Optical Configurations for Imaging Spectrometers

Imaging spectrometers or hyperspectral imagers are radiation sensors that provide a continuous collection of spectral images of an inhomogeneous scene, allowing to obtain a spectral signature of each point in the scene. They are applied to perform many different tasks such as accurate mapping of wide areas, object identification and recognition, target detection, process monitoring and control, clinical diagnosis imaging and environment assessment and management. Application areas include forestry, geology, agriculture, medicine, security, manufacturing, colorimetry, oceanography, ecology and others [1].

The simplest way to obtain information of a scene by optical means is taking a photograph. With a black and white photograph we get an irradiance map of the radiation reflected by each point in the scene. A colour photograph allows to get some spectral information corresponding to the superposition of the radiation reflected in three broad band of the spectrum, typically blue, green and red bands. Much more information can be obtained if the photographs are taken in tens or hundreds of different spectral bands. Imaging spectrometers do this work. They take separated images at narrow and contiguous spectral bands.