one aspect of the present disclosure may be

[17] "the optically excited magnetic sensor module according to any one of [1] to

[12] , wherein the contact portion and the separating portion are configured by roughening a contact surface of the housing with the cell unit or a contact surface of the cell unit with the housing." In this case, the proportion of the separating portion can be increased, thereby effectively improving thermal insulation performance.

[0024] The optically excited magnetic sensor module according to one aspect of the present disclosure may be

[18] "the optically excited magnetic sensor module according to any one of [1] to

[16] , wherein the contact portion and the separation portion are configured by a sheet member having openings formed in a predetermined arrangement pattern and being disposed between the cell unit and the housing." In this case, the contact portion and the separation portion can be configured by the sheet member.

[0025] According to one aspect of the present disclosure, it is possible to provide an optically excited magnetic sensor module that can reduce power consumption and lower the temperature on the outer surface.

[0026] 2(a) and 2(b) are diagrams for explaining the operation of the photo-excited magnetic sensor module. FIG. 2(a) is a perspective view of the photo-excited magnetic sensor module, and FIG. 2(b) is a perspective view of the photo-excited magnetic sensor module with the outer cover removed. FIG. 2(b) is a perspective view of the photo-excited magnetic sensor module with the housing lid of the housing removed from FIG. 2(b). FIG. 3 is a cross-sectional view along line IV-IV of FIG. 3. FIG. 3 is a plan view of the photo-excited magnetic sensor module with the case lid of the cell case removed from FIG. 3. FIG. 3 is an enlarged view of a portion of FIG. 3. FIG. 3 is a perspective view of the housing main body. FIG. 3 is a perspective view of the housing lid. FIG. 3 is a perspective view of the cell case main body. FIG. 3 is a diagram showing simulation results for an example. FIG. 3 is a diagram showing simulation results for a comparative example. FIG. 3 is a diagram for explaining the operation of the photo-excited magnetic sensor module according to the first modified example. FIG. 3 is a plan view of the photo-excited magnetic sensor module according to the second modified example. FIG. 2(a), (b), (c), and (d) are diagrams for explaining examples of the arrangement of contact portions and separation portions.

[0027] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be designated by the same reference numerals, and redundant description will be omitted.

[0028] The optically excited magnetic sensor module 1 (hereinafter also referred to as "sensor module 1") shown in Figures 1 to 5 is an optically pumped magnetic sensor (OPM: Optically Pumped Magnetometer) and is used, for example, for measuring biomagnetic fields. As an example, the sensor module 1 can be used as a magnetoencephalograph that measures magnetic fields generated in the brain, or a magnetocardiograph or magnetospinograph that measures magnetic fields generated in the heart or spinal cord. [Configuration of the sensor module]

[0029] 1 to 5, the sensor module 1 includes a cell unit 2, a housing 3 that houses the cell unit 2, and an outer cover 4 that covers the outer surface of the housing 3. The cell unit 2 has a cell 11, a heater 12, a heat insulating member 13, and a cell case 14, and is at least partially surrounded by a coil unit 15. The sensor module 1 further includes a light source 21, a lens 22, a mirror 23, a quarter-wave plate 24, a photodetector 25, a connector member 26, and a connector cover 27. [Operation of the Sensor Module]

[0030] The operation of the sensor module 1 (the principle of detecting magnetic field changes) will be described with reference to FIG. 1 . During measurement, the sensor module 1 (cell 11) is placed near the object to be measured. The cell 11 is filled with a gas GS containing an alkali metal. During measurement, the alkali metal in the cell 11 is heated by a heater 12, and the cell 11 is filled with alkali metal vapor. In this state, laser light L output from a light source 21 passes through the cell 11. The laser light L is circularly polarized by a quarter-wave plate 24 and enters the cell 11. This circularly polarized laser light L optically pumps (optically excites) the alkali metal vapor in the cell 11 to make it spin-polarized. That is, the laser light L functions as pump light that optically pumps the alkali metal vapor in the cell 11 to make it spin-polarized.

[0031] The laser light L that passes through the cell 11 is detected by the photodetector 25. At this time, the intensity of the laser light L detected by the photodetector 25 (i.e., the degree to which the laser light L is absorbed by the alkali metal vapor in the cell 11) changes depending on the spin polarization state of the alkali metal vapor in the cell 11. Here, the spin polarization state of the alkali metal vapor in the cell 11 changes under the influence of the magnetic field of the measurement target. Therefore, changes in the magnetic field of the measurement target can be detected based on the detected intensity of the laser light L. In this way, the laser light L also functions as probe light for detecting the spin polarization state of the alkali metal vapor in the cell 11. In this case, the sensor module 1 is a one-laser type sensor module in which the laser light L serves as both pump light and probe light. [Configuration of Each Part of the Sensor Module]

[0032] The configuration of each part of the sensor module 1 will be described with reference to FIGS. 2 to 5. The following description will be made with reference to the X direction (first direction), the Y direction (second direction) perpendicular to the X direction, and the Z direction (third direction) perpendicular to both the X and Y directions, as shown in FIGS. 2 to 5. The housing 3 is formed, for example, from a resin material in a substantially rectangular parallelepiped shape and includes a housing main body 3a and a housing lid 3b. FIG. 2(b) shows the housing with the lid 3b attached, while FIG. 3 shows the housing with the lid 3b removed. Note that FIGS. 3 to 5 omit illustrations of the uneven portion 35 (described later) formed on the housing 3 and the uneven portion 55 (described later) formed on the cell case 14.

[0033] 4 and 5, the housing 3 is provided with a cell unit arrangement section 3c in which the cell unit 2 is arranged, an optical member arrangement section 3f in which the light source 21, lens 22, and mirror 23 are arranged, and a photodetector arrangement section 3g in which the photodetector 25 is arranged. The optical member arrangement section 3f is provided with an optical path section 3h, which is a space through which the laser light L output from the light source 21 and directed toward the cell unit 2 travels. The photodetector arrangement section 3g is arranged on the opposite side of the cell unit arrangement section 3c from the optical path section 3h.

[0034] The light source 21 is, for example, a vertical cavity surface emitting laser, and outputs laser light L. In this example, the light source 21 is mounted on a connector member 26.

[0035] The lens 22 collimates the laser light L output from the light source 21. The mirror 23 reflects the laser light L collimated by the lens 22 toward the cell unit 2. The quarter-wave plate 24 is disposed between the mirror 23 and the cell unit 2. The quarter-wave plate 24 imparts a phase difference of π / 2 (=λ / 4) between the vertically polarized components of the incident light. The quarter-wave plate 24 converts the linearly polarized laser light L output from the light source 21 into circularly polarized light.

[0036] The cell unit 2 is arranged in the cell unit arrangement section 3c. The cell unit 2 has a cell 11 in which a gas GS containing an alkali metal is sealed. Details of the cell unit 2 will be described later. Circularly polarized laser light L converted by a quarter-wave plate 24 is incident on the cell unit 2. The laser light L incident on the cell unit 2 passes through the cell 11 and is emitted from the cell unit 2 toward the photodetector 25. In this example, the laser light L passes through the cell 11 along the X direction. The photodetector 25 is arranged in the photodetector arrangement section 3g. The photodetector 25 is, for example, a photodiode, and detects the laser light L that has passed through the cell unit 2.

[0037] The connector member 26 is provided on one side in the Z direction of the housing 3. The heater 12, the coil unit 15, the light source 21, and the photodetector 25 are electrically connected to the connector member 26, and the connector member 26 is used for electrically connecting these components to the outside. A connector cover 27 is detachably attached to the connector member 26. As shown in FIG. 2, the outer cover 4 is formed in a substantially rectangular parallelepiped shape, and covers the outer surface of the housing 3 except for the surface on the side where the connector cover 27 is arranged (one side in the Z direction). [Cell Unit]

[0038] 3 to 5, the cell unit 2 will be described in detail. As described above, the cell unit 2 has a cell 11, a heater 12, a heat insulating member 13, and a cell case 14, and is at least partially surrounded by a coil unit 15. The cell 11, the heater 12, and the heat insulating member 13 are housed within the cell case 14, and the coil unit 15 is disposed outside the cell case 14.

[0039] The cell 11 has a main body 11a and a protruding portion 11b. The cell 11 is formed of a translucent material such as glass or silicon. The cell 11 is filled with a gas GS consisting of an alkali metal and an inert gas. The alkali metal filled in the cell 11 is, for example, one or more of potassium, lithium, sodium, rubidium, and cesium. The inert gas filled in the cell 11 is, for example, one or more of helium, neon, argon, krypton, xenon, nitrogen, and hydrogen. The main body 11a is, for example, a rectangular parallelepiped container portion. The protruding portion 11b is a tubular portion connected to the main body 11a, and is sealed off after being used as a passage for gas introduction, e.g., exhaust, or introduction of the gas GS.

[0040] The heater 12 is disposed in a state of being thermally connected to the cell 11, and in this embodiment, is provided on the surface of the main body 11a of the cell 11 (in this example, the surface on one side in the Y direction). The heater 12 is formed, for example, in a sheet shape including a metal wire (resistor) that generates heat when electricity is passed through it. In this example, the heater 12 is formed including a titanium wire and is fixed to the cell 11 by an adhesive layer. The heater 12 generates heat when electricity is passed through it, thereby heating the cell 11.

[0041] The heat insulating member 13 is disposed within the cell case 14 so as to be positioned outside the cell 11. In this example, the heat insulating member 13 is composed of a plurality of plate-shaped members 13a. The plurality of plate-shaped members 13a are disposed to fill the space between the cell 11 and the cell case 14. More specifically, the plurality of plate-shaped members 13a are disposed in the space between the main body 11a of the cell 11 and the cell case 14 so as to fill as few gaps as possible except for the area of ​​the main body 11a through which the laser light L passes. In the space between the protrusion 11b of the cell 11 and the cell case 14, the plurality of plate-shaped members 13a are disposed so as to surround and fill the entire protrusion 11b while leaving an area spaced apart from the outer surface of the protrusion 11b of the cell 11. The plate-shaped members 13a are members whose heat insulating properties are enhanced, for example, by forming an air layer inside. The cell case 14 is formed, for example, in a substantially rectangular parallelepiped shape from a resin material, and includes a case main body 14a and a case lid 14b. Fig. 3 shows a state in which the case lid 14b is attached, and Fig. 5 shows a state in which the case lid 14b is removed. Note that hatching of the plate-like member 13a is omitted in Fig. 4.

[0042] As shown in FIG. 5 , the case body 14a has a pair of first walls 14c facing each other in the X direction and a pair of second walls 14d facing each other in the Z direction. A plurality of (two in this example) plate-like members 13a are disposed between each of the first walls 14c and the cell 11, and a plurality of (four in this example) plate-like members 13a are disposed between each of the second walls 14d and the cell 11. Although not shown, heat insulating members 13 (a plurality of plate-like members 13a) are also disposed between the Y-direction wall of the case body 14a (the wall facing the case lid 14b in the Y direction) and the cell 11, and between the case lid 14b and the cell 11. Thus, in this example, the cell 11 is housed in the cell case 14 with the heat insulating member 13 interposed between the cell 11 and the cell case 14. As shown in Figure 4, one of the pair of first wall portions 14c has an opening 14e through which laser light L reflected by the mirror 23 passes toward the cell 11, and the other of the pair of first wall portions 14c has an opening 14f through which laser light L that has passed through the cell 11 passes.

[0043] 3, the coil unit 15 is disposed outside the cell case 14. The coil unit 15 is configured to include, for example, a plurality of coils, which generate a magnetic field that acts on the cell 11. In the sensor module 1, the coil unit 15 generates a magnetic field that acts on the cell 11, and the sensor module 1 detects changes in the magnetic field within the cell 11 using laser light L (probe light).

[0044] The coil unit 15 generates a correction magnetic field, for example, so that the influence of magnetic fields other than the magnetic field to be measured on the cell 11 approaches zero. For example, the coil unit 15 may generate a magnetic field in the opposite direction to the geomagnetic field to cancel the influence of the geomagnetic field. Alternatively or additionally, the coil unit 15 may generate a modulated magnetic field acting on the cell 11. For example, the coil unit 15 may generate an AC magnetic field modulated at a predetermined frequency to increase sensitivity, or may generate a modulated magnetic field to enable detection of the direction of magnetic field change (positive and negative directions on each axis). In this example, the coil unit 15 is formed of a flexible circuit board and is arranged to surround four sides of the cell case 14 (cell 11) (sides of the cell case 14 other than the second wall portions 14d) (sides of the cell 11 other than the two sides in the extension direction of the protrusion 11b), and is pulled out to one side in the Z direction and electrically connected to the connector member 26. [Thermal Insulation Structure]

[0045] 6 to 9, the thermal insulation structure provided in the sensor module 1 will be described. In the sensor module 1, a first thermal insulation structure is provided at the contact interface S1 between the cell unit 2 (cell case 14) and the housing 3, and a second thermal insulation structure is provided at the contact interface S2 between the thermal insulation member 13 and the cell case 14. Below, the first thermal insulation structure will be described first. Note that, regarding the contact interface S1, a coil unit 15 is actually disposed between the cell case 14 and the housing 3, but in the following description, the coil unit 15 will be considered to be part of the cell case 14. In this way, the coil unit 15 can be considered to constitute part of the cell case 14.

[0046] FIG. 7 is a perspective view of the housing main body 3a, and FIG. 8 is a perspective view of the housing lid 3b. FIG. 8 shows the housing lid 3b as seen from the back side (inside). The housing 3 (housing main body 3a and housing lid 3b) is made of a material that is insulating and not magnetic (non-magnetic). The thermal conductivity of the material that makes up the housing 3 is lower than the thermal conductivity of the material that makes up the cells 11. In this example, the housing 3 is made of a resin material. Examples of resin materials that make up the housing 3 include heat-resistant resins such as PEEK (polyether ether ketone), PPS (polyphenylene sulfide), polyimide, and fluororesin.

[0047] As shown in Figure 7, the housing main body 3a has side surfaces 31 and 32, a pair of side surfaces 33 and 33, and a bottom surface 34 that define the cell unit arrangement section 3c. In this example, the cell unit 2 (cell case 14) is formed in a roughly rectangular parallelepiped shape, and the cell unit arrangement section 3c is formed in a roughly rectangular parallelepiped shape that corresponds to the outer shape of the cell unit 2. The side surfaces 31 and 32 face each other in the X direction, and the side surfaces 33 and 33 face each other in the Z direction. The side surfaces 31 and 32 are flat surfaces perpendicular to the X direction, and the side surfaces 33 and 33 are flat surfaces perpendicular to the Z direction. The bottom surface 34 is a flat surface perpendicular to the Y direction and is connected to the side surfaces 31 to 33.

[0048] 6, the side surfaces 31 to 33 form a contact interface S1 between the cell case 14 and the housing main body 3a (housing 3). Although not shown, the bottom surface 34 also forms the contact interface S1. That is, the housing main body 3a contacts the outer surface of the cell case 14 at the side surfaces 31 to 33 and the bottom surface 34. The side surfaces 31 to 33 and the bottom surface 34 are contact surfaces of the housing main body 3a with the cell case 14.

[0049] 6 and 7, uneven portions 35 are formed on the side surfaces 31 to 33 and the bottom surface 34. In this example, the uneven portions 35 include a plurality of (seven in this example) protrusions 36 formed on the side surfaces 31, 32 and the bottom surface 34, and a plurality of (two in this example) protrusions 37 formed on the side surfaces 33, 33.

[0050] Each protrusion 36 is formed across the side surface 31, the bottom surface 34, and the side surface 32. The protrusion 36 extends straight along the Y direction on the side surface 31, and is formed across the entire side surface 31 in the Y direction. The protrusion 36 extends straight along the X direction on the bottom surface 34, and is formed across the entire bottom surface 34 in the X direction. The protrusion 36 extends straight along the Y direction on the side surface 32, and is formed across the entire side surface 32 in the Y direction. Each protrusion 36 extends across the side surfaces 31, 32, and the bottom surface 34 so as to be located on the same plane perpendicular to the Z direction. The multiple protrusions 36 are arranged at equal intervals along the Z direction. As an example, the width of the protrusion 36 is 2 mm, the height is 0.2 mm, and the arrangement pitch is 2.5 mm.

[0051] Each protrusion 37 extends straight along the Y direction on the side surface 33 and is formed over the entire side surface 33 in the Y direction. In the uneven portion 35, protrusions are formed by the protrusions 36, 37, and recesses are formed by gaps (grooves) between adjacent protrusions 36, gaps (grooves) between adjacent protrusions 37, and gaps (grooves) between the protrusions 37 and the side surfaces 31, 32.

[0052] 6 , due to the formation of the uneven portion 35, the contact interface S1 between the cell case 14 and the housing main body 3a is formed with a contact portion 38 where the cell case 14 contacts the housing main body 3a and a separation portion 39 (non-contact portion) where the cell case 14 is separated from the housing main body 3a and an air layer A is formed between the cell case 14 and the housing main body 3a. The contact portion 38 and the separation portion 39 are formed by the housing main body 3a contacting the outer surface of the cell case 14 at the uneven portion 35. More specifically, the housing main body 3a contacts the outer surface of the cell case 14 at the top surfaces of the protrusions 36, 37 (contact portion 38), but does not contact the outer surface of the cell case 14 in areas (separation portion 39) where the protrusions 36, 37 are not formed. Air layer A is formed by gaps between adjacent convex portions 36, gaps between adjacent convex portions 37, and gaps between convex portion 37 and side surfaces 31, 32 (concave portions of uneven portion 35). Air layer A is formed between the bottom surfaces of the concave portions of uneven portion 35 (side surfaces 31 to 33 and bottom surface 34) and the outer surface of cell case 14. The thickness of air layer A (the length in the direction perpendicular to the bottom surfaces of the concave portions of uneven portion 35) is smaller than the thickness of heat insulating member 13 (the thickness of the entire heat insulating member 13 or the thickness of one plate-like member 13a), and is set to, for example, 1 mm or less.

[0053] 8, the housing lid 3b has a side surface 4142 that defines the cell unit arrangement area 3c, a pair of side surfaces 43, 43, and a top surface 44. The side surfaces 41, 42 face each other in the X direction, while the side surfaces 43, 43 face each other in the Z direction. The side surfaces 41, 42 are flat surfaces perpendicular to the X direction, and the side surfaces 43, 43 are flat surfaces perpendicular to the Z direction. The top surface 44 is a flat surface perpendicular to the Y direction and is connected to the side surfaces 41 to 43.

[0054] The side surfaces 41 to 43 form a contact interface S1 between the cell case 14 and the housing lid 3b (housing 3). The top surface 44 also forms the contact interface S1. That is, the housing lid 3b contacts the outer surface of the cell case 14 at the side surfaces 41 to 43 and the top surface 44. The side surfaces 41 to 43 and the top surface 44 are the contact surfaces of the housing lid 3b with the cell case 14.

[0055] 8, uneven portions 45 are formed on the side surfaces 41 to 43 and the top surface 44. In this example, the uneven portions 45 have a plurality of (seven in this example) protrusions 46 formed on the side surfaces 41, 42 and the top surface 44, and a plurality of (two in this example) protrusions 47 formed on the side surfaces 43, 43.

[0056] Each protrusion 46 is formed across the side surface 41, the top surface 44, and the side surface 42. The protrusion 46 extends straight along the Y direction on the side surface 41, and is formed across the entire side surface 41 in the Y direction. The protrusion 46 extends straight along the X direction on the top surface 44, and is formed across the entire top surface 44 in the X direction. The protrusion 46 extends straight along the Y direction on the side surface 42, and is formed across the entire side surface 42 in the Y direction. Each protrusion 46 extends across the side surfaces 41, 42, and the top surface 44 so as to be located on the same plane perpendicular to the Z direction. The multiple protrusions 46 are arranged at equal intervals along the Z direction. When the housing cover 3b is combined with the housing main body 3a to form the housing 3, the multiple protrusions 46 are each continuous with the multiple protrusions 36, forming a continuous protrusion. Each of these continuous protrusions is located on the same plane perpendicular to the Z direction.

[0057] The convex portion 47 extends straight along the Y direction on the side surface 43 and is formed over the entire side surface 43 in the Y direction. In the uneven portion 45, convex portions are formed by the convex portions 46 and 47, and concave portions are formed by the gaps (grooves) between adjacent convex portions 46 and the gaps (grooves) between the convex portions 47 and the side surfaces 41 and 42.

[0058] As with the uneven portion 35, the uneven portion 45 forms a contact portion 38 where the cell case 14 contacts the housing lid portion 3b, and a separation portion 39 where the cell case 14 is separated from the housing lid portion 3b, forming an air layer A between the cell case 14 and the housing lid portion 3b, at the contact interface S1 between the cell case 14 and the housing lid portion 3b. The contact portion 38 and the separation portion 39 are formed by the housing lid portion 3b contacting the outer surface of the cell case 14 at the uneven portion 45. More specifically, the housing lid portion 3b contacts the outer surface of the cell case 14 at the top surfaces of the protrusions 46, 47 (contact portion 38), but does not contact the outer surface of the cell case 14 in areas (separation portion 39) where the protrusions 46, 47 are not formed.

[0059] Over the entire contact interface S1, the area of ​​the separation portions 39 is larger than the area of ​​the contact portions 38, and the ratio of the area of ​​the separation portions 39 to the area of ​​the contact portions 38 is 9 or more. That is, the area of ​​the separation portions 39 is 9 times or more the area of ​​the contact portions 38. Also, on each of the side surfaces 31 to 33, the bottom surface 34, the side surfaces 41 to 43, and the top surface 44, the ratio of the area of ​​the separation portions 39 to the area of ​​the contact portions 38 is 9 or more.

[0060] Next, a second heat insulating structure provided at the contact interface S2 between the heat insulating member 13 and the cell case 14 will be described. The cell case 14 (case body 14a and case lid 14b) is made of a material that is insulating and not magnetic (non-magnetic). The thermal conductivity of the material that makes up the cell case 14 is lower than the thermal conductivity of the material that makes up the cell 11. In this example, the cell case 14 is made of the same resin material as the housing 3.

[0061] As shown in FIG. 9 , the case body 14a has a pair of side surfaces 51, 51, a pair of side surfaces 52, 52, and a bottom surface 53 that define the internal space 14g of the cell case 14. The side surfaces 51, 51 are the inner surfaces of the pair of first wall portions 14c of the case body 14a, and the side surfaces 52, 52 are the inner surfaces of the pair of second wall portions 14d. The side surfaces 51, 51 face each other in the X direction, and the side surfaces 52, 52 face each other in the Z direction. The side surface 51 is a flat surface perpendicular to the X direction, and the side surface 52 is a flat surface perpendicular to the Z direction. The bottom surface 53 is a flat surface perpendicular to the Y direction and is connected to the side surfaces 51, 51, 52, 52. In this example, the internal space 14g is formed in a substantially rectangular parallelepiped shape. As described above, the cell 11, the heater 12, and the heat insulating member 13 are arranged in the internal space 14g.

[0062] 6, the side surfaces 51 and 52 form a contact interface S2 between the case body 14a (cell case 14) and the heat insulating member 13 (plate-shaped member 13a). Although not shown, the bottom surface 53 also forms the contact interface S2. That is, the case body 14a contacts the heat insulating member 13 at the side surfaces 51 and 52 and the bottom surface 53. The side surfaces 51 and 52 and the bottom surface 53 are contact surfaces of the case body 14a with the heat insulating member 13.

[0063] 6 and 9 , uneven portions 55 are formed on the side surfaces 51, 52 and the bottom surface 53. In this example, the uneven portions 55 include a plurality of (six in this example) convex portions 56 formed on the side surfaces 51 and the bottom surface 53, and a plurality of (two in this example) groove portions 57 formed on the side surfaces 52.

[0064] Each protrusion 56 is formed across the side surfaces 51, 51 and the bottom surface 53. The protrusion 56 extends straight along the Y direction on the side surface 51, and is formed across the entire side surface 51 in the Y direction. The protrusion 56 extends straight along the X direction on the bottom surface 53, and is formed across the entire bottom surface 53 in the X direction. Each protrusion 56 extends across the side surfaces 51, 51 and the bottom surface 53 so as to be located on the same plane perpendicular to the Z direction. The multiple protrusions 56 are lined up at equal intervals along the Z direction.

[0065] Two grooves 57 are formed on each of the side surfaces 52, 52. The grooves 57 extend straight along the Y direction on the side surface 52 and are formed over the entire side surface 52 in the Y direction. In the uneven portion 55, convex portions are formed by the convex portions 56, and concave portions are formed by the gaps (grooves) between adjacent convex portions 56. In addition, concave portions are formed by the grooves 57, and convex portions are formed by the portions of the side surface 52 where the grooves 57 are not formed.

[0066] 6 , the uneven portion 55 is formed, and thus the contact interface S2 between the case body 14a and the heat insulating member 13 includes a contact portion 58 (additional contact portion) where the heat insulating member 13 contacts the case body 14a, and a separation portion 59 (additional separation portion) where the heat insulating member 13 is separated from the case body 14a, forming an air layer B between the heat insulating member 13 and the case body 14a. The contact portion 58 and the separation portion 59 are formed by the case body 14a contacting the heat insulating member 13 at the uneven portion 55. More specifically, the case body 14a contacts the heat insulating member 13 at the top surfaces of the convex portions 56 (contact portions 58) and at the portions of the side surfaces 52 where the groove portions 57 are not formed (contact portions 58), while the side surfaces 51 and the bottom surface 53 where the convex portions 56 are not formed (separation portions 59) and the groove portions 57 (separation portions 59) do not contact the heat insulating member 13. The air layer B is formed by the gaps between adjacent convex portions 56 and the grooves 57 (recesses of the uneven portion 35). The air layer B is formed between the bottom surfaces (side surfaces 51, 52 and bottom surface 53) of the recesses of the uneven portion 55 and the heat insulating member 13. The thickness of the air layer B (the length in the direction perpendicular to the bottom surfaces of the recesses of the uneven portion 55) is smaller than the thickness of the heat insulating member 13 (the thickness of the entire heat insulating member 13 or the thickness of one plate-like member 13a), and is set to, for example, 1 mm or less.

[0067] The case lid 14b is formed in a flat plate shape and has a surface (top surface) (not shown) that defines the internal space 14g. This surface is, for example, a flat surface that faces the bottom surface 53 of the case body 14a in the Y direction. This surface is the contact surface of the case lid 14b with the heat insulating member 13 and constitutes the contact interface S2. A plurality of protrusions having a configuration similar to that of the protrusion 56 are formed on this surface, and these protrusions form an uneven portion. As with the uneven portion 55, the formation of the uneven portion forms a contact portion 58 (additional contact portion) where the heat insulating member 13 contacts the case lid 14b, and a separation portion 59 (additional separation portion) where the heat insulating member 13 is separated from the case lid 14b, forming an air layer B between the heat insulating member 13 and the case lid 14b.

[0068] Throughout the entire contact interface S2, the area of ​​the separation portions 59 is larger than the area of ​​the contact portions 58, and the ratio of the area of ​​the separation portions 59 to the area of ​​the contact portions 58 is 9 or more. That is, the area of ​​the separation portions 59 is 9 times or more the area of ​​the contact portions 58. Also, on each of the above-mentioned surfaces of the side surfaces 51, 52, the bottom surface 53, and the case lid 14b, the ratio of the area of ​​the separation portions 59 to the area of ​​the contact portions 58 is 9 or more.

[0069] 10 and 11 are diagrams showing simulation results for an example and a comparative example. The example shown in FIG. 10 corresponds to a sensor module 1 provided with the first and second heat insulating structures described above. The comparative example shown in FIG. 11 corresponds to a case where the first and second heat insulating structures are not provided in the sensor module 1, and the inner surfaces of the housing 3 and the cell case 14 are formed flat. In the example and comparative example, the cell 11 was heated by the heater 12 so that the temperature inside the cell 11 was uniform (so that the temperature inside the cell 11 reached a predetermined target temperature). The heat convection in the air was set to 7 W / (m ２ ・K).

[0070] In the example, the power consumption of the heater 12 was 0.14 W. The surface temperature of the cell 11 was 151.0°C, and the surface temperature of the sensor module 1 (surface temperature of the outer cover 4) was 31.6°C. In the comparative example, the power consumption of the heater 12 was 0.225 W. The surface temperature of the cell 11 was 151.2°C, and the surface temperature of the outer cover was 37.0°C. From these results, it can be seen that the surface temperature of the sensor module 1 was reduced by 5.4°C in the example compared to the comparative example. It can also be seen that the power consumption of the heater 12 was reduced by 0.085 W (37%) in the example compared to the comparative example. [Actions and Effects]

[0071] In the sensor module 1, the contact interface S1 between the cell unit 2 and the housing 3 includes a contact portion 38 where the cell unit 2 contacts the housing 3 and a separation portion 39 where the cell unit 2 is separated from the housing 3, forming an air layer A between the cell unit 2 and the housing 3. This reduces the contact area (heat conduction area) between the cell unit 2 and the housing 3, suppressing heat conduction and improving thermal insulation performance. As a result, heat is less likely to escape from the cell 11, reducing the power consumption of the heater 12 when heating to a target temperature. Furthermore, heat from the cell 11 is less likely to be transmitted to the outer surface of the sensor module 1 (the outer surface of the outer cover 4), reducing the temperature at the outer surface of the sensor module 1 when the cell 11 is heated to the target temperature. Therefore, the sensor module 1 can reduce power consumption and the temperature at the outer surface.

[0072] The cell unit 2 has a cell case 14 that houses the cells 11, heater 12, and heat insulating member 13, and the contact interface S1 between the cell case 14 and the housing 3 is formed with a contact portion 38 where the cell case 14 contacts the housing 3, and a separation portion 39 where the cell case 14 is separated from the housing 3 to form an air layer A between the cell case 14 and the housing 3. As a result, since the cell unit 2 has the cell case 14, it is possible to facilitate the arrangement of the heat insulating member 13, etc.

[0073] At the contact interface S2 between the heat insulating member 13 and the cell case 14, there are formed a contact portion 58 (additional contact portion) where the heat insulating member 13 contacts the cell case 14, and a separation portion 59 (additional separation portion) where the heat insulating member 13 is separated from the cell case 14 to form an air layer B between the heat insulating member 13 and the cell case 14. This makes it possible to suppress heat conduction not only at the contact interface S1 between the cell case 14 and the housing 3, but also at the contact interface S2 between the heat insulating member 13 and the cell case 14, thereby further improving the heat insulating performance.

[0074] Concave and convex portions 35 are formed on the side surfaces 31 to 33 and bottom surface 34 (contact surfaces of the housing 3 with the cell unit 2), and convex and concave portions 45 are formed on the side surfaces 41 to 43 and top surface 44 (contact surfaces of the housing 3 with the cell unit 2), and the housing lid 3b comes into contact with the cell unit 2 at the concave and convex portions 35, 45, thereby forming contact portions 38 and separation portions 39. As a result, the convex and convex portions 35, 45 formed on the housing 3 can form the contact portions 38 and separation portions 39.

[0075] Uneven portions 55 are formed on the side surfaces 51, 52 and bottom surface 53 (contact surfaces of the cell case 14 with the insulating member 13) of the case main body 14a, and the cell case 14 comes into contact with the insulating member 13 at the uneven portions 55, thereby forming contact portions 58 and separation portions 59. In addition, uneven portions 55 are formed on the surface of the case lid 14b, and the cell case 14 comes into contact with the insulating member 13 at the uneven portions, thereby forming the contact portions 58 and separation portions 59. As a result, the contact portions 58 and separation portions 59 can be formed by the uneven portions 55 formed on the cell case 14.

[0076] At the contact interface S1, the ratio of the area of ​​the separation portion 39 to the area of ​​the contact portion 38 is equal to or greater than 9. At the contact interface S2, the ratio of the area of ​​the separation portion 59 to the area of ​​the contact portion 58 is equal to or greater than 9. This allows the proportion of the separation portions 39, 59 to be increased, and the heat insulating performance to be effectively improved.

[0077] The thickness of the air layer A and the thickness of the air layer B are 1 mm or less, which can prevent air convection from occurring and increase the thermal conductivity in the air layers A and B, thereby effectively improving the heat insulating performance.

[0078] The contact portion 38 (protrusions 36, 37, 46, 47) and the contact portion 58 (protrusion 56) are formed to extend straight. This increases the proportion of the separation portions 39, 59, and effectively improves the heat insulating performance. [Modification]

[0079] In the above embodiment, the sensor module 1 is configured as a one-laser system in which the laser light L serves as both the pump light and the probe light. However, as in a first modified example shown in FIG. 12 , the sensor module 1 may be configured as a two-laser system in which the pump light L1 and the probe light L2 are independent. The sensor module 1 of the first modified example includes, instead of the light source 21, a light source 21A that outputs linearly polarized pump light L1 and a light source 21B that outputs circularly polarized probe light L2. Furthermore, in the sensor module 1 of the first modified example, the photodetector 25 is configured as a differential detector including a first photodetector 25A and a second photodetector 25B. In the two-laser system, for example, the probe light L2 passes through the cell 11 along the X direction, and the pump light L1 passes through the cell 11 along the Y direction perpendicular to the X direction.

[0080] In the sensor module 1 of the first modification, the alkali metal vapor in the cell 11 is optically pumped by the pump light L1 output from the light source 21A to become spin-polarized. The probe light L2 output from the light source 21B and passing through the cell 11 is detected by the photodetector 25. Here, the spin-polarized state of the alkali metal vapor in the cell 11 changes due to the influence of the magnetic field of the object to be measured, so the polarization direction of the probe light L2 passing through the alkali metal vapor is changed to be tilted. The first photodetector 25A detects the light intensity of the polarization direction component corresponding to the polarization direction of the probe light L2 before the polarization direction change, and the second photodetector 25B detects the light intensity of the polarization direction component corresponding to the polarization direction of the probe light L2 after the polarization direction change. This detects the difference in light intensity between the two polarization direction components of the probe light L2. Based on this difference, the spin-polarized state of the alkali metal vapor in the cell 11 can be detected, and thus changes in the magnetic field of the object to be measured can be detected.

[0081] In the second modified example shown in FIG. 13 , the cell unit 2 does not have a cell case 14, and is disposed within the housing 3 so that the insulating member 13 directly contacts the housing 3. That is, the cell unit 2 includes a cell 11, a heater 12, and an insulating member 13, and is at least partially surrounded by a coil unit 15 (not shown). In the second modified example, the contact interface S1 is the contact interface between the insulating member 13 and the housing 3. The contact interface S2 does not exist. The contact interface S1 includes a contact portion 38 where the insulating member 13 contacts the housing 3 (the housing body portion 3 a and the housing lid portion 3 b), and a separation portion 39 where the insulating member 13 is separated from the housing 3, forming an air layer A between the insulating member 13 and the housing 3. In the second modified example, as in the above embodiment, the housing 3 has uneven portions 35 and 45, and the housing 3 contacts the cell unit 2 at the uneven portions 35 and 45, thereby forming the contact portion 38 and the separation portion 39. In the second modified example, similarly to the above embodiment, it is possible to reduce power consumption and also to lower the temperature on the outer surface of the sensor module 1 .

[0082] The arrangement of the contact portions 38, 58 and the separation portions 39, 59 constituting the first and second thermal insulation structures is not limited to the above-described example. The following describes an example of the contact portion 38 consisting of the protrusion 36 formed on the side surface 31, but the other contact portions 38, 58 may be configured in a similar manner. In Figures 14(a) to 14(d), the contact portion 38 is indicated by hatching. In the above embodiment, the contact portion 38 is composed of multiple linearly extending portions as shown in Figure 14(a). However, the contact portion 38 may be formed in a lattice pattern as shown in Figure 14(b). The arrangements shown in Figures 14(a) and 14(b) allow for a larger proportion of the separation portions 39, effectively improving thermal insulation performance. Furthermore, the contact portions 38 and the separation portions 39 can be easily formed flat (making it easier to align the height of the protrusions 36), facilitating the placement of the cell unit 2 relative to the housing 3. Furthermore, even when the contact portion 38 is in contact with a flexible member, the air layer A is easily formed.

[0083] The contact portion 38 may be formed of a plurality of dot-shaped portions as shown in FIG. 14( c). The arrangement of FIG. 14( c) allows for a larger proportion of the separation portions 39, effectively improving the heat insulating performance. Furthermore, the contact portion 38 and the separation portions 39 can be easily formed in a planar shape. As shown in FIG. 14( d) , the contact portion 38 and the separation portions 39 may be formed by arranging a plurality of separation portions 39 having the same shape along two mutually perpendicular directions. In FIG. 14( d) , circular separation portions 39 are arranged along two directions (e.g., the X direction and the Z direction). In FIG. 14( d) , the arrangement of the contact portion 38 and the separation portions 39 may be interchanged. That is, the contact portion 38 and the separation portions 39 may be formed by arranging a plurality of contact portions 38 having the same shape along two mutually perpendicular directions. The arrangement of FIG. 14( d) allows for a more easily formed contact portion 38 and separation portions 39 in a planar shape.

[0084] As another modification, the contact portion 38 and the separation portion 39 may be formed by roughening the contact surface of the housing 3 with the cell unit 2. For example, the contact surface may be textured or blasted to form uneven portions on the housing 3. Alternatively, the contact portion 38 and the separation portion 39 may be formed by roughening the contact surface of the cell unit 2 with the housing 3 (for example, the outer surface of the cell case 14). In this case, the proportion of the separation portion 39 can be increased, and the heat insulating performance can be effectively improved.

[0085] The present disclosure is not limited to the above-described embodiments and modifications. For example, the materials and shapes of the components are not limited to those described above, and various materials and shapes can be adopted.

[0086] In the above embodiment, the contact portion 38 and the separation portion 39 are formed at the contact interface S1 by forming the uneven portions 35, 45 on the housing 3. However, the contact portion 38 and the separation portion 39 may be formed at the contact interface S1 by forming uneven portions on the outer surface of the cell case 14. Alternatively, the contact portion 38 and the separation portion 39 may be formed by disposing a sheet member or a seal member having a shape corresponding to the contact portion 38 and the separation portion 39 between the housing 3 and the cell case 14 (cell unit 2). As such a sheet member, for example, a sheet member having openings formed in an arrangement pattern corresponding to the separation portion 39 of the above embodiment may be used. Alternatively, a sheet member having openings formed in an arrangement pattern corresponding to any of the separation portions 39 shown in Figures 14(a) to 14(d) may be used. Similarly, for the contact interface S2, the contact portion 58 and the separation portion 59 may be formed by disposing a sheet member or a seal member having a shape corresponding to the contact portion 58 and the separation portion 59 between the cell unit 2 and the heat insulating member 13. In this way, the contact portion 38 and the separation portion 39 may be configured by a sheet member having openings formed in a predetermined arrangement pattern, which is disposed between the cell unit 2 and the housing 3. Also, the heat insulating member 13 may be disposed so as to cover the outer peripheral surface of the cell case 14, rather than being disposed within the cell case 14. In this case, it can be said that the cell case 14 is disposed between the cell 11 and the heat insulating member 13 in the second modified example shown in FIG.

[0087] In the above embodiment, the second heat dissipation structure (contact portion 58 and separation portion 59) may not be provided. That is, the cell case 14 may not have the uneven portion 55 formed thereon, and the inner surface of the cell case 14 may be formed flat. In the above embodiment, the first heat dissipation structure (contact portion 38 and separation portion 39) may not be provided. In this case, the cell 11, heater 12, and heat insulating member 13 may be considered to constitute a "cell unit," and the cell case 14 may be considered to constitute a "casing that houses the cell unit," and the contact portion 58 and separation portion 59 may be considered to be formed at the contact interface between the cell unit (heat insulating member 13) and the casing (cell case 14).

[0088] The width, height, and arrangement pitch of the protrusions 36, 37, 46, 47, 56 and the grooves 57 may be changed as appropriate. Instead of forming a protrusion (e.g., protrusion 36) on the housing 3, a recess (e.g., a slit or groove) may be formed on the housing 3 to form the contact portion 38 and the separation portion 39. Instead of forming a protrusion (e.g., protrusion 56) on the cell case 14, a recess (e.g., a slit or groove) may be formed on the cell case 14 to form the contact portion 58 and the separation portion 59. At the contact interface S1, the ratio of the area of ​​the separation portion 39 to the area of ​​the contact portion 38 may be less than 9. At the contact interface S2, the ratio of the area of ​​the separation portion 59 to the area of ​​the contact portion 58 may be less than 9. The thicknesses of the air layers A and B may be greater than 1 mm.

[0089] 1...optically excited magnetic sensor module, 2...cell unit, 3...housing, 11...cell, 12...heater, 13...insulating member, 14...cell case, 35, 45, 55...uneven portion, 38...contact portion, 39...separation portion, 58...contact portion (additional contact portion), 59...separation portion (additional separation portion), A, B...air layer, S1, S2...contact interface.

Claims

1. An optically excited magnetic sensor module comprising: a cell unit; and a housing that houses the cell unit, wherein the cell unit has a cell in which an alkali metal is sealed, a heater that heats the cell, and an insulating member that is arranged outside the cell, and the contact interface between the cell unit and the housing is formed with a contact portion where the cell unit contacts the housing and a separation portion where the cell unit is separated from the housing to form an air layer between the cell unit and the housing.

2. An optically excited magnetic sensor module according to claim 1, wherein the thermal conductivity of the material that constitutes the housing is lower than the thermal conductivity of the material that constitutes the cell.

3. An optically excited magnetic sensor module as described in claim 1 or 2, wherein the cell unit further has a cell case that houses the cell, the heater, and the insulating member, and the contact interface between the cell case and the housing is formed with the contact portion where the cell case contacts the housing and the separation portion where the cell case is separated from the housing to form an air layer between the cell case and the housing.

4. An optically excited magnetic sensor module according to claim 3, wherein the thermal conductivity of the material constituting the cell case is lower than the thermal conductivity of the material constituting the cell.

5. An optically excited magnetic sensor module as described in claim 3 or 4, wherein the contact interface between the insulating member and the cell case is formed with an additional contact portion where the insulating member contacts the cell case, and an additional separation portion where the insulating member is separated from the cell case to form an air layer between the insulating member and the cell case.

6. An optically excited magnetic sensor module as described in claim 1, wherein the cell unit is arranged within the housing so that the insulating member is in direct contact with the housing, and the contact interface between the insulating member and the housing is formed with the contact portion where the insulating member contacts the housing and the separation portion where the insulating member is separated from the housing to form an air layer between the insulating member and the housing.

7. An optically excited magnetic sensor module as described in any one of claims 1 to 5, wherein an uneven portion is formed on the contact surface of the housing with the cell unit, and the housing comes into contact with the cell unit at the uneven portion, thereby forming the contact portion and the separation portion.

8. An optically excited magnetic sensor module as described in claim 5, wherein an uneven portion is formed on the contact surface of the cell case with the insulating member, and the additional contact portion and the additional separation portion are formed by the cell case contacting the insulating member at the uneven portion.

9. An optically excited magnetic sensor module according to any one of claims 1 to 8, wherein the area of ​​the separation portion is larger than the area of ​​the contact portion.

10. The optically excited magnetic sensor module according to claim 9, wherein the ratio of the area of ​​the separation portion to the area of ​​the contact portion is 9 or more.

11. An optically excited magnetic sensor module according to any one of claims 1 to 10, wherein the thickness of the air layer is smaller than the thickness of the heat insulating member.

12. The optically excited magnetic sensor module according to claim 11, wherein the thickness of the air layer is 1 mm or less.

13. An optically excited magnetic sensor module according to any one of claims 1 to 12, wherein the contact portion is formed to extend straight.

14. An optically excited magnetic sensor module according to any one of claims 1 to 12, wherein the contact portion is formed in a lattice pattern.

15. An optically excited magnetic sensor module according to any one of claims 1 to 12, wherein the contact portion is formed in a dot shape.

16. An optically excited magnetic sensor module according to any one of claims 1 to 12, wherein the contact portions and the separation portions are configured by arranging a plurality of the contact portions or separation portions having the same shape along two mutually perpendicular directions.

17. An optically excited magnetic sensor module described in any one of claims 1 to 12, wherein the contact portion and the separation portion are formed by roughening the contact surface of the housing with the cell unit or the contact surface of the cell unit with the housing.

18. An optically excited magnetic sensor module as described in any one of claims 1 to 16, wherein the contact portion and the separation portion are formed by a sheet member having openings formed in a predetermined arrangement pattern, which is placed between the cell unit and the housing.

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