A precision length calibrator based on the optical zooming positioning stage

A sub-nanometer positioning system using a zooming interferometer and an optical comb was proposed previously. That positioning stage had a positioning resolution of 0.2 nm and a stability of 0.6 nm. In this paper, we describe the length calibrator that we developed by using the proposed positioning system. For the purpose of evaluating this length calibrator, the cyclic error of a roughly-aligned commercial laser interferometer was measured. This cyclic error was observed to have a magnitude of 3.5 nm. The combined standard uncertainty was 0.7 nm for the cyclic error measurement.