Precision Float Polishing

Technology Transfer of the float polishing process from Japan has begun. Initially crystalline quartz was float polished. All of this work was reported at the Science of Optical Finishing Conference at Monterey, California. Photo-acoustic spectroscopy measurements indicated that float polishing removed a substantial portion of subsurface damage. Next, Corning 7940 substrates were float polished. After 230 microns of material had been removed through float polishing, there were no signs of any surface defects. Future directions to further develop float polishing for optical surfaces are discussed. Crystalline quartz was chosen for polishing based upon previous studies using a rather crude, single spindle polishing machine. The float polishing technique was utilized in the fabrication of disc-shaped quartz resonators, having a diameter of 6.35 mm and a polished thickness of 104 microns to increase the fracture strength of the resonators. We were able to remove all the subsurface damage that manifests itself in lower stress failures.