JP2019092023A - Atomic oscillator, signal generation system, and electronic apparatus - Google Patents

Abstract

An atomic oscillator capable of reducing a temperature gradient around a gas cell is provided. In addition, a signal generation system and an electronic device including the atomic oscillator are provided. An atomic oscillator includes an atomic cell in which alkali metal atoms are enclosed, a light source that emits light that excites alkali metal atoms, and a light detection element that detects light transmitted through the atomic cell. The wiring 510 connected to the light detection element, the heater 203 for heating the atomic cell, and the light detection element 202 are arranged on the opposite side of the atomic cell, and are thermally connected to the heater 203 and the wiring 510. A heat transfer member 210. [Selection] Figure 3

Description

  The present invention relates to an atomic oscillator, a signal generation system, and an electronic device.

  In an atomic oscillator that oscillates based on energy transition of alkali metal atoms such as rubidium and cesium, generally, alkali metal atoms are enclosed in a gas cell, and the alkali metal atoms are maintained in a predetermined gas state, The gas cell is heated by the heater.

  For example, in the atomic oscillator described in Patent Document 1, the gas cell holding member holding the gas cell heats the gas cell by transferring the heat from the heater to the gas cell. Further, a light detection unit for detecting light transmitted through the gas cell is joined to the gas cell holding member via an adhesive.

JP, 2017-112515, A

  Although not described in Patent Document 1, in general, a wire extracted to the outside is connected to the light detection unit. In the atomic oscillator described in Patent Document 1, heat from the heater may move through the wiring. Patent Document 1 does not disclose heat transfer through the wiring. In the conventional configuration, the movement of heat through the wiring may cause an unintended temperature gradient around the gas cell.

  An object of the present invention is to provide an atomic oscillator capable of reducing a temperature gradient around a gas cell, and also to provide a signal generation system and electronic equipment provided with the atomic oscillator.

  The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as the following applications or embodiments.

  The atomic oscillator of this application example includes an atomic cell in which an alkali metal atom is enclosed, a light source for emitting light for exciting the alkali metal atom, and a light detection element for detecting the light transmitted through the atom cell. A wire connected to the light detection element, a heater for heating the atom cell, and an opposite side to the atom cell with respect to the light detection element, and thermally connected to the heater and the wiring And a heat transfer member.

  According to such an atomic oscillator, since the heat transfer member thermally connected to the heater and the wiring is disposed on the opposite side to the atomic cell with respect to the light detection element, the heater via the heat transfer member is The temperature of the light detection element or the wiring can be suitably adjusted (heated) similarly to the atomic cell by the heat from. Therefore, the atomic cell is not easily affected by the external temperature due to the heat transfer through the wiring, and the temperature gradient around the atomic cell can be reduced.

In the present specification, “thermally connected” means that, among the following conditions a, b and c, the condition a or the condition b is satisfied and the condition c is satisfied. Condition a: Two members are in physical contact directly or through other members. Condition b: Two members are disposed directly or through other members, and a gap between these members (between the two members or one of the two members and the other member Gap) is 50 μm or less. Condition c: When another member is interposed between two members, the thermal conductivity of the constituent material of the other member is 10 W · m ⁻¹ · K ⁻¹ or more. The gap is a portion having a thermal conductivity of less than 10 W · m ⁻¹ · K ⁻¹ , and the portion may have an adhesive or the like or may be a space (air layer).

  In the atomic oscillator of this application example, it is preferable that the holding member holding the atomic cell is provided, and the heater be thermally connected to the atomic cell and the heat transfer member through the holding member. .

  Thereby, the number of heaters can be reduced, and the degree of freedom in design regarding the installation of the heaters can be increased.

  In the atomic oscillator of this application example, it is preferable that the thermal conductivity of the holding member is higher than the thermal conductivity of the atomic cell, and the heat transfer member is fixed to the holding member.

  Thereby, the heat from the heater can be efficiently conducted to the atom cell and the heat transfer member through the holding member.

  In the atomic oscillator of this application example, the light detection element is disposed, and the heat transfer member includes the wiring substrate provided with the wiring, and the heat transfer member biases the wiring substrate toward the holding member. Is preferred.

  Thus, the wiring substrate can be brought into close contact with the holding member and the heat transfer member, and heat conduction between these can be stably performed.

  In the atomic oscillator of this application example, it is preferable to include a temperature sensor disposed on the wiring substrate.

  Since the temperature difference between the atom cell and the wiring substrate is reduced by the heat transfer member, the temperature of the atom cell can be detected with high accuracy by using the temperature sensor disposed on the wiring substrate. Thereby, the frequency characteristic of the atomic oscillator can be improved.

  In the atomic oscillator of this application example, the wiring substrate is preferably a flexible wiring substrate.

  As a result, the heat capacity of the wiring board can be reduced, and conduction of heat from the heat transfer member to the wiring can be efficiently performed.

In the atomic oscillator of this application example, the container includes a container which is thermally connected to the heater and the wiring, and accommodates the atomic cell and the light detection element, and the container is the atom relative to the light detection element. It is preferable to include the part arrange | positioned on the opposite side to a cell.
This can further reduce the temperature gradient around the atom cell.

In the atomic oscillator of this application example, the thermal conductivity of the constituent material of the heat transfer member is preferably 10 W · m ⁻¹ · K ⁻¹ or more.
Thereby, the heat detection member can heat the light detection element vicinity part of wiring suitably.

  The signal generation system of this application example includes the atomic oscillator of this application example, and a processing unit that processes a signal from the atomic oscillator.

  According to such a signal generation system, the characteristics of the signal generation system can be improved by reducing the temperature gradient around the atomic cell of the atomic oscillator.

The electronic device of this application example includes the atomic oscillator of this application example.
According to such an electronic device, the characteristics of the electronic device can be improved by reducing the temperature gradient around the atomic cell of the atomic oscillator.

It is a schematic diagram showing an atomic oscillator concerning an embodiment. FIG. 3 is a cross-sectional side view (cross-sectional view along the XZ plane) of the atomic oscillator according to the embodiment. It is a top view (cross section along an XZ plane) of an atomic oscillator concerning an embodiment. It is sectional drawing along XY plane of the atomic cell unit with which the atomic oscillator which concerns on embodiment is equipped. It is sectional drawing along XZ plane of the atomic cell unit with which the atomic oscillator which concerns on embodiment is equipped. It is a perspective view which shows the fixed state of the heat-transfer member with which the atomic oscillator which concerns on embodiment is equipped. It is a figure which shows schematic structure of the positioning system (an example of a signal generation system) using GPS (Global Positioning System) satellite.

  Hereinafter, an atomic oscillator, a signal generation system, and an electronic apparatus according to the present invention will be described in detail based on embodiments shown in the attached drawings.

1. Atomic Oscillator FIG. 1 is a schematic view showing an atomic oscillator according to an embodiment.

  The atomic oscillator 1 shown in FIG. 1 is a quantum that causes a phenomenon in which, when two resonance lights of a specific different wavelength are simultaneously irradiated to an alkali metal atom, the two resonance lights are transmitted without being absorbed by the alkali metal atoms. It is an atomic oscillator that uses the interference effect. The phenomenon due to the quantum interference effect is referred to as a CPT (Coherent Population Trapping) phenomenon or an Electromagnetically Induced Transparency (EIT) phenomenon.

  As shown in FIG. 1, the atomic oscillator 1 includes a light emitting element module 10, an atomic cell unit 20, an optical system unit 30 provided between the light emitting element module 10 and the atomic cell unit 20, and a light emitting element And a control unit 50 that controls the operation of the module 10 and the atomic cell unit 20. Hereinafter, an outline of the atomic oscillator 1 will be described first.

  The light emitting element module 10 includes a Peltier element 101, a light emitting element 102 (light source unit), and a temperature sensor 103. The light emitting element 102 emits linearly polarized light LL including two types of light having different frequencies. Further, the temperature sensor 103 detects the temperature of the light emitting element 102. Further, the Peltier element 101 adjusts the temperature of the light emitting element 102 (warms or cools the light emitting element 102).

  The optical system unit 30 includes a light reduction filter 301, a condenser lens 302 (lens), and a 1⁄4 wavelength plate 303, which are aligned along the optical axis a of the light LL. The light reduction filter 301 reduces the intensity of the light LL from the light emitting element 102 described above. Further, the condenser lens 302 adjusts the radiation angle of the light LL (for example, the light LL approaches parallel light). In addition, the 1⁄4 wavelength plate 303 converts two types of light having different frequencies included in the light LL from linearly polarized light to circularly polarized light (right circularly polarized light or left circularly polarized light).

  The atomic cell unit 20 includes an atomic cell 201, a light receiving element 202 (light receiving unit), a heater 203, a temperature sensor 204, and a coil 205.

  The atom cell 201 is transparent to light LL, and an alkali metal is enclosed in the atom cell 201. The alkali metal atom has an energy level of a three-level system composed of two ground levels and excitation levels different from each other. The light LL from the light emitting element 102 is incident on the atom cell 201 through the light reducing filter 301, the condenser lens 302 and the 1⁄4 wavelength plate 303. Then, the light receiving element 202 receives the light LL that has passed through the atom cell 201, and outputs a signal according to the received light intensity.

  The heater 203 heats the alkali metal in the atomic cell 201 to bring at least a part of the alkali metal into a gas state of a desired concentration. Further, the temperature sensor 204 detects the temperature of the atomic cell 201. The coil 205 applies a magnetic field in a predetermined direction to the alkali metal in the atomic cell 201 to cause Zeeman splitting of the energy level of the alkali metal atom. Thus, in the state where the alkali metal atom is Zeeman-split, when the alkali metal atom is irradiated with the resonance light pair of circular polarization as described above, the desired energy among a plurality of levels in which the alkali metal atom is Zeeman-split is desired. The number of alkali metal atoms in the level can be made relatively larger than the number of alkali metal atoms in other energy levels. Therefore, the number of atoms expressing a desired EIT phenomenon increases, and a desired EIT signal (a signal appearing in the output signal of the light receiving element 202 along with the EIT phenomenon) becomes large. As a result, the oscillation characteristics of the atomic oscillator 1 (particularly, Short-term frequency stability can be improved.

  The control unit 50 includes a temperature control unit 501, a light source control unit 502, a magnetic field control unit 503, and a temperature control unit 504. The temperature control unit 501 controls the energization of the heater 203 based on the detection result of the temperature sensor 204 so that the temperature in the atomic cell 201 becomes a desired temperature. Further, the magnetic field control unit 503 controls the energization of the coil 205 so that the magnetic field generated by the coil 205 becomes constant. Further, based on the detection result of the temperature sensor 103, the temperature control unit 504 controls the energization of the Peltier element 101 so that the temperature of the light emitting element 102 becomes a desired temperature (within the temperature range).

  The light source control unit 502 controls the frequencies of the two types of light included in the light LL from the light emitting element 102 based on the detection result of the light receiving element 202 so that the EIT phenomenon occurs. Here, when these two types of light become a resonant light pair of a frequency difference corresponding to an energy difference between two ground levels of alkali metal atoms in the atomic cell 201, an EIT phenomenon occurs. The light source control unit 502 also includes a voltage controlled crystal oscillator (not shown) whose oscillation frequency is controlled to be stabilized in synchronization with the control of the two types of light frequencies described above. An output signal of a controlled oscillator (VCO: Voltage controlled Oscillator) is output as an output signal (clock signal) of the atomic oscillator 1.

  The outline of the atomic oscillator 1 has been described above. Hereinafter, a more specific configuration of the atomic oscillator 1 will be described based on FIGS. 2 to 6.

  FIG. 2 is a cross-sectional side view (cross-sectional view along the XZ plane) of the atomic oscillator according to the embodiment. FIG. 3 is a plan view (cross-sectional view along the XZ plane) of the atomic oscillator according to the embodiment. FIG. 4 is a cross-sectional view along an XY plane of an atomic cell unit provided in the atomic oscillator according to the embodiment. FIG. 5 is a cross-sectional view along an XZ plane of an atomic cell unit provided in the atomic oscillator according to the embodiment. FIG. 6 is a perspective view showing a fixed state of the heat transfer member provided in the atomic oscillator according to the embodiment.

  In the following, for convenience of explanation, the description will be made using the X axis, the Y axis, and the Z axis which are three axes orthogonal to each other. In the present specification, the Z axis is an axis perpendicular to the mounting surface 42 of the support member 40 described later. The X axis is an axis along the light LL emitted from the light emitting element module 10. In other words, the X axis is an axis along the arrangement direction of the light emitting element module 10 and the atomic cell unit 20. The Y axis is an axis perpendicular to the X axis and the Z axis.

  As shown in FIG. 2, the atomic oscillator 1 collectively includes a light emitting element module 10, an atomic cell unit 20, an optical system unit 30 holding the light emitting element module 10, an atomic cell unit 20 and an optical system unit 30. And a control unit 50 which is electrically connected to the light emitting element module 10 and the atomic cell unit 20, and a package 60 which accommodates them.

(Light emitting element module)
The light emitting element module 10 includes a Peltier element 101, a light emitting element 102, a temperature sensor 103, and a package 104 that accommodates these.

  Although not shown, the package 104 has a base and a lid joined to each other, and an airtight space is formed between these to accommodate the Peltier element 101, the light emitting element 102 and the temperature sensor 103. The inside of such a package 104 is preferably in a reduced pressure (vacuum) state. Thereby, the influence of the temperature change outside the package 104 on the light emitting element 102 and the temperature sensor 103 in the package 104 is reduced, and the temperature fluctuation of the light emitting element 102 and the temperature sensor 103 in the package 104 is reduced. it can. The inside of the package 104 does not have to be in a reduced pressure state, and an inert gas such as nitrogen, helium or argon may be sealed.

  Here, the base is made of, for example, an insulating ceramic material. Further, on the inner surface of the base, a plurality of connection electrodes electrically connected to Peltier element 101, light emitting element 102 and temperature sensor 103 are provided, and these connection electrodes respectively penetrate through the base The electrodes are electrically connected to external mounting electrodes provided on the outer surface of the base via the electrodes. On the other hand, the lid is made of, for example, a ceramic and a metallic material such as Kovar which has a linear expansion coefficient close to that of the ceramic. The lid is joined to the base by seam welding, for example. Further, the lid is provided with a hole through which the light LL from the light emitting element 102 is transmitted, and this hole is airtightly closed by a light transmitting plate-like member such as a glass material. Although not shown, a Peltier device 101 is fixed to the inner surface of the base of such a package 104 by an adhesive.

  The Peltier element 101 can switch between a state in which the light emitting element 102 is on the heat generation side and a state in which the light emitting element 102 is on the heat absorption side according to the direction of the supplied current. Therefore, even if the range of the environmental temperature is wide, the temperature of the light-emitting element 102 and the like can be adjusted to a desired temperature (target temperature). Thereby, an adverse effect (for example, wavelength fluctuation of light LL) due to temperature change can be further reduced. Here, the target temperature of the light emitting element 102 is determined according to the characteristics of the light emitting element 102, and is not particularly limited, and is, for example, about 30 ° C. or more and 40 ° C. or less. A light emitting element 102 and a temperature sensor 103 are provided on such a Peltier element 101.

  The light emitting element 102 is, for example, a semiconductor laser such as a vertical cavity surface emitting laser (VCSEL). The semiconductor laser can emit two types of light having different wavelengths by superimposing (modulating) a high frequency signal on a DC bias current. In the present embodiment, the light emitted from the light emitting element 102 is linearly polarized. Further, the temperature sensor 103 is, for example, a temperature detection element such as a thermistor or a thermocouple.

(Optical system unit)
As shown in FIG. 2, the optical system unit 30 includes a light reduction filter 301, a condensing lens 302, a quarter wavelength plate 303, and a holder 304 for holding these. Here, the holder 304 has a through hole 305 which is open at both ends. The through hole 305 is a passage area of the light LL, and in the through hole 305, the light reducing filter 301, the condenser lens 302 and the quarter wavelength plate 303 are arranged along the optical axis a of the light LL in this order. They are arranged side by side. As shown in FIG. 3, the light reduction filter 301, the condenser lens 302 and the quarter wavelength plate 303 are each fixed to the holder 304 by an adhesive or the like (not shown). Such a holder 304 is made of, for example, a metal material such as aluminum and has heat dissipation.

  As described above, the light reduction filter 301 has a function of reducing the intensity of the light LL from the light emitting element 102 described above. The light reducing filter 301 is not particularly limited, and may be either an absorption type or a reflection type. In addition, the condenser lens 302 has a function of adjusting the radiation angle of the light LL (for example, to make the light LL approach parallel light). As a result, it is possible to reduce the change in the power density of the light LL in the traveling direction in the atom cell 201, and to suppress the spread of the line width of the EIT signal. As a result, the oscillation characteristics (especially short-term frequency stability) of the atomic oscillator 1 can be improved. In addition, the 1⁄4 wavelength plate 303 has a function of converting two types of light having different frequencies included in the light LL from linearly polarized light to circularly polarized light (right circularly polarized light or left circularly polarized light). Thereby, the strength of the EIT signal can be increased by the interaction with the magnetic field from the coil 205.

  The optical system unit 30 can omit the light reduction filter 301 depending on the intensity of the light LL from the light emitting element 102 and the like. Further, the optical system unit 30 may have optical elements other than the light reduction filter 301, the condensing lens 302, and the 1⁄4 wavelength plate 303. Further, the arrangement order of the neutral density filter 301, the condenser lens 302 and the quarter wavelength plate 303 is not limited to the illustrated order and is arbitrary. Further, the postures of the neutral density filter 301, the condensing lens 302 and the quarter wavelength plate 303 are arbitrary.

(Atom cell unit)
As described above, the atomic cell unit 20 includes the atomic cell 201, the light receiving element 202, the heater 203, the temperature sensor 204, and the coil 205. In addition to these, as shown in FIG. 4, the atomic cell unit 20 includes a holding member 206 holding the atomic cell 201, a heat transfer member 210 fixed to the holding member 206, and an atomic cell 201. , The first container 207 containing the light receiving element 202, the temperature sensor 204, the coil 205, the holding member 206 and the heat transfer member 210, the second container 208 containing the first container 207, and the first container 207 And a plurality of spacers 209 disposed between the second container 208 and the second container 208.

  In the atomic cell 201, gaseous alkali metals such as rubidium, cesium, sodium and the like are enclosed. In the atomic cell 201, if necessary, a rare gas such as argon or neon, or an inert gas such as nitrogen may be enclosed as a buffer gas together with an alkali metal gas.

  The atomic cell 201 has a body portion 201a having two columnar through holes, and a pair of window portions 201b and 201c joined to the body portion 201a, and an internal space hermetically sealed by these. S is formed.

  In the present embodiment, the internal space S has a space S1 through which the light LL passes, and a space S2 communicating with the space S1 and containing a solid or liquid alkali metal (not shown). Here, the light LL entering the space S1 is transmitted through the one window portion 201b, and the light LL emitted from the space S1 is transmitted through the other window portion 201c. In addition, the internal space S is not limited to the form which has space S1 and S2 which were mentioned above, For example, the form which abbreviate | omitted space S2 may be sufficient.

  The constituent material of each window portion 201 b and 201 c is not particularly limited as long as it has transparency to the light LL, and examples thereof include a glass material, quartz crystal, and the like. On the other hand, the constituent material of the body portion 201a is not particularly limited, and metal materials, glass materials, silicon materials, quartz crystals, etc. may be mentioned, but from the viewpoint of processability and bonding of the windows 201b and 2013c, glass materials, It is preferred to use a silicon material. The method of bonding the body portion 201a and the windows 201b and 201c may be determined according to the constituent materials thereof, and is not particularly limited. For example, the direct bonding method, the anodic bonding method, and the fusion bonding method And optical bonding methods can be used.

As shown in FIG. 4, the holding member 206 is composed of two blocks 206 a and 206 b provided so as to cover the outer surface of the atomic cell 201 while avoiding the passage area of the light LL. Here, the two blocks 206 a and 206 b each have a thermal conductivity of 10 W · m ⁻¹ · K ⁻¹ or more, and do not inhibit the magnetic field from the coil 205 to the atomic cell 201, such as aluminum. Is made of nonmagnetic metal material. The holding member 206 is provided with an opening 206 c through which the light LL incident on the atom cell 201 passes, and an opening 206 d through which the light LL emitted from the atom cell 201 passes. In the following, that 10 W · m ⁻¹ · K ⁻¹ or more may be expressed as “excellent in heat conductivity”, “good in heat conductivity”, and the like.

  The block 206 a (a part of the holding member 206) is thermally connected to the space S 1 side of the outer surface of the atomic cell 201. Specifically, the block 206a is in contact with or is connected to a portion on the space S1 side of the outer surface of the atomic cell 201 via a member (such as metal) excellent in thermal conductivity. . The block 206 a (a part of the holding member 206) is thermally connected to the heater 203 via the first container 207. Thereby, the atom cell 201 (more specifically, the space S1) can be heated by the heat from the heater 203. Further, by interposing the block 206a between the atom cell 201 and the heater 203 as described above, the distance between the atom cell 201 and the heater 203 is increased, and an unnecessary magnetic field generated by energization of the heater 203 is generated. An adverse effect on alkali metal atoms in the atomic cell 201 can be suppressed. In addition, there is an advantage that the number of heaters can be reduced as compared with the configuration in which the heater is in contact with the atomic cell 201.

  On the other hand, the block 206 b is thermally connected to the space S 2 side of the outer surface of the atomic cell 201. Specifically, the block 206b is in contact with or is connected to a portion on the space S2 side of the outer surface of the atom cell 201 via a member (such as metal) excellent in thermal conductivity. . The block 206b is spaced apart from the block 206a. Therefore, the heat from the heater 203 is less likely to be transmitted to the block 206 b than to the block 206 a. Thereby, the temperature of space S2 can be made lower than the temperature of space S1. Therefore, solid or liquid alkali metal can be stably present in the space S2.

  The shapes of the blocks 206a and 206b are not limited to the illustrated shape as long as heat from the heater 203 can be transmitted to the space S1 while allowing passage of the light LL to the space S1. Further, the holding member 206 may be integrated with the blocks 206a and 206b, or the blocks 206a and 206b may be configured by a plurality of members.

  A coil 205 wound around the center axis of the holding member 206 along the optical axis a of the light LL is disposed on the outer periphery of the holding member 206. The coil 205 is a solenoid coil or a pair of Helmholtz coils. The coil 205 generates a magnetic field in a direction (parallel direction) along the optical axis a of the light LL in the atomic cell 201. As a result, the gap between the degenerate different energy levels of the alkali metal atoms in the atomic cell 201 can be expanded by Zeeman splitting, the resolution can be improved, and the line width of the EIT signal can be reduced. The magnetic field generated by the coil 205 may be either a DC magnetic field or an AC magnetic field, or may be a magnetic field in which a DC magnetic field and an AC magnetic field are superimposed.

  Further, the light receiving element 202 and the temperature sensor 204 are disposed in the opening 206 d of the holding member 206. The light receiving element 202 is not particularly limited as long as it can detect the intensity of the light LL (resonant light pair) transmitted through the inside of the atom cell 201, but for example, a light detector (light receiving element) such as a photodiode It can be mentioned. The temperature sensor 204 is not particularly limited as long as the temperature of the atom cell 201 or the heater 203 can be detected, and examples thereof include various known temperature sensors such as a thermistor and a thermocouple.

  Here, the light receiving element 202 and the temperature sensor 204 are disposed on a flexible wiring board 508 b described later. The flexible wiring board 508 b has a wire 510 electrically connected to the light receiving element 202 and the temperature sensor 204, and is held between the holding member 206 and the heat transfer member 210, thereby holding the holding member 206. It is fixed against. Thereby, the light receiving element 202 and the temperature sensor 204 can be positioned with respect to the atomic cell 201.

  The heat transfer member 210 has thermal conductivity and is thermally connected to the holding member 206 and the flexible wiring board 508 b (wiring 510). The heat transfer member 210 is also thermally connected to the heater 203 via the holding member 206. Thus, the heat transfer member 210 can conduct the heat from the holding member 206 to the flexible wiring board 508 b (the wiring 510) and the light receiving element 202. In the present embodiment, as shown in FIGS. 4 and 5, the heat transfer member 210 has a plate shape, is disposed along the YZ plane, and is a screw using the screw 211 with respect to the block 206a of the holding member 206. It is fixed by the stop. Further, as shown in FIG. 6, the holding member 206 is provided with a groove 206f into which a part of the outer peripheral portion of the heat transfer member 210 is inserted, and the part of the heat transfer member 210 is formed by the groove 206f. Positioning in the X-axis direction is performed. The thickness of the heat transfer member 210 is not particularly limited, but is preferably 0.3 mm or more.

  As described above, by fixing the heat transfer member 210 to the holding member 206 using the screw 211 and the groove 206f, aging as in the case of fixing the heat transfer member 210 to the holding member 206 only with an adhesive agent There is no problem of deterioration, and the heat transfer member 210 can be stably fixed to the holding member 206 for a long time. In addition, the contact state of the flexible wiring board 508b with the holding member 206 and the like can be kept constant over a long period of time. Therefore, it is possible to reduce the temporal change of the heat conduction path from the heater 203 to the atomic cell 201 and to reduce the temporal change of the characteristic of the atomic oscillator 1. When the heat transfer member 210 is fixed by the screw 211, the heat transfer member 210 urges the flexible wiring board 508 b toward the holding member 206. In other words, the heat transfer member 210 presses the flexible wiring board 508 b against the holding member 206. Therefore, the flexible wiring board 508 b is easily in close contact with the holding member. In addition, the shape of the heat-transfer member 210 is not limited to the shape of illustration, For example, you may make block shape. Further, the method of fixing the heat transfer member 210 to the holding member 206 is not limited to the above-described fixing method using the screw 211 and the groove 206f, for example, the number of screws or grooves may be plural. It may be fixed only by itself or may be fixed only by the groove. Moreover, you may use the fixing method by an adhesive agent together with the fixing method by a screw | thread or a groove | channel.

  Here, as shown in FIG. 4 and FIG. 5, the heat transfer member 210 is provided to close the opening 206 d of the holding member 206 as much as possible. Thus, the heat transfer member 210 can conduct heat integrally with the holding member 206. Further, the heat transfer member 210 overlaps the light receiving element 202 and the temperature sensor 204 when viewed from the optical axis a direction. Thereby, the heat from the heat transfer member 210 is easily conducted to the light receiving element 202 and the temperature sensor 204.

  As a constituent material of such a heat transfer member 210, a material which is excellent in thermal conductivity and does not inhibit the magnetic field from the coil 205 to the atomic cell 201, for example, nonmagnetic metal material such as copper and aluminum, carbon fiber A reinforced plastic (CFRP: carbon fiber reinforced plastic), a resin material to which a thermally conductive filler such as silica is added, and the like can be mentioned.

The thermal conductivity of the constituent material of the heat transfer member 210 is preferably 10 W · m ⁻¹ · K ⁻¹ or more, more preferably 20 W · m ⁻¹ · K ⁻¹ or more, and 100 W · m ⁻ More preferably, it is ¹ · K ⁻¹ or more. Thus, the heat transfer member 210 can suitably heat the portion of the wiring 510 near the light receiving element 202. On the other hand, if the heat conductivity is too small, the heat transfer member 210 tends to be prone to a temperature gradient.

  The atomic cell 201, the light receiving element 202, the temperature sensor 204, the coil 205, the holding member 206, and the heat transfer member 210 as described above are accommodated in the first container 207, as shown in FIG. The first container 207 supports the atomic cell 201 via the holding member 206, and is thereby thermally connected to the atomic cell 201 via the holding member 206. Further, the first container 207 is provided with an opening 207a which allows the passage of the light LL incident on the atom cell 201 (space S1). In addition, the first container 207 has a portion 207 b opposed to the heat transfer member 210 in a separated state. The first container 207 may be in contact with the heat transfer member 210.

  Here, as a constituent material of the first container 207, it is preferable to use a material which is excellent in thermal conductivity and has a magnetic shielding property, and specifically, iron (Fe), kovar, permalloy (Ni alloy) It is preferable to use an iron-based alloy such as stainless steel or the like. The heat conductivity from the heater 203 can be efficiently conducted to the holding member 206 because the first container 207 has excellent thermal conductivity. Further, the temperature distribution of the first container 207 can be made uniform, and the temperature gradient around the atom cell 201 can also be reduced. Furthermore, the first container 207 having magnetic shielding properties can reduce fluctuations in the magnetic field in the first container 207 (particularly in the atomic cell 201) due to the external magnetic field.

  Such a first container 207 is housed in a second container 208, as shown in FIG. The second container 208 supports the first container 207 via a plurality of spacers 209, thereby separating the first container 207 from the first container 207. Thereby, a gap is formed between the first container 207 and the second container 208, and the gap functions as a heat insulating layer, so that the transfer of heat between the first container 207 and the second container 208 is reduced. be able to. Here, each spacer 209 is preferably made of a heat insulating material, for example, a resin material such as a polyimide resin or an acrylic resin. Thereby, the transfer of heat between the first container 207 and the second container 208 via the spacer 209 can be reduced. Further, the second container 208 is provided with an opening 208a which allows the passage of the light LL incident on the atom cell 201 (space S1).

  Here, as a constituent material of the second container 208, like the first container 207 described above, it is preferable to use a material which is excellent in thermal conductivity and has a magnetic shielding property, and specifically, iron (Fe) It is preferable to use iron-based alloys such as Kovar, permalloy (Ni alloy), stainless steel and the like. Thereby, it is possible to reduce the fluctuation of the magnetic field in the second container 208 (particularly in the atomic cell 201) due to the external magnetic field.

  In addition, a heater 203 is installed in the second container 208, and the heater 203 is thermally connected to the outer surface of the first container 207. The heater 203 is not particularly limited as long as it can heat the atom cell 201 (more specifically, the alkali metal in the atom cell 201), but various heaters having a heating resistor, a Peltier element, etc. may be mentioned. Be

(Supporting member)
Here, referring back to FIG. 2, the support member 40 has a plate shape, and the atomic cell unit 20 and the optical system unit 30 described above are mounted on one surface of the support member 40. The support member 40 has an installation surface 401 along the shape of the lower surface of the holder 304 of the optical system unit 30. A stepped portion 402 is formed on the installation surface 401. The stepped portion 402 engages with (is in contact with) the stepped portion on the lower surface of the holder 304 to restrict the movement of the holder 304 to the atomic cell unit 20 side (right side in FIG. 2). Similarly, the support member 40 has an installation surface 403 along the shape of the lower surface of the second container 208 of the atomic cell unit 20. A stepped portion 404 is formed on the installation surface 403. The step portion 404 engages (contacts) the end surface (the end surface on the left side in FIG. 2) of the second container 208, and the second container 208 moves to the optical system unit 30 side (the left side in FIG. 2). Regulate.

  Thus, the relative positional relationship between the atomic cell unit 20 and the optical system unit 30 can be defined by the support member 40. And since the light emitting element module 10 is fixed to the holder 304, the relative positional relationship of the light emitting element module 10 with respect to the atomic cell unit 20 and the optical system unit 30 is also defined. Here, the second container 208 and the holder 304 are each fixed to the support member 40 by a fixing member such as a screw (not shown). The support member 40 is fixed to the package 60 by a fixing member such as a screw (not shown). The support member 40 is made of, for example, a metal material such as aluminum and has heat dissipation. Thereby, heat dissipation of the light emitting element module 10 can be performed efficiently.

(Controller unit)
As shown in FIG. 3, the control unit 50 includes a circuit board 505, two connectors 506a and 506b provided on the circuit board 505, and a flexible wiring board connecting the connector 506a and the light emitting element module 10. A flexible wiring board 508 b connecting the connector 506 b to the atomic cell unit 20 and a plurality of lead pins 509 penetrating the circuit board 505 are provided.

  Here, the circuit board 505 is provided with an electric circuit (not shown), and this electric circuit functions as the temperature control unit 501, the light source control unit 502, the magnetic field control unit 503, and the temperature control unit 504 described above. Also, the circuit board 505 has a through hole 5051 through which the support member 40 described above is inserted. The circuit board 505 is supported by the package 60 via a plurality of lead pins 509. The plurality of lead pins 509 pass through the inside and the outside of the package 60 and are electrically connected to the circuit board 505.

  The configuration for electrically connecting the circuit board 505 to the light emitting element module 10 and the configuration for electrically connecting the circuit board 505 to the atomic cell unit 20 are the connectors 506a and 506b and the flexible wiring board 508a shown in the figure. , 508b, and may be other known connectors and wires, respectively.

  Similar to the first container 207 and the second container 208 described above, the package 60 is preferably made of a metallic material having magnetic shielding properties such as Kovar. This can reduce the adverse effect of the external magnetic field on the characteristics of the atomic oscillator 1. The inside of the package 60 may be decompressed or may be atmospheric pressure, but is preferably an airtight space.

  As described above, the atomic oscillator 1 includes the atomic cell 201 in which alkali metal atoms are enclosed, the light emitting element 102 which is a light source for emitting light LL for exciting the alkali metal atoms in the atomic cell 201, and the atomic cell 201 And the wiring 510 connected to the light receiving element 202, the heater 203 for heating the atomic cell 201, and the atomic cell 201 with respect to the light receiving element 202. And a heat transfer member 210 disposed on the opposite side (the + X axis direction side) and thermally connected to the heater 203 and the wire 510.

  According to such an atomic oscillator 1, since the heat transfer member 210 thermally connected to the heater 203 and the wiring 510 is disposed on the opposite side of the light receiving element 202 to the atomic cell 201, the heat transfer is performed. The light receiving element 202 or the wiring 510 can be suitably temperature-controlled (heated) similarly to the atomic cell 201 by the heat from the heater 203 via the member 210. Therefore, the atomic cell 201 is not easily affected by the external temperature due to the heat transfer through the wiring 510, and the temperature gradient around the atomic cell 201 can be reduced. By thus reducing the temperature gradient around the atom cell 201, the atom cell 201 can be stably provided with a desired temperature distribution, and as a result, the short-term frequency stability of the atomic oscillator 1 can be improved. it can. In addition, the frequency temperature characteristic of the atomic oscillator 1 can be improved because it becomes less susceptible to the influence of the external temperature change.

  As described above, the atomic oscillator 1 includes the holding member 206 holding the atomic cell 201, and the heater 203 is thermally connected to the atomic cell 201 and the heat transfer member 210 via the holding member 206. . As a result, the number of heaters 203 can be reduced, and the degree of freedom in design regarding the installation of the heaters 203 can be increased.

  As described above, the heat transfer member 210 is fixed to the holding member 206 (in this embodiment, screwed by the screw 211). Here, the thermal conductivity of the holding member 206 is preferably higher than the thermal conductivity of the atomic cell 201. Thereby, the heat from the heater 203 can be efficiently conducted to the atom cell 201 and the heat transfer member 210 through the holding member 206.

  Further, as described above, the atomic oscillator 1 includes the flexible wiring board 508 b which is a wiring board on which the light receiving element 202 (detection element) is disposed and the wiring 510 is provided, and the heat transfer member 210 is a flexible wiring board 508 b is urged toward the holding member 206. Thus, the flexible wiring board 508 b can be brought into close contact with the holding member 206 and the heat transfer member 210, and heat conduction between these can be stably performed. Here, the flexible wiring board 508 b can reduce the heat capacity as compared to a general rigid wiring board. Therefore, the conduction of heat from the heat transfer member 210 to the wiring 510 can be efficiently performed.

  Note that a rigid wiring board may be used instead of the flexible wiring board 508b, and in this case, it is preferable to use a board that is as good as possible in thermal conductivity. Examples of the rigid wiring substrate excellent in thermal conductivity include a substrate using a metal as a substrate, a substrate using a thermal conductive filler, and a substrate having a conductor post for thermal conduction penetrating in the thickness direction. .

  Furthermore, the atomic oscillator 1 includes a temperature sensor 204 disposed on the flexible wiring board 508 b (wiring board). Thereby, since the temperature difference between the atom cell 201 and the flexible wiring board 508 b is reduced by the heat transfer member 210, the temperature of the atom cell 201 can be reduced by using the temperature sensor 204 disposed on the flexible wiring board 508 b. It can be detected with high accuracy. Thereby, the frequency characteristic of the atomic oscillator 1 can be improved.

  Further, the atomic oscillator 1 includes a first container 207 which is a container which is thermally connected to the heater 203 and the wiring 510 and accommodates the atomic cell 201 and the light receiving element 202 (light detecting element). Includes a portion 207 b disposed on the opposite side of the light receiving element 202 from the atom cell 201. Thereby, this portion 207 b functions in the same manner as the heat transfer member 210, and the temperature gradient around the atom cell 201 can be further reduced.

2. Signal Generation System The atomic oscillator 1 as described above can be incorporated into various electronic devices. Hereinafter, an embodiment of a signal generation system including such an electronic device will be described.

  FIG. 7 is a diagram showing a schematic configuration of a positioning system (an example of a signal generation system) using GPS satellites.

A positioning system 1100 (an example of a signal generation system) shown in FIG. 7 is configured of a GPS satellite 1200, a base station device 1300, and a GPS receiving device 1400.
The GPS satellites 1200 transmit positioning information (GPS signals).

  The base station device 1300 receives the positioning information from the GPS satellite 1200 with high accuracy via the antenna 1301 installed at the electronic reference point (GPS continuous observation station), for example, and the receiving device 1302 And a transmitter 1304 for transmitting positioning information via the antenna 1303.

  Here, the receiving device 1302 includes an atomic oscillator 1 that is the reference frequency oscillation source, and a processing unit 1302 a that processes a signal from the atomic oscillator 1. Also, the positioning information received by the receiving device 1302 is transmitted by the transmitting device 1304 in real time.

  Thus, the receiver 1302 which is an electronic device includes the atomic oscillator 1. According to such a receiver 1302, the characteristics of the receiver 1302 can be improved by reducing the temperature gradient around the atom cell 201 of the atomic oscillator 1.

  The GPS receiver 1400 includes a satellite receiver 1402 that receives positioning information from the GPS satellite 1200 via the antenna 1401, and a base station receiver 1404 that receives positioning information from the base station 1300 via the antenna 1403. Prepare.

  As described above, the positioning system 1100, which is a signal generation system, includes the atomic oscillator 1 and a processing unit 1302a that processes the signal from the atomic oscillator 1. According to such a positioning system 1100, the characteristics of the positioning system 1100 can be improved by reducing the temperature gradient around the atomic cell 201 of the atomic oscillator 1.

  Note that the electronic device is not limited to the one described above, and for example, a smartphone, a tablet terminal, a watch, a mobile phone, a digital still camera, an inkjet discharge device (for example, an inkjet printer), a personal computer (mobile personal computer, laptop) Type personal computers), TVs, video cameras, video tape recorders, car navigation devices, pagers, electronic organizers (including communication functions), electronic dictionaries, calculators, electronic game devices, word processors, workstations, video phones, television for crime prevention Monitors, electronic binoculars, POS (Point of Sales) terminals, medical devices (such as electronic thermometers, sphygmomanometers, blood glucose meters, electrocardiogram measuring devices, ultrasound diagnostic devices, electronic endoscopes), fish finders, various measuring devices, meters (E.g., gages for vehicles, aircraft, and ships), a flight simulator, terrestrial digital broadcasting, can be applied to a mobile phone base station or the like. Further, the signal generation system may be any system that processes a signal from the atomic oscillator to generate a signal, and is not limited to the one described above, and may be, for example, a clock transmission system.

  Although the atomic oscillator, the signal generation system, and the electronic device of the present invention have been described above based on the illustrated embodiments, the present invention is not limited to these.

  In addition, the configuration of each part of the present invention can be replaced with an arbitrary configuration that exerts the same function as that of the above-described embodiment, and any configuration can be added.

  Although the case where the present invention is applied to an atomic oscillator using a quantum interference effect has been described as an example in the embodiment described above, the present invention is not limited to this and is also applied to an atomic oscillator using double resonance phenomenon. In this case, the light source is not limited to the semiconductor laser. For example, a light emitting diode, a lamp in which an alkali metal is sealed, or the like can be used.

DESCRIPTION OF SYMBOLS 1 ... atomic oscillator, 10 ... light emitting element module, 20 ... atomic cell unit, 30 ... optical system unit, 40 ... support member, 50 ... control unit, 60 ... package, 101 ... Peltier element, 102 ... light emitting element (light source), DESCRIPTION OF SYMBOLS 103 ... Temperature sensor, 104 ... Package, 201 ... Atomic cell, 201a ... Body part, 201b ... Window part, 201c ... Window part, 202 ... Light receiving element (light detection element), 203 ... Heater, 204 ... Temperature sensor, 205 ... Coil 206 holding member 206a block 206b block 206c opening 206d opening 206f groove 207 first container 207a opening 207b portion 208 second container 208a ... opening portion, 209 ... spacer, 210 ... heat transfer member, 211 ... screw, 301 ... attenuation filter, 302 Condenser lens, 303: 4 wavelength plate, 304: holder, 305: through hole, 401: installed surface, 402: stepped portion, 403: installed surface, 404: stepped portion, 501: temperature controller, 502: light source controller 503: magnetic field control unit 504: temperature control unit 505: circuit board 506a: connector 506b: connector 508a: flexible wiring board 508b: flexible wiring board (wiring board) 509: lead pin 510: wiring 1100 ... positioning system, 1200 ... GPS satellite, 1300 ... base station apparatus, 1301 ... antenna, 1302 ... receiving apparatus, 1302 a ... processing unit, 1303 ... antenna, 1304 ... transmitting apparatus, 1400 ... GPS receiving apparatus, 1401 ... antenna, 1402 ... satellite reception unit, 1403 ... antenna, 1404 ... base station reception unit, 20 3c ... window portions, 5051 ... through hole, LL ... light, S ... internal space, S1 ... space, S2 ... space, a ... optical axis

Claims (10)

An atomic cell in which an alkali metal atom is enclosed,
A light source for emitting light for exciting the alkali metal atom;
A light detection element for detecting the light transmitted through the atom cell;
A wire connected to the light detection element;
A heater for heating the atomic cell;
An atomic oscillator comprising: a heat transfer member disposed on the opposite side to the atom cell with respect to the light detection element and thermally connected to the heater and the wiring. A holding member holding the atom cell,
The atomic oscillator according to claim 1, wherein the heater is thermally connected to the atomic cell and the heat transfer member via the holding member. The thermal conductivity of the holding member is greater than the thermal conductivity of the atomic cell,
The atomic oscillator according to claim 2, wherein the heat transfer member is fixed to the holding member. Including a wiring board on which the light detection element is disposed and the wiring is provided;
The atomic oscillator according to claim 2, wherein the heat transfer member biases the wiring substrate toward the holding member.   The atomic oscillator according to claim 4, further comprising a temperature sensor disposed on the wiring substrate.   The atomic oscillator according to claim 4, wherein the wiring substrate is a flexible wiring substrate. A container thermally connected to the heater and the wiring and containing the atomic cell and the light detection element;
The atomic oscillator according to any one of claims 1 to 6, wherein the container includes a portion disposed on the opposite side to the atomic cell with respect to the light detection element. The atomic oscillator according to any one of claims 1 to 7, wherein a thermal conductivity of a constituent material of the heat transfer member is 10 W · m ^-1 · K ^-1 or more. An atomic oscillator according to any one of claims 1 to 8;
And a processor configured to process a signal from the atomic oscillator.   An electronic device comprising the atomic oscillator according to any one of claims 1 to 8.

Images