Laser sensors measures the distance along the emitted beam. They are based on laser mass spectrometry that can be applied to any sample, solid, liquid or gas. They use laser beams in conjunction with mass spectrometers, nuclear detectors and gas chromatographic techniques. Typically, laser beams hit targets and the backscattered light is collected and processed. Depending upon the way in which the wave is transmitted, laser sensors are classified as pulse detection or amplitude modulation. In the former, the distance is obtained from the time elapsed between the emission and the receipt of a pulse. In the latter, the lasers emit an amplitude-modulated wave, and the distance depends on the difference of the phase between the emitted and the received wave.