
Grating surface
The grating surface is a planar ruled surface that deflects light through diffraction. The ruling is in the x-direction, which causes diffraction of light in the y-direction. LensForge traces the diffraction order that you specify using the surface parameter m. The situation for m=+1 is shown in the figure below:

The effect of refraction is included, if the refractive index after the surface differs from the refractive index before the surface.
Parameters
- T
- Density of grating lines, in lines per micron.
- m
- Diffraction order (initial value is one)