Surface Quality

A specification of allowable flaws in the surface on an optic indicated by a hyphenated number (i.e. 60-40). The first number is referred to as the scratch number and quantifies defects of a long nature, such as scratches; the second number is the dig number and indicates round defects such as pits and dents. Scratch-Dig numbers for surface quality conform to the US government standards MIL-PRF-13830B.