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Applied Optics

Applied Optics


  • Vol. 30, Iss. 15 — May. 20, 1991
  • pp: 2042–2048

Approximation to extinction efficiency for randomly oriented spheroids

Georges R. Fournier and Blair T. N. Evans  »View Author Affiliations

Applied Optics, Vol. 30, Issue 15, pp. 2042-2048 (1991)

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A semiempirical approximation to the extinction efficiency Qext for randomly oriented spheroids, based on an extension of the anomalous diffraction formula, is given and compared to the extended boundary condition method or T-matrix method. Using this formula, Qext can be evaluated over 104 times faster than by previous methods. This approximation has been verified for complex refractive indices m = nik, where 1.01 ≤ n ≤ 2.00 and 0 ≤ k ≤ 1 and aspect ratios from 0.5 to 4. We believe the approximation is uniformly valid over all size parameters and aspect ratios. It has the correct Rayleigh and large particle asymptotic behavior. The accuracy and limitations to this formula are extensively discussed.

© 1991 Optical Society of America

Original Manuscript: August 10, 1990
Published: May 20, 1991

Georges R. Fournier and Blair T. N. Evans, "Approximation to extinction efficiency for randomly oriented spheroids," Appl. Opt. 30, 2042-2048 (1991)

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