JP2012195788A - Atomic oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an atomic oscillator that stably exerts desired characteristics by maintaining a gas cell and a light emission section in a predetermined temperature range irrespective of environmental temperature.SOLUTION: An atomic oscillator 1 includes: a first package 6 housing a gas cell 2, a first variable temperature section 41 for controlling the temperature of the gas cell 2, a light emission section 5, and a second variable temperature section 42 for controlling the temperature of the light emission section 5; a third variable temperature section 43 for controlling the temperature of the first package 6; and a control section 8 for controlling the drive of the temperature control sections 41-43. When TL and TH denote lower and upper limit values of environmental temperature where the first variable temperature section 41 can control the gas cell 2 to a predetermined temperature Ta and the second variable temperature section 42 can control the light emission section 5 to a predetermined temperature Tb, the control section 8 is configured to maintain the temperature of the first package 6 at TL or higher and TH or lower by driving the third variable temperature section 43 when the environmental temperature is lower than TL or higher than TH.

Description

  The present invention relates to an atomic oscillator.

2. Description of the Related Art Conventionally, an atomic oscillator that obtains an oscillation signal having high frequency stability based on energy transition of atoms of alkali metals such as rubidium and cesium is known (for example, Patent Document 1).
An atomic oscillator described in Patent Document 1 includes a light source that emits excitation light, an optical system that includes an optical lens that performs optical processing on the excitation light, and a polarizing plate, a gas cell in which gaseous alkali metal atoms are enclosed, And a light detection unit that detects excitation light that has passed through the gas cell. Further, this atomic oscillator has a first temperature adjusting means (for example, a heater) for keeping the gas cell at a predetermined temperature and a second temperature adjusting means (for example, for maintaining the light source at a predetermined temperature) in order to stably exhibit desired characteristics. , Peltier element).

By the way, it is assumed that the field of use of atomic oscillators will expand in the future, and that it will be used in a wide temperature range (-50 ° C to + 80 ° C at present). However, the first temperature control means and the second temperature control means have limited temperature control capability, and depending on the environmental temperature, it may be difficult to maintain the gas cell and the light source at a predetermined temperature. For example, when the environmental temperature is as extremely low as −50 ° C., the gas cell and the light source may not be sufficiently heated, and the gas cell and the light source may not be maintained at a predetermined temperature.
As described above, the atomic oscillator disclosed in Patent Document 1 has a problem that it cannot be affected by the environmental temperature and exhibit desired characteristics.

US Pat. No. 6,320,472

  An object of the present invention is to provide an atomic oscillator that can maintain a gas cell and a light emitting portion in a predetermined temperature range regardless of the environmental temperature and can stably exhibit desired characteristics.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
[Application Example 1]
The atomic oscillator of the present invention includes a gas cell,
A first temperature variable section having means for changing the temperature of the gas cell;
A light emitting portion for emitting excitation light for exciting gas atoms in the gas cell;
A second temperature variable unit having means for changing the temperature of the light emitting unit;
A first package that houses the gas cell, the first temperature variable unit, the light emitting unit, and the second temperature variable unit;
A third temperature variable unit having means for changing the temperature of the first package;
The driving of the first temperature variable unit, the second temperature variable unit, and the third temperature variable unit is controlled, and the temperature of the gas cell, the temperature of the light emitting unit, and the temperature of the first package are controlled. A control unit,
The control unit drives the third temperature variable unit when the environmental temperature is lower than a predetermined temperature TL or higher than a predetermined temperature TH higher than the TL.
Accordingly, it is possible to provide an atomic oscillator that can maintain the gas cell and the light emitting portion in a predetermined temperature range regardless of the environmental temperature and can stably exhibit desired characteristics.

[Application Example 2]
In the atomic oscillator according to the aspect of the invention, when the environmental temperature is equal to or higher than the TL and equal to or lower than the TH, the control unit stops driving the third temperature variable unit, and the first temperature variable unit and the It is preferable that the second temperature variable unit is driven to control the gas cell and the light emitting unit to a predetermined temperature.
Thereby, power saving drive is possible.

[Application Example 3]
In the atomic oscillator of the present invention, when the predetermined temperature of the gas cell is Ta and the predetermined temperature of the light emitting unit is Tb, the control unit sets the temperature of the first package between Ta and Tb. It is preferable to control the temperature.
As a result, the gas cell can be set to the predetermined temperature by the first temperature variable unit and the light emitting unit can be set to the predetermined temperature by the second temperature variable unit more efficiently and reliably. Further, the first temperature variable unit, the second temperature variable unit, and the third temperature variable unit are driven in a balanced manner, that is, the first temperature variable unit, the second temperature variable unit, and the third temperature variable unit. Since any one of the temperature control units can be prevented from being excessively driven with respect to the other temperature control units, power-saving drive is possible. In addition, this makes it possible to suppress the work amount of each temperature control unit, and to reduce the size of each temperature control unit, that is, to reduce the size of the atomic oscillator.

[Application Example 4]
In the atomic oscillator of the present invention, the third temperature variable unit includes a Peltier element,
It is preferable that one surface of the Peltier element is provided in contact with the outer surface of the first package.
Thereby, the temperature of the first package can be adjusted with higher accuracy.

[Application Example 5]
In the atomic oscillator according to the aspect of the invention, it is preferable to include a second package that houses the first package and the third temperature variable unit.
Thereby, the temperature of the internal space of the second package (that is, the periphery of the first package) can be controlled together with the first package by the third temperature variable unit, so that the third package can be more efficiently operated. The temperature of the first package can be adjusted by the temperature variable unit.

[Application Example 6]
In the atomic oscillator according to the aspect of the invention, it is preferable that the second package is provided in contact with the other surface of the Peltier element.
As a result, the heat generated from the heat absorbing and generating body can be efficiently released to the outside of the atomic oscillator.
[Application Example 7]
In the atomic oscillator of the present invention, it is preferable that the second package is made of a material having a thermal conductivity of 14 (W · m ⁻¹ · K ⁻¹ ) or more.
As a result, the heat generated from the heat absorption and heating element can be efficiently released to the outside of the atomic oscillator.

[Application Example 8]
In the atomic oscillator according to the aspect of the invention, the first package may be a partition that partitions the space in which the gas cell and the first temperature variable unit are located from the space in which the light emitting unit and the second temperature variable unit are positioned. It is preferable that the partition has a light transmission property.
The temperature of the gas cell and the light emitting part can be adjusted to a predetermined temperature efficiently and stably.

It is sectional drawing which shows schematic structure of the atomic oscillator which concerns on suitable embodiment of this invention. It is a figure for demonstrating the energy state of the alkali metal in the gas cell with which the atomic oscillator shown in FIG. 1 was equipped. 2 is a graph showing a relationship between a frequency difference between two lights from a light emitting unit and a detection intensity of the light detecting unit for the light emitting unit and the light detecting unit provided in the atomic oscillator shown in FIG. 1. It is the graph which illustrated an example of the relationship between environmental temperature, the temperature of a 2nd package, the temperature of a 1st package, the temperature of a gas cell, and a light emission part.

Hereinafter, an atomic oscillator of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a cross-sectional view showing a schematic configuration of an atomic oscillator according to a preferred embodiment of the present invention, and FIG. 2 is a diagram for explaining an energy state of an alkali metal in a gas cell provided in the atomic oscillator shown in FIG. FIGS. 3A and 3B are graphs showing the relationship between the frequency difference between two lights from the light emitting portion and the detection intensity of the light detecting portion for the light emitting portion and the light detecting portion provided in the atomic oscillator shown in FIG. FIG. 4 is a graph illustrating an example of the relationship between the environmental temperature, the temperature of the second package, the temperature of the first package, the temperature of the gas cell and the light emitting unit. In the following, for convenience of explanation, the upper side in FIG. 1 is referred to as “upper”, the lower side as “lower”, the left side as “left”, and the right side as “right”.

1. First, the configuration of the atomic oscillator 1 will be described.
In the following, the case where the present invention is applied to an atomic oscillator using the quantum interference effect will be described as an example. However, the present invention is not limited to this, and the atomic oscillator using the double resonance effect is described. It is also applicable to.
As shown in FIG. 1, the atomic oscillator 1 includes a gas cell 2 in which gaseous metal atoms are sealed, a light detection unit 3, a first temperature variable unit 41 having means for changing the temperature of the gas cell 2, and excitation. The light emission part 5 which emits light, the 2nd temperature variable part 42 which has a means to change the temperature of the light emission part 5, the 1st package 6 which accommodates these, The temperature of the 1st package 6 is set. Controls the driving of the third temperature variable section 43 having means for changing, the second package 7 housing the first package 6 and the third temperature variable section 43, and the temperature control sections 41, 42, 43. And a control unit 8 for detecting the environmental temperature (a temperature around the atomic oscillator 1). Hereinafter, each of these units will be sequentially described in detail.

(Gas cell)
The gas cell 2 has a cylindrical main body 21 and window portions 22 and 23 for sealing both end openings of the main body 21, and a sealed cavity is formed therein. In this cavity, gaseous alkali metal atoms such as rubidium, cesium and sodium are enclosed.

  The windows 22 and 23 constitute an entrance surface and an exit surface of the optical path of excitation light that excites the metal atom gas. Therefore, each window part 22 and 23 is comprised with the material which has light transmittances, such as glass, for example. On the other hand, since the main body 21 does not require light transmission, the main body 21 may be formed of various metal materials, various resin materials, and the like, and is formed of a light-transmitting material such as the same glass as the windows 22 and 23. It may be.

(Light detector)
The light detection unit 3 is provided on the right side of the gas cell 2. The light detection unit 3 has a function of detecting the intensity of excitation light (resonance light 1 and 2 described later) transmitted through the gas cell 2. The light detection unit 3 is not particularly limited, and for example, a solar cell or a photodiode can be used.

(First temperature variable part)
The first temperature variable unit 41 includes a heating unit 411 for heating the gas cell 2 (means for changing the temperature of the gas cell 2), and a temperature detection unit 412 for detecting the temperature of the gas cell 2 (the temperature of the outer surface of the main body 21). have.
The heating unit 411 includes a first heater 411 a provided on the outer surface of the window portion 22 and a second heater 411 b provided on the outer surface of the window portion 23. Each of these heaters 411a and 411b is made of a transparent electrode material such as an oxide such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), In ₃ O ₃ , SnO ₂ , Sb-containing SnO ₂ , and Al-containing ZnO. Transparent electrode film.

  When the heaters 411a and 411b are each made of a transparent electrode material, these heaters 411a and 411b can be provided in a portion serving as an optical path of excitation light on the outer surface of the gas cell 2. Therefore, the incident part and the emission part of the excitation light of the gas cell 2 can be efficiently heated by the heaters 411a and 411b. As a result, it is possible to prevent alkali metal atoms from precipitating (condensation) on the portion of the inner wall surface of the gas cell 2 that serves as the optical path of the excitation light, and to extend the life of the atomic oscillator 1.

The temperature detection part 412 is comprised with the thermistor provided in the outer surface of the main body 21 of the gas cell 2, for example. Thereby, the temperature of the gas cell 2 can be detected more accurately.
The first and second heaters 411a and 412b and the temperature detection unit 412 are electrically connected to the control means (control circuit) 8, respectively. The control unit 8 is configured to keep the gas cell 2 at a predetermined temperature by controlling the drive (output) of the first and second heaters 411a and 412b based on the detection result of the temperature detection unit 412. The temperature of the gas cell 2 is controlled to about 60 ° C. or more and about 80 ° C. or less by the first and second heaters 411a and 411b, for example.

(Light emitting part)
The light emitting unit 5 has a function of emitting excitation light that excites alkali metal atoms in the gas cell 2. More specifically, the light emitting unit 5 emits two types of light (resonant lights 1 and 2) having different frequencies as coherent light having coherence such as laser light. As such a light emission part 5, a vertical cavity surface emitting laser (VCSEL) can be used, for example.

Here, as shown in FIG. 2, the alkali metal atom in the gas cell 2 has a three-level energy level, and two ground states (ground states 1 and 2) having different energy levels, , And can be in three states: an excited state. Here, the ground state 1 is a lower energy state than the ground state 2.
The frequency ω1 of the resonant light 1 can excite the alkali metal atoms in the gas cell 2 from the ground state 1 to the excited state, and the frequency ω2 of the resonant light 2 describes the alkali metal atoms in the gas cell 2 as described above. It can be excited from the ground state 2 to the excited state.

  When two types of resonant lights 1 and 2 having different frequencies are irradiated to the alkali metal atoms in the gas cell 2, according to the difference (ω1-ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 The light absorptivity (light transmittance) of the alkali metal atoms of the resonant lights 1 and 2 changes. When the difference (ω1−ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 coincides with the energy difference between the ground state 1 and the ground state 2, the ground states 1 and 2 change to the excited state. Each excitation stops. At this time, both the resonant lights 1 and 2 are transmitted without being absorbed by the alkali metal atoms. Such a phenomenon is called a CPT phenomenon or an electromagnetically induced transparency (EIT) phenomenon.

  For example, if the frequency ω2 of the resonant light 2 is changed while the frequency ω1 of the resonant light 1 is fixed, the difference (ω1−ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 is the ground state. When the frequency coincides with the frequency ω0 corresponding to the energy difference between 1 and the ground state 2, the detection intensity of the light detection unit 3 increases sharply as shown in FIG. Such a steep signal is detected as an EIT signal. This EIT signal has an eigenvalue determined by the type of alkali metal. Therefore, an oscillator with high frequency stability can be configured by using such an EIT signal.

  Here, an optical component (not shown) may be provided between the light emitting unit 5 and the gas cell 2. Optical components include, for example, a collimator lens for making excitation light into parallel light, or performing spectroscopy that removes unnecessary light components from the excitation light LL and passing only necessary light components, and adjusting the light intensity. Or an optical element layer. As the optical element layer, for example, a layer formed by laminating a neutral density filter (ND filter) and a λ / 4 wavelength plate can be used. By disposing such an optical component, it is possible to perform a desired optical process on the excitation light, so that the characteristics of the atomic oscillator 1 are improved.

(Second temperature variable part)
The second temperature variable unit 42 detects the temperature (surface temperature) of the light emitting unit 5 and the heating / cooling unit 421 (means for changing the temperature of the light emitting unit 5) for heating and cooling the light emitting unit 5. And a temperature detector 422.
The heating / cooling unit 421 includes a plate-like (planar) Peltier element 421a, and the light emitting unit 5 is provided on the upper surface of the Peltier element 421a. By controlling the direction of the flowing current, the upper surface of the Peltier element 421a can function as a heat generating surface or a heat absorbing surface. Therefore, by providing the light emitting part 5 on the upper surface of the Peltier element 421a, the temperature of the light emitting part 5 can be controlled with higher accuracy. By controlling the temperature of the light emitting section 5 with such a Peltier element 421a, excitation light having a desired characteristic can be emitted, and the reliability of the atomic oscillator 1 is improved.

The temperature detection part 422 is comprised with the thermistor provided in the upper surface of the Peltier element 421a, for example. Thereby, the temperature of the upper surface of the Peltier element 421a can be accurately detected. For example, by setting this temperature as the temperature of the light emitting unit 5, the temperature of the light emitting unit 5 can be easily detected.
The Peltier element 421a and the temperature detection unit 422 are each electrically connected to the control unit 8. The control unit 8 is configured to keep the light emitting unit 5 at a predetermined temperature by controlling the driving (direction and intensity of current) of the Peltier element 421a based on the detection result of the temperature detection unit 422. . Note that the temperature of the light emitting unit 5 is controlled by the Peltier element 421a to about 20 ° C. or more and 40 ° C. or less, for example.

(First package)
As shown in FIG. 1, the first package 6 houses the gas cell 2, the light detection unit 3, the first temperature variable unit 41, the light emitting unit 5, and the second temperature variable unit 42. ing. The first package 6 has a partition 61 that partitions the internal space into two spaces S1 and S2. The gas cell 2, the light detection unit 3, and the first temperature variable unit 41 are located in the space S1, and the light emitting unit 5 and the second temperature variable unit 42 are accommodated in the space S2. As described above, since the temperature of the gas cell 2 (60 ° C. to 80 ° C.) and the temperature of the light emitting unit 5 (20 ° C. to 40 ° C.) are different, the partition unit 61 spatially separates them ( By thermally separating), the gas cell 2 and the light emitting part 5 can be adjusted to a predetermined temperature efficiently and stably.

In addition, since the partition part 61 is located on the optical path of excitation light, it is comprised with the material which has light transmittances, such as glass, for example.
Of the spaces S1 and S2 in the first package 6, at least the space S2, preferably both the spaces S1 and S2, are preferably in a reduced pressure state or a state filled with a rare gas such as argon gas. Thereby, the reliability of the atomic oscillator 1 is improved.

The constituent material of the first package 6 is not particularly limited, but is preferably a material having a relatively high thermal conductivity, preferably a material having a thermal conductivity of 14 (W · m ⁻¹ · K ⁻¹ ) or more. . Accordingly, the first package 6 can be efficiently heated or cooled by a Peltier element 431a described later of the third temperature variable unit 43. Such a material is not particularly limited, for example, various metals such as iron, nickel, cobalt, gold, platinum, silver, copper, manganese, aluminum, magnesium, zinc, lead, tin, titanium, tungsten, or these An alloy containing at least one of them can be used.
The configuration of the first package 6 is not particularly limited. For example, the first package 6 may be configured by joining a first package having a space S1 inside and a second package having a space S2 inside. .

(Third temperature variable part)
The third temperature variable unit 43 includes a heating / cooling unit 431 that heats and cools the first package 6 and a temperature detection unit 432 that detects the temperature (surface temperature) of the first package 6. .
The heating / cooling unit 431 is configured by a Peltier element 431a, like the second temperature variable unit 42. Further, the Peltier element 431 a is provided such that the upper surface (that is, the surface that becomes the heat generation surface or the heat absorption surface) is in contact with the outer surface of the first package 6. Thus, the temperature of the first package 6 can be more accurately controlled by the Peltier element 431a.

  In addition, when the surface of the first package 6 on which the gas cell 2 is provided is the top surface and the surface on which the light emitting portion 5 is provided is the bottom surface, the Peltier element 431 a has the side surface 6 a of the first package 6. It is provided so that it may contact. Thereby, since the Peltier element 431a can be moved away from the gas cell 2 and the light emitting part 5 as much as possible, it is possible to suppress the temperature of the gas cell 2 and the light emitting part 5 from fluctuating unintentionally by driving the Peltier element 431a. .

The temperature detection unit 432 is configured by, for example, a thermistor provided on the outer surface of the first package 6. Thereby, the temperature of the first package 6 can be accurately detected.
The Peltier element 431a and the temperature detection unit 432 are each electrically connected to the control unit 8. The control unit 8 is configured to keep the first package 6 within a predetermined temperature range by controlling the driving (direction and strength of current) of the Peltier element 431a based on the detection result of the temperature detection unit 432. Has been.

(Second package)
The second package 7 houses the first package 6 and the third temperature variable unit 43. Thereby, the temperature of the internal space of the second package 7 (that is, the periphery of the first package 6) can be controlled with the first temperature variable portion 43 together with the first package 6, so that it can be more efficiently performed. The temperature of the first package 6 can be controlled by the third temperature variable unit 43.

Such a second package 7 is provided such that its inner surface is in contact with the lower surface of the Peltier element 431a. Thereby, the heat generated from the lower surface of the Peltier element 431a can be efficiently released to the outside of the atomic oscillator 1. From such a viewpoint, the second package 7 is made of a material having a relatively high thermal conductivity, preferably a material having a thermal conductivity of 14 (W · m ⁻¹ · K ⁻¹ ) or more. preferable. Thereby, the above effect becomes more remarkable. Examples of such materials include various metals such as iron, nickel, cobalt, gold, platinum, silver, copper, manganese, aluminum, magnesium, zinc, lead, tin, titanium, and tungsten, or at least one of these. Examples include alloys containing seeds.

The second package 7 is preferably made of a material having a high magnetic permeability, preferably a material having a magnetic permeability of 100 (N / A ² ) or more. Thereby, a magnetic shielding effect can be imparted to the second package 7, and in particular, it is possible to prevent an unintentional magnetic field from acting on the gas cell 2. Thereby, even if the gas cell 2 is disposed on a substrate on which various circuit elements are integrated, the atomic oscillator 1 can stably exhibit desired characteristics. Such a material is not particularly limited, but in consideration of the above-described heat conduction parameters, for example, iron, cobalt, nickel, or an alloy containing at least one of them can be used.

(Environmental temperature detector 9)
The environmental temperature detector 9 is provided in the second package 7 so as to be exposed to the outside of the atomic oscillator 1. Thereby, the ambient temperature can be accurately detected by the ambient temperature detector 9. The environmental temperature detection 9 is not particularly limited, and for example, a thermistor, a thermopile, or the like can be used.
The environmental temperature detection unit 9 is connected to the control unit 8, and the detection result of the environmental temperature detection unit 9 is transmitted to the control unit 8.
The configuration of the atomic oscillator 1 has been described above.

2. Next, a method for controlling the atomic oscillator 1 will be described with reference to FIG. FIG. 4 is a graph illustrating an example of the relationship among the environmental temperature, the temperature of the second package 7, the temperature of the first package 6, the temperature of the gas cell 2 and the light emitting unit 5.
As described above, in the atomic oscillator 1, the temperature of the gas cell 2 is controlled by the first temperature variable unit 41, the temperature of the light emitting unit 5 is controlled by the second temperature variable unit 42, and the third temperature variable unit 43 is used. The first package 6 is configured to be temperature controlled. Here, the capability of the first temperature variable unit 41 and the second temperature variable unit 42 is limited, and the capability is not sufficiently high from the viewpoint of reducing the size of the atomic oscillator 1. Therefore, for example, if the environmental temperature (the ambient temperature of the atomic oscillator 1) where the atomic oscillator 1 is placed is too low, the gas cell 2 can be heated to a predetermined temperature even if the first temperature variable unit 41 is driven at the maximum output. There are cases where it is not possible. The same applies to the second temperature variable unit 42.

Therefore, the atomic oscillator 1 is configured such that the gas cell 2 and the light emitting unit 5 can be set to a predetermined temperature regardless of the environmental temperature. Hereinafter, although specifically described, the first temperature variable unit 41 can control the temperature of the gas cell 2 to an arbitrary predetermined temperature Ta (for example, 65 ° C. ± 0.5 ° C.) in the range of 60 ° C. to 80 ° C. In addition, the lower limit value of the environmental temperature at which the second temperature variable unit 42 can control the temperature of the light emitting unit 5 to an arbitrary predetermined temperature Tb in the range of 20 ° C. to 40 ° C. (for example, 25 ° C. ± 0.5 ° C.). Is TL and the upper limit is TH. In other words, when the environmental temperature is equal to or higher than TL and equal to or lower than TH, the first and second temperature variable units 41 and 42 can set the gas cell 2 and the light emitting unit 5 to a predetermined temperature. In the present embodiment, since the first temperature variable unit 41 does not have a cooling function, the temperature Ta and the temperature TH are set to substantially the same temperature.
In the atomic oscillator 1, the control method differs between the case where the environmental temperature is TL or more and TH or less (first case) and the other cases (second case). explain.

(First case)
The relationship between the environmental temperature in the first case, the temperature of the second package 7, the temperature of the first package 6, the temperature of the gas cell 2 and the light emitting unit 5 is indicated by a two-dot chain line C in FIG. Become.
When the environmental temperature detected by the environmental temperature detector 9 is not less than TL and not more than TH, as described above, the first and second heaters 411a and 411b and the Peltier element 421a allow the gas cell 2 and the light emitting unit 5 to be used. Can be set to a predetermined temperature. Therefore, the control unit 8 stops driving the third temperature variable unit 43, drives the first and second heaters 411a, 411b, and the Peltier element 421a, and sets the gas cell 2 and the light emitting unit 5 to the predetermined temperatures Ta, Tb. Control the temperature. Such temperature control can be performed while feeding back the detection results of the temperature detection units 412 and 422 to the control unit 8.
If the environmental temperature is substantially equal to TH, the gas cell 2 can be set to the predetermined temperature Ta without driving the first and second heaters 411a and 411b. The unit 8 may stop driving the first temperature variable unit 41.

(Second case)
The relationship between the environmental temperature in the second case, the temperature of the second package 7, the temperature of the first package 6, the temperature of the gas cell 2 and the light emitting unit 5 is indicated by a solid line A and a one-dot chain line B in FIG. It will be a thing.
When the environmental temperature detected by the environmental temperature detection unit 9 is lower than TL or higher than TH, the gas cell 2 and the light emitting unit 5 are set to a predetermined state only by driving the first and second heaters 411a and 411b and the Peltier element 421a. The temperatures Ta and Tb cannot be set.

  Therefore, in the second case, the control unit 8 drives the Peltier element 431a as well as the first and second heaters 411a and 411b and the Peltier element 421a. At this time, for example, the control unit 8 first controls the drive of the third temperature variable unit 43 so that the temperature of the first package 6 (the detection temperature of the temperature detection unit 432) is not less than TL and not more than TH. The first and second heaters 411a and 411b and the Peltier element 421a are brought into a state where the gas cell 2 and the light emitting unit 5 can be set to the predetermined temperatures Ta and Tb. Such temperature control can be performed while the detection result of the temperature detection unit 432 is fed back to the control unit 8.

  Here, more preferably, the control unit 8 controls the driving of the third temperature variable unit 43 so that the temperature of the first package 6 is Tb or more and Ta or less. More specifically, when the environmental temperature is lower than TL, the control unit 8 controls the driving of the third temperature variable unit 43 so that the temperature of the first package 6 is near Tb. When the environmental temperature is higher than TH, it is preferable to control the driving of the third temperature variable unit 43 so that the temperature of the first package 6 is in the vicinity of Ta. By setting the temperature of the first package 6 within this range, the burden (work amount) of the first and second heaters 411a and 411b and the Peltier element 421a is reduced, and the first and second heaters 411a and 411b and the Peltier element 421a are reduced. Can be reduced in size, and power saving driving can be achieved. Further, the first and second heaters 411a and 411b and the Peltier elements 421a and 431a are excellent in driving balance (balance of work amount), that is, for example, there is no great difference in work amount between the Peltier elements 421a and 431a. The second heaters 411a and 411b and the Peltier elements 421a and 431a can be reduced in size uniformly, and also in this respect, power saving driving is possible.

  Next, the control unit 8 controls the driving of the first and second heaters 411a and 411b and the Peltier element 421a to set the gas cell 2 and the light emitting unit 5 to the predetermined temperatures Ta and Tb. As described above, after the temperature of the first package 6 is controlled by the third temperature variable unit 43, the first and second heaters 411a and 411b and the Peltier element 421a are started to be driven. The useless driving of the two heaters 411a and 411b and the Peltier element 421a is eliminated, and power saving driving is possible.

The control method of the atomic oscillator 1 has been described above. According to the atomic oscillator 1, the gas cell 2 and the light emitting unit 5 can be controlled to a predetermined temperature regardless of the environmental temperature, so that desired characteristics can be stably exhibited. In the first case, since the Peltier element 431a is not driven, power saving can be achieved. In addition, since the work of the first and second heaters 411a and 411b and the Peltier element 421a can be prevented from increasing, the apparatus can be downsized.
The atomic oscillator of the present invention has been described based on the illustrated embodiments. However, the present invention is not limited to these, and the configuration of each part may be replaced with an arbitrary configuration having the same function. Can do. Moreover, other arbitrary structures and processes may be added.

In the above-described embodiment, the first package is partitioned into two spaces by the partition portion, but the present invention is not limited to this, and the partition portion may be omitted.
In the above-described embodiment, the second package is provided. However, the present invention is not limited to this, and the second package may be omitted. In this case, the environmental temperature detection unit may be provided in the first package, and the temperature detection unit of the third temperature variable unit may also serve as the environmental temperature detection unit.

  DESCRIPTION OF SYMBOLS 1 ... Atomic oscillator 2 ... Gas cell 21 ... Main body 22, 23 ... Window part 3 ... Light detection part 41 ... 1st temperature variable part 411 ... Heating part 411a ... 1st heater 411b ... 1st 2 heaters 412 ... temperature detector 42 ... second temperature variable part 421 ... heating / cooling part 421a ... Peltier element 422 ... temperature detector 43 ... third temperature variable part 431 ... heating / cooling Section 431a ... Peltier element 432 ... Temperature detection section 5 ... Light emitting section 6 ... First package 6a ... Side 61 ... Partition section 7 ... Second package 8 ... Control section 9 ... Environment Temperature detector S1, S2 ... Space

Claims (8)

A gas cell;
A first temperature variable section having means for changing the temperature of the gas cell;
A light emitting portion for emitting excitation light for exciting gas atoms in the gas cell;
A second temperature variable unit having means for changing the temperature of the light emitting unit;
A first package that houses the gas cell, the first temperature variable unit, the light emitting unit, and the second temperature variable unit;
A third temperature variable unit having means for changing the temperature of the first package;
The driving of the first temperature variable unit, the second temperature variable unit, and the third temperature variable unit is controlled, and the temperature of the gas cell, the temperature of the light emitting unit, and the temperature of the first package are controlled. A control unit,
The atomic oscillator according to claim 1, wherein the control unit drives the third temperature variable unit when the environmental temperature is lower than a predetermined temperature TL or higher than a predetermined temperature TH higher than the TL.   The control unit stops the driving of the third temperature variable unit when the environmental temperature is equal to or higher than the TL and equal to or lower than the TH, and the first temperature variable unit and the second temperature variable unit are stopped. The atomic oscillator according to claim 1, wherein the atomic oscillator is driven to control each of the gas cell and the light emitting unit to a predetermined temperature.   2. The control unit controls the temperature of the first package to a temperature between Ta and Tb, where Ta is the predetermined temperature of the gas cell and Tb is the predetermined temperature of the light emitting unit. Or the atomic oscillator of 2. The third temperature variable unit includes a Peltier element,
4. The atomic oscillator according to claim 1, wherein one surface of the Peltier element is in contact with an outer surface of the first package. 5.   The atomic oscillator according to claim 4, further comprising a second package that houses the first package and the third temperature variable unit.   The atomic oscillator according to claim 5, wherein the second package is provided in contact with the other surface of the Peltier element. The atomic oscillator according to claim 5, wherein the second package is made of a material having a thermal conductivity of 14 (W · m ⁻¹ · K ⁻¹ ) or more.   The first package has a partition part that partitions the space in which the gas cell and the first temperature variable part are located and the space in which the light emitting part and the second temperature variable part are located, The atomic oscillator according to claim 1, wherein the partition portion is light transmissive.

Images