JPS5917903B2 - atomic oscillator - Google Patents

Description

[Detailed description of the invention] The present invention relates to an atomic oscillator.

Atomic oscillators, which control crystal oscillators based on the permanently unchanging resonance frequencies of atoms and molecules, are used as frequency standards because they have extremely high long-term frequency stability.

Such atomic oscillators can be classified into active maser type, passive absorption type, atomic beam type, gas cell type, etc. Among them, optical pumping method is used. Passive 5
Rubidium gas cell type atomic oscillators based on the gas cell system can be constructed in a relatively small size, so they are used as frequency standards for various devices. Such a rubidium gas cell type atomic oscillator has, for example, the configuration shown in FIG.

That is, the optical microwave section 11 and the voltage controlled crystal oscillator 12
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,
It is composed of a gas cell 7, a photodetector 8, an amplifier 9, a multiplier 10, etc. Rubidium Rb exists in two types of isotopes Rb87 and Rb85 in nature.Rb87 is sealed in the lamp cell 1, Rb85 is filled in the filter cell 5, and Rb87 is sealed in the gas cell T, and the high frequency output from the lamp exciter 4 is j0 When applied to the lamp excitation coil 2, the lamp cell 1 discharges light. This lamp cell 1 has Rb
In addition to 87, buffer gases include He, H2, Ne, N2,
Generally, Ar, Kr, Xe, etc. are sealed. j
Among the wavelength components of the light generated from the five-lamp cell 1, unnecessary wavelength components are absorbed by the filter cell 5, and only the light of the desired wavelength component is incident on the gas cell 7.

The oscillation output of the voltage controlled crystal oscillator 12 is multiplied by the frequency multiplier synthesizer 13 and the multiplier 10 to 683468...MH2, which is the resonant frequency of j0Rb87, and is applied to the cavity resonator 6. When the microwave applied to the cavity resonator 6 matches the resonant frequency of Rb8'' in the gas cell T, the light 5 passing through the gas cell T is absorbed by optical microwave double resonance, thereby allowing optical detection. The detection output of the device 8 decreases.

This is identified and amplified by an amplifier 9 and used as a control voltage for the voltage controlled crystal oscillator 12.
Since the oscillation frequency of No. 2 is controlled based on the extremely stable resonance frequency of Rb87, it is accurate and highly stable. The present invention provides an improvement to the lighting means for light source lamps that use atomic oscillators. The aim is to provide the means to do so. Conventionally, when lighting such a light source lamp, an excitation coil wound around a single lamp cell is
A high-frequency power of 0 to 100 MHz is applied to excite the gas in the lamp cell, causing a discharge and lighting the lamp.
Even after lighting, the high-frequency power is applied while maintaining the power at the time of lighting, and the magnetic field applied to the high-frequency power causes the lighting to continue.
With this kind of lighting/maintenance means, the same power as when lighting is started continues to be applied during lighting maintenance, which shortens the life of the lamp and also reduces the atomic oscillator's Temperature characteristics and long-term stability will deteriorate.

If the value of high-frequency power is made small, the life of the lamp will be improved, but lighting will become difficult. Moreover, conventionally, instead of such means, for example, as shown in FIG.
At the time of lighting, a high voltage pulse is applied to the lamp cell 21 from the pulse generator 22 to forcefully start discharging (lighting). The numeral 23 is a lamp exciter for maintaining lighting. According to such lighting means, discharge can be maintained after lighting using low high frequency power. Therefore, the lamp life, temperature characteristics as an atomic oscillator, long-term stability, etc. are improved. However, such means requires a pulse generator 22, which requires further downsizing and
This is not preferable when constructing an atomic oscillator that requires high reliability. The present invention aims to eliminate the problems of the prior art and to provide a configuration of an atomic oscillator that can start lighting (discharge) using a simpler means. Therefore, according to the present invention, in addition to the excitation coil for maintaining lighting of the lamp on the outer periphery of the light source lamp, a lighting starting electrode that is connected to ground and does not have a driving source itself is provided near the excitation coil for maintaining lighting of the lamp. According to the present invention, it is basically proposed to utilize a high frequency electric field as a lamp lighting means.

That is, as shown in FIG. 3, a lighting (discharge maintaining) excitation coil 32, which is also wound around the lamp cell 31 and placed at the ground potential, is placed near the excitation coil 32 for lighting maintenance (discharge maintenance) wound around the lamp cell 31. ) A starting electrode (coil) 33 is provided. In this configuration, the lamp exciter 3
4 to the excitation coil 32, a strong high frequency electric field is generated between the lighting start electrode 33 connected to the ground, and the gas in the lamp cell corresponding to that part is first excited. , when it discharges and lights up,
This spreads to other parts of the lamp cell, causing the entire lamp cell to light up.
After lighting, this state is maintained by high frequency power (magnetic field) supplied from the lamp exciter 34. Therefore, according to the present invention, there is no need to apply large excitation power or high-voltage pulses to the light source lamp cell during gas excitation, which improves the life of the light source lamp and improves the life of the atomic oscillator. This is extremely advantageous in achieving miniaturization and high reliability. Specifically, in the lamp cell configuration shown in FIG. 3, the distance between the excitation coil 32 and the lighting start electrode (coil) 33 is selected depending on the size of the lamp cell, the value of the discharge sustaining power, etc.

The present invention can also be applied to other optically pumped atomic oscillators, such as optically pumped atomic beam atomic oscillators.

Furthermore, the shape of the lamp cell, the position and form of each electrode are not limited to the above embodiments.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one example of the configuration of an atomic oscillator, FIG. 2 is a diagram showing conventional light source lamp lighting and lighting maintenance means, and FIG. 3 is a light source lamp lighting and lighting maintenance means according to the present invention. FIG. In the drawings, 31... light source lamp, 32...
. . . Excitation coil for lighting maintenance, 33 . . . Lighting starting electrode, 34 . . . Lamp exciter.

Claims (1)

[Claims] 1. A lighting starting electrode is disposed on the outer periphery of a light source lamp together with an excitation coil for lighting maintenance of the lamp and near the excitation coil for lighting maintenance, and the lighting starting electrode is connected to ground. An atomic oscillator characterized by: