Wavefront correction with a ferrofluid deformable mirror: experimental   results and recent developments
  We present the research status of a deformable mirror made of a magnetic liquid whose surface is actuated by a triangular array of small current carrying coils. We demonstrate that the mirror can correct a 11 microns low order aberrated wavefront to a residual RMS wavefront error 0.05 microns. Recent developments show that these deformable mirrors can reach a frequency response of several hundred hertz. A new method for linearizing the response of these mirrors is also presented. 
Denis Brousseau, Ermanno F. Borra, Simon Thibaul, Anna M. Ritcey,   Jocelyn Parent, Omar Seddiki, Jean-Philippe Dery, Luc Fa...