11·î22Æü(ÌÚ) 14:30 -- 15:30 Johannes Elschner (Weierstrass-Institute for Applied Analysis and Stochastics, Germany) ``Inverse problems for diffraction gratings'' ¡ã¸¦µæÈ¯É½Í×»Ý(Prof. J. Elschner)¡ä We consider the 2D TE and TM diffraction problems for a time harmonic plane wave incident on a periodic grating structure. An inverse diffraction problem is to determine the grating profile from measured reflected and transmitted waves away from the structure. We present a new approach to this problem which is based on the material derivative with respect to the variation of the dielectric coefficient. This leads to local stability estimates in the case of interfaces with corner points. Another application concerns the optimal design problem for diffraction gratings. The talk presents joint work with Gunther Schmidt.