JPS59207747A - Light source lamp driver for atomic oscillator - Google Patents

Abstract

PURPOSE:To sharply improve the frequency stability of an atomic oscillator, by comparing an output obtained when detecting the quentity of light of a lamp with a reference voltage and controlling the feedback so as to change a driving power to the lamp in accordance with the differential voltage. CONSTITUTION:The lamp 12 of an atomic resonator 15 receives its driving power from a voltage controlling lamp driver 11 and emits light. A resonance cell 14 contained in a cavity resonator 13 is driven by an external microwave. The light generated by the lamp 12 is detected by a photodetector 16 after passing through the cell 14 and generates an electric signal of a DC voltage in accordance with the detected intensity. The electric signal is amplified 17 and used for controlling the frequency of the driving microwave. Moreover, the voltage of the detector 16 is compared with a reference voltage by a comparator 18 and the differential voltage is outputted from the comparator 18. A control voltage generator 19 generates a control voltage corresponding to the differential voltage and feeds back the control voltage to the driver 11 to control the varactor diode of an oscillator. Therefore, the lamp is automatically controlled so that its quantity of light is always fixed at a constant value.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a light source lamp exciter for optical bombing in an atomic oscillator using an optical bombing method, and in particular to a light source for an atomic oscillator whose emission intensity is stabilized using feedback control. It concerns lamp exciters.

Prior Art and Problems An atomic oscillator using the optical bombing method includes a light source lamp, and the light generated from the light source lamp excites rubidium (Rh') atoms sealed in a resonant cell. When microwaves are externally applied to excited atoms and the frequency matches the resonance frequency of rubidium (RA) atoms, the excited atoms undergo stimulated emission and return to the ground level. Taking advantage of the fact that the absorption of light in the resonant cell is strongest at this time, the oscillation frequency of the crystal oscillator, which is the source of the microwave, is controlled to obtain a stable frequency.

Such a light source lamp for bombing generally uses rubidium (Rh) sealed in a glass cell and a suitable gas to generate a still frequency discharge of several + MHg to 100 MHg and 100 degrees Hg using an oscillator to emit light. It is being

FIG. 1 shows a conventional light source lamp and its excitation circuit. In the figure, reference numeral 1 denotes a lamp cell in which rubidium (RA) and a suitable gas are sealed. An excitation coil L is wound around the lamp cell 1 several times, and the excitation coil L constitutes a series resonant circuit together with a capacitor CV, and is connected in parallel between the base and collector of the transistor T to generate 50 oscillations. forming a circuit.

Here, R1 and R are bias resistances, R3 is an emitter resistance, and cl and c are feedback capacitors.

In the circuit shown in FIG. 1, high-frequency oscillation is generated at a frequency approximately determined by the inductance of the excitation coil L and the capacitance of the capacitor CV, and this high-frequency power excites the gas in the lamp cell 1 to cause discharge and emit light.

The excitation power of the light source lamp is affected by variations in the inductance of the excitation coil, variations in circuit equivalent constants, and even variations in the internal impedance of the excited lamp itself. Excitation power and emission intensity are generally in a proportional relationship, and therefore the emission intensity of the lamp varies depending on the variation in excitation power.(3) The emission intensity of the light source lamp is one of the factors that greatly influences the frequency stability of the atomic oscillator. It is. For example, as the emission intensity increases, the long-term stability or frequency-temperature characteristics of the atomic oscillator deteriorates, and the lamp life tends to become shorter. On the other hand, if the emission intensity is too low, the atomic resonance signal becomes small and the short-term frequency stability of the atomic oscillator deteriorates.

In order to achieve high stability in the atomic oscillator as described above, it is necessary to adjust the excitation power in order to eliminate fluctuation factors due to various variations and to select an appropriate value for the luminous intensity of the lamp. Conventionally, for this purpose, a variable capacitor such as a trimmer capacitor was used as the capacitor CV constituting the resonant circuit, and by adjusting the variable capacitor, the oscillation intensity was adjusted and the excitation power was set at an appropriate level.

Figure 2 shows an example of the relationship between the lamp excitation power and the variable capacitor (1'V) in the circuit of Figure 1. In the figure, the vertical axis represents the excitation power value, and the horizontal axis represents the capacitance value. , it is shown that as the capacitance of the variable capacitor Cv increases (4), the excitation power decreases5. Therefore, by using this relationship to adjust the capacitance value of the variable capacitor Cv, Lamp excitation power can be set to an appropriate level.

However, the light source lamp excitation circuit shown in FIG.
Since its oscillation frequency is relatively high, in order to operate the excitation circuit stably, it is necessary to place circuit components including the capacitor Cv near the light source lamp. For this reason, it has been impossible to install the variable capacitor CV away from the light source lamp so that it can be easily adjusted from the outside.

Furthermore, even if the lamp emission intensity is adjusted to an appropriate level in this way, there are many other factors that can cause fluctuations in the emission intensity, such as stabilizing the power supply voltage of the exciter,
Alternatively, measures have been taken to reduce the effects of temperature changes, such as placing an excitation circuit near the constant temperature bath for the lamp, but it is difficult to completely stabilize the lamp emission intensity, and for this reason the lamp emission Stabilizing the strength has been one of the challenges in achieving high stability in atomic oscillators.

OBJECTS OF THE INVENTION The present invention attempts to solve the problems of the prior art, and its purpose is to adjust and stabilize the emission intensity of a pumping light source lamp in an atomic oscillator to an appropriate value. An object of the present invention is to provide an excitation circuit that can electronically control the excitation type and force of a lamp exciter that is dominant to the luminous intensity.

Embodiment of the Invention FIG. 6 shows the structure of an embodiment of the light source lamp exciter for an atomic oscillator according to the present invention. In the figure, 11 is a voltage controlled lamp exciter, 12 is a lamp, 16 is a cavity resonator, 1
4 is a resonance cell, 15 is an atomic resonator, 16 is a photodetector, 1
7 is a signal amplifier, 18 is a comparator, and 19 is a control voltage generator.

In FIG. 6, lamp 12 is connected to voltage-controlled lamp exciter 1
Excited type by 1, it emits light when given a force. The resonance cell 14 is housed within the cavity resonator 13, and by applying microwave power to the cavity resonator 15 from the outside,
Excited by microwaves. The light generated by the lamp 12 passes through the resonant cell 14 and reaches the photodetector 16, which generates an electric signal consisting of a direct current voltage whose magnitude corresponds to the intensity of the light.

The electrical signal generated by the photodetector 16 is supplied to a frequency control system (not shown) via a signal amplifier 17, thereby controlling the frequency of the excitation microwave. Voltage controlled lamp exciter 11. Lamp 12. Cavity resonator 16. Resonance cell 14 and photodetector 16 form an atomic resonator 15 .

On the other hand, a part of the electrical signal output from the photodetector 16 is transmitted to the comparator 18.
The comparator 18 compares this with a constant reference voltage and outputs the difference voltage between the two.

The control voltage generator 19 generates a control voltage according to this differential voltage and feeds it back to the voltage controlled lamp exciter.

By configuring such a closed loop, feedback control is performed to control the excitation power of the voltage-controlled lamp exciter so that the output of the photodetector 16 is always constant. Since the output voltage of the photodetector 16 is proportional to the amount of lamp light it receives, the feedback control described above will keep the photodetector output pressure constant (7). By performing such control, the amount of lamp light will always be constant. Automatic control is performed to keep it constant. Note that the lamp light amount level during control can be arbitrarily set by changing the reference voltage value in the comparator 18.

In this way, according to the embodiment shown in FIG. 5, it is possible to suppress the change in the light intensity of the lamp, which is the most dominant factor in the characteristics of the atomic oscillator, to an extremely small level, and therefore, it is possible to suppress the change in the light amount of the lamp, which is the most dominant factor in the characteristics of the atomic oscillator, and therefore to improve the stability of the atomic oscillator. It is valid.

Although the embodiment of FIG. 2 has been described with reference to the case where it is applied to a gas cell type atomic oscillator, it goes without saying that the present invention can also be applied to a beam type atomic oscillator using optical pumping.

FIG. 4 shows an example of the configuration of the voltage-controlled lamp exciter in the embodiment shown in FIG. 'In the same figure, the same parts as in Figure 1 are indicated by the same reference numerals, and D
l is a varactor diode, C3 is a DC cut capacitor, and R4 is a high frequency blocking resistor.

In FIG. 4, an excitation coil (8) L for the lamp cell 1 is connected to a varactor diode D! via a DC cut capacitor C3. A series resonant circuit formed by the inductance of the excitation coil L and the equivalent capacitance of the varactor diode D1 is connected in parallel between the base and collector of the transistor Tr, thereby operating as an LC oscillation circuit. The series resonant circuit generates high frequency oscillation at a substantially fixed frequency, and the lamp cell 1 can be excited by this high frequency power. At this time, the equivalent capacitance of the varactor diode Dl changes depending on the control voltage Vc applied via the high frequency blocking resistor R4. Therefore, from the relationship shown in FIG. 2, the excitation voltage for the lamp cell 1 can be set arbitrarily by adjusting the control voltage Ve.

In the embodiment of the invention shown in FIG. 3, voltage control is achieved by controlling the varactor diode D1 in the voltage controlled lamp exciter 11 shown in FIG. lamp exciter 1
1 to the lamp 12 is kept constant, thereby suppressing the change in the lamp light intensity level as described above, and stabilizing the frequency in the atomic oscillator. Unlike conventional circuits, there is no need to draw out the variable capacitor to the outside, so structural difficulties in constructing the atomic resonator are eliminated.

As described in detail, according to the light source lamp exciter for an atomic oscillator of the present invention, the output obtained by detecting the light amount of the lamp is compared with the reference voltage, and the excitation power for the lamp is adjusted according to the error voltage. Since the feedback control is performed so that the lamp excitation power is always constant by changing the output power, the light intensity of the optical bombing lamp is stabilized, and therefore the frequency stability of the atomic oscillator can be improved. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional light source lamp and its excitation circuit;
2 is a diagram showing an example of the relationship between lamp excitation power and variable capacitor capacity in the circuit of FIG. 1, FIG. 6 is a diagram showing the configuration of an embodiment of the light source lamp exciter for an atomic oscillator of the present invention, FIG. 4 is a diagram showing an example of the configuration of the voltage-controlled lamp exciter in the embodiment shown in FIG. 6. DESCRIPTION OF SYMBOLS 1... Lamp cell, 11... Voltage controlled lamp exciter, 12... Lamp, 16... Cavity resonator, 14...
- Resonance cell, 15... Atomic resonator, 16... Photodetector, 17... Signal amplifier, 18... Comparator, 19.
...Control voltage generator, L...Excitation coil, Cv...
Variable capacitor, Tr...transistor, Dl...
Varactor diode, C1゜C2,c,...Capacitor, R11R2v R3g R4...Resistance Patent applicant Fujitsu Limited Representative patent attorney Tama Mushikugo Department (1 other person) (11) Procedural amendment (voluntary) February 17, 1981 1, Indication of the case 1988 Patent Application No. 81488 2, Name of the invention Light source lamp exciter for atomic oscillator 3, Person making the amendment Relationship with the case Patent applicant Address Kanagawa Prefecture 1015 Kamiodanaka, Nakahara-ku, Saki-shi Name (522) Fujitsu Limited Representative Takashi Yamamoto 4, Agent address 2-5-2 Minami-Nagasaki, Toshima-ku, Tokyo Name (
7139) Patent Attorney Tamamushi Gobe 5, Number of inventions increased by amendment None 6, Subject of amendment Full text of specification and drawings. 7. Contents of amendment The entire specification and Figure 3 of the drawing are amended as shown in the attached sheet. Description 1, Title of the invention Atomic oscillator 2, Claims In an atomic oscillator equipped with a light source lamp exciter for an atomic oscillator that excites a light bombing lamp for excitation of atoms, the light intensity of the lamp is detected. A photodetector that generates an output according to the amount of light, a comparator that compares the output voltage of the photodetector with a reference voltage and outputs an error voltage, and a series circuit of a lamp excitation coil and a varactor diode are used as resonant elements. 3. Detailed Description of the Invention Technical Field of the Invention The present invention relates to an optical pumping method in an atomic oscillator using an optical pumping method. The present invention relates to a light source lamp exciter for commercial use, and in particular relates to an atomic oscillator (1) in which the emission intensity is stabilized using feedback control. Prior Art and Problems An atomic oscillator using an optical pumping method is equipped with a light source lamp, and rubidium (Rh) atoms sealed in a resonant cell are excited by light generated from the light source lamp. When microwaves are applied externally to excited atoms, and when the frequency matches the resonance frequency of the rubidium (Rh) atom, the excited atoms undergo stimulated emission and return to the ground level, and the light from the light source lamp is emitted again. is excited by Taking advantage of the fact that the absorption of light in the resonant cell is strongest at this time, the oscillation frequency of the crystal oscillator, which is the source of the microwave, is controlled to obtain a stable frequency. Such a light source lamp for bombing generally has a power of several tens of MHz.
The device used is one in which a high frequency oscillator with a frequency of approximately 100 MHz to 100 MHz causes a high frequency discharge in rubidium (Rh) sealed in a glass cell and a suitable gas to emit light. FIG. 1 shows (2) a conventional light source lamp and its excitation circuit. In the same figure (=, 1 indicates a lamp cell, and rubidium (Rh) and a suitable gas are sealed inside. An excitation coil L is wound around the lamp cell 1 several times, and the excitation coil L is connected to a capacitor C2. Together, they form a series resonant circuit, and two (parallel) connections between the base and collector of the transistor Tr form an LC oscillation circuit. Here, R,, R, are bias resistances, R3
is an emitter resistor, and C1 and C are feedback capacitors. In the circuit shown in FIG. 1, high-frequency oscillation is generated at a frequency approximately determined by the inductance of the excitation coil L and the capacitance of the capacitor Cr, and the lamp cell 1 is excited by this high-frequency power to cause discharge and emit light. The excitation power of the light source lamp is affected by variations in the inductance of the excitation coil, variations in circuit equivalent constants, and even variations in the internal impedance of the excited lamp itself. There is generally a proportional relationship between the excitation power and the luminous intensity, and therefore, variations in the excitation power cause variations in the luminous intensity of the lamp (3). The emission intensity of the light source lamp is one of the factors that greatly influences the frequency stability of the atomic oscillator. For example, as the emission intensity increases, the long-term stability or frequency-temperature characteristics of the atomic oscillator deteriorates, and the lamp life tends to become shorter. And vice versa (
If the double emission intensity is too small, the atomic resonance signal becomes small, which deteriorates the short-term frequency stability of the atomic oscillator. In order to achieve high stability in the atomic oscillator as described above, it is necessary to adjust the excitation power in order to remove fluctuation factors based on various variations and to select the lamp's emission intensity to an appropriate value. Conventionally, for this purpose, a variable capacitor such as a trimmer capacitor was used as the capacitor Cr constituting the resonant circuit.
By adjusting this, the oscillation intensity is adjusted and the excitation power is set at an appropriate level. FIG. 2 shows an example of the relationship between the lamp excitation power and the capacitance of the variable capacitor CV in the circuit of FIG. In the figure, the vertical axis shows the excitation power value, and the horizontal axis shows the capacitance value, and it is shown that the excitation power decreases as the capacitance of the variable capacitor amplifier r increases (4). Therefore, by utilizing this relationship and adjusting the capacitance value of the variable capacitor C, the lamp excitation power can be set to an appropriate level. However, the light source lamp excitation circuit shown in FIG.
Since its oscillation frequency is relatively high, in order to operate the excitation circuit stably, it is necessary to place circuit components including the capacitor C near the light source lamp. For this reason, it has been impossible to install the variable capacitor CF away from the light source lamp so that it can be easily adjusted from the outside. Furthermore, even if the lamp emission intensity is adjusted to an appropriate level in this way, there are many other factors that can cause fluctuations in the emission intensity, such as stabilizing the power supply voltage of the exciter,
Alternatively, measures have been taken to reduce the effects of temperature changes, such as placing a C-2 excitation circuit near the thermostat for the lamp, but it is difficult to completely stabilize the lamp emission intensity, and therefore the lamp Stabilizing the emission intensity is one of the challenges in achieving high stability of atomic oscillators (
5) There was. OBJECT OF THE INVENTION The present invention attempts to solve the problems of the prior art, and its purpose is to adjust and stabilize the emission intensity of a pumping light source lamp in an atomic oscillator to an appropriate value. Therefore, it is an object of the present invention to provide an exciter that can electronically control the excitation power of the lamp exciter that is dominant with respect to the emission intensity, and an atomic oscillator that stabilizes the amount of light using this exciter. Embodiment of the Invention FIG. 3 shows the structure of an embodiment of the atomic oscillator of the invention. In the figure, 11 is a voltage controlled lamp exciter;
2 is a lamp, 13 is a cavity resonator, 14 is a resonance cell, 15
is an atomic resonator, 16 is a photodetector, 17 is a signal amplifier, 1
8 is a comparator, and 19 is a control voltage generator. In FIG. 3, the lamp 12 is connected to the voltage controlled lamp exciter 1
1 provides excitation power and emits light. The resonance cell 14 is housed in a cavity resonator 16, and microwave power cannot be applied to the cavity resonator 13 from the outside (6).
) is excited by microwaves. The light generated by the lamp 12 passes through the resonant cell 14 and reaches the photodetector 16, which generates an electric signal consisting of a direct current voltage whose magnitude corresponds to the intensity of the light. The electrical signal generated by the photodetector 16 is supplied to a frequency control system (not shown) via a signal amplifier 17.
This controls the frequency of the excitation microwave. Voltage controlled lamp exciter 11. Lamp 12, cavity resonator 1
3. Resonance cell 14 and photodetector 16 are atomic resonators 15
is formed. On the other hand, a part of the electrical signal output from the photodetector 16 is transmitted to the comparator 18.
The comparator 1 compares this with a constant reference voltage and outputs the difference voltage between the two. The control voltage generator 19 generates a control voltage corresponding to this differential voltage C2 and feeds it back to the voltage controlled lamp exciter. By configuring such a closed loop, the excitation power of the voltage-controlled lamp exciter is controlled so that the output of the photodetector 16 is always constant C2. Feedback control is performed. Since the output voltage of the photodetector 16 is proportional to the amount of lamp light it receives, the amount of lamp light can be increased by controlling the feedback side (7) as described above so that the photodetector output voltage is constant. Automatic control is performed so that the lamp light level remains constant at all times.The lamp light intensity level during this control can be arbitrarily set by changing the reference voltage value in the comparator 18. According to the embodiment shown in Fig. 3, it is possible to suppress the light intensity change of the lamp, which is the most dominant factor in the characteristics of the atomic oscillator, to an extremely small level, and is therefore very effective in stabilizing the atomic oscillator. Although the embodiment shown in Fig. 2 has been described with reference to the case where it is applied to a gas cell type atomic oscillator, it goes without saying that the present invention can also be applied to a beam type atomic oscillator using optical pumping. 6 shows an example of the configuration of the voltage controlled lamp exciter according to the embodiment shown in FIG.
The same parts as in the figure are indicated by the same symbols, D,
is a varactor diode, C3 is a DC cut capacitor, and R is a high frequency blocking resistor. (8) In FIG. 4, the excitation coil L for the lamp cell 1 is connected in series with the varactor diode D1 via the DC cut capacitor Cs', and is formed by the inductance of the excitation coil L and the equivalent capacitance of the varactor diode D. A series resonant circuit connected in parallel between the pace and collector of the transistor Tr operates as an LC oscillator circuit, and this series resonant circuit generates high frequency oscillation with a frequency that is approximately determined. At this time, the equivalent capacitance of the varactor diode D1 changes according to the control voltage VC applied via the high frequency blocking resistor R+w. Therefore, as shown in FIG. Accordingly, the excitation voltage for the lamp cell 1 (2) can be arbitrarily set. In the embodiment of the invention shown in FIG. The voltage-controlled lamp exciter 11 is controlled by controlling the varactor diode D by the voltage generated by the control voltage generator 19.
It is possible to control the oscillating power of the lamp 12 (2), thereby suppressing changes in the lamp light intensity level as described above, and to stabilize the frequency in the atomic oscillator. Unlike the conventional circuit shown in Figure 1, there is no need to pull out a variable capacitor to the outside to adjust the excitation power, so structural difficulties in constructing an atomic resonator are eliminated.Details of the Invention As explained (2), according to the light source lamp exciter for an atomic oscillator of the present invention, the output obtained by detecting the light amount of the lamp is compared with the reference voltage, and the excitation power for the lamp is adjusted according to the error voltage. Since the atomic oscillator's frequency stability can be greatly improved, the atomic oscillator's frequency stability can be greatly improved. 4. A brief explanation of the drawings. Figure 1 is a diagram showing a conventional light source lamp and its excitation circuit. (10) A diagram showing the configuration of an embodiment of the atomic oscillator of the present invention, and FIG. 4 is a diagram showing an example of the configuration of the voltage-controlled lamp exciter in the embodiment shown in FIG. 3. 1. - Lamp cell, 11... Voltage controlled lamp exciter, 12... Lamp, 13... Cavity resonator, 14...
・Resonance cell. 15... Atomic resonator, 16... Photodetector, 17...
・Signal amplifier, 1st... Comparator, 19... Control voltage generator, L... Excitation coil, Cr... Variable capacitor, Tr... Transistor, D... Varactor diode, C ,,C,,C3...Capacitor,R,,R
,,R3,R,,,resistance (11)

Claims (1)

[Claims] In a light source pump exciter for an atomic oscillator that excites a light bombing lamp for excitation of atoms in an atomic oscillator, a photodetector that detects the amount of light of the lamp and generates an output according to the amount of light, and the photodetector. It has a comparator that compares the output voltage of the device with a reference voltage and outputs an error voltage, and an LC oscillator that includes a series circuit of a lamp excitation coil and a varactor diode as a resonant element, and a DC bias of the varactor diode. A light source lamp exciter for an atomic vibration isolator, characterized in that it is configured to apply the error voltage.