RU81317U1 - Device for measuring angular speeds of rotation - Google Patents

Device for measuring angular speeds of rotation Download PDF

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Publication number
RU81317U1
RU81317U1 RU2008140497/22U RU2008140497U RU81317U1 RU 81317 U1 RU81317 U1 RU 81317U1 RU 2008140497/22 U RU2008140497/22 U RU 2008140497/22U RU 2008140497 U RU2008140497 U RU 2008140497U RU 81317 U1 RU81317 U1 RU 81317U1
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RU
Russia
Prior art keywords
rotation
base
mirror
photodetector
mirrors
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RU2008140497/22U
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Russian (ru)
Inventor
Валерия Владимировна Богатырева
Александр Леонидович Дмитриев
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Государственное образовательное учреждение высшего профессионального образования "Санкт-Петербургский государственный университет информационных технологий, механики и оптики"
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Priority to RU2008140497/22U priority Critical patent/RU81317U1/en
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Abstract

A device for measuring the angular velocity of rotation relates to measuring technique, and can be used in devices and systems for measuring the angular velocity of rotation of elements of various designs, as well as in navigation. The device comprises a radiation source and a lens sequentially located along the beam, a rotating base on which reflecting mirrors are located - movable and stationary, mounted opposite and parallel to each other, and a photodetector, the output of which is connected to the input of the data processing unit. Moreover, the first mirror is rigidly fixed to the base, and the second mirror has its own axis of rotation normal to the base and not aligned with the axis of rotation of the base, and the working planes of the mirrors are perpendicular to the plane of rotation of the base. The device allows you to measure small angular rotational speeds with high accuracy, and the simplicity of the design ensures low manufacturing cost of the device.

Description

The utility model relates to measuring technique, namely, it serves to measure the angular velocity of rotation, and can be used in devices and systems for measuring the angular velocity of rotation of elements of various designs, as well as in navigation.
Known devices for measuring the angular velocity of rotation, based on various physical phenomena: the Sagnac effect, the gyroscopic effect, the Coriolis phenomenon, etc.
Known fiber-optic angular velocity meter (RF patent No. 2112927, IPC G01C 19/72, 08/03/1994, 10.06.1996), containing sequentially optically coupled radiation source, depolarizer, radiation splitting-connection device and fiber measurement loop , at the ends of which phase modulators of auxiliary and compensating modulations are made, allowing to reduce the random drift of the output signal.
The disadvantages of a fiber-optic gyroscope are its high sensitivity to changes in temperature, mechanical vibration, radiation polarization, fiber bending, etc., which affects the accuracy of measurements, in addition, the high cost of the device.
A laser gyroscope is used to measure angular velocity and small variations in rotational speed (RF patent No. 2117251, IPC G01C 19/64, 05/06/1997, 08/10/1998). The gyroscope contains two deaf mirrors, an output translucent mirror, two reflective diffraction gratings, which are located at the vertices of a regular pentagon. A polarization converter is located between the photodetector system and the output translucent mirror. The first polarizer is placed between the first reflective diffraction grating and the second blind mirror. Second
a polarizer is placed between the first lattice and a translucent mirror. The transmission planes of the polarizers are mutually orthogonal. Two resonant circuits are formed in the gyroscope. In each circuit, two beams running in the same direction are polarized orthogonally, which provides a narrow synchronization band and leads to an increase in sensitivity.
The disadvantages of a laser gyro are high sensitivity to changes in temperature and mechanical vibration, difficulties in alignment and calibration, etc.
The prototype of the claimed device is a rotating ring laser interferometer (laser interferometer) (Instrumentation and automatic control [Coll. Articles]. Issue 2. Laser devices and their application / Editorial: VVKazakevich et al. - M .: Engineering, 1985, p. 84-85.), Designed to measure angular displacements (speeds). The laser interferometer contains a rotating base, a radiation source represented by an active medium placed in a system of mirrors (two deaf and one translucent), forming a ring resonator, a beam splitter, two photodetectors located one relative to the other at a distance of a quarter of the interference strip after the beam splitter cube, two slotted diaphragms installed in front of the photodetectors, a data processing unit including a logic circuit, a reverse counter.
The physical principle is that in a laser interferometer two waves of laser radiation travel in opposite directions. In a stationary laser interferometer, the waves have equal frequencies. If the laser interferometer rotates in its plane, then the round-trip time of the resonator by one wave increases and the other decreases as much. A difference in the oscillation frequencies of two waves appears, which is proportional to the frequency of rotation in the space of the laser ring interferometer. The speed of the interference pattern is determined by the beat frequency or the rotation speed of the ring interferometer.
The principle of operation of a laser gyro. Two waves traveling in the opposite direction are reflected from the deaf mirrors of the resonator and exit in different directions through a translucent mirror. Then, after passing through a prism that changes the directions of the rays, so that they overlap each other, they are divided by a beam-splitting cube into two rays. Along each of them, slotted diaphragms and photodetectors are sequentially arranged. To determine the direction of rotation, a logic circuit is used, and with the help of a reversible counter, the number of pulses is calculated corresponding to the passage of the maxima of the interference pattern during rotation of the interferometer.
The disadvantage of this laser interferometer is the lack of measurement accuracy, which is affected by backscattering on reflective surfaces, and the complexity of the mechanical part of the structure.
The problem is solved of the possibility of determining small angular velocities of rotation with high accuracy and reducing the cost of the device.
The essence is that in the device for measuring the angular velocity of rotation, containing a radiation source, two reflective mirrors, a photodetector located in series along the beam and mounted on a rotating base, and a data processing unit, the input of which is connected to the output of the photodetector, a lens is introduced, located behind the radiation source, the first mirror is rigidly fixed to the base, and the second has its own axis of rotation, normal to the base and not aligned with the axis of rotation of the base, while working planes of mirrors are perpendicular to the plane of rotation of the base.
The lens is used to reduce the divergence of the laser beam, which increases the accuracy of determining the position of the beam on the surface of the photodetector. The data processing unit includes a digital oscilloscope and a PC.
The inventive device is illustrated by a figure, which shows a functional diagram of the device.
The device comprises a rotating base 1, combined with an object (not shown), on which a radiation source 2 and a lens 3 are arranged in series along the beam, reflecting mirrors - movable 4 and fixed 5, mounted opposite and parallel to each other, and a photodetector 6, and outside the base 1 is a data processing unit 7, including a digital oscilloscope and a PC in series. In this case, the first mirror 5 is rigidly fixed to the base 1 using a thin metal plate (not shown in the figure), and the second mirror 4 has its own axis of rotation, normal to the base 1 and not aligned with the axis of rotation of the base 1, and the working planes of the mirrors 4 and 5 are perpendicular to the plane of rotation of the base 1. The input of the data processing unit 7 is connected to the output of the photodetector 6.
The device operates as follows.
The beam from the light source 2, focused by the lens 3, falls on the movable reflecting mirror 4 at a point located on the axis of its rotation at an angle θ to the straight line lying in the plane of the reflecting mirror 4 perpendicular to the axis of rotation. Then it repeatedly passes between mirrors 4 and 5. In the initial position, the angle between mirrors 4 and 5 is equal to zero. The rotation of the object leads to the rotation of the base 3, due to which the mirror 4 under the action of centrifugal force is deflected by an angle α, as a result, the position of the beam on the surface of the photodetector 6 changes.
The output signal of the photodetector 6 is fed to the data processing unit 6, for example, to a digital oscilloscope, and then processed using a PC. A light source 2, a lens 3, reflective mirrors 4 and 5, and a photodetector 6 are mounted on a rotating base 1.
The magnitude of the output electrical signal of the photodetector 6 is related to the angle of the reflecting mirror 4. When using the corresponding analog or computer processing of the electrical signal of the photodetector 6, high accuracy of measuring the angular velocity of rotation is achieved, compatible with the simplicity of the general optical-mechanical design of the device.
In the initial state, the angle α and the angle of incidence of the beam on the surface of the photodetector P are set equal to zero. For the angle of incidence of the input beam θ and the distance between the mirrors d, the dependence of the beam displacement Δx in the plane P on the quantity α is represented by the formula
where n is the number of reflection pairs (in this calculation, a ray of light hits a rotary mirror at a point lying on the axis of rotation of the mirror).
For example, with d = 6.2 cm, L = 8.2 cm, N = 5, θ = 2.5 °
the calculated values of the displacement value and the corresponding beam deflection angles are given in the following Table
Δх, mm α, * 10 -4 rad
2 5,683
one 2,843
0.1 0.2843
0.01 0.02835
0.005 0.00569
An example of a specific implementation of the claimed device.
A semiconductor laser can be used as a radiation source. A lens designed to reduce the convergence of radiation should have such a focal length that is approximately equal to the optical path of the light beam from the lens to the working surface of the photodetector such that for given values of d = 6.2 cm, L = 8.2 cm, N = 5, θ = 2.5 ° is about 80 cm. Mirrors have a reflection coefficient of 80-90%. A photodetector is position-sensitive, for example, a multi-scan (Podlaskin B.G., Guk E.G. An analog processor based on a multiscan photodetector for aperture correction of the median of a distorted optical signal // Journal of Technical Physics, 2006. V. 76. Issue 8 S. 94-99 .; Dlugaszek A., Jabczynski J., Janucki J., Skrzeczanowski W. Optoelectronic sensor of longitudinal and angular displacements // Semiconductor Physics, Quantum Electronics & Optoelectronics, 1999. V.2. N 3. P .71-3.), Providing high accuracy of 1 μm measurement of changes in the coordinate of the beam along its surface.
The corresponding angle of deviation of the movable mirror, as follows from the Table, is about 10 -6 -10 -7 rad. Such angular deviations of the mirror under the action of centrifugal forces are practically achieved at angular rotational velocities of the order of several tens of degrees / hour. Obviously, the proposed device with all its structural simplicity has a very high sensitivity to changes in the angle between the mirrors of the mirror multiplier, and therefore, to changes in the angular velocity of rotation of the base of the device.
The inventive device allows you to measure small angular rotational speeds with high accuracy, and the simplicity of design ensures low manufacturing cost of the device.

Claims (1)

  1. A device for measuring angular rotational velocities containing a radiation source, two reflecting mirrors, a photodetector located in series along the beam and mounted on a rotating base, and a data processing unit, the input of which is connected to the output of the photodetector, characterized in that the lens located behind the source is inserted radiation, the first mirror is rigidly fixed to the base, and the second has its own axis of rotation, normal to the base and not aligned with the axis of rotation of the base, and the working planes of the mirrors erpendikulyarny plane of rotation of the base.
    Figure 00000001
RU2008140497/22U 2008-10-13 2008-10-13 Device for measuring angular speeds of rotation RU81317U1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2554316C1 (en) * 2014-03-03 2015-06-27 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Южный федеральный университет" (Южный федеральный университет) Single-wave method of measurement of interferometer rpm

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2554316C1 (en) * 2014-03-03 2015-06-27 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Южный федеральный университет" (Южный федеральный университет) Single-wave method of measurement of interferometer rpm

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