Bal-tec™ Home Microscope Profilometer Calibration Spheres
A very precise ball is the outstanding device for calibration of optical profilometers. Master balls can be supplied with a flat surface to act as a stable base. See Figure Number 1.
The ball can also be fixed to a base plate to provide a stable location. Tiny reference balls are often epoxy glued to a glass microscope slide, for use with microscopic optical profilometers. See Figure Number 2. The radius of curvature of the master reference spheres can be provided with NIST-traceable long-form certification.