JPS6153879B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a miniaturized rubidium gas cell type atomic oscillator.

Atomic oscillators control crystal oscillators based on the permanently unchanging resonance frequencies of atoms and molecules.
Because of its extremely high long-term frequency stability, it is used as a frequency standard. Such atomic oscillators can be classified into active maser type, passive absorption type or atomic beam type, and gas cell type. Since the rubidium gas cell type atomic oscillator according to the invention can be constructed in a relatively small size, it is used as a frequency standard for various devices.

Such a rubidium gas cell type atomic oscillator has, for example, the configuration shown in FIG. That is, it is composed of an optical microwave section 11, a voltage controlled crystal oscillator 12, a frequency multiplier synthesizer 13, etc.
The optical microwave section 11 includes a lamp cell 1, a lamp excitation coil 2, a reflector 3, a lamp exciter 4, a filter cell 5, a cavity resonator 6, a gas cell 7, a photodetector 8, an amplifier 9, a multiplier 10, etc. has been done. Rubidium Rb exists in two types of isotopes in nature.
There are Rb ⁸⁷ and Rb ⁸⁵ , and in lamp cell 1
Rb ⁸⁷ , Rb ⁸⁵ is sealed in the filter cell 5, and Rb ⁸⁷ is sealed in the gas cell 7, and the high frequency output from the lamp exciter 4 is applied to the lamp excitation coil 2, so that the lamp cell 1 discharges and emits light. In this lamp cell 1
In addition to Rb ⁸⁷ , buffer gases include He, Hz, Ne, N ₂ ,
Generally, Ar, Kr, Xe, etc. are sealed.

Among the wavelength components of the light emitted from the lamp cell 1, unnecessary wavelength components are absorbed by the filter cell 5, and only the light of the desired wavelength component is transmitted to the gas cell 7.
is incident on the The oscillation output of the voltage controlled crystal oscillator 12 is multiplied by the frequency multiplier synthesizer 13 and the multiplier 10 to 6834.68 MHz, which is the resonance frequency of Rb ⁸⁷ , and is applied to the cavity resonator 6.

When the microwave applied to the cavity resonator 6 matches the resonant frequency of Rb ⁸⁷ in the gas cell 7, the light passing through the gas cell 7 is absorbed by optical microwave double resonance, thereby detecting the photodetector 8. Detection output decreases. This is identified and amplified by the amplifier 9 and used as the control voltage of the voltage controlled crystal oscillator 12. The oscillation frequency of the voltage controlled crystal oscillator 12 is as follows.
Since it is controlled based on the extremely stable resonance frequency of Rb ⁸⁷ , it is accurate and highly stable.

In order to miniaturize such a rubidium gas cell type atomic oscillator, the configuration shown in FIG. 2 has been proposed. In this figure, the same reference numerals as in FIG. 1 indicate the same parts, and 7a is a gas cell that serves both as a gas cell and a filter cell, in which Rb ⁸⁷ and Rb ⁸⁵ are sealed. In this configuration, unnecessary wavelength components of the light from the lamp cell 1 are absorbed into the gas cell 7a.
When the resonant frequency of Rb ⁸⁷ and the microwave frequency applied to the cavity resonator 6 match, the lamp cell 1 is absorbed by Rb ⁸⁵ due to optical microwave double resonance.
Since absorption of light occurs, the photodetector 8 detects this absorption. In this way, by having a configuration that combines a gas cell and a filter cell,
Compared to the configuration shown in FIG. 1, the optical microwave section can be made smaller.

An object of the present invention is to further reduce the size of the rubidium gas cell type atomic oscillator as described above and to provide an economical configuration. Examples will be described in detail below.

FIG. 3 is an explanatory diagram of an embodiment of the present invention, and the first
The same reference numerals as in the figure indicate the same parts, and 7
A is a gas cell that integrates a lamp cell, a filter cell, and a gas cell. In this gas cell 7A
Rb ⁸⁷ and Rb ⁸⁵ are sealed, and a light emitting section is formed in which a lamp excitation coil 2 is provided in a part thereof. When the high frequency output from the lamp exciter 4 is applied to the lamp excitation coil 2, high frequency discharge light emission is generated in the light emitting part of the gas cell 7A, and unnecessary wavelength components of the light are absorbed by Rb ⁸⁵ in the gas cell 7A. When the microwave frequency applied to the cavity resonator 6 and the resonance frequency of Rb ⁸⁷ match, light absorption occurs due to optical microwave double resonance, which is detected by the photodetector 8. As mentioned above, it controls a voltage controlled crystal oscillator.

When an atomic oscillator is configured with multiple cells as in the past, each cell has a slightly different optimal operating temperature, so it is necessary to insulate each cell and control the temperature independently, and the temperature fluctuations of each cell are synergistic. Although it affects frequency fluctuation, the gas cell 7 has a structure in which these are integrated as in the present invention.
In case A, if the temperature is kept constant at a predetermined temperature within the range of, for example, about 70 to 90°C, it will operate sufficiently stably. The present invention can achieve high stability and economy in that such temperature control can be performed at only one place.

As explained above, in the present invention, rubidium gas Rb ⁸⁷ for optical microwave double resonance and rubidium gas Rb ⁸⁵ that absorbs unnecessary wavelength components are mixed and sealed in the gas cell 7A of the optical microwave section 11. ,
This gas cell 7A is arranged inside the cavity resonator 6, and a part of the gas cell 7A is made to protrude outside the cavity resonator 6, and the lamp excitation coil 2 is wound around the protrusion. ,
Since the gas cell can be integrated into a cell structure, it has the advantage of being extremely compact.

Furthermore, since it has an integrated configuration, temperature control only needs to be done in one place, which makes temperature control easier and allows for highly stable control, and the circuit configuration is simplified, resulting in lower power consumption. There are advantages that can be achieved. Furthermore, since it is possible to output an oscillation frequency based on the resonance frequency of Rb ⁸⁷ , there is an advantage that highly stable oscillation output can be obtained.
Note that the integrated cell structure is not limited to the shape shown in the embodiments, as long as it has a protrusion around which the excitation coil 2 can be wound, and the shape of the cavity resonator 6, etc. It can be of any shape in relation to.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams of a conventional rubidium gas cell type atomic oscillator, and FIG. 3 is an explanatory diagram of an embodiment of the present invention. 2 is a lamp excitation coil, 4 is a lamp exciter, 6
7A is a cavity resonator, 7A is an integrated gas cell, 8
1 is a photodetector, and 11 is an optical microwave section.

Claims (1)

[Claims] 1. In a rubidium gas cell type atomic oscillator, rubidium gas for optical microwave double resonance and rubidium gas that absorbs unnecessary wavelength components are mixed and sealed in the gas cell of the optical microwave section to create a cavity resonator. What is claimed is: 1. An atomic oscillator characterized in that the atomic oscillator is constructed by forming a protruding part disposed inside the cavity resonator and partially protruding outside the cavity, and winding a lamp excitation coil around the protruding part.