CS199404B1 - Equipment for scanning of acoustic emission by laser beam from the surface of rigid material under load - Google Patents

Description

The invention relates to a device for acoustic emission imaging by a laser beam from the surface of a solid material under load.

At present, and to capture acoustic emission from the surface of a solid material, they use sensors with direct contact. These are then able to sense the acoustic emission only up to a certain heating temperature of the loaded material. High temperature sensors can be used up to a maximum temperature of about 500 ° C and are unusable for higher temperatures. In addition, said sensors and direct contact are threatened by possible destruction of the material.

The aforementioned disadvantages aa substantially eliminate the laser beam acoustic emission emitting device from the surface of the solid material under load, which consists of a continuous-beam gas laser equipped with a semipermeable mirror, the optical system deflecting the reflected laser beam to which an evaluation and recording apparatus is connected via an indicator to form the oscillating movement of the laser beam.

A continuous-beam gas laser excited by a high-frequency generator emits a laser beam passing through a semi-permeable mirror, and which impinges on the surface of the loaded solid material when it also forms a reflective surface that moves under the influence of acoustic waves. The movement of the reflective surface causes a change in the frequency of the reflected beam passing through

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an optical system for deflecting a reflected laser beam impinging on an indicator that transforms the oscillating motion of the laser beam passing through the optical array into an electrical signal that is evaluated and registered.

With the device according to the invention, a distance control of the material is achieved without having to place the sensor on the material surface under load. It will be achieved. These two advantages in relation to prior art methods using contact sensors. The worker is not threatened by the controlled design when placing the sensor, for example, by sudden accident, increased radiation, temperature, etc.! A second advantage is that the control is not influenced by the technique of positioning the sensor on the surface of the material and thus can be applied to high temperature materials at inaccessible locations of the structure, whereby unwanted interruption of measurements by dropping the sensor cannot occur.

An example of a device for sensing acoustic emission by a laser beam of a solid material under tension according to the invention is shown in the attached drawing.

The continuous-beam gas laser 1 excited by the high-frequency generator 2 radiates a laser beam 6 which impinges on the surface of the solid encapsulated material 2 Pd by a certain angle due to its reflection. The acoustic emission displacement of the surface of the embedded material 2 causes a change in the frequency of the reflected beam passing through the optical system 6 to deflect the reflected laser beam incident on the indicator 6 which transforms the oscillating motion of the laser beam into an electrical signal which is evaluated and registered in the evaluation and registration a device that is connected to indicator J.

The acoustic emission sensing device according to the invention finds application in the non-destructive checks of the imperfections of solid materials, as well as welding. pressure receptacles and wherever direct contact sensing devices cannot be used.

Claims (2)

Device for sensing acoustic emission by laser beam from the surface of solid material under load, characterized in that it consists of a gas laser (1) with continuous radiation, equipped with a semipermeable mirror (3), the optical system (6) serves to deflect the reflected laser beam. to which an evaluation and registration device (8) is connected via an indoctor (7) for transforming the oscillating movement of the laser beam.