Laser Based Spectroscopies for Minerals Prospecting

Luminescence Lidar (Light Detection and Ranging) is active instrument, which sends out coherent waves to the object concerned. A fraction of the transmitted energy is transformed by the objects and sends back to the sensor. Lidar instruments measure both the traveling time interval between sensor/object/sensor as well as the difference between emitted and returning energy, providing information on the exact position of the objects and on the material the objects are made of. Spectral selectivity was achieved usually with the aid of narrow band interference filters. 

Gaft et al.. Modern Luminescence Spectroscopy of Minerals and Materials, Springer Mineralogy, DOI 10.1007/978-3-319-24765-6 7 

In the first attempts to overcome background problem using decay time, the variation of the fluorescence decay time as a function of wavelength across the entire emission profile for a variety of materials have been used (Measures et al. 1974 Measures 1985). For a variety of rocks and minerals, it was proved that this information represents a new kind of signature, the so called fluorescence decay spectrum, that possesses considerable discrimination power, being able to characterize the irradiated material with far superior precision than the normal luminescence spectrum (Fig. 7.2). 

According to accumulated experience, the discovered luminescence in this selective window may be related to certain ore bodies, such as uranium, wolfram. 

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