| 1. |
- Beckman, Claes, 1962-
(författare)
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Disputing Viking navigation by polarized skylight.
- 1994
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 33:21, s. 4754-5
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Tidskriftsartikel (refereegranskat)abstract
- The widely held notion that the Vikings utilized polarization of skylight on overcast days for navigational purposes is demonstrated to have no scientific basis. The use of polarized skylight for navigation under partly cloudfree skies should be treated with caution and skepticism.
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| 2. |
- Beckman, Claes, 1962-
(författare)
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Intraocular light scattering in vision, artistic painting, and photography.
- 1994
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 33:21, s. 4749-53
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Tidskriftsartikel (refereegranskat)abstract
- Light scattering in the eye is reviewed, and its influence on vision is discussed in some detail. Isotropic scattering and formation of halos around point sources are described with reference to theory and experiments. Artists usually take intraocularly scattered light into account when painting natural scenes. A method to achieve similar effects in photography by the use of diffraction filters in front of the camera lens is demonstrated. A number of photos that illustrate the effects of such filters are shown.
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| 3. |
- Beckman, Claes, 1962-
(författare)
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Optical properties of diffractive, bifocal, intraocular lenses.
- 1992
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 31:13, s. 2377-84
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Tidskriftsartikel (refereegranskat)abstract
- The resolution of diffractive, bifocal, intraocular lenses was studied with regard to pupil displacement and diameter size through computer simulations, bench measurements, and patient vision-acuity measurements. Good agreement was obtained between these three methods of investigation. In particular, we find that pupil displacements of the order of 1 mm reduce the resolution considerably for these lenses.
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| 4. |
- Benckert, Lars
(författare)
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A method to resolve the 180° ambiguity in speckle photography
- 1991
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 30:4, s. 376-378
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A new way of resolving the 180° ambiguity in speckle photography is presented. Results from a study of the deformation of a wooden block caused by drying illustrates the method
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| 5. |
- Benckert, Lars, et al.
(författare)
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Fresnel diffraction of a Gaussian laser beam by polished metal cylinders
- 1990
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 29:3, s. 416-421
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Tidskriftsartikel (refereegranskat)abstract
- A laser beam touching the periphery of a polished cylinder is subjected to both diffraction and reflection. Inthe area where diffracted light and reflected light interact the resulting intensity distribution differs from thepattern predicted by diffraction theory for a sharp edge. The difference increases with cylinder radius. Inthis paper it is shown that a good description of the resulting intensity pattern is obtained by adding thereflected light amplitude to the diffracted amplitude as predicted by the Fresnel-Kirchhoff theory for a sharpedge.
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| 6. |
- Huntley, J.M., et al.
(författare)
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Parallel processing system for rapid analysis of speckle-photography and particle-image-velocimetry data
- 1993
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 32:17, s. 3152-3155
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Tidskriftsartikel (refereegranskat)abstract
- An automated system has been constructed to process double-exposure speckle-photography andparticle-image-velocimetry images. A 3 × 3 array of laser beams probes the photograph, forming ninefringe patterns in parallel; these are then analyzed sequentially by digital computer and the use of atwo-dimensional Fourier-transform method. Results are presented showing that the random errors inthe measured displacements from such a system approach the expected speckle-noise-limited performance,with a total analysis time per displacement vector of 160 ms.
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| 7. |
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| 8. |
- Huntley, J.M., et al.
(författare)
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Temporal phase-unwrapping algorithm for automated interferogram analysis
- 1993
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 32:17, s. 3047-3052
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Tidskriftsartikel (refereegranskat)abstract
- A new algorithm is proposed for unwrapping interferometric phase maps. Existing algorithms searchthe two-dimensional spatial domain for 2ir discontinuities: only one phase map is required, but phaseerrors can propagate outward from regions of high noise, corrupting the rest of the image. Analternative approach based on one-dimensional unwrapping along the time axis is proposed. It isapplicable to an important subclass of interferometry applications, in which a sequence of incrementalphase maps can be obtained leading up to the final phase-difference map of interest. A particularexample is quasi-static deformation analysis. The main advantages are (i) it is inherently simple, (ii)phase errors are constrained within the high-noise regions, and (iii) phase maps containing globaldiscontinuities are unwrapped correctly, provided the positions of the discontinuities remain fixed withtime. The possibility of real-time phase unwrapping is also discussed
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| 9. |
- Roos, A., et al.
(författare)
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Diffuse reflectance and transmittance spectra of an interference layer : 1. Model formulation and properties
- 1994
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 33:34, s. 7908-7917
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Tidskriftsartikel (refereegranskat)abstract
- A model for the calculation of the diffuse reflectance and transmittance of a single interference layer with rough interfaces on a transparent substrate is presented. The model is based on electric field calculations and scalar scattering theory, and it assumes that the interfaces of the layer are totally uncorrelated. Examples are given of calculated spectra in which the parameters of the model are varied systematically to show the influence from different interface roughness and refractive index combinations as well as absorption in the film. A wavelength-dependent effective root-mean-square roughness is introduced. This depends on the nature of the roughness, and the bandwidth limits are given by the experimental conditions. Finally, total integrated scattering spectra are calculated and the importance of taking multiple reflections in the substrate into account is shown.
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| 10. |
- Rönnow, Daniel, et al.
(författare)
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Determination of interface roughness by using a spectroscopic total-integrated-scatter instrument
- 1993
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 32:19, s. 3448-3451
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Tidskriftsartikel (refereegranskat)abstract
- A spectroscopic total-integrated-scatter instrument has been constructed. It uses a Coblentz sphere for the collection of the scattered light and a lamp with a monochromator as a light source. It can be used to measure diffuse reflectance as well as transmittance. The instrument has been used to measure diffuse reflectance of thermally and chemical-vapor-deposition oxidized silicon wafers. Comparisons are made with measurements by using a spectrophotometer with an integrating sphere. The data have been interpreted with a parameterized model for light scattering from a double layer, to obtain rms surface roughness values for the two interfaces of the oxide film.
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