Optometrics USA Inc. has designed a line of replicated gratings for use in transmission. Transmission gratings are suitable for fixed-grating applications such as spectrographs. They are available with or without a visible broadband AR coating on the back surface. The incident light is dispersed on the opposite side of the grating at a fixed angle and at different levels, for optimum performance in the visible spectrum. The company says these blazed gratings are forgiving for some types of alignment errors and are relatively polarization-insensitive.