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Optical metrology

3D-shape measurement of nozzles on the micrometric scale

Optical metrology
Honorary Chairman of Sensofar Metrology, President and CEO of Sensofar Medical, Ph.D. in Physics | Other articles

Founding member of Sensofar in 2001 and Sensofar Medical in 2012.
Academic career at Barcelona Tech (UPC), Professor of Optical Engineering at the BCN Master in Photonics and founding member and former director of CD6, a Center for Technological Innovation belonging to UPC and recognized by the Government of Catalonia as a member of the TECNIO network.
He is the author of more than 150 scientific contributions, supervisor of 10 master's and doctoral theses, inventor of 3 international family patents and responsible for more than 50 research projects funded by national and European public agencies and also by private companies.
He also led the process of creating the "Southern European Cluster in Photonics and Optics" (SECPhO) and managed for 14 years a Venture Capital company focused on high-tech investments.

3D-shape measurement of nozzles on the micrometric scale full article
Ferran Laguarta1, Roger Artigas1, Cristina Cadevall1
1Universitat Politècnica de Catalunya (UPC) Rambla Sant Nebridi, 10, E-08222 Terrassa, Spain.
Proceedings Volume 5457, Optical Metrology in Production Engineering; (2004)
Event: Photonics Europe, 2004, Strasbourg, France


One of the most challenging applications of optical metrology is measuring the shape of the inner surfaces of nozzles such as those of fuel injectors, wiring dies and printheads. A current non-contact solution is confocal laser scanning microscopy (CLSM). However, the inner surfaces of the nozzles behave as though they were optically polished, which gives rise to very weak, backscattered light signals. Therefore, measuring with CLSM is a very slow process and the uncertainty of the results is very high. Moreover, new nozzle designs are moving towards even steeper walls, which means that CLSM may well become useless in the near future. In this paper, we introduce a new method based on a proprietary unfolded confocal arrangement, which uses the light that is reflected onto the inner surfaces and that passes through the nozzle instead of the backscattering signal. The setup and implementation of this new method and the attendant profiling algorithms are explained. With regard to real applications, we focus on measuring the 3D topography of conical nozzles drilled into organic polymer films with excimer lasers. These films are used in the manufacture of the orifice plates, which are attached to the printheads of thermal inkjet cartridges. Fast measurements and accurate results obtained for nozzles of 25 micrometers in diameter and wall angles close to 17º are demonstrated.

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