Scanning Probe Position Encoder (SPPE)–a new approach for a high precision and high speed position measurement system

and is made available as an electronic reprint (preprint) with permission of SPIE. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in the paper for a fee or commercial purposes, or modification are prohibited. ABSTRACT The NanoWave Scanning Probe Position Encoder (SPPE) is a real-time position measurement device developed for next generation nano-scale positioning applications. The performance level sought is: 1nm precision over 300mm, 0.01nm resolution, and a detection speed of 5-10 m/sec all simultaneously. These devices use holographic gratings as reference scales in conjunction with Scanning Probe Microscopy (SPM) technologies, which may include focused beams as probes, and a patented phase-tracking detection method. The SPPE sensor probe is oscillated near its resonant frequency above the (100nm – 300nm period) holographic grating surface while it scans the grating across the grating land and grooves. This generates the output with high-order harmonics of the probe oscillation, which contain quadrature signals corresponding to the position information. The peak-to-peak amplitude of the probe scanning range at the resonant frequency needs to be only a little larger than a grating period for stable gap distance control, high precision oscillation control and low heat generation. Furthermore, high probe oscillation frequency allows decoupling the position measurement in X and Z directions, maintaining enough bandwidth in each axis measurement, leading to a unique multi-axis position measurement capability.