The Grating and Cross Grating boundary conditions, together with the Diffraction Order (Grating) and Diffraction Order (Cross Grating) subnodes, respectively, are used to separate rays by diffraction at a periodic structure. The Grating is periodic in one direction and homogeneous in the orthogonal direction; the Cross Grating is periodic in two directions. Either feature can release both reflected and transmitted rays. You can specify the direction of periodicity and the size of the unit cell.

The Mirror boundary condition is a simplified Wall that only causes specular reflection.

The Scattering Boundary feature can be used to scatter rays in both transmission and reflection.

The Axial Symmetry boundary condition is only available in 2D axisymmetric models. It is automatically applied at the axis of symmetry and can’t be applied anywhere else.

Optical devices like the Linear Polarizer and Linear Wave Retarder are available when ray intensity or power is computed. They don’t have any effect on the ray direction but they can affect the ray polarization.