Caption:
White light dispersed by a diffraction grating. Transmissive diffraction grating is an optical element that has many thin lines of either absorptive material or thin grooves (indentations) on an otherwise transparent substrate. Light transmission through a diffraction grating occurs along discrete directions, called diffraction orders. Here a beam of white light incident from above is split into many diffraction orders, with +1 order containing most of the power. Within each order, different wavelengths of light are diffracted at slightly different angles, as is particularly evident for the +1 order.