Laser schlieren deflectometry (LSD) is a method for a high-speed measurement of the gas temperature in microscopic dimensions, in particular for temperature peaks under dynamic conditions at atmospheric pressure. The principle of LSD is derived from schlieren photography : a narrow laser beam is used to scan an area in a gas where changes in properties are associated with characteristic changes of refractive index. Laser schlieren deflectometry is claimed to overcome limitations of other methods regarding temporal and spatial resolution.