A prototype optical encoder system with nanometer measurement capability

摘要

Optical gratings are becoming available with precision down to the 2 nm level, or below. Such gratings can be employed to make highly accurate measuring tools such as optical encoders and coordinate measuring tools which can find numerous applications in precision machining applications and integrated circuit industry such as image placement inspection. Such tools are significantly less expensive than interferometers because of the relaxed mechanical tolerances required on the associated stages. In this paper, a novel prototype optical encoder system is developed for grating-based measurement tools with nanometer accuracy. The location of the grating was determined with an error of 0.09 nm. This is comparable to the accuracy of state-of-the-art interferometers, but at much lower cost.