Now that we have dealt with the fundamentals, we’ll focus on the derived phenomenon of angular dispersion. Angular dispersion is an important quantity in optics that describes the ability for an optical element, such as a diffraction grating or prism, to geometrically spread a beam of light as a function of wavelength. Mathematically it is expressed by the differential (∂ θ/∂λ). For spectrophotometers and wavelength meters based on dispersive elements, such as diffraction gratings and prism arrays, the dispersion should be as large as possible since that enables a higher wavelength spatial resolution.