Curvature sensing with a Shack-Hartmann sensor

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Shack-Hartmann (SH) sensor, based on sampling of wavefront tilts in subapertures, is a simple, reliable, and widely used in adaptive optics wavefront sensor. A wavefront curvature sensor has the advantage of providing the results suitable for direct control of membrane and bimorph deformable mirrors [1], but requires linear registration of intensity in two planes. SH sensor modifications using astigmatic microlens array [2] and three SH sensors [3] provide measurement both in the form of wavefront gradients and Laplacian curvatures. In this work, we consider a simple arrangement that turns a standard SH sensor into a curvature sensor by moving the camera chip of the SH sensor into the optical plane conjugated to a deformable mirror. This establishes a direct geometric correspondence between the coordinates on the DM surface and the sensor chip. Then, change in the local centroid density corresponds to the Laplacian curvature of the mirror, and the phase at the boundary can be found from the centroid displacements along the edge of the pupil. We investigate the feasibility of this approach for direct control of membrane deformable mirror by measuring the dependence of the calculated centroid density on the control signal applied to the mirror actuators. The experimental results demonstrate a good linear dependence.
Original languageEnglish
Title of host publicationProceedings the 10th International Workshop on Adaptive Optics for Industry and Medicine 2015
EditorsS Bonora
Place of PublicationPadova, Italy
PublisherInst. of Photonics and Nanotechnology-Nat. Res. Council of Italy
Publication statusPublished - 2015
EventInternational Workshop on Adaptive Optics for Industry and Medicine - Padova, Italy
Duration: 15 Jun 201519 Jun 2015
Conference number: 10


ConferenceInternational Workshop on Adaptive Optics for Industry and Medicine
Abbreviated titleAOIM


  • Adaptive optics
  • Shack-Hartmann sensor
  • curvator sensor
  • membrane deformable mirror


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