Optical Interferometry / Profilometry

Optical interferometry is a method for making exact measurements by mixing light from many sources in an optical instrument. The topography, profile, and roughness of surfaces have all been described using this method.

Optical interferometry and Profilometry method

The WYKO RST Plus surface profiling device from Infinita lab provides accurate surface texture characterization. A non-contact optical profiler called the RST Plus employs two technologies to measure a variety of surface properties. Vertical-scanning interferometry (VSI) mode can detect rough surfaces and steps at the nanoscale level to the micrometre level, whereas phase-shifting interferometry (PSI) mode can measure smooth surfaces at the Angstrom level. Unlike stylus-type profilers, which only provide roughness over a single line, the RST Plus produces 3D and 2D surface profiles over an area.

The optical interferometer is a superb metrology tool for measuring surface texture and roughness on:

• Precise machining of the surfaces
• Built-in optical circuits
• Waveguides
• Fibres and optics
• Ceramics \sThin-films
• MEMS technology as well as many other industrial measurements

Optical profiler surface measurement parameters available:

• Roughness Average (Ra)
• Root Mean Square (Rq) (RMS) Maximum profile peak height and maximum profile valley depth are known as roughness Rp, Rv.
• Rt, Rsk, Rku, Pc, and more have profiles with an average maximum height of Rz.

Video1: The Zeta-20 Optical Profilometer from Zeta Instruments