Eric S. Johnstone

Quintessential phase: A method of mitigating turbulence effects in interferometer measurements of precision motion

This paper describes a method of mitigating the effect of turbulence in interferometer measurements. In this paper, we will use the example of turbulence disturbing the interferometric estimate of the position of a moving stage, as a 1-D analog of wafer scanning stages used in chip making. The QP method uses a multi-segment detector to detect variations of the drift velocity of the air moving through the interferometer beam, and combines these with a turbulence model to create a set of auxiliary turbulence states. These states are then combined with the states of the moving electromechanical system to form a model of the moving stage in which the turbulence has been removed from the stage position estimate.