SGoptics can provide the flats for windows, Filters, Graticules (reticles) and Waveplates.
Material:
Common Glass (Schott, Ohara, Hoya, CDGM)
Infrared Material ZnSe, ZnS, Ge, Si;
Fused Silica (Corning Material, JGS1, JGS2, JGS3)
Sapphihre, Color Glasses
