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| United States Patent | 5,850,068 |
| Peters, et. al. | Dec. 15, 1998 |
Focus control of lasers in material processing operations
Abstract
When a laser beam interacts with a workpiece to be welded by the beam, a plume of optical radiation is generated. An apparatus and method is disclosed in which radiation from the plume is received back through a beam delivery path comprising optical elements (L1,L2) having chromatic aberration. This alters the focus of different spectral bands of the plume radiation and a discriminating aperture is formed by a face of an optical fibre (3). After passing through the fibre, the plume radiation is separated from any laser radiation and the respective powers of the different spectral bands are measured (5). By subtraction, an error signal is obtained which is used to control the focus of the laser beam.
| Inventors: | Peters; Christopher Nicholas David
(Rugby, GB);
Jones; Julian D C
(West Linton, GB);
Hand; Duncan Paul
(Edinburgh, GB);
Haran; Francis Martin
(Horfield, GB).
|
| Assignee: | Lumonics Ltd.
(GB).
|
| Appl. No.: | 867,813 |
| Filed: | Jun. 3, 1997 |
Foreign Application Priority Data
| Jul. 6, 1996 [GB] | 9611942 |
| Intl. Cl. : | B23K 26/04 |
| Current U.S. Cl.: | 219/121.83; 219/121.73 |
| Field of Search: | 219/121.83, 121.63, 121.64, 121.62, 121.73; 355/53 |
References Cited | [Referenced By]
U.S. Patent Documents
| 5,155,329 | Oct., 1992 | Terada et al. | 219/121.64 |
| 5,371,570 | Dec., 1994 | Morris et al. | 355/53 |
| 5,486,677 | Jan., 1996 | Maischner et al. | 219/121.83 |
| 5,670,068 | Sept., 1997 | Kuriyama et al. | 219/121.83 |
Foreign Patent Documents
| 60-121095 | Jun., 1985 | JP | 219/121.83 |
| 63-278692 | Nov., 1988 | JP | 219/121.62 |
| 93/03881 | Mar., 1993 | WO | 219/121.83 |
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Other References
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Browne, Mark A. et al. "Stage-Scanned Chromatically Aberrant Confocal Microscope for 3-D Surface Imaging" Proc SPIE Int Soc Opt, Eng; Proceedings of SPIE-The International Society of Optical Engineering, vol. 1660, No. Part 2, 10-13 Feb. 1992, pp. 532-541.
Primary Examiner: Evans; Geoffrey S.
Attorney, Agent or Firm: Nixon & Vanderhye P.C.
18 Claims, 14 Drawing Figures
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