LIDAR is the first generation of laser remote sensing developed for detection of gas molecule in atmosphere. LIDAR is the abbreviated word for laser radar (laser light detection and ranging). It combines advantages of lasers ability to detect atoms and molecules and radars ability for remote sensing. The advance of technologies: tunable solid state laser (Ti sapphire, OPO etc), optical fiber, photonics imaging technique and last but not least computational techniques, have promoted the development of new types of laser remote sensors capable of detecting toxic and radioactive chemicals and metals not in gas form and not exposed in air but under ground water and subsurface soil. The high power laser is used to vaporize the target material and generate plasma. Optical fiber is often used to delivery the laser beam and to collect the emission for imaging. The combination of spectroscopy with advanced photonics imaging techniques can study both the chemical components of sample in situ under ambient conditions and spatial distribution of different chemicals in remote operation without requiring sample preparation or extensive sample handing. These new developments have greatly enlarged the horizon of traditional capability of remote sensing. LIDAR is the first generation of laser remote sensing developed for detection of gas molecule in atmosphere. LIDAR is the abbreviated word for laser radar (laser light detection and ranging). It has advantages of laser’s ability to detect atoms and molecules and radar The advance of technologies: tunable solid state laser (Ti sapphire, OPO etc), optical fiber, photonics imaging technique and last but not least computational techniques, have promoted the development of new types of laser remote sensors capable of detecting toxic and radioactive chemicals and metals not in gas form and not exposed in air but under ground water and subsurface soil. The high power laser is used to vaporize the target material and generate plasma. to collect the emission for imaging. The combination of spectroscopy with advanced photonics imaging techniques can study both the chemical components of sample in situ under ambient conditions and spatial distribution of different chemicals in remote operation without requiring sample preparation or extensive sample handing. These new developments have greatly enlarged the horizon of traditional capability of remote sensing.