RU2810720C1 - Method and device for extracting rotation information in four-frequency zeeman laser gyroscope - Google Patents

Abstract

FIELD: laser technology.

SUBSTANCE: method for extracting information about rotation in a four-frequency Zeeman laser gyroscope includes obtaining sine-cosine signals for heterodyning the beat frequencies of counterpropagating waves of two longitudinal orthogonal modes using an optical mixer, separating the beat signals of these modes, counting for each half-cycle of the synchronizing signal the number of pulses of the beat frequency of the modes using a counter block, calculating the rotation frequency and the perimeter detuning signal using a processor, while using an electronic mode separation device, the sine-cosine heterodyning signals of the mode beat frequencies are converted into two signals, in one of which, during the first half-cycle of the clock signal, a signal of the first mode is formed, during the second half-cycle of the clock signal, a signal of the second mode is formed, in the second signal, during the first half-cycle of the clock signal, a signal of the second mode is formed, during the second half-cycle of the clock signal, a signal of the first mode is formed, and the alternation of signals in the processor is taken into account when calculating the rotation speed and the perimeter mismatch signal.

EFFECT: using a ring laser with a large angle of incidence and simplifying the design of the optical mixer.

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Description

The invention relates to laser technology, namely laser gyroscopy.

A known method and device for obtaining information about the rotation of a laser gyroscope with a Faraday non-reciprocal device based on a permanent magnet [1]. To obtain information about rotation, they use an optical mixer, photodetectors, the outputs of which are connected to the inputs of the electronic mode separation device, the output of the electronic mode separation device is connected to the control inputs of the piezo drives of the ring laser mirrors through a series-connected converter of the rms value of signal amplitudes into direct current levels, a difference amplifier, integrator and final amplifier.

The disadvantage of this method and device is that they work in a laser gyroscope with a Faraday non-reciprocal device based on a permanent magnet, which creates a constant frequency bias, and is unsuitable for a laser gyroscope with a Zeeman non-reciprocal device, which creates an alternating frequency bias.

The closest in technical essence to the proposed method and device is the method and device for adjusting the perimeter of a four-frequency Zeeman laser gyroscope [2].

In this method, in a four-frequency Zeeman laser gyroscope, sine-cosine signals are obtained for heterodyning the beat frequencies of counterpropagating waves of two longitudinal orthogonal modes using an optical mixer, the beat signals of these modes are separated, the number of pulses of the beat frequency of the modes is counted for each half-cycle of the synchronizing signal using a block of counters, and the frequencies are calculated rotation and perimeter detuning signal using a processor.

The disadvantage of this method is that for the optical separation of beat signals of counterpropagating waves of longitudinal orthogonal modes, a complex design of an optical mixer (containing special optical compensators and polarization-anisotropic elements) is used. The complex design of the optical mixer leads to additional output power losses and backscattering of light, as well as increased cost of the device.

A known device for adjusting the perimeter of a four-frequency Zeeman laser gyroscope [2] includes photodetectors of the output radiation of a ring laser equipped with four mirrors, the first and second of which are made with a piezo drive, the third is reflective, and on the fourth there is an optical mixer that forms the output radiation of the ring laser, as well as a frequency support block, the coils of which are included in the arms of the ring laser, and a clock pulse generator, the first output of which is connected to the input of the frequency support block, a block of pulse counters for signal frequencies of beats of counterpropagating waves of longitudinal orthogonal modes, a processor, the first input of which is connected to the output of the counter block, and the second input is connected to the second output of the clock pulse generator, a digital-to-analog converter, the input of which is connected to the output of the processor, and an amplifier, the input of which is connected to the output of the digital-to-analog converter, and the output is connected to the control inputs of the piezo drives of the first and second mirrors of the ring laser.

The disadvantage of the known device is the need to use a ring laser with a small angle of incidence on a mirror with an optical mixer, as well as the complex design of the optical mixer. Obtaining a small angle of incidence on the output mirror is associated with a significant decrease in the scale factor of the laser gyroscope or with a violation of the symmetry of the resonator.

The objective of the present invention is to provide the possibility of using a ring laser with a large incidence angle and a simplified design of an optical mixer.

The problem is solved due to the fact that in the known method of adjusting the perimeter of a four-frequency Zeeman laser gyroscope, including obtaining sine-cosine signals for heterodyning the beat frequencies of counterpropagating waves of two longitudinal orthogonal modes using an optical mixer, separating the beat signals of these modes, counting the number for each half-cycle of the clock signal mode beat frequency pulses using a counter block, calculation of the rotation frequency and perimeter detuning signal using a processor, using an electronic mode separation device, sine-cosine mode beat frequency heterodyning signals are converted into two signals, in one of which a signal is generated during the first half-cycle of the clock signal of the first mode, during the second half-cycle of the clock signal a signal of the second mode is formed, in the second signal during the first half-cycle of the clock signal a signal of the second mode is formed, during the second half-cycle of the clock signal a signal of the first mode is formed and the alternation of signals in the processor is taken into account when calculating the rotation speed and the perimeter mismatch signal.

The problem is solved due to the fact that in the known device for adjusting the perimeter of a four-frequency Zeeman laser gyroscope, including photodetectors of the output radiation of a ring laser equipped with four mirrors, the first and second of which are made with a piezo drive, the third is reflective, and on the fourth there is an optical mixer that forms output radiation of the ring laser, as well as a frequency support unit, the coils of which are included in the arms of the ring laser, and a clock pulse generator, the first output of which is connected to the input of the frequency support unit, a block of pulse counters for signals of beat frequencies of counterpropagating waves of longitudinal orthogonal modes, a processor, the first input of which connected to the output of the counter block, the second input is connected to the second output of the clock pulse generator, a digital-to-analog converter, the input of which is connected to the output of the processor, and an amplifier, the input of which is connected to the output of the digital-to-analog converter, the output is connected to the control inputs of the piezo drives of the first and second mirrors ring laser, the outputs of the photodetectors are connected to the inputs of an additionally installed device for electronic separation of signals from the beats of counterpropagating waves of longitudinal orthogonal modes, the outputs of this device are connected to the input of the counter block.

The essence of the proposed method is that in order to extract information about rotation in a four-frequency Zeeman laser gyroscope using an electronic mode separation device, sine-cosine heterodyning signals of mode beat frequencies are converted into two signals, in one of which a signal of the first mode is formed during the first half-cycle of the clock signal , during the second half-cycle of the clock signal a signal of the second mode is formed, in the second signal during the first half-cycle of the clock signal a signal of the second mode is formed, during the second half-cycle of the clock signal a signal of the first mode is formed and the alternation of signals in the processor is taken into account when calculating the rotation speed and the perimeter mismatch signal.

The proposed device is illustrated in the drawing. The drawing shows:

in fig. 1 is a functional diagram of a device for extracting information about rotation in a four-frequency Zeeman laser gyroscope;

in fig. 2 - block diagram of an electronic mode separation device;

in fig. 3 - input signals for heterodyning the beat frequencies of counterpropagating waves of longitudinal orthogonal modes;

in fig. 4 - output signals of the electronic mode separation device;

The device for isolating information about rotation in a four-frequency Zeeman laser gyroscope (Fig. 1) contains a ring laser 1, including photodetectors 2 output radiation, equipped with four mirrors, the first 3 and second 4 of which are made with a piezo drive, the third 5 is reflective, and the fourth 6, an optical mixer 7 is installed, which forms the output radiation of the ring laser, a frequency stand block 8 with coils 9, a clock pulse generator 10, a block 11 of pulse counters for signals of the beat frequencies of counterpropagating waves of longitudinal orthogonal modes, a processor 12, a digital-to-analog converter 13, an amplifier 14 and a device 15 electronic separation of beat signals of counterpropagating waves of longitudinal orthogonal modes.

The proposed device for extracting rotation information in a four-frequency Zeeman laser gyroscope works as follows. The output sine-cosine signal for heterodyning the beat frequencies of counterpropagating waves of two longitudinal orthogonal modes from photodetectors 7 is fed to the input of the electronic mode separation device 9. The electronic mode separation device 9 consists of phase-shifting integrating and differentiating RC circuits, each of which shifts the signal phase by (Fig. 2). The sine-cosine heterodyning signals of mode beat frequencies are converted into two signals, in one of which, during the first half-cycle of the clock signal, a signal of the first mode is formed, during the second half-cycle of the clock signal, a signal of the second mode is formed, in the second signal, during the first half-cycle of the clock signal, a signal of the second mode is formed, During the second half-cycle of the clock signal, a signal of the first mode is formed. Using the counter block 14, the number of pulses of the mode beat frequency is counted for each half-cycle of the clock signal, and using the processor 15, the alternation of signals is taken into account when calculating the rotation speed and the perimeter detuning signal.

The effectiveness of the proposed method and the performance of the presented device are confirmed by computer modeling of sine-cosine signals for heterodyning the beat frequencies of counterpropagating waves of two longitudinal orthogonal modes from photodetectors, and their subsequent passage through an electronic mode separation device. If these signals (Fig. 3) are present at the input of the electronic mode separation device (Fig. 2), harmonic signals with the beat frequency of the first and second modes are generated at the output of this device (Fig. 4). During the first half-cycle of the clock signal, a signal of the first mode is generated, during the second half-cycle of the clock signal, a signal of the second mode is formed, in the second signal, during the first half-cycle of the clock signal, a signal of the second mode is formed, during the second half-cycle of the clock signal, a signal of the first mode is formed. Thus, the proposed method and device make it possible to use a ring laser with a large incidence angle and simplify the design of the optical mixer.

Information sources

1. Pat. US 5116132, G01B 9/02, 356/350 Ring laser gyroscope output optic detection system / Robert A. Mitchell, David B. Hall, Kenneth W. Shafer: Litton Systems, Inc - appl. 01/12/1990; publ. 05/26/1992, 20 p.: 8 ill.

2. Pat. 2744420 Russian Federation, IPC G01C 19/66, G01R 29/02, H01S 3/086. Device for adjusting the perimeter of a four-frequency Zeeman laser gyroscope / Gorshkov V.N., Kolbas Yu.Yu., Savelyev I.I., Dronov I.V., Ivanov M.A., Varenik A.I.; applicant and patent holder Joint Stock Company "Polyus Research Institute named after M.F. Stelmakh". - Application No. 2020121811; appl. 07/02/20; publ. 03/09/21, Bulletin. No. 7. - 11 p.: 4 ill.

Claims (2)

1. A method for extracting information about rotation in a four-frequency Zeeman laser gyroscope, including obtaining sine-cosine signals for heterodyning the beat frequencies of counterpropagating waves of two longitudinal orthogonal modes using an optical mixer, separating the beat signals of these modes, counting for each half-cycle of the synchronizing signal the number of pulses of the beat frequency of the modes at using a counter block, calculating the rotation frequency and the perimeter detuning signal using a processor, characterized in that, using an electronic mode separation device, the sine-cosine heterodyning signals of mode beat frequencies are converted into two signals, in one of which, during the first half-cycle of the clock signal, the first signal is formed modes, during the second half-cycle of the clock signal a signal of the second mode is formed, in the second signal during the first half-cycle of the clock signal a signal of the second mode is formed, during the second half-cycle of the clock signal a signal of the first mode is formed and the alternation of signals in the processor is taken into account when calculating the rotation speed and the perimeter mismatch signal. 2. A device for isolating information about rotation in a four-frequency Zeeman laser gyroscope, including photodetectors of the output radiation of a ring laser equipped with four mirrors, the first and second of which are made with a piezo drive, the third is reflective, and the fourth has an optical mixer that forms the output radiation of the ring laser , as well as a frequency support block, the coils of which are included in the arms of the ring laser, and a clock pulse generator, the first output of which is connected to the input of the frequency support block, a block of pulse counters for signals of beat frequencies of counterpropagating waves of longitudinal orthogonal modes, a processor, the first input of which is connected to the output of the block counters, the second input is connected to the second output of the clock pulse generator, a digital-to-analog converter, the input of which is connected to the output of the processor, and an amplifier, the input of which is connected to the output of the digital-to-analog converter, the output is connected to the control inputs of the piezo drives of the first and second mirrors of the ring laser, different in that the outputs of the photodetectors are connected to the inputs of an additionally installed device for electronic separation of signals from the beats of counterpropagating waves of longitudinal orthogonal modes, the outputs of this device are connected to the input of the counter block.

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