Specifications for Low Scatter Optics

The 1970’s and 80’s generated considerable concern over scatter in optical systems. Although it was often recognized in advance that low scatter optics were required for a given application, the specifications were usually either non-existent (a best effort requirement) or inappropriate. The easiest, most available and cheapest scatter measurement was the Total Integrated Scatter (TIS) measurement. Until the mid-1980’s most of the specifications written to handle scatter concerns were either TIS (often given without angle limits) or rms roughness found from some sort of profile data (and given without the corresponding spatial frequency limits).