Showing papers on "Apochromat published in 1982"

Optical properties of a cephalopod eye (the short finned squid,Illex illecebrosus)

Abstract: The extent to which the cephalopod eye is optically similar to the teleost eye was determined by measuring refractive error, accommodative ability, spherical and chromatic aberrations, and refractive indices and radii of curvature of the ocular media. The squid eye is well corrected optically underwater although a tendency toward hyperopia exists. This may be due to the existence of chromatic aberration and the fact that an aquatic environment is somewhat limited to the blue end of the spectrum. Accommodation takes place by movement of the lens toward the retina in a manner similar to the teleost eye. However, the squid lens is not spherical but slightly flattened. The lens is overcorrected as far as spherical aberration is concerned. Thus peripheral light rays focus further from the lens than paraxial ones. The function of this unusual example of lens development is unknown.

Wave-front aberration measurements on GRIN-rod lenses.

Abstract: A survey of the optical quality of commercial and experimental Selfoc GRIN-rod lenses was made using a digital Twyman-Green wave-front interferometer. The technique provides an accurate and reproducible method for predicting lens performance in microoptic devices. Wave-front aberrations are reported for ¼ pitch lenses measured in a double-pass configuration. It was found that spherical aberration is dominant in commercial lenses. SLW ¼ pitch lenses have lower aberrations than SLS lenses and are quite suitable for microoptic devices based on fiber-to-fiber coupling. Measured multimode coupling efficiency under steady-state modal propagation is compared to measured spherical aberration for a number of lenses. The slope of the coupling dependence on spherical aberration was found to be −0.1 dB/wave. Effects due to mechanical alignment and the modal distribution in the fibers had a greater influence on the measured coupling efficiency than the contribution due the intrinsic lens aberrations, especially for the SLW lenses. Comparison of this empirical dependence with theoretical predictions for a uniform distribution, which suggests a stronger dependence, is discussed. This work suggests that commercially available GRIN-rod lenses are suitable for use in microoptic components.

Chromatic aberration of a dipteran corneal lens

Abstract: The longitudinal chromatic aberration (variation in the position of focus with wavelength) of corneal facet lenses of the houseflyMusca domestica is measured directly. The result is shown to agree with that calculated using the thick-lens formulas, the measured lens parameters and the dispersion of the refractive index of the lenses, measured with an interference microscope. The longitudinal chromatic aberration between the two wavelengths of peak absorption of fly rhabdomeres (360 nm and 495 nm) is about 2.5 μm and comparable to the depth of focus of the lens, assuming the lens to be diffraction limited. Chromatic aberration is therefore expected to have little effect on optical image quality in the fly; in particular the effect on the modulation transfer function at the receptor level and on the angular sensitivity of the rhabdomeres is insignificant.