Shack-Hartmann

A Hartmann-Shack or Shack-Hartmann is a type of wavefront sensor. It is commonly used in adaptive optics systems. It consists of an array of lenses (called lenslets) of the same focal length. Each is focused onto a photon sensor (typically a CCD array or quad-cell). The local tilt of the wavefront across each lens can then be calculated from the position of the focal spot on the sensor. Any phase aberration can be approximated to a set of discrete tilts. By sampling an array of lenslets all of these tilts can be measured and the whole wavefront approximated.

Since only tilts are measured the Shack-Hartmann can not detect discontinuous steps in the wavefront.

The design of this sensor was proposed by the German Hartmann in 1900 [Hartmann "Bemerkungen über den Bau und die Justirung von Spektrographen." Z. Instrumentenkd 20:47, 1900] and built by Shack and Platt in 1971 [Shack, Platt "Production and use of a lenticular Hartmann screen," JOSA 61:656, 1971] . Therefore the common terminology is Hartmann-Shack (or as proposed by Shack and Platt 'Hartmann-screen'), while in the US there is prevalence to place the US-American Shack at the front in other countries the historical sequence is used.The fundamental principle seems to be documented even before Huygens by a Jesuit philosopher named Scheiner [Scheiner, "Oculus, sive fundamentum opticum," Innspruk 1619] in Austria.

References

Industry

Different companies that sell Shack-Hartmann sensors :
* [http://www.metrolux.de/contenido/cms/wavefront-sensor/ metrolux GmbH]
* [http://www.optocraft.com OPTOCRAFT GmbH]
* [http://www.wavefrontsciences.com WaveFront Sciences]
* [http://www.imagine-optic.com Imagine Optic]
* [http://www.pulstec.co.jp/en/index.html Pulstec Industrial]
* [http://www.okotech.com Flexible Optical BV (OKOTech)]