NEW PRODUCT ANNOUNCEMENT General Modal Diffraction Grating Model  This software solves the general modal problem.   It can handle aperiodic structures, complex multilayers, all angles of incidence, and a microscope image simulator will soon be available.  This product is an excellent design tool for tough diffraction grating problems that cannot be solved by other means.  Spectel Research Corp. provides simulation and metrology software for the semiconductor industry as well as optical design software for diverse applications.