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Proceedings Paper

Automatic laser beam positioning for high-power CO2 laser beams using high-reflective transmissive optics
Author(s): Martin Sparkes; Walter Perrie; William M. Steen; Peter J. Modern
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Paper Abstract

This paper discusses the principals of automatic laser beam positioning, and shows that two distinct advantages are achieved over using a conventional fixed mirror system: (1) The initial alignment of the system may be achieved significantly faster than when using conventional techniques, making multiple workstations for one laser more economic. (2) The laser beam may be maintained during processing, and hence the optimum process parameters maintained through the process cycle. The system was developed as part of a 50 m long beam path operating over power ranges from a few hundred watts to 6 kW. Results are given showing the `beam wander' of a laser system as the laser is run through heating and cooling cycles, hence showing the necessity of in process alignment at this location. These results are then compared to results obtained during closed loop position control. The design of the beam position sensor is based around the use of a silicon leaky mirror customized to have a low value of transmitted power, and reflectivity greater than 99.8%. The transmitted radiation is then focused down onto either a one or two quadrant thermopile detector system, depending upon the length of the beam path, and the desired positional accuracy. This motorized system is then used as part of a closed loop control system and the performance of the system evaluated. Results for positional accuracy and response rate are given, and the system shown to have a high degree of accuracy, coupled to a relatively fast response rate at a low capital cost.

Paper Details

Date Published: 7 September 1994
PDF: 10 pages
Proc. SPIE 2207, Laser Materials Processing: Industrial and Microelectronics Applications, (7 September 1994); doi: 10.1117/12.184726
Show Author Affiliations
Martin Sparkes, Univ. of Liverpool (United Kingdom)
Walter Perrie, British Nuclear Fuels Plc. (United Kingdom)
William M. Steen, Univ. of Liverpool (United Kingdom)
Peter J. Modern, British Nuclear Fuels Plc. (United Kingdom)

Published in SPIE Proceedings Vol. 2207:
Laser Materials Processing: Industrial and Microelectronics Applications
Eckhard Beyer; Maichi Cantello; Aldo V. La Rocca; Lucien Diego Laude; Flemming O. Olsen; Gerd Sepold, Editor(s)

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