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 based on an aperture array that had been developed in 1900 by Johannes Franz Hartmann as a means to trace individual rays of light through the optical system of a large telescope, thereby testing the quality of the image.[1] In the late 1960s Shack and Platt modified the Hartmann screen by replacing the apertures in an opaque screen by an array of lenslets.[2][3]. The terminology as proposed by Shack and Platt was 'Hartmann-screen'. The fundamental principle seems to be documented even before Huygens by the Jesuit philosopher, Christopher Scheiner,[4] in Austria.
References
- ^ Hartmann "Bemerkungen über den Bau und die Justirung von Spektrographen." Z. Instrumentenkd 20:47, 1900
- ^ Platt, Ben C.; Ronald Shack (2001). "History and Principles of Shack-Hartmann Wavefront Sensing". Journal of Refractive Surgery 17.
- ^ Shack and Platt "Production and use of a lenticular Hartmann screen," JOSA 61:656, 1971
- ^ Scheiner, "Oculus, sive fundamentum opticum," Innspruk 1619
Industry
Different companies that sell Shack-Hartmann sensors :
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