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Focusing schlieren systems can use compact optics with a large background illumination pattern, which is particularly easy to produce with a projection system. For systems with large demagnification, the illumination pattern needs to be around twice larger than the field of view to allow defocusing of the background pattern.
Schlieren imaging system setup: linear lens-based configuration. The optical setup of a schlieren imaging system may comprise the following main sections: [citation needed] Parallel beam, focusing element, stop (sharp edge) and a camera. The parallel beam may be achieved by a point-like light source (a laser focused into a pinhole is sometimes ...
Schlieren (/ ˈ ʃ l ɪər ən / SHLEER-ən; German: [ˈʃliːʁn̩] ⓘ, German for 'streaks') are optical inhomogeneities in transparent media that are not necessarily visible to the human eye. Schlieren physics developed out of the need to produce high-quality lenses devoid of such inhomogeneities.
Here, Mach 4 flow over a pitot probe is observed by schlieren optics in the Penn State Supersonic Wind Tunnel. The flow direction is left-to-right. The flow direction is left-to-right. A supersonic wind tunnel is a wind tunnel that produces supersonic speeds (1.2< M <5) The Mach number and flow are determined by the nozzle geometry.
It is related to, but simpler than, the schlieren and schlieren photography methods that perform a similar function. Shadowgraph is a type of flow visualisation. In principle, a difference in temperature, a different gas, or a shock wave in the transparent air cannot be seen by the human eye or cameras.
A major advantage of the technique is that it is less sensitive to mechanical vibration, and it is therefore widely used in the ophthalmic industry for laminar analysis. A similar implementation in wind tunnel application for quantitative measurement is moire schlieren, a variation of schlieren photography. [3]
This page was last edited on 23 December 2005, at 01:22 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.
Foucault test setup to measure a mirror. The Foucault knife-edge test is an optical test to accurately measure the shape of concave curved mirrors. It is commonly used by amateur telescope makers for figuring primary mirrors in reflecting telescopes. It uses a relatively simple, inexpensive apparatus compared to other testing techniques.