Results 121 to 130 of about 470 (166)

Photorefractive Keratoplasty: Photorefractive Keratomania?

Archives of Ophthalmology, 1996
Push the buttonand eliminate glasses. Sounds too good to be true, and those who are in the field of photorefractive keratoplasty (PRK) know the facts remain somewhere else. Certainly there are many happy patients who are ecstatic about the elimination of most or all of their myopia.
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Photorefractive shooting stars

Optics Letters, 1998
Under certain conditions the direction of a beam diffracted from a photorefractive grating wanders as the grating decays. This phenomenon is due to competition between the original grating and those formed spontaneously by the Fabry-Perot modes produced by the crystal's surfaces.
R S, Cudney, M H, Garrett
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Pharmacotherapy of photorefractive keratectomy

Journal of Cataract and Refractive Surgery, 1996
To compare the pharmacotherapeutic practices of high-volume photorefractive keratectomy (PRK) surgeons with suggested practices gleaned from the current literature.York Finch Eye Associates, Toronto, Canada.Seventy-five ophthalmic surgeons believed by the authors to do a high-volume of PRKs were surveyed over the summer of 1994 about their ...
S A, Arshinoff, M D, Mills, S, Haber
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Fixing the photorefractive soliton

Optics Letters, 1999
We report the formation of permanent two-dimensional 12-microm waveguides in a bulk strontium barium niobate crystal. The waveguides are made by formation of a photorefractive spatial soliton in which the space-charge field induces ferroelectric domains that are permanently polarized opposite to the crystal c axis.
M, Klotz, H, Meng, G J, Salamo, M, Segev, S R, Montgomery   +4 more
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Photorefractive effect in GaP

Optics Letters, 1990
The photorefractive effect in undoped semi-insulating GaP was observed. GaP has a photorefractive sensitivity in the spectral region of 0.6 to 0.9 microm. The photorefractive center is the deep donor resulting from the P antisite defect. We measured the two-beam coupling gain coefficient and its time constant as functions of the grating period and the ...
K, Kuroda, Y, Okazaki, T, Shimura, H, Okamura, M, Chihara, M, Itoh, I, Ogura   +6 more
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Photorefractive Phase Conjugators

Proceedings of the IEEE, 1992
The author presents a tutorial review of various kinds of optical phase conjugators using photorefractive materials. These include externally pumped phase conjugators (EPPCs), self-pumped phase conjugators (SPPCs), and mutually pumped phase conjugators (MPPCs). He briefly describes optical phase conjugation and the photorefractive effect.
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Optics for photorefractive keratectomy

Journal of Cataract and Refractive Surgery, 1993
Matrix calculations are applied to Gaussian optics in the study of myopic correction by photorefractive keratectomy. The Colliac matrix formula determines the postoperative anterior curvature radius of the treated cornea. It also calculates the maximal depth of the removed corneal tissue and the ablation zone diameter needed to achieve emmetropia.
J P, Colliac, H J, Shammas
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Photorefractive integrator characterization

Applied Optics, 1995
We describe the recent results of our efforts to characterize a photorefractive crystal to be used as a time-integrating device in an optically implemented null-steering adaptive processor for phased-array radar. We review frequency response data for the Bi(12)SiO(20) crystals, measured with an acousto-optic apparatus, and we present measured dynamic ...
J H, Hong, J B, Norman, T Y, Chang, F, Vachss, D C, Pletcher   +4 more
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Enhanced photorefractive performance in a photorefractive polymeric composite

Journal of Applied Physics, 1994
We characterize the photorefractive behavior of a photorefractive multicomponent polymer composite of PVK-TCP:C60:DEANST. Efficient plasticization of the host polymeric matrix and utilization of a nonlinear chromophore with a large dipole moment provide a large poling-induced electro-optic coefficient.
Maciek E. Orczyk, Bogdan Swedek, Jaroslaw Zieba, Paras N. Prasad   +3 more
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Photorefractive keratectomy in children

Journal of Cataract and Refractive Surgery, 2002
To evaluate photorefractive keratectomy (PRK) in pediatric patients who fail traditional methods of treatment for myopic anisometropic amblyopia and high myopia.Nonhospital surgical facility with follow-up in a hospital clinic setting.Photorefractive keratectomy was performed in 40 eyes of 27 patients.
William F, Astle, Peter T, Huang, Anna L, Ells, Robin G, Cox, Micheline C, Deschenes, Heather M, Vibert   +5 more
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