By: Peter Bechtold
The trend in manufacturing today is to make everything smaller. Electronic gadgets, mechanical devices – everything is shrinking. Examples that come to mind are tiny MEMS accelerometers built into automotive seat belts, or miniature medical-diagnostic labs-on-a-chip, or one-inch hard-disk drives.
At the same time there is a demand for an increased functionality of devices, so more and more components have to be precisely positioned relative to each other. It is, however, impractical to achieve the precise alignments needed in a single manufacturing step. Instead, the prevailing technique, especially for nanometer-scale manufacturing, is to assemble parts in approximately the correct position, and then make high-precision adjustments to get the positioning within tolerances. Many adjustment processes, such as the laser-based temperature-gradient mechanism can often meet the demands of nano-manufacturing. Unfortunately, there are also cases where these processes are far from ideal, and sometimes they fail altogether. Thus, it is crucial to develop new micro- and especially nano-scale adjustment processes to meet the demands of current and future products.
Within the paper and presentation we will describe such a new process. We use ultrashort laser pulses to induce a micro shockwave in the workpiece, resulting in a highly controllable, sub-nanometer deformation of the piece. The process is effective in a wide variety of materials, and the interaction mechanism is almost non-thermal, which means that there is a negligible thermal impact on the workpiece.
An analysis based on models of ultrashort laser pulse – material interaction will be introduced and compared to experimental results and the long-term stability will be discussed. As another possible application of this process mechanism besides micro adjustment virtually free-form mirrors fabricated by micro shockwave bending will be presented. The topography of such a mirror is depicted in the attached figure. The original substrate material was a totally flat silicon wafer of 300 µm thickness. It was deformed into a four-facetted mirror geometry using micro shockwave bending solely. Such mirrors could be used in a wide variety of optical systems, for wavefront error correction or beam profile modification for instance.
The above brief overview was extracted from its original abstract and paper presented at The International Congress on Applications of Lasers & Electro-Optics (ICALEO) in Orlando, FL. To order a copy of the complete proceedings from this conference click here