An experimental comparison of the ring-lens and the astigmatic techniques of generating a focus-error signal (FES) in optical disk systems reveals that the ring lens generates a FES curve over two times steeper than that produced by the astigmat. Partly because of this large slope and partly because of its diffraction-limited behavior, the ring-lens scheme exhibits superior performance characte...

The energy scaling up of pulse postcompression is still an open issue. In this work we analyze the use of astigmatic focusing to improve the output pulses in a filamentation based postcompression setup. Unlike spherical conditions, astigmatic focusing enhances the output energy and the spectral broadening of the filament. This is due to the increase of critical power, allowing a considerable im...

PURPOSE To test the hypothesis that spatially selective corneal stromal stiffening can alter corneal astigmatism and assess the effects of treatment orientation, pattern, and material model complexity in computational models using patient-specific geometries. SETTING Cornea and Refractive Surgery Service, Academic Eye Institute, Cleveland, Ohio, USA. DESIGN Computational modeling study. M...

The article investigated conditions for shaping astigmatic-invariant structured Laguerre-Gaussian (LG) beams in the case of simple astigmatism. We have theoretically and experimentally confirmed that astigmatic invariance are q-phase parameter LG (sLG) beam is equal to arctangent ratio Rayleigh length z0 focal fcyl a cylindrical lens single amplitude epsilon;=1. For rest values, epsilon;NotEqua...

PURPOSE To determine if a fogging lens ameliorates accommodative effects driven by the closed-view design of the BHVI-EyeMapper (EM) instrument. We compared cycloplegic refraction and higher-order aberration measurements of the EM with those obtained with a fogging lens. METHODS Twenty-six, young, participants (15F, 25±5 years, range: 18-35 years, SE: +0.25 D and -3.50 D) with good ocular hea...

PURPOSE To demonstrate how using the Wavelight Contoura measured astigmatism and axis eliminates corneal astigmatism and creates uniformly shaped corneas. PATIENTS AND METHODS A retrospective analysis was conducted of the first 50 eyes to have bilateral full WaveLight® Contoura LASIK correction of measured astigmatism and axis (vs conventional manifest refraction), using the Layer Yolked Redu...

AIMS To study the refractive development in children with Down's syndrome longitudinally. METHODS An unselected population of 60 children with Down's syndrome was followed with repeated retinoscopies in cycloplegia for 2 years or more (follow up 55 (SD 23) months). Accommodation was assessed with dynamic retinoscopy. RESULTS From longitudinal spherical equivalent values of the right eye, th...

The feasibility of an off-axis x-ray reflection zone plate to perform wavelength-dispersive spectroscopy, on-axis point focusing, and two-dimensional imaging is demonstrated by means of one and the same diffractive optical element (DOE) at a synchrotron radiation facility. The resolving power varies between 3×101 and 4×102 in the range of 7.6 keV to 9.0 keV, with its maxim...