Method and apparatus for assisting laser material processing
Inactive Publication Date: 2007-01-04
COHERENT INC
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- Abstract
- Description
- Claims
- Application Information
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Benefits of technology
[0012] A fluid vacuum adapted to withdraw fluid discharged across the workpiece may be provided to remove excess fluid and keep the thickness of the fluid over the workpiece optimized. It is anticipated that the flow control means, nozzle, fluid vacuum and other mechanical elements of the present invention be computer controlled as is known in the art wherein predefined procedures and optimizations in the process may be reproduced consistently.
[0013] In an embodiment of the invention, a computer processor is communicatively coupled to the flow control means and a computer readable medium is communicatively coupled to the computer processor. A fluid control module stored on the computer readable medium is adapted to stop the discharge of fluid across the workpiece prior to completing a cut-through of the workpiece by the laser beam.
Problems solved by technology
Excimer lasers have been considered poor choices as exposure radiation sources for machining metals due to the generation of severe recast and debris during the laser interaction.
However, the generation of recast and debris using a YAG laser in this way will still not be eliminated or even suppressed below a sufficient tolerance level.
However, particularly at laser repetition rates such as greater than a few Hz and particularly at repetition rates above 1 kHz, such use of thick liquid flow layers, e.g., greater than 1 mm, results in high turbulence and reduced performance through refraction affects of the liquid.
Unfortunately, this adds time to the process and generally does not eliminate the recast and debris altogether.
Method used
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[0025]FIG. 1 generally illustrates an apparatus for assisting laser material processing according to the invention. The apparatus shown at FIG. 1 includes an exposure source 20 such as a laser for generating a beam of radiation at wavelengths less than 1100 nm, although longer wavelength radiation sources may be used and benefit from use with the preferred embodiments. It is important that the wavelength of the laser radiation is highly transmissive for the liquid being used as the assist material. In the case of far infrared sources, e.g., carbon dioxide (CO2) lasers emitting around 10.6 microns, a liquid gas like N2, Ar, CO2 and the like may be used as the assist material to aid the laser machining where simple liquids like water strongly absorb the radiation. The repetition rate may be as low as a few Hz or may be operated in cw mode, although operating at higher repetition rates such as 1 kHz or more, the low thickness water layer preferred herein is particularly advantageous as...
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Abstract
A laser machining apparatus includes a nozzle connected to a pressurized gas and liquid reservoir for propelling a fine spray, mist or stream of a liquid such as water at the workpiece to be machined. A laser beam, preferably as may be generated by a UV laser or other source of exposure radiation, but is not strongly absorbed by the liquid assist material, is focused to the workpiece using, e.g., a focusing or imaging lens, while the fine spray, mist or liquid stream is propelled at the workpiece creating a layer of the liquid on its surface as the beam is incident upon the workpiece for machining.
Description
CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional application of U.S. patent application Ser. No. 10 / 065,262, filed Sep. 30, 2002, and claims the benefit of Provisional Application No. 60 / 327,413, filed Oct. 3, 2001, and Provisional Application No. 60 / 328,737, filed Oct. 10, 2001.BACKGROUND OF THE INVENTION [0002] Excimer lasers have been considered poor choices as exposure radiation sources for machining metals due to the generation of severe recast and debris during the laser interaction. High repetition rate, Q-switched YAG lasers also generate a recast and debris field when machining metals. These YAG lasers may be focused to a small spot and rastered over the area to be cut so that the generation of recast and debris may be somewhat tempered. However, the generation of recast and debris using a YAG laser in this way will still not be eliminated or even suppressed below a sufficient tolerance level. [0003] Laser etching of materials submersed in liq...
Claims
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Patent Timeline
Login to View More IPC IPC(8): C23F1/00B23K26/12B23K26/14B23K26/38B23P25/00
CPCB23K26/121B23P25/003B23K26/385B23K26/1417B23K26/1224B23K26/146B23K26/389
InventorSCAGGS, MICHAEL J.
OwnerCOHERENT INC