The surface quality of watch and clock parts depends on white-light-interferometry. Optical metrology is gaining importance for quality assurance of precision micro-parts. Fast, high resolution measurements using a non-contact, non-reactive (zero mass loading) optical technique are particularly appealing for micro-parts. This story takes a closer look over the watchmaker’s shoulder to see, how white-light interferometry can support their precision engineering. In contrast to several other optical surface metrology methods, such as fringe projection or focus variation, white-light interferometry can be used for measurements on both rough and optically smooth surfaces.
A minute wheel drive from a watch shown as 3D topography profile. To verify the manufactured quality, the surface roughness on the inclined area, which is about 100 x 300 μm2 must be measured. Tactile measurement methods would cause problems due to the geometry of the measurement area. On the other hand, optical techniques such as white-light interferometry allow the topography to be captured within a matter of seconds.