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Optical Engineering

In-plane laser forming for high precision alignment
Author(s): Ger Folkersma; Gert-Willem Römer; Dannis Brouwer; Bert Huis in 't Veld
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Paper Abstract

Laser microforming is extensively used to align components with submicrometer accuracy, often after assembly. While laser-bending sheet metal is the most common laser-forming mechanism, the in-plane upsetting mechanism is preferred when a high actuator stiffness is required. A three-bridge planar actuator made out of Invar 36 sheet was used to characterize this mechanism by experiments, finite element method modeling, and a fast-reduced model. The predictions of the thermal models agree well with the temperature measurements, while the final simulated displacement after 15 pulses deviates up to a factor of 2 from the measurement, using standard isotropic hardening models. Furthermore, it was found from the experiments and models that a small bridge width and a large bridge thickness are beneficial to decrease the sensitivity to disturbances in the process. The experiments have shown a step size as small as 0.1  μm, but with a spread of 20%. This spread is attributed to scattering in surface morphology, which affects the absorbed laser power. To decrease the spread and increase the positioning accuracy, an adapted closed-loop learning algorithm is proposed. Simulations using the reduced model showed that 78% of the alignment trials were within the required accuracy of ±0.1  μm.

Paper Details

Date Published: 10 December 2014
PDF: 12 pages
Opt. Eng. 53(12) 126105 doi: 10.1117/1.OE.53.12.126105
Published in: Optical Engineering Volume 53, Issue 12
Show Author Affiliations
Ger Folkersma, Univ. Twente (The Netherlands)
Gert-Willem Römer, Univ. Twente (The Netherlands)
Dannis Brouwer, Univ. Twente (The Netherlands)
Bert Huis in 't Veld, Univ. Twente (The Netherlands)

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