RU78946U1 - DEVICE FOR MEASURING LINEAR MOVEMENTS OF OBJECTS WITH A FLAT MIRROR-REFLECTING SURFACE - Google Patents

Abstract

A device for measuring linear displacements of objects with a flat mirror-reflecting surface, containing a central fiber with a splitter, peripheral fiber optic fibers located symmetrically with respect to the central fiber with the same aperture angle θ, photodetectors optically coupled to central and peripheral fiber fibers, respectively, a half-signal measurement unit electrically connected to the photodetectors of the peripheral optical fibers, a signal conditioning unit, the half-signal measuring unit and the photodetector of the central fiber, a collimation device located between the radiation source and the central fiber with the aperture angle θ associated with θ by the ratio θ-θ≥2ε, where ε is the maximum possible angular deviation of the reflecting surface from the given initial position characterized in that the peripheral optical fibers are placed along the circumference symmetrically with respect to the central optical fiber, while the unit for measuring the half-sum of the electric signals it is connected with photodetectors of peripheral optical fibers, and a half-signal measuring unit of peripheral optical signals and a photodetector of the central optical fiber are connected to the signal ratio forming unit.

Description

The proposed technical solution relates to measuring technology and can be used in fiber-optic measuring systems for non-contact measurements of various physical quantities, for example, pressure, temperature, linear displacements, etc.

The closest technical solution is a device for determining the linear displacements of an object with a flat mirror-reflecting surface, containing a central optical fiber with a splitter, two peripheral output fiber optical fibers located symmetrically with respect to the central optical fiber with the same aperture angle θ, photodetectors optically coupled to the central and peripheral optical fibers accordingly, a half-signal measuring unit electrically connected to peripheral photodetectors optical fibers, a signal ratio generating unit to which the half-signal measuring unit and the photodetector of the central optical fiber are connected, a collimation device located between the radiation source and the central fiber optical fiber with an aperture angle θ ₀ associated with θ by the relation θ - θ ₀ ≥2ε _max , where ε _max - the maximum possible angular deviation of the reflecting surface from a given initial position (see RF patent No. 1774233 class G01N 21/55 11/07/1992 Bull. No. 41).

A disadvantage of the known device is that to exclude random angular displacements can only be relative to one axis

rotation given by a pair of peripheral optical fibers placed symmetrically with respect to the central optical fiber. In addition, the sensitivity of this sensor to linear movements is also limited by these two peripheral optical fibers.

The purpose of this technical solution is to increase the sensitivity and increase the accuracy of measurements by eliminating the influence of random angular movements of the mirror-reflecting surface during its rotation relative to the axis of rotation lying in the plane of the end faces of the central and peripheral optical fibers.

The solution of this problem is provided by the fact that in the device for measuring the linear displacements of objects with a flat mirror-reflecting surface containing a central fiber with a splitter, peripheral output fiber optics located symmetrically relative to the central fiber with the same aperture angle θ, photodetectors optically coupled to the central and peripheral fiber optic fibers, respectively, the half-signal measuring unit, electrically connected to the photodetectors, is peripheral x optical fibers, a signal-ratio generating unit, to which a half-signal measuring unit and a photodetector of the central optical fiber are connected, a collimation device located between the radiation source and the central fiber optical fiber with an aperture angle θ ₀ associated with θ by the relation θ - θ ₀ ≥2ε _max , where ε _max - maximum possible angular deviation of the reflecting surface from a predetermined reference position, the peripheral light guides are arranged along the circumference in pairs symmetrically with respect to the central waveguide, When this half-sum signal measuring unit electrically connected to the photodetectors peripheral fibers and to block the formation of

the signal ratios are connected to the half-sum measurement unit of the signals of the peripheral optical fibers and the photodetector of the central optical fiber.

The figure 1 shows the device, a top view (i.e., the mutual placement of the optical fibers 1 to 7, located in the device in pairs), in figure 2 - functional diagram of the device (conditional scan).

The device contains a central optical fiber 1 (Fig. 1) and n pairs of peripheral optical fibers 2, 3, 4, 5, 6, 7 (in Fig. 1 n = 3), each of which is located symmetrically with respect to the central optical fiber 1, which increases n times the number of degrees of freedom of the mirror-reflecting surface 8 when it rotates relative to these axes.

The figure 2 shows the Central fiber 1 with a splitter, peripheral fibers 2, 3, 4, 5, 6, 7, located as shown in figure 1. The ends of the optical fibers 1 to 7, facing the reflective surface 8, lie in the same plane. In addition, the device contains photodetectors 9 — central and 10 — peripheral, optically coupled to fiber optical fibers 1 and 2, 3, 4, 5, 6, 7, respectively, block 11 for summing 2n signals, block 12 for generating a signal ratio to which the photodetector is connected the central fiber 9 and block 11. The collimation device 13 has an aperture angle θ ₀ associated with ε _{max by the} relation θ - θ ₀ ≥2ε _max , where ε _max is the maximum possible angular deviation of the reflecting surface from a given initial position. The device contains a radiation source 14.

The device operates as follows:

The light beam formed by the collimation device 13 from the source 14 passes through the inlet end of the central fiber 1 to the reflective surface 8. At a distance Δz from the end surfaces of the optical fibers 1 to 7 to the reflective surface 8, which is equal to

zero, the reflected light beam completely returns to the central fiber 1. As Δz increases, the light beam reflected from surface 8 enters all 7 faces of the optical fibers 1-7.

The summation of the light intensity from the output ends of the optical fibers 2-7 and its measurement increases the ratio of the registered radiation fluxes from the peripheral 2-7 and the central 1 optical fibers n times, where n is the number of pairs of peripheral optical fibers 2-7 located symmetrical relative to the central optical fiber 1 if the analog has a functional dependence of the output signal on the value of linear displacements, which is formed as the ratio P of registered radiation fluxes from peripheral and central optical fibers, the expression zheniem:

where S is the area of each of the two illuminated peripheral optical fibers for a given Δz, α - the radius of the core of the Central fiber, then in the proposed device a similar expression has the form:

where n is the number of pairs of peripheral fibers,

It follows that the scale factor of the function P (Δz), defined as the tangent of the angle of inclination of the function, n times exceeds the corresponding parameter of the analogue, and therefore increases the sensitivity of the sensor.

In this case, the proposed device eliminates the influence of angular displacements when the slopes of the mirror-reflecting surface relative to n rotation axes, as shown in figure 1.

Thus, the proposed technical solution increases the sensitivity of the sensor and increases the accuracy of the measurements.

Claims (1)

A device for measuring linear displacements of objects with a flat mirror-reflecting surface, containing a central fiber with a splitter, peripheral fiber optic fibers located symmetrically with respect to the central fiber with the same aperture angle θ, photodetectors optically coupled to central and peripheral fiber fibers, respectively, a half-signal measurement unit electrically connected to the photodetectors of the peripheral optical fibers, a signal conditioning unit, otorrhea connected half sum signal measuring unit and the photodetector of the central optical fiber collimating device positioned between the radiation source and the central fiber with an aperture angle θ _0, θ related to the relation θ-θ ₀ ≥2ε _max, where ε _max - maximum possible angular deviation of the reflecting surface from a predetermined initial position, characterized in that the peripheral optical fibers are arranged along the circumference symmetrically with respect to the central optical fiber, while the half-sum measurement unit of the signals it is electrically connected to the photodetectors of the peripheral optical fibers, and a half-signal measuring unit of the peripheral optical signals and a photodetector of the central optical fiber are connected to the signal ratio generating unit.