An inverse problem in diffractive optics: conditional stability

Abstract
In this paper, we prove conditional stability for the inverse problem in diffractive optics of determining a periodic curve in the case of perfect reflection. Introducing a time-periodic solution, we formulate the problem in terms of the Helmholtz equation. Taking a plane wave as an incident wave, we observe the total field along a segment which is remote from the unknown curve. Our proof is based on a Carleman estimate for the Laplace operator.