What are Hyperspectral Sensors?

Hyperspectral sensors are devices which record images using a wide portion of the electromagnetic spectrum. These sensors capture an image in a number of slices or spectral bands, each representing a portion of the spectrum. These spectral bands are then combined to form a three dimensional composite image. The resultant images or hyperspectral cubes allow definitive, deep layer analysis of the materials or minerals which make up the scanned area. Hyperspectral imaging is a valuable diagnostic tool in the physics, agricultural, surveillance, and mineralogy fields.

Humans can only discern images in the visible light portion of the electromagnetic spectrum. Several creatures in nature such as the mantis shrimp can “see” objects in a far wider range including ultraviolet and infra red light. Hyperspectral sensors have the same broad spectral sensitivity characteristics and detect reflected light wavelengths invisible to the human eye. Hyperspectral imaging equipment records these images in wavelength defined slices or spectral bands. Different materials and minerals reflect separate light wavelengths in a unique manner, thereby allowing the equipment to build an accurate compositional cross-section image of any object.

The spectral “signatures” of most materials are known factors which makes for easy identification of the information captured by the sensor. This can greatly expedite the exploration process when searching for ores and oil. Hyperspectral sensors in this type of exploration are typically transported in light aircraft and the data collected assimilated upon landing. Geographical spectral analysis is also carried out from space via satellite located sensors. In these cases, the collected data is sent back to earth by radio link.

Hyperspectral sensors are also commonly used in the agricultural industry. There they are used to create images which may assist in the early detection of plant disease outbreaks. They are also used to establish nutrient levels in standing crops and water levels in the surrounding soil. Another important use of hyperspectral imaging in agriculture is the detection of animal proteins in livestock feeds. This information is then used as a counter measure to the spread animal afflictions such as mad cow disease.

The security and surveillance industries are also regular users of hyperspectral sensors. In these applications, the sensors are used to differentiate between real vegetation and camouflage paints and detect areas of heavy traffic movement. They can also pinpoint subterranean emplacements and identify the location of minefields. Investigators can also use hyperspectral sensors to locate recently disturbed earth which may indicate the location of graves or buried objects.