A diffraction grating is an optical component with a regular pattern. The form of the light diffracted by a grating depends on the structure of the elements and the number of elements present, but all gratings have intensity maxima at angles θ m which are given by the grating equation d ( sin ⁡ ⁡ θ θ m ± ± sin ⁡ ⁡ θ θ i ) = m λ λ , where θ θ i is the angle at which the light is incident, d is the separation of grating elements, and m is an integer which can be positive or negative.