Optics: measuring and testing – Range or remote distance finding – Base line instrument
Patent
1984-09-12
1987-10-06
Rosenberger, R. A.
Optics: measuring and testing
Range or remote distance finding
Base line instrument
356 9, 356 1, G01C 324
Patent
active
046979212
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a device for detecting a relative change in distance between two measuring points, according to the preamble of the independent patent claim 1, and to a use of this device according to the characterising clause of the independent patent claim 8.
It is known from Swiss Patent Application No. 278,632 that, in high structures such as, for example, towers or barrages, it is possible for a point of the structure to be horizontally displaced. This horizontal displacement is resolved into two mutually perpendicular components which are regarded as significant. One important component of these is that which is perpendicular to a vertical plane, and hence that which is able to indicate tilting of the structure. Accordingly, it is suggested to suspend a pendulum in the said vertical plane and to measure the change in the distance between the structure and the filament.
On the other hand, Swiss Patent Application No. 366,982 has also disclosed the determination of the distance by forming a double image of, for example, a levelling rod.
It has been found, however, in particular in mining, that continuous monitoring of the walls of cavities in rock is necessary in order to be able to establish when the rock has come to rest again. For this reason, it is not sufficient to detect the displacement in only one direction, but all three coordinates in the spatial Cartesian coordinate system should be observed in order to enable all the possible displacements, bulges and dislocations to be detected in this way.
It is therefore an object of the invention to provide a device, by means of which such movements of structures can be detected, that case to be taken into account particularly where not only a wall of a structure but also the reference point might move.
According to the invention, this is achieved by a device which is characterised by the features in the characterising clause of the independent patent claim 1. A particularly advantageous application is defined in the independent patent claim 8.
Illustrative embodiments of the invention are described below by reference to the drawing in which:
FIG. 1 shows a geometrical representation for an explanation of the principle of the invention,
FIG. 2 shows a diagrammatic representation of a first simple embodiment and
FIG. 3 shows a diagrammatic representation of a second universally applicable embodiment.
The main problem is to ensure sufficiently large deflections for even small changes, so that useful measured results can easily be obtained. Structures, whether tall buildings or cavity structures, can change in various directions, as mentioned at the outset. The measuring system must therefore be capable of automatically carrying out the resolution into components. One component should be suitable for surveying.
As shown in FIG. 1, two measuring points I and II are defined as points on the surfaces of two mutually opposite walls W1, W2. A light beam S is emitted at a right angle from the measuring point I and strikes the mirror plane E at point II, which plane E is fixed on wall W2 at the measuring point II, at a right angle.
At the measuring point II, a plane mirror E is located. The light beam S is radiated back as a reflected beam R1 by this mirror E. At the receiving point P, the reflected beam R1 strikes again the wall W1 with the measuring point I. Provided that the wall W1 remains unchanged, a displacement of the wall W2 by the amount .DELTA.L can be detected, because the receiving point for the originally reflected beam R1, which has also shifted into the parallel beam R2, so that point P becomes shifted by an amount B to point P'.
If the angle between the incident light beam S and the reflected beam R1 on the mirror E is termed 2.alpha., the angle at the apex Q between the plane of the wall W2 and the extended mirror plane, displaced by .DELTA.L, is to be termed .alpha., as can readily be derived from the theorem of pairs of mutually perpendicular arms.
Thus, a displacement by the amount A corresponds to the value .DELTA.L/tan.alph
REFERENCES:
patent: 3765764 (1973-10-01), Niss
patent: 4409842 (1983-10-01), Scott et al.
Alder Werner
Amberg Rudolf
Amberg Messtechnik AG
Cooper Crystal D.
Rosenberger R. A.
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