-Surface Metrology Basics

Surface metrology involves measuring surface texture, roughness, and topography using contact or non-contact techniques.

• Stylus instruments: a physical stylus traces and record surface profiles.
  • Skidded instrument: a fixed reference (skid) filters out waviness in order to make roughness measurements.
  • 2D profiling instruments: capture surface data along a line to evaluate parameters such as Ra, Rq, and Rt.
  • 3D profiling instruments: generate full 3D topographic maps of surfaces for advanced analysis.
• Optical surface measuring: mon-contact techniques that use light interference or focusing for precise surface characterization.
  • Phase-shifting interferometry: capture surface height by analyzing phase differences in interfered light.
  • Confocal chromatic probe microscopy: utilizes chromatic dispersion to focus light at different depths and build surface profiles.
  • Coherence Scanning Interferometry (Scanning White Light Interferometry): measure surface texture by scanning vertical positions with white light interference patterns.
  • Point auto focusing microscopy: Find surface points by detecting optimal focus using contrast or light intensity peaks.
• Other methods
  • Light scattering measurement techniques: estimate roughness based on how light scatters off the surface.
  • Capacitance measurement: evaluate surface topography by sensing capacitance changes due to height variations.
  • Elastomeric platform: capture surface texture by pressing a deformable gel and imaging the resulting deformation.