Real surfaces are covered with asperities. The texture of a surface is complicated, and many parameters are used to quantify the various surface characteristics. This practice is common in microelectronic industries. There are three primary methods of numerically representing surface roughness: centerline average (
c), root-mean-square (
q), and maximum peak-to-valley height (
t). These are deﬁned as:
1. Centerline average (CLA) is the most common designation of surface roughness and is also called the arithmetic average (
a is calculated from:
N is the total number of measurements and
Z is the absolute peak-to-valley height with respect to a reference line.