The UV Transmission Gratings are described by their maker as an elegantly simplistic method of dispersing light for fixed grating applications in the 250 - 450 nm wavelength range. They employ a UV-grade fused silica substrate and are relatively polarization insensitive and are fairly impervious to alignment errors. Incident light strikes the grating’s coarse groove spacing where it is dispersed to the opposite side of the grating at a fixed angle. As the groove spacing increases, the diffraction angle decreases. Gratings are available in multiple diffraction angles as well as with 300, 600, 830, and 1200 grooves/mm in three sizes: 12.7, 25 and 50 mm square. EDMUND OPTICS INC., Barrington, NJ. (800) 363-1992.