Light scattering

About: Light scattering is a research topic. Over the lifetime, 37721 publications have been published within this topic receiving 861581 citations.

Computations of Light-Scattering and Extinction by Spheres According to Diffraction and Geometrical Optics, and Some Comparisons with the Mie Theory

Abstract: The scattering and extinction of light by systems of transparent, spherical particles have been calculated on the basis of classical diffraction and of geometrical scattering by external reflection and transmission, for the refractive index range 1.1 to 2.0 and scattering angles up to about 40°, and presented as a set of graphs for general use. Provided that the particles are larger than 3 or 4 wavelengths of light, and that there is a sufficient range (say 2:1) of particle sizes present to average out effects of phase, the scattering and extinction calculated in this way agree well with such direct calculations by the Mie theory as are at present available. It is thought that the treatment should also be successful with irregular particles, and to some extent with nontransparent ones, such as often occur in airborne dusts in industry. The conditions under which scattering and extinction measurements can be used to estimate the surface-area of particles in suspension in air or liquid are discussed.

Rayleigh scattering by neutral atoms, 100 eV to 10 MeV

Abstract: We calculate the contribution to elastic photon scattering from an atom due to scattering off the bound atomic electrons (Rayleigh scattering). We compare predictions resulting from our numerical evaluation of the relativistic second-order $S$ matrix in a screened central potential with other theories, particularly the form-factor approximation. We give a prescription for accurate $O(1%)$ evaluation of total-atom Rayleigh amplitudes (summed over electrons) and present sample tabulations for lead ($Z=82$) for energies of experimental interest in the range from 22.1 to 2750 keV. Based on our prescription we compare elastic-scattering cross sections using Rayleigh amplitudes with selected experiments and are able to remove the large factor-of-two discrepancies previously reported.

Ultraviolet DIAL measurements of O3 profiles in regions of spatially inhomogeneous aerosols.

Abstract: The differential absorption lidar (DIAL) technique generally assumes that atmospheric optical scattering is the same at the two laser wavelengths used in the DIAL measurement of a gas concentration profile. Errors can arise in this approach when the wavelengths are significantly separated, and there is a range dependence in the aerosol scattering distribution. This paper discusses the errors introduced by large DIAL wavelength separations and spatial inhomogeneity of aerosols in the atmosphere. A Bernoulli solution for determining the relative distribution of aerosol backscattering in the UV region is presented, and scattering ratio boundary values for these solutions are discussed. The results of this approach are used to derive a backscatter correction to the standard DIAL analysis method. It is shown that for the worst cases of severe range dependence in aerosol backscattering, the residual errors in the corrected DIAL O3 measurements were <10 ppbv for DIAL wavelengths at 286 and 300 nm.

Fourier transform light scattering of inhomogeneous and dynamic structures.

Abstract: Fourier transform light scattering (FTLS) is a novel experimental approach that combines optical microscopy, holography, and light scattering for studying inhomogeneous and dynamic media. In FTLS the optical phase and amplitude of a coherent image field are quantified and propagated numerically to the scattering plane. Because it detects all the scattered angles (spatial frequencies) simultaneously in each point of the image, FTLS can be regarded as the spatial equivalent of Fourier transform infrared spectroscopy, where all the temporal frequencies are detected at each moment in time.

Exact and Approximate Solutions for Multiple Scattering by Cloudy and Hazy Planetary Atmospheres

Abstract: Solutions are obtained for the problem of multiple scattering by a plane parallel atmosphere with anisotropic phase functions typical of cloud and haze particles. The resulting albedos, angular distributions of intensities, and planetary magnitudes are compared to solutions obtained with approximate analytic phase functions and, in the case of the cloud phase function, to the solution obtained with the forward diffraction peak omitted from the phase function. It is shown that the cloud phase function with the truncated peak yields results practically identical to those obtained with the complete cloud phase function, not only for albedos and magnitudes, but also for the angular distribution; the approximation introduces errors of several per cent in the angular distribution for direct backscattering (the region of the glory), for emergent angles near grazing regardless of the incident angle, and, of course, a larger error occurs for total scattering angles near 0°. However, the errors are unimpor...