The ChemCam instrument for NASA's Mars Science Laboratory mission uses a pulsed laser beam to vaporize a pinhead-size target, producing a flash of light from the ionized material -- plasma -- that can be analyzed to identify chemical elements in the target.

This image from testing of ChemCam shows a ball of luminous plasma erupting from the surface of an iron pyrite crystal in the sample chamber approximately 3 meters from the instrument. The laser beam itself is invisible.

NASA / JPL