Reduced mist laser shock peening

1. Field of the Invention A laser unit includes a laser beam source for generating a laser beam along a laser beam centerline. A beam tube surrounds at least a portion of the beam centerline. A beam aperture is located at an exit of the tube. A final beam optical lens is mounted within the tube upstream of the aperture. A gas purging means flows purge gas into the tube between the lens and the aperture. A converging section of the tube is located between the lens and the aperture. At least one telescoping section in the tube is located between the lens and the aperture in the converging section of the tube. The lens has a focal number less than 8 and may be less than 7 and down to about 5. A gas knife located between the aperture and the focal point of the lens is used for flowing a large volume of clearing gas across the laser beam between the aperture and the focal point.