High-resolution parallel multipass laser interferometer with an interference fringe spacing of 15 nm

Abstract

We present a high-resolution laser interferometer based on the parallel multipass configuration with a pair of right-angle prisms to increase the optical fringe subdivision order up to 21. In the experiment, a multipass homodyne Michelson interferometer (MHMI) with the fringe spacing of 15 nm was demonstrated, resulting in the displacement measurement with a measurement resolution of 180 pm limited by the sampling rate of the employed analog-to-digital converter. We show that the ultimate resolution of the demonstrated MHMI scales with 1/N and it is estimated to be 8.7 pm for N=21. (C) 2010 Elsevier B.V. All rights reserved.