Filtering Surface metrology

to obtain surface characteristic measurements subject filtering. 1 of important topics when comes specifying , controlling surface attributes such roughness, waviness, , form error. these components of surface deviations must distinctly separable in measurement achieve clear understanding between surface supplier , surface recipient expected characteristics of surface in question.

typically, either digital or analog filters used separate form error, waviness, , roughness resulting measurement. main multi-scale filtering methods gaussian filtering, wavelet transform , more recentlty discrete modal decomposition. there 3 characteristics of these filters should known in order understand parameter values instrument may calculate. these spatial wavelength @ filter separates roughness waviness or waviness form error, sharpness of filter or how cleanly filter separates 2 components of surface deviations , distortion of filter or how filter alters spatial wavelength component in separation process.