Transmission Gratings are designed to disperse incident light at specific angles. Angular dispersion is a function of angle of incidence and groove spacing. Dispersion increases as angle of incidence increases or as groove spacing decreases. Coarse groove spacing maintains high efficiency while fine groove spacing reduces transmission at long wavelengths resulting in low efficiency.

Transmission Gratings offer low polarization sensitivity as opposed to reflection gratings because incident light is not reflected by a mirror coating such as aluminum. Since light is transmitted through the grating, transmission gratings can be used in compact, in-line configurations. They are ideal for use in monochromators and spectrometers.

Transmission Gratings are manufactured in the same way as ruled reflection gratings in which a replica of a master grating is created by duplicating its grooved surface with a thin, vacuum deposition-coated layer, except they have no reflective overcoat.