Joseph C. Andreshak

Minimum fluence for laser blow‐off of thin gold films at 248 and 532 nm

The minimum 248 nm, 25 ns, and 532 nm, 15 ns laser fluences required to blow off thin gold films from optical quartz have been measured as a function of film thickness. The films apparently blow off when the gold‐quartz interface reaches the normal boiling point of gold. Even though the initial reflectivities at the two wavelengths are very different, the actual laser fluences required to blow off the films are very similar. While the reflectivities above the melting point appear to be very low, as expected, large decreases in the reflectivity at 532 nm may also occur prior to film melting.

Surface Finishing of High Speed Print Bands I. A Prototype Tool for Electrochemical Microfinishing and Character Rounding of Print Bands

A prototype tool is described for electrochemical surface finishing of an anodic workpiece in strip form, such as the stainless steel print bands used in high speed printers. The tool consists of two units, an electropolishing unit for microfinishing of print bands, and a directional electroetching assembly to provide rounding of characters in the print band. The prototype tool is completely automated and has provisions for rinsing and drying of the mounted print band. Buffed and unbuffed print band samples were used for process development and feasibility testing of the tool. Results demonstrated that the described electrolytic process yields reproducible mirror-finished print band surfaces with desired leading and trailing edges of characters. The process is applicable either as a complement to traditional buffing to give a final microfinish to print bands, or it can replace the presently used buffing technique for character rounding and surface finishing.