Optical polishing pitches: impact frequency responses and indentation depths

The short-term dynamic properties of a wide range of commercially available optical polishing pitches were determined with an impact frequency response test. A simple dynamic model is presented to evaluate the relevance of the measurement variations across the range of pitches tested. Test results show that harder pitches have higher natural frequencies and lower damping ratios. Strong correlations between pitch hardness (as measured by the indent test) and the natural frequency only existed among pitches from the same series, i.e., the Gugolz or Acculap series. This implies that pitches with similar hardness values from different manufacturers have different dynamic properties.