Laser forming of thin foil by a newly developed sample holding method

Abstract

A sample holding method is newly developed for laser forming, in which the target material is held between two transparent plates. During laser beam scanning on the target, the target foil is kept flat. After the scanning is finished, the foil is detached from the holder; the foil bends toward the beam scanned surface. Experiments are carried out with a Nd:yttrium–aluminum–garnet laser beam for a spot size of 25μm and for a traverse speed of 10 mm/s. A bending angle of about 30° is obtained for stainless steel (AISI 304) foil of 10 μm in thickness with a power of 0.3 W and a scanning repetition number of 20. On the other hand, if the laser beam is focused and scanned on the convex side along the ridge line of a curved foil, it bends toward the concave side and the bending angle increases. The increment angle of about 20° for a prebent angle of 45° is obtained for stainless steel foil 20 μm in thickness under the conditions of the power of 1.3 W and scanning repetition number of 10. If the sample is rotated counterclockwise with the increase in bending angle, a total angle of 90° or more is easily obtained. A microcube, of which side length is about 500 μm, and other objects of complicated shapes are made on the basis of the bending characteristics obtained experimentally.