3D Surface Roughness and Wear Measurement, Analysis and Inspection

Root Mean Square Profile Wavelength Along (X, Y)

Stylus (X,Y) λq

Stylus (X ,Y) λq , the Root Mean Square (rms) Profile Wavelength Along (X, Y), is a measure of the dominant spatial wavelength that comprises the surface weighted by the amplitude of the various spatial components. The evaluation of these parameters stems from Fourier analysis of the surface texture resulting in the following:

Depiction of the evaluation of the lq parameter. The contour plot (A) shows a line through the center over which the profile (B) is selected. After evaluation, a representation of λq is depicted in (B).


The λq measurements along the X and Y directions provide a quantitative measure of the key spatial wavelengths that comprise the texture in the respective directions. A surface that has a high amplitude long wavelength wavy structure on which are superimposed small amplitude short wavelength texture features will have a λq representative of the long wavelength structure. However, as the amplitude of the shorter wavelength structure begins to approach that of the long wavelength structure, the measured λq will seek a value somewhere between the long wavelength and short wavelength values. λq is used when tool feed rates are under investigation and as a further means to differentiate surfaces/processes that yield similar amplitude parameters (e.g. Ra) but function differently. λq may be related to the appearance of a surface and also the real area of contact between loaded components.