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In keratoplasty with cataract extraction and intraocular lens (IOL) implanta­tion, preoperative keratometry is the major source of error in lens power selection. Different keratometry readings are used. To find the most accurate reading, IOL power values for emmetropia (IOL1), calculated in 100 normal eyes, were compared with those obtained using the following keratometry values: of the fellow eye (IOL2), Katz Foster value 42.6 D (IOL3), Hoffer value 43.8 D (IOL4). IOL2 was the closest to IOL1 (p = n.s.), IOL3 the furthest (p = 0.001). Fellow eye keratometry is advised if available (if not use Hoffer value).

We present recent results of the study of surface properties and quantum efficiency (QE) of CsI photocathodes prepared on various substrates. Microanalysis methods provide laterally resolved surface morphology and chemical composition of the photoemissive film. Integral measurements of the QE of CsI were done with a monochromator system and a RICH device. It was shown that CsI films deposited on large area Ni- or Ni-Au-coated printed circuit electrodes have a uniform crystalline structure and an average QE close to that reached on polished stainless steel. The films have a good stability in air over periods of Ih. On a microscopic scale of 3-30 mu m, the films exhibit nonuniform emission properties correlated with variations in the chemical composition.

We used a combination of internal photoemission and of near-field optical microscopy (SNOM) to study the lateral Variations in solid interface properties such as energy barriers and electron-hole recombination. Ln particular we investigated the fully formed Pt-GaP, Au-GaAs, Au-SiNx-GaAs and PtSi-Si Schottky barriers. Our approach enabled us to measure large lateral variations in the photocurrent with spatial resolution on the nanometric scale. Due to the ability of SNOM to supply parallel topographic information, we observed photocurrent variations from zone to zone that only correlated in a few cases with local variations in surface morphology. We assigned the uncorrelated fluctuations to local variations in the interface stoichiometry, the presence of interface states induced by the metallic overlayer and to defect states at the junction. Furthermore, by tuning the photon energy and applied bias we were able to measure the surface distribution of the diffusion length.

Mossbauer spectroscopy was used to investigate the early aging stage of iron(III) hydroxide sols prepared by oxidation of Fe(CO) 5 in ethanolic solution, followed by vacuum drying at room temperature. One sample was composed of amorphous particles, while two other samples were partially crystallized, either as a result of solvent change or of spontaneous aging. The main results of Mossbauer measurements in the 80–320 K temperature range are: (a) partially crystallized particles exhibit a strong, S-shaped temperature dependence of the quadrupole splitting, in contrast to a weak and linear variation for amorphous particles; (b) the recoilless fraction temperature dependence is affected by vibration of the particles as a whole, with an effective force constant which is smaller for crystallized particles than for amorphous ones. Furthermore, the former exhibit an f -factor discontinuity near 0°C, which is attributed to melting of a surface layer built up during the crystallization process.