Reduced mist laser shock peening

摘要

A laser unit (12) includes a laser beam source (14) for generating a laser beam along a laser beam centerline (20). A beam tube (22) surrounds at least a portion (24) of the beam centerline (20). A beam aperture (26) is located at an exit of the tube (22). A final beam optical lens (30) is mounted within the tube (22) upstream of the aperture (26). A gas purging means (34) flows purge gas (35) into the tube (22) between the lens (30) and the aperture (26). A converging section (48) of the tube (22) is located between the lens (30) and the aperture (26). At least one telescoping section in the tube (22) is located between the lens (30) and the aperture (26) in the converging section (48) of the tube (22). The lens (30) has a focal number (FN) less than 8 and may be less than 7 and down to about 5. A gas knife (60) located between the aperture (26) and the focal point of the lens (30) is used for flowing a large volume of clearing gas across the laser beam between the aperture and the focal point.