Moiré pattern movement compensation and quadrature averaging phase retrieval from time series of speckled arbitrary phase shift interferograms for automatic computation of fundus pulsation curve of the human eye.

PURPOSE: the method described here allows for automatic calculation of the fundus pulse from interferometric measurements. METHOD: a low intensity laser beam is coupled into the eye. Two strong reflections, one of the cornea and one of the retina, interfere on a high-speed complementary metal-oxide-semiconductor camera chip. After eye movement compensation, a speckle-free phase of the interferograms is calculated from a series of interference fringes. Then, the fundus pulsation is calculated from the phase shift between two consecutive interferograms. PROBLEMS: occurring speckle perturbs the fringe images, and therefore, classical geometrical movement compensation algorithms do not work with sufficient accuracy. The movement compensation algorithm needs to work without prior knowledge of the phase. RESULTS: the proposed algorithms yield the fundus pulse from speckled interferograms, overcoming the above mentioned problems.

Micro displays as intraocular vision aid--design of an optical system.

All over the world about 10 million people suffer from blindness caused by an opaque, irreversible damaged and inoperable cornea. Many of these people still have intact retinal functions. After Prof. Heimann of the University of Köln miniaturized and implantable displays might help such people to restore partially their vision. Optical and physiological constraints of such vision aids are discussed.

High-speed gated surface profiling with closed-loop optical coherence topography.

The here presented work describes a surface profiling technique, for which the term closed-loop optical coherence topography (CLOCT) was proposed [1]. This technique is a scanning beam, servo-locked variation of low-coherence interferometry. It allows for the sub-wavelength-resolution tracking of a weakly scattering macroscopic-scale surface with the absence of significant real-time computational overhead and is thus particularly well suited to real-time surface profiling of in vivo, macroscopic biological surfaces.

High-speed, high-sensitivity, gated surface profiling with closed-loop optical coherence topography.

We describe and experimentally demonstrate a novel (to our knowledge) surface profiling technique, for which we propose the term closed-loop optical coherence topography. This technique is a scanning beam, servo-locked variation of low-coherence interferometry. It allows for the sub-wavelength-resolution tracking of a weakly scattering macroscopic-scale surface, with the surface profile being directly output by the controlling electronics. The absence of significant real-time computational overhead makes the technique well suited to high-speed tracking. The use of a micrometer-scale coherence gate efficiently suppresses signals arising from structures not associated with the surface. These features make the technique particularly well suited to real-time surface profiling of in vivo, macroscopic biological surfaces.