Reduction of speckles in retinal reflection

Speckle noise can deteriorate the quality of wave-front sensors measuring ocular aberrations. To counter that, a narrow laser beam was acoustically modulated before entering the eye and creating a spot on the retina. Light was scattered back through the aberrations into the sensor. The increased spot size, wider angular spread, and temporal modulation of the incoming beam averaged out the speckles, producing a more uniform response of the wave-front sensor. The method applies also to retinal imagers and to nonbiological speckle.

[1]  Roberto Ragazzoni,et al.  Extended source pyramid wave-front sensor for the human eye. , 2002, Optics express.

[2]  P Artal,et al.  Dynamics of the eye's wave aberration. , 2001, Journal of the Optical Society of America. A, Optics, image science, and vision.

[3]  B. Vohnsen,et al.  Guided light and diffraction model of human-eye photoreceptors. , 2005, Journal of the Optical Society of America. A, Optics, image science, and vision.

[4]  Andrey V. Larichev,et al.  ERRATA: Measurement of eye aberrations in a speckle field , 2001 .

[5]  Pascal Puget,et al.  Curvature sensor for the measurement of the static corneal topography and the dynamic tear film topography in the human eye. , 2005, Optics letters.

[6]  Mark Hewko,et al.  Speckle noise attenuation in optical coherence tomography by compounding images acquired at different positions of the sample , 2007 .

[7]  E N Ribak,et al.  Simulated annealing in ocular adaptive optics. , 2006, Optics letters.

[8]  Carmen Canovas,et al.  Comparison of Hartmann analysis methods. , 2007, Applied optics.

[9]  E. Ribak.  Harnessing caustics for wave-front sensing. , 2001, Optics letters.

[10]  B. D. Cook,et al.  Unified Approach to Ultrasonic Light Diffraction , 1967, IEEE Transactions on Sonics and Ultrasonics.

[11]  Erez N. Ribak,et al.  Fast Fourier demodulation , 2004 .

[12]  Lingli Wang,et al.  Speckle reduction in laser projections with ultrasonic waves , 2000 .

[13]  S A Burns,et al.  Model for cone directionality reflectometric measurements based on scattering. , 1998, Journal of the Optical Society of America. A, Optics, image science, and vision.

[14]  Jungtae Rha,et al.  Adaptive optics flood-illumination camera for high speed retinal imaging. , 2003, Optics express.