Robert Kreuzer

Learn More
Split beams of varying separations from a helium-neon laser were directed through the crystalline lenses of a number of vertebrates. Photographs of the focal effects indicate the extent to which the refractive index variation of the lens and lens shape control spherical aberration. Of the fish studied, only rock bass lenses are relatively free of spherical(More)
Spherical aberration of the eyes of a spectrum of freshwater fishes was determined by photographing the refractive effects of excised crystalline lenses on multiple parallel split laser beams. In general, spherical aberration is minimized by the developmentally related variation in lens refractive index. However, spherical aberration is marked and(More)
A split-laser technique employing red and blue lasers was used for direct measurement of longitudinal chromatic aberration of excised lenses from a spectrum of vertebrates (fish, amphibians, birds and mammals). The chromatic aberration (442-633 nm) of lenses of most species amounts to a relatively constant 4.6% of equivalent focal length. Dog lenses show(More)
This paper explores the effectiveness of different semantic web page segmentation algorithms on modern websites. We compare three known algorithms each serving as an example of a particular approach to the problem, and one self-developed algorithm, WebTerrain, that combines two of the approaches. With our testing framework we have compared the performance(More)
Concern has been expressed in the literature regarding the frequency and amount of astigmatism found in patients with intraocular lens implants. Postoperative tilting of the implants is one suggested cause. We have measured the effect of tilt on focal length in lenses supplied by two companies. The method used involved photographing the refractive effect of(More)
  • 1