<title>Simulation of linearity in optical microscopes</title>

A modal model for diffraction gratings

“…In [9,30] an approach was presented which was based on contour integral theorems for analytic functions. The approach used here is a generalization of the TayebPetit method [11] which was also used successfully in [12,13,[26][27][28][29]. In order to solve the general eigenvalue problem one starts with a known solution and then varies the parameters of the problem slowly and continuously to change the object from the known one to the desired case, all the while tracking the continuous motion of the eigenvalues.…”

“…The modal method has been applied in this context in [26][27][28][29], although the author was not aware of the earlier work at that time, and so the method was referred to as the Analytic Waveguide Method with the tradename Metrologia. Recent interest in grating simulation has increased because of the use of diffraction grating scatterometry for measuring linewidths and cross-sections in semiconductor manufacturing.…”