LONG WAVELENGTH INFRARED DETECTION AND IMAGING WITH LONG WAVELENGTH INFRARED SOURCE

摘要

An infrared detection system comprises the following elements. A laser sourceprovides radiation for illuminating atarget (5). This radiation is tuned to at least one wavelength in thefingerprint region of the infrared spectrum. A detector (32) detectsradiation backscattered from the target (5). An analyser determines from atleast the presence or absence of detected signal in said atleast one wavelength whether a predetermined volatile compound is present. Anassociated detection method is also provided. Inembodiments, the laser source is tunable over a plurality of wavelengths, andthe detector comprises a hyperspectral imaging system.The laser source may be an optical parametric device has a laser gain mediumfor generating a pump beam in a pump laser cavity, apump laser source and a nonlinear medium comprising a ZnGeP2 (ZGP) crystal. Onstimulation by the pump beam, the ZnGeP2(ZGP) crystal is adapted to generate a signal beam having a wavelength in afingerprint region of the spectrum and an idler beamhaving a wavelength in the mid- infrared region of the spectrum. The lasergain medium and the ZnGeP2 (ZGP) crystal are locatedin the pump wave cavity.