Near infrared
As a near infrared or near infrared ( NIR ) region of the is the electromagnetic spectrum indicated extending in the direction of larger wavelengths to the visible light is connected. This range of infrared light extends from 780 nm to 3 µm and thus includes the spectral ranges IR-A and IR-B .
Remote sensing
In remote sensing , the near infrared is used, among other things, to analyze aerial and satellite images to assess the vitality of the vegetation . In the near infrared, chlorophyll has a significantly (approximately factor 6) higher reflectivity than in the visible (especially green) spectrum. This effect is used to detect vegetation. One image is shot in the visible (preferably in the red) spectrum and one in the near infrared. Useful objects have approximately the same reflectivity in the visible as well as in the near infrared range, while vegetation containing chlorophyll has a significantly higher degree of reflection in the near infrared . Thus z. For example, green useful objects can also be distinguished from green vegetation.
Signal transmission
Technically, this area is used for signal transmission in optical glass fibers . It is therefore divided into several frequency bands .
| designation | Wavelength range | Alternative name | Remarks |
|---|---|---|---|
| O-band | 1260-1360 nm | original | Original data transmission with negligible dispersion of group speed |
| E-band | 1360-1460 nm | extended | |
| S-band | 1460-1530 nm | short | |
| C band | 1530-1565 nm | central | Lowest attenuation in a glass fiber |
| L-band | 1565-1625 nm | long | |
| U-band | 1625-1675 nm | ultra-long |
medicine
Medically, the range from approximately 700 to 1100 nm is used in ophthalmology ( ophthalmology ) both for diagnosis (for example: optical coherence tomography ) and for surgery (for example: welding on the retina) due to the transparency of the optical apparatus . Depending on the wavelength, the depth of penetration of the radiation also differs .
Chemistry and astronomy
In chemistry and astronomy, infrared spectroscopy (absorption bands) can be used to detect the presence of molecules or functional groups , for example acetone and water or CH and OH groups .
literature
- Donald A. Burns: Handbook of near-infrared analysis. CRC Press Boca Raton 2008, ISBN 978-0-8493-7393-0 .
- Ramesh Raghavachari: Near-infrared applications in biotechnology. Dekker, New York 2001, ISBN 0-8247-0009-0 .
- John T. Houghton: Infra-red physics. Clarendon Press, Oxford 1966.
- Martin Giard: Infrared and submillimeter space astronomy. EDP Sciences, Les Ulis 2002, ISBN 2-86883-612-7 .