2- and 3-dimensional optical microscopy

Confocal laser microscope: analysis of battery particles.
© Fraunhofer IST
Confocal laser microscope: analysis of battery particles.

Confocal Laser Microscopy CLM

The confocal laser microscope enables the production of three-dimensional optical images of surfaces. The image is created by moving the very sharply defined focal plane vertically through the object. The lateral resolution is in the range of 1 μm, while the height resolution extends to a few nanometers. Within a few minutes, the method provides quantitative information on, amongst other things, the surface topography, roughness, step heights, pitch angles or particle sizes.

Rapid quantitative 3D information on surfaces

Compared to tactile profilometric methods, confocal laser microscopy is significantly faster and can also be used to image soft or unstable surfaces, such as polymers or powders. To a certain extent, it is also possible to measure through transparent cover layers and determine the layer thickness in this way. In addition to pure imaging, there are a variety of software tools available for obtaining the maximum amount of quantitative information from the images.

 

Layer spalling on a steel surface

Delamination on a steel surface
© Fraunhofer IST
Konfokale Lasermikroskopie in der Praxis.

Overview and detail image of a scratch in a DLC layer on a cylindrical steel bolt

Scratch mark in hard cover layer.
© Fraunhofer IST, Kirsten Schiffmann
Scratch mark in hard cover layer.
Beim Scratchtest werden die steigende Last, die Eindringtiefe, der Reibungskoeffizient und die beim Scratch erzeugte akustische Emission aufgezeichnet. Die Auswertung geschieht durch 2- oder 3-dimensional optische Abbildung des Scratches.
© Fraunhofer IST

Honeycomb structured surface for minimization of the contact area after a tribological test

Wabenförmig strukturierte Oberfläche zur Minimierung der Kontaktfläche nach einem tribologischem Versuch
© Fraunhofer IST

CLM image of particles on a surface

CLM image of particles on a surface.
© Fraunhofer IST

The 3D particle image also allows the statistical evaluation of particle diameters, particle shapes, and particle thickness.

CLM image of Vickers indentations in a surface

CLM image of Vickers impressions in a surface.
© Fraunhofer IST

The example of Vickers indentations shows that a quantitative determination of hole depths and aperture angles is possible. 

Elevation profile of a point grid

Evaluation of line cross-section profiles of a point grid.
© Fraunhofer IST

Evaluation of line cross-section profiles from a point grid.