Using confocal fusion for measurement of metal AM surface texture
Journal article, 2020

The highly complex nature of as printed metal AM surfaces pose other challenges for making measurements compared to surfaces made with many conventional processing methods. The high complexity is caused by high aspect ratios, a mix of high and low reflexivity, steep angles etc. It is not clear which method is the most suitable for measuring these surfaces. The objective of this study was to compare four different measurement modes available in one instrument to evaluate the advantages and drawbacks of the respective techniques regarding measurements of metal AM surfaces. The evaluated measurement modes are Confocal Microscopy, Coherence Scanning Interferometry, Focus Variation and Confocal Fusion. The effect of advantages and drawbacks of studied techniques was tested on typical surfaces produced by L-PBF process. Surfaces printed at 0° and 90° inclinations were compared regarding the measurement results achieved from the different methods. The Power Spectral Density analysis and visual comparison were used for the examination of studied measurements methods. Besides the comparison of areal measurements acquired by different modes available in the instrument also extracted profile measurements were compared with profile images acquired using an Optical Microscope. This study reveals that confocal fusion is a promising technique for AM surface characterisation, due to the highest amount of valid data points in the typical measurement. The new approach developed in the study showed that PSD analysis can be used for evaluation of fill in algorithms incorporated in different software. Results of the profile comparisons help to illustrate features that can be depicted by surface measurements, applying different measurement principles, as well as enables comparison of raw profile data between different types of measurements. Further investigation of measurements on AM surfaces in the frequency domain will bring more understanding about the limitations of measurement techniques.

confocal microscopy

confocal fusion

surface topography

coherence scanning microscopy

power spectral density

additive manufacturing

powder bed fusion


Olena Flys

Halmstad University

RISE Research Institutes of Sweden

Johan C Berglund

RISE Research Institutes of Sweden

Chalmers, Industrial and Materials Science

Bengt-Göran Rosen

Halmstad University

Surface Topography: Metrology and Properties

2051-672X (eISSN)

Vol. 8 2 024003

Subject Categories

Medical Laboratory and Measurements Technologies

Geotechnical Engineering

Atom and Molecular Physics and Optics



More information

Latest update