SU761847A1 - Apparatus for contactless measuring linear displacements and resonance frequencies of articles - Google Patents

Description

The invention relates to vibration-measuring equipment, in particular to optical devices for measuring linear displacements of various objects and determining the resonant frequencies of the structural elements of the products.

The closest in technical essence to the invention is a device for contactless measurement of linear displacements and resonant frequencies of products, containing a monochromatic light source sequentially installed along the optical axis, a beam splitter and an optical system positioned at an angle of visibility to the beam splitter and amplifier, whose output is connected to the input the registrar [1].

The disadvantage of this device is the relatively low measurement accuracy when determining the mechanical parameters of products due to the high sensitivity to external mechanical and thermal effects.

The purpose of the invention is to increase the sensitivity of the device and measurement accuracy.

This is achieved by the fact that the device

equipped with an optical collimator installed between a source of monochromatic light and a beam splitter, and dia2

a fragment located between the beam splitter and the photodetector, and the beam splitter is made in the form of a full-reflecting mirror, which is turned by a mirror surface to the article under investigation, and has central holes.

FIG. 1 shows a block diagram of a device for contactless measurement of linear movements of vibrations and resonant frequencies; in fig. 2 - diagram of the formation of the reflected light beam at different positions of the object under study.

The device contains monochromatic light source 1 sequentially installed along the optical axis, a beam splitter 2 and an optical system 3 positioned at an angle of visibility to the beam splitter 4, the amplifier 4 and amplifier 5 whose output is connected to the recorder 6, an optical collimator 7 installed between the source of monochromatic light and a beam splitter, and the diaphragm 8, located between the beam splitter and the photodetector. The beam splitter is made. In the form of a full-reflecting mirror, turned by the mirror surface to the article 9, and has a central hole 10.

The device works as follows.

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From the source I of monochromatic light, the light beam through the collimator 7, the central hole 10, the light divider 2 and the optical lens 3 is directed to the test article 9 installed at a distance from the focal plane / lens (Fig. 2). When the surface of the product moves in the direction of light propagation (positions “a” and “b”), the angle of convergence of the reflecting beam of the light beam changes, resulting in a change in the diameter of the reflected beam in the plane of the beam splitter and, accordingly, the aperture 8, which passes only its central part on the photodetector 4. When the product is periodically moved, the intensity of the reflected beam in the plane of the diaphragm also changes periodically, respectively. An electrical signal proportional to the output signal changes at the photodetector output. The intensity of the reflected light flux supplied through the amplifier 5 to the recorder 6, which is used as an electron-beam oscilloscope.

With a gradual change in the frequency of movement of the investigated product from the lower value to the upper one and when resonant oscillations occur, its amplitude A increases sharply, which is observed by an increase in the oscillogram amplitude on the registrar screen.

The mechanical resonance frequency is read from the scale of the voltage generator, which excites the causative agent of mechanical oscillations of the product.

By calibrating the device accordingly, you can measure amplitudes.

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mechanical movements and vibrations of products and structural elements.

The device allows to improve the quality and reliability of electronic products 5 and structural elements operating under the influence of external mechanical loads.

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Claims (1)

Claim A device for contactless measurement of linear displacements and resonant frequencies of products, containing a source of monochromatic light, a beam splitter and an optical system successively installed along the optical axis, a beam splitter and an optical system positioned at a photodetector and amplifier, whose output 20 is connected to the recorder input, characterized in that In order to increase the sensitivity of the device and the accuracy of measurements, it is equipped with an optical collimator installed between a source of monochromatic and that a beam splitter, and a diaphragm situated between the beamsplitter n photodetector, a beam splitter is formed as a totally reflecting mirror facing the mirror surface 30 to the test article, and has a central hole.