Fraunhofer Institute for Surface Engineering and Thin Films IST
Confocal laser microscope: analysis of battery particles.
2- and 3-dimensional optical microscopy
3-dimensional surface imaging can be performed using tactile methods such as profilometry or atomic force microscopy (AFM), but also non-contact confocal laser microscopy.
Confocal Laser Microscopy
MicroscopyThe confocal laser microscope CLM enables the production of not only 2-dimensional but also 3-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 2- or 3-dimensional images.
Layer spalling on a steel surface
Konfokale Lasermikroskopie in der Praxis.
Partial delamination of layers on a steel surface can be reliably detected and documented using a confocal laser microscope.
Overview and detail image of a scratch in a DLC layer on a cylindrical steel bolt
Scratch mark in hard cover layer.
CLM image of a scratch in a DLC layer.
Minimizing the contact area can lead to a reduction in the coefficient of friction. The confocal microscope can be used to easily check whether the 3-dimensional microstructures can withstand the tribological load.
Honeycomb structured surface for minimization of the contact area after a tribological test
Minimizing the contact area can lead to a reduction in the coefficient of friction. The confocal microscope can be used to easily check whether the 3-dimensional microstructures can withstand the tribological load.
CLM image of particles on a surface
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
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 from a point grid.