Theory of Spectroscopy

Spectroscopy pertains to the study of light by dispersing it into its component colours. Light may be regarded as a wave and each distinct colour of light has its own wavelength. The wavelength of light is usually described in units of nanometres (nm). Visible light exists between the wavelengths 380 nm to 780 nm. The energy of light is related to its wavelength, with shorter wavelengths having higher energy than longer wavelengths.

Ultraviolet radiation is light that has wavelengths between 100 nm and 380 nm. This has much higher energy than visible lights and can cause eye and skin damage, for instance, sunburn.

Infra red radiation is light that has wavelengths above 780 nm, up to 5000 nm. Any hot object emits infra red radiation, so infra red imaging techniques can be used in thermal imaging applications such as motion thermography.