Israel’s Laser Detect System (LDS) has developed the SpectroDrone that can identify explosives and other hazardous materials from several meters away. The system uses a multi-wavelength laser, range-finder, high resolution camera and an algorithm and can be placed on a UAV, robot or vehicle.
https://www.youtube.com/watch?v=n-yC6ihdmbg
http://www.timesofisrael.com/drone-capable-of-remotely-finding-bombs-unveiled-in-tel-aviv/