Laser speckle extensometer

The laser speckle extensometer is a non-contact deformation measuring device for material testing, based on laser speckle evaluation.

Schematic structure of the measuring system: (1) High-resolution CCD cameras for detection (2) Laser diodes for generating the speckle patterns — Schematic structure of the measuring system:
(1) High-resolution CCD cameras for detection
(2) Laser diodes for generating the speckle patterns

Measuring principle

The test object is illuminated with laser light, which creates a "speckle pattern" on the surface of the sample. During the tensile test, the pattern is continuously recorded by two cameras. At the beginning of the measurement, the "speckle pattern" coming from the object is recorded by the cameras and stored as a reference. Each time the cameras take another image, the pattern of the reference image is searched for in the image and the offset or displacement is calculated.

Setup: 2 laser diodes - 2 speckle patterns - 2 detector cameras

Advantages

no sample marking necessary, but generation of the speckle pattern by the laser
use in temperature chamber possible
tests on a variety of materials possible

Laser speckle extensometer

Measuring principle

Advantages

Data sheets

Second-hand accessories for material testing