Effects of finite stylus width in surface contact profilometry

Area of Science:

• Surface Metrology
• Applied Physics
• Materials Science

Background:

• Profilometry is crucial for characterizing surface topography.
• Stylus tip geometry is known to influence measurement accuracy.
• Understanding these effects is vital for reliable surface analysis.

Purpose of the Study:

• To investigate the influence of stylus width on surface profilometry.
• To develop a theoretical model for stylus-surface interaction.
• To quantify the effect of stylus size on measured surface parameters.

Main Methods:

• Developed an approximate analytical solution for stylus path on arbitrary surfaces.
• Modeled the surface and its derivatives as jointly Gaussian variates.
• Averaged the solution to compute the first two moments of the measured profile.

Main Results:

• Expressed stylus path as a nonlinear function of surface height and derivatives.
• Derived the measured surface variance as a function of stylus width.
• Observed a decrease in measured surface variance with increasing stylus width.

Conclusions:

• Stylus width is a critical parameter in surface profilometry.
• The study provides a theoretical basis for understanding stylus-induced measurement artifacts.
• Results align with and are validated by computational simulations.