Precision shafts and spindles are generally finished utilizing a centerless grinding process. This machining technique is cost effective and typically produces a quality cylindrical surface in which ball and roller bearings ride. The surface finish is important because any imperfection can be transferred through the bearing system creating unwanted noise, vibration and premature failure. Unfortunately, tool wear, improper feed rates and grinding wheel runout can lead to a poor surface finish. One commonly found defect in the grinding process is called chatter. It is a series of microscopic “waves” in the machined surface, which must be minimized to avoid adverse effects. As the height of these waves increase, so does the noise and vibration. A Major Tier 1 supplier to the automotive industy approached MTII looking for a method to measure and classify these imperfections. The application was critical enough to demand 100% in-process inspection. They required a production environment sensor that had small spatial resolution, high frequency response and ultra-high resolution. For proper defect classification the measurement accuracy had to be less than 4 micro-inches (0.1 microns) with a resolution of 1 micro-inch (0.025 microns).