JPS6358386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas cell type atomic oscillator using optical pumping, and more particularly to structural improvement of an optical microwave resonance part in a rubidium gas cell type atomic oscillator.

A rubidium gas cell type atomic oscillator is a highly stable oscillator that automatically controls a voltage-controlled crystal oscillator based on the resonance frequency of rubidium atoms, and is particularly excellent in long-term frequency stability. For this reason, this oscillator is used in various devices that require an oscillator with high frequency stability in communications, broadcasting, measurement, and the like.

Such a conventional rubidium gas cell type atomic oscillator generally has the configuration shown in FIG. That is, the oscillator is an optical microwave resonator 1
1, a voltage controlled crystal oscillator 12, a frequency multiplier synthesizer 13, and the like. The optical microwave resonator 11 includes a lamp cell (light source lamp) 1, a lamp excitation coil 2, a lamp container 3 having a reflecting mirror 3a, a lamp exciter 4, a filter cell 5, a cavity resonator 6, a resonant cell 7, and a light source. It is composed of a detector 8, a servo amplifier 9, a multiplier 10, heater windings 14, 15, 16, temperature controllers 17, 18, 19, etc.

Rubidium (Rb) has two types of isotopes, Rb ⁸⁷ and Rb ^85. In lamp cell 1, Rb ⁸⁷ is
Filter cell 5 contains Rb ⁸⁵ , and resonance cell 7
contains Rb ⁸⁷ . The lamp cell 1 emits high-frequency discharge light by a lamp exciter 4 via a lamp excitation coil 2. When this emitted light passes through the filter cell 5, unnecessary wavelengths of the light are absorbed by the filter cell 5, and only the desired wavelength components enter the resonance cell 7. Further, the output signal of the voltage controlled crystal oscillator 12 is guided to a predetermined circuit (not shown), and also to a frequency multiplier synthesizer 13 and a multiplier 10, and these devices 13 and 10 increase the frequency. The resonance frequency of rubidium Rb ⁸⁷ is increased to 6834.68 MHz (microwave) and input into the cavity resonator 6. When the frequency of the microwave input into the cavity resonator 6 completely matches the resonance frequency (6834.68...MHz) of rubidium Rb ⁸⁷ in the resonance cell 7,
A light-microwave double resonance occurs and the light from the filter cell 5 passing through the resonant cell 7 is absorbed by the resonant cell 7. For this reason, from the resonant cell 7 to the photodetector 8
Since the incident light on the photodetector 8 decreases, the detection output of the photodetector 8 decreases. The output signal of this photodetector 8 is input to the voltage controlled crystal oscillator 12 via the servo amplifier 9, and this signal causes the voltage controlled crystal oscillator 1 to
2 is controlled. Therefore, the output frequency of the crystal oscillator 12 is highly stable because it is controlled based on the extremely stable resonance frequency (6834.68...MHz) of rubidium Rb ⁸⁷ . In addition, in such a rubidium gas cell type atomic oscillator, the lamp cell 1 in the optical microwave resonance section 11,
Since the filter cell 5 and the resonance cell 7 have different optimum temperatures, they are generally temperature-controlled independently. Therefore, both the lamp housing 3 and the cavity resonator 6 also have the function of a heating tank, and the filter cell 5 is provided with a heating tank 5'. However, although the rubidium gas cell atomic oscillator configured in this way has high frequency stability,
It is extremely large-scale, has a large shape, has a complicated structure, and is expensive.

In order to miniaturize such a gas cell type atomic oscillator, an optical microwave resonator 11' having a configuration as shown in FIG. 2 has been proposed. In the figure, the same parts as in FIG. 1 mentioned above are given the same reference numerals. As shown, there is provided a single integrated cell 20 in which a mixture of rubidium Rb ⁸⁵ and Rb ⁸⁷ is encapsulated, which serves as the lamp cell 1, filter cell 5 and resonant cell 7 in FIG. 1 above. It serves as both. That is, the small diameter portion of the integrated cell 20 is a light source lamp (lamp cell).
The large diameter portion of the filter 20a is formed as a resonance cell 20b which also serves as a filter cell. Further, a cavity resonator 6' is provided which is formed by integrating the lamp container 3 and the cavity resonator 6 shown in FIG. 1 and has the functions of both. In this way, since only one integrated cell 20 is required instead of the various cells shown in FIG. 1, the structure of the optical microwave resonator 11' is extremely simple, and the shape is also significantly reduced. . In this case as well, the cavity resonator 6' also functions as a heating tank for the integrated cell 20.

In addition, in the rubidium gas cell atomic oscillator shown in FIG. 1 or 2, each heating tank for maintaining each cell at its optimum operating temperature has heating heater windings 14, 15, and 16 on its outer periphery, respectively. The heating power is controlled by temperature controllers 17, 18, and 19. In particular, in the microwave resonator 11 having the conventional general configuration shown in FIG. 1, it is necessary to provide a through hole for light passage in the end wall of the heating tank of each cell. For this reason, each cell is housed in a very imperfect heating tank and is susceptible to the effects of outside temperature. Moreover, the structure of the heating device is complicated and assembly is also cumbersome. Furthermore, in the microwave resonator 11' having the configuration shown in FIG. 2, the integrated cell 20 can be completely surrounded by a heating tank made of a material with high thermal conductivity, such as aluminum or copper. Temperature effects and assembly complexity are reduced. However, this microwave resonator 11'
However, it is still not completely satisfactory in terms of its miniaturization, complexity of assembly, etc.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a gas cell type atomic oscillator in which the structure of the optical microwave resonance part in the rubidium gas cell type atomic oscillator is further miniaturized and simplified.

To achieve this objective, according to the invention:
In the optical microwave resonator of a gas cell type atomic oscillator, a heating tank that integrates a cavity resonator and a container for an optical pumping lamp is formed of a material with good thermal conductivity, and a cylindrical cylinder is placed inside the heating tank. A cylindrical dielectric is inserted, an integrated cell is mounted inside the cylindrical dielectric, and the heating tank is mounted on the printed board so as to be in close contact with a heating transistor mounted on the printed board. A gas cell type atomic oscillator is provided, characterized in that a temperature control circuit for a heating transistor and a lamp excitation circuit for the optical pumping lamp are mounted on the same printed board.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 3 is a cross-sectional view of the microwave resonance part 11'' in the gas cell type atomic oscillator according to the embodiment of the present invention;
FIG. 4 is an exploded perspective view of the microwave resonator 11'' in FIG. 3. In the figure, the same parts as in FIG. 6'' is a cavity resonator, 8 is a photodetector, 20 is an integrated cell, 21 is a heating transistor, 22 is a dielectric, and 23 is a printed board. As in the case of FIG. 2, the cavity resonator 6'' is a combination of a lamp container and a cavity resonator, and also functions as a heating tank for the integrated cell 20. The integrated cell 20 also functions as a lamp cell (light source lamp), a filter cell, and a resonance cell, and its small diameter portion is formed as a light source lamp 20a, and its large diameter portion is formed as a resonance cell 20b that also serves as a filter cell. Although not shown, a temperature control circuit and a lamp excitation circuit are mounted on the printed board 23, and a heating transistor 21 is integrated with the heating tank (i.e., the cavity resonator 6''). It has been implemented in such a way that it can be combined. Generally, in a heating tank that is large in shape and has a large heat capacity, by heating with a heater winding,
Although it is possible to obtain a uniform temperature distribution, it is difficult to obtain a uniform temperature distribution because heating using only a heating transistor causes the heated portion to be localized. The conventional resonant cell heating tank (ie, cavity resonator) described above is so large that it is impossible to heat it using only a heating transistor. Therefore, in the present invention, as shown in FIG. 3, by inserting a cylindrical dielectric material 22 into the peripheral space inside the cavity resonator 6'', it is possible to downsize the cavity resonator 6''. , has been significantly downsized. The dielectric 22 is made of a material with low high-frequency loss, such as Teflon (registered trademark), and has a higher dielectric constant than air, making it possible to downsize the cavity resonator 6''. Therefore, the cavity resonator 6'' miniaturized in this way is formed from a material with good thermal conductivity such as aluminum or copper, and the heating transistor 2
1 is closely fixed to a heating tank (ie, cavity resonator 6'') and heated, sufficient heating efficiency and temperature uniformity can be obtained without using a heater winding.
Therefore, by integrally combining this heating tank (cavity resonator 6'') and the heating transistor 21 on the printed board 23, the structure is extremely simple, easy to assemble, and the shape is small. It is possible to form an optical microwave resonance section 11''. As shown in FIG.
(See FIG. 4), they can be easily and closely connected to each other.

In addition, in the above embodiment, the heating transistor 21
Although the case where there is one is illustrated, this may be increased to a plurality of numbers. For example, another heating transistor can be embedded in the end face location A (FIG. 3) of the cavity resonator 6''. In this case, a plurality of heating transistors may be connected in parallel or in series. As a result, the heating power is shared between each transistor and the heating locations are dispersed, making it easy to obtain a uniform temperature distribution even in a heating tank with a relatively large volume. By making appropriate selections, it is possible to finely change the temperature distribution of each heated portion, and therefore the same effect as adjusting the density of the heater winding or adjusting the temperature sensor placement position in a conventional heating tank can be obtained.

It is also possible to closely fix the light source lamp excitation transistor to the heating tank (cavity resonator 6'') at the same time as the heating transistor 21. In this case, the power consumption of the light source lamp excitation transistor can also be used for heating. Since it can be used effectively, the power consumption of the atomic oscillator is reduced.

Furthermore, although the above embodiment shows an example in which the dielectric 22 is inserted into the cavity resonator 6'', the present invention is not limited to this, and the excitation mode of the cavity resonator 6'' is changed. This allows for miniaturization.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of a conventional general gas cell type atomic oscillator, and FIG. 2 is an explanatory diagram of the configuration of a conventional optical microwave resonator proposed to miniaturize the atomic oscillator shown in FIG. 1. FIG. 3 is a diagram showing an embodiment of the optical microwave resonance section in the atomic oscillator according to the present invention, and FIG. 4 is an exploded perspective view of the optical microwave resonance section of FIG. 3. 1, 20a...Lamp cell (light source lamp), 2
... Lamp excitation coil, 3 ... Lamp container, 4
... Lamp exciter, 5 ... Filter cell, 6,
6', 6''... Cavity resonator, 7, 20b... Resonance cell, 8... Photodetector, 11, 11', 11''... Optical microwave resonator, 12... Voltage controlled crystal oscillator, 13... Frequency multiplier/synthesizer, 14, 15,
16... Heater winding, 17, 18, 19... Temperature controller, 20... Integrated cell, 21... Heating transistor, 22... Dielectric, 23... Printed board, 24... Fixing screw.

Claims (1)

[Claims] 1. In the optical microwave resonator of the gas cell type atomic oscillator, a heating tank that integrates the cavity resonator and the container for the optical pumping lamp is formed of a material with good thermal conductivity, and inside the heating tank A cylindrical dielectric is inserted, an integrated cell is mounted inside the cylindrical dielectric, and the heating tank is mounted on the printed board so as to be in close contact with a heating transistor mounted on the printed board. A gas cell type atomic oscillator, characterized in that a temperature control circuit for the heating transistor and a lamp excitation circuit for the optical pumping lamp are mounted on the same printed board.