Surface Relief Optical Grating Calculator. It calculates diffraction efficiencies vs Angle of Incidence or Wavelength or Thickness for any linear polarization and any rotation of the plane of incidence around propagation axis for 1D and 2D-dimensional surface relief gratings and 1D Volume Phase Holographic gratings. Material database included. Grating region composed of up to 20 different layers. Different type of gratings can be modeled by adjusting "Offsets" of each later, i.e, Blazed Gratings, Triangular Gratings, etc.