Magnesium oxide, sapphire, beryllium, and depleted uranium are used in materials science experiments where they are commonly required to be formed into flats, wedges, or surfaces having ripples. Once shaped, the laser processed materials are shot by extremely powerful lasers to test their material properties. One of the constraints imposed by these types of experiments are that the samples must be limited in size, and consequently these components are typically small, being mm in size and um in thickness. The desired thickness ranges from a few um to several tens of um, with a thickness tolerance of less than one um and surface smoothness of less than 200 nm Ra. Furthermore, where ripples and steps are to be machined into the surface of the flat, a typical amplitude of the ripple is of the order of a few um but a typical spatial wavelength can be over a hundred um. To meet these fabrication requirements,  laser processing parameters that produce a sufficiently stable ablation process to maintain the required dimensional tolerances and smoothness are needed. Some of these will be discussed along with the control systems used for some of the toxic materials that we laser machine.

Work supported by General Atomics Internal Research and Development.