Lapmaster International’s SPI Interferometers with grazing incidence are an inexpensive, fast and accurate means for flatness inspection of ground, fine ground, lapped or polished parts. Flatness readings of non-reflective ground surfaces on all materials are clearly displayed as easily read fringes. Contact Lapmaster International to receive a light band (fringe) reading chart on an accompanying monitor. Eliminate secondary polishing operations, where polishing is performed only for the purpose of checking for flatness with optical flats (secondary polishing can alter flatness characteristics of the original lapped or ground surface). Whether used directly next to the lapping, fine grinding or grinding machine, or in the inspection lab, Lapmaster SPI Interferometers are a cost effective solution for simple flatness qualification requirements.