Results 171 to 180 of about 5,922 (213)

Wavefront correction with photon echoes

Optics Communications, 1977
Abstract If a first pulse with accumulated phase ϕ( x , y , z 0 ) and a plane wave second pulse generate a photon echo, the echo has phase -ϕ( x , y , z 0 ) and is wavefront corrected when returned along the path of the first pulse.
C.V. Heer, P.F. McManamon
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Wavefront correction based on a reflective liquid crystal wavefront sensor

Journal of Optics A: Pure and Applied Optics, 2008
A novel wavefront sensor (WFS) based on liquid crystal on silicon (LCOS) is demonstrated. The design of the liquid crystal microlens array with LCOS is given in detail. To save the energy of the incident light, an optimized optical design of the WFS is also considered.
L Hu, L Xuan, D Li, Z Cao, Q Mu, Y Liu, Z Peng, X Lu   +7 more
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Wavefront correcting properties of corner-cube arrays

Applied Optics, 1988
The performance of corner-cube arrays as pseudophase-conjugation wavefront correctors is investigated theoretically and experimentally. Hollow electroformed arrays and solid plastic arrays of corner-cube retroreflectors have been optically characterized and studied in a pseudophase-conjugate imaging system.
R A, Chipman, J, Shamir, H J, Caulfield, Q B, Zhou   +3 more
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A discussion of two wavefront aberration correction procedures

Ultrasonic Imaging, 1992
This review paper discusses the basic properties of two adaptive signal processing procedures for dealing with weak scattering in a phased array transducer system. A fundamental improvement in the lateral resolution of ultrasonic echo scanners will result if the weight vector of a large phased array transducer can be modified to account for distortion ...
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Liquid crystal lens with corrected wavefront asymmetry

Applied Optics, 2018
We propose a simple technique allowing the correction of the inherent wavefront asymmetry in electrically variable liquid crystal lenses with relatively small diameters. This is achieved by splitting the peripheral hole patterned electrode of the lens in the direction of the ground-state anisotropy axis.
Louis, Begel, Tigran, Galstian
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Aperture size effect on ultrasonic wavefront distortion correction

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2004
The influences of aperture size on wavefront distortion correction are investigated both theoretically and numerically. A multilayer, phase-screen model is assumed to be the underlying, distorting medium. Numerical simulations were performed using three wavefront distortion correction methods: time-shift compensation (TSC), backpropagation followed by ...
Deng-Huei, Huang, Jenho, Tsao
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Wavefront correction by liquid-crystal devices

Soviet Journal of Quantum Electronics, 1986
An experimental investigation was made of the use of liquid-crystal phase correctors of wavefronts. Prototype correctors were prepared with independent addressing of the elements and these were found capable of compensating distortions of wavefronts of radiation of wavelengths 0.5–6μ.
A A Vasil'ev, A F Naumov, V I Shmal'gauzen   +2 more
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Correction of large amplitude wavefront aberrations

SPIE Proceedings, 2005
Recently, a number of research groups around the world have developed ophthalmic instruments capable of in vivo diffraction limited imaging of the human retina. Adaptive optics was used in these systems to compensate for the optical aberrations of the eye and provide high contrast, high resolution images. Such compensation uses a wavefront sensor and a
S. A. Cornelissen, P. A. Bierden, T. G. Bifano, R. H. Webb, S. Burns, S. Pappas   +5 more
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Measurement and correction of ultrasonic wavefront distortion

The Journal of the Acoustical Society of America, 1996
Wavefront distortion produced by transmission through abdominal wall, breast, and chest wall has been measured in a two-dimensional aperture and the abdominal wall measurements have been compared to distortion simulated using sound speed and density determined from stained cross sections.
Robert C. Waag, Dong-Lai Liu, Laura M. Hinkelman, T. Douglas Mast   +3 more
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Fundamentals of Ocular Wavefront Correction

2009
For vision correction, the key is to help patients achieve good visual performance. In most cases, this means good visual acuity and good contrast sensitivity. The ocular aberrations can be considered as a combination of the spherocylindrical aberrations and irregular aberrations.
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