RU2397446C2 - Method of capture area exclusion in laser gyroscope and device for its realisation (laser gyroscope) - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: method of capture area exclusion means that mode of counterbeam periodic unidirectional emission is created in ring laser, and phase incursion of each counterbeam of ring laser are transfered on differential frequency electric signal with the help of optical heterodyning. Thereafter their difference in proximate references shall be proportional to rate of angle increase rusulting, from projection of absolute angular velocity Ω on the ring laser response axis during variation period. Laser hyroscope comprises ring laser, two beam-adding circuit, two light-sensitive detector, processing and control unit, as well as unidirectional emission shuffling circuit within ring laser resonator, optical heterodyne. Its output is optically linked with inputs of beam-adding circuit, and secondary inputs of beam-adding circuit are optically linked with ring laser counterbeams, and processing and control unit outputs contain code of angular velocity in inertial space during veriation period.

EFFECT: higher gyroscope accuracy.

2 cl, 3 dwg

Description

Usage: for building a new generation of laser gyroscopes. The essence of the invention: the method consists in the fact that in the ring laser receive the regime of periodic unidirectional generation of oncoming rays, then using the optical heterodyning transfer phase incursion of each of the oncoming rays on an electric signal of difference frequency.

Then, the phase shift of each of the electrical signals is measured, then the phase difference of the two neighboring samples is determined, which is proportional to the increment of the angle caused by the projection of the absolute angular velocity on the sensitivity axis of the ring laser for the measurement period.

A laser gyroscope containing a ring laser, two beam-adding circuits, two photodetectors, the outputs of which are optically coupled to the outputs of the beam-adding circuits, a processing and control unit, the information inputs of which are connected to the photodetector outputs, a unidirectional generation switching circuit located in the ring laser resonator, controlling the inputs of which are connected to the control outputs of the processing and control unit, an optical local oscillator, the outputs of which are optically coupled to the inputs of the beam adding circuits, and the second input The beam addition schemes are optically coupled to the oncoming beams of a ring laser. The outputs of the processing and control unit contain the code of the increment of the angle in inertial space for the measurement period.

The invention relates to the field of instrumentation and is intended for measuring angular velocities and angles and is used in navigation, measuring and other systems.

Known methods for reducing the influence of the capture zone [1], which consist of introducing both constant and variable supports, however, the interaction of counterpropagating rays leads to a number of nonlinear effects that affect the instability of the zero shift and the instability of the scale factor. The reason for this is the lack of complete reciprocity of the oncoming rays, which impedes the realization of the potential capabilities of the laser gyro.

Therefore, the disadvantage of all known methods is the incomplete exclusion of the capture zone.

The objective of the invention is to eliminate the capture zone and thereby increase the accuracy of laser gyroscopes.

To solve the problem, in the method of eliminating the capture zone in a laser gyroscope in a ring laser, the mode of periodic unidirectional generation of counterpropagating rays is obtained, then the phase incidence of each of the counterpropagating rays is transferred to the difference-frequency electric signal using optical heterododing, then the phase incidence of each of the obtained electrical signals, then determine the difference between adjacent samples of the phase incursion, proportional to the increment of the angle caused by the projection of the absolute angular velocity on the axis of sensitivity of a ring laser of the measurement period.

To solve the problem, a unidirectional generation switching circuit is introduced into the laser gyroscope, located in the cavity of the ring laser, the control inputs of which are connected to the control outputs of the processing and control unit, an optical local oscillator whose output is optically coupled to the inputs of the beam addition circuits, and the second inputs of the beam addition circuits optically coupled to the oncoming beams of the ring laser, and the outputs of the processing and control unit contain the code of the increment of the angle in the inertial space for the period of measurement rhenium.

The rationale for the proposed method is as follows. Periodic unidirectional lasing in a ring laser can be obtained both on the basis of the effect of suppressing counterpropagating rays in a magnetic field [2], and on other nonlinear optical effects, for example, in liquid crystal optical cells (modulators) controlled by an electric field, etc. Figure 1 shows a timing diagram explaining the operation of the method. Figure 1 marked: t _p - switching time (the lifetime of the bi-directional generation of oncoming rays); t _and - measurement time (unidirectional generation time); T is the sampling period.

Since the measuring time interval t _and there exists only a one-way generation, the scale factor will have the form

,

,

Where:

S is the resonator area of the ring laser;

L is the length of the perimeter of the ring laser;

λ is the wavelength.

Given that the measurement takes place only on a fraction of the sampling period, a correction factor should be introduced

.

.

Then the phase difference for the sampling period will be

,

,

Where:

Ω is the projection of the absolute angular velocity on the sensitivity axis of the ring laser.

Figure 2 presents a diagram of a laser gyro. The laser gyroscope contains a ring laser 1, two addition schemes for rays 2 and 3, two photodetectors 4 and 5, the inputs of which are optically coupled to the outputs of the respective addition schemes for rays 2 and 3, a processing and control unit 6, the information inputs of which 9 and 10 are connected to the outputs photodetectors 4 and 5, a unidirectional generation switching circuit 7, located in the cavity of the ring laser 1, the control inputs of which are connected to the control outputs 11 and 12 of the processing and control unit 6, an optical local oscillator 8, the outputs of which are optically coupled with the inputs of the schemes of addition of rays 2 and 3, and the second inputs of the schemes of addition of rays 2 and 3 are optically coupled to the oncoming beams of the ring laser 1. The outputs of the processing and control unit 6 contain the code of the increment of the angle in inertial space during the measurement T.

The unidirectional generation switching circuit 7 can be made in the form of an anisotropic plate placed in the passive part of the ring laser 1, and a solenoid that creates an axial magnetic field in the active zone of the ring laser 1 [2]. If the switching circuit of unidirectional generation 7, as described above, the processing and control unit can be made in the form shown in Fig.3. Figure 3 shows: multiplexer 13, the inputs of which are connected to the outputs of the photodetectors 4 and 5, a counter 14, the input of which is connected to the output of the multiplexer 13, a current source 15, the outputs of which are connected to the inputs of the unidirectional generation switching circuit 7, the controller 16, the inputs of which connected to the outputs of the counter 14.

The control outputs of the controller 16 are connected to the control inputs of the multiplexer 13, the counter 14 and the current source 15, and the information outputs contain the code of the increment of the angle in the inertial space for time T. The time t _p is due to transients in the switching circuit of unidirectional generation 7, and the bi-directional generation mode this time is used for generating control signals for the stabilization and perimeter ring laser power pump 1. The time t _and is selected based on the necessary sampling period T. control In addition to controlling the operating mode of the laser gyroscope, lerr 16 determines the phase difference between the phases of electrical signals, performs scaling, and also controls all subsystems of a ring laser (stabilization of the perimeter, pump power, etc.).

Thus, the problem of the complete exclusion of the capture zone of laser gyroscopes was solved, which should significantly increase the accuracy and stability of the latter.

Literature

1. Aronowitz F. Laser gyroscopes // In the book: "The use of lasers." - M .: Mir, 1974.

2. Gupalov V.I., Mynbaev D.K. On the influence of a magnetic field on a laser gyroscope // Collection of articles. Ed. Prof. P.I. Saidova. - L .: Publishing house of the Leningrad University, 1973, S.24-27.

Claims (2)

1. A method of eliminating the capture zone in a laser gyroscope, which consists in the fact that in the ring laser receive the regime of periodic unidirectional generation of counterpropagating rays, then using the optical heterodyne transfer phase incidence of each of the counterpropagating rays of the ring laser on an electric signal of a difference frequency, then measure in turn the phase shift of each of the received electrical signals, then determine the difference between adjacent samples of the phase shift, proportional to the increment of the angle caused by the projection of the absolute angular th speed on the sensitivity axis of the ring laser for the measurement period. 2. A laser gyroscope containing a ring laser, two beam adding circuits, two photodetectors, the inputs of which are optically coupled to the outputs of the corresponding beam adding circuits, a processing and control unit, the information inputs of which are connected to the outputs of the photodetectors, characterized in that, in order to exclude the zone capture, it introduced a unidirectional generation switching circuit located in the resonator of a ring laser, the control inputs of which are connected to the control outputs of the processing and control unit, optical Goethe homeland, the outputs of which are optically coupled to the inputs of the beam-adding circuits, and the second inputs of the beam-adding circuits are optically coupled to the oncoming beams of the ring laser, and the outputs of the processing and control unit contain an increment code of the angle in inertial space for the measurement period.

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