Ferrofluid mirrors have the potential to be an inexpensive adaptive optical element which can be used to improve images of structures at the rear of the eye. Their low cost could allow adaptive optics technology to find widespread use in clinical settings. As discussed elsewhere1, their stroke and speed are suitable for correcting the aberrations of the human eye. We present work on the static and dynamic responses of these mirrors using a Hartmann-Shack wavefront reconstruction technique. The displacement of the mirror versus the current in the magnetic field actuators has been measured, as well as actuator influence functions (including non-linearities). In addition, the real-time dynamics of the mirror have been characterized.
Optical aberrations reduce the imaging quality of the human eye. In addition to degrading vision, this limits our ability to illuminate small points of the retina for therapeutic, surgical or diagnostic purposes. When viewing the rear of the eye, aberrations cause structures in the fundus to appear blurred, limiting the resolution of ophthalmoscopes (diagnostic instruments used to image the eye). Adaptive optics, such as deformable mirrors may be used to compensate for aberrations, allowing the eye to work as a diffraction-limited optical element. Unfortunately, this type of correction has not been widely available for ophthalmic applications because of the expense and technical limitations of current deformable mirrors. We present preliminary design and characterisation of a deformable mirror suitable for ophthalmology. In this ferrofluidic mirror, wavefronts are reflected from a fluid whose surface shape is controlled by a magnetic field. Challenges in design are outlined, as are advantages over traditional deformable mirrors.