Eliminating Mid-Spatial Frequency (MSF) Errors with VIBE Finishing

摘要

The surface figure error on mirrors can be divided into low, mid, and high spatial frequency errors. Conventional optical aberrations are represented by the low frequency errors. Finish (also gloss or roughness) are described by the high frequency errors. Mid frequency errors are typically the cause of small angle scattering. A process called VIBE, which uses a vibrating lap, was applied to flat borosilicate glass surfaces for up to 60 seconds. Only nanometers of material were removed. Tens of compliant polishing pads were evaluated with the technique. The power spectral density was used to evaluate frequency content. Initial results indicate that VIBE finishing can reduce the mid-frequency errors on flats.