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 In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, ...

. Laser schlieren deflectometry is claimed to overcome limitations of other methods regarding temporal and spatial resolution. The theory of the method is analogous to the scattering experiment of Ernest Rutherford from 1911. However, instead of

alpha particle Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be prod ...

scattered Scattered may refer to: Music * ''Scattered'' (album), a 2010 album by The Handsome Family * "Scattered" (The Kinks song), 1993 * "Scattered", a song by Ace Young * "Scattered", a song by Lauren Jauregui * "Scattered", a song by Green Day from ' ...

by gold atoms, here an

optical ray In optics a ray is an idealized geometrical model of light, obtained by choosing a curve that is perpendicular to the ''wavefronts'' of the actual light, and that points in the direction of energy flow. Rays are used to model the propagation o ...

is deflected by hot spots with unknown temperature. A general equation of LSD describes the dependence of the measured maximum deflection of the ray ''δ''₁ on the local maximum of the neutral gas temperature in the hot spot ''T''₁: :

\frac + \frac = 1,

where ''T''₀ is ambient temperature and ''δ''₀ is a calibration constant depending on the configuration of the experiment. Laser schlieren deflectometry has been used for investigation of the temperature dynamics,

heat transfer Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy ( heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conducti ...

and energy balance in a miniaturized kind of

atmospheric-pressure plasma Atmospheric-pressure plasma (or AP plasma or normal pressure plasma) is a plasma in which the pressure approximately matches that of the surrounding atmosphere – the so-called normal pressure. Technical significance Atmospheric-pressure pla ...

References

{{reflist Plasma physics Thermodynamics Fluid dynamics

See also

References