Database of Optical Constants -- Misc: SVM code(s)

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Light scattering by spheroidal particles
treated with the separation of variables method

Program hom_c (version 4.3q2a)

The code calculates the extinction, scattering and absorption efficiency factors for prolate or oblate homogeneous spheroids. The separation of variables method and an original scheme of solution of the light scattering problem are used (see for more details the papers cited below).
We provide the code with a test input file and two output files. A run of the code with such an input should lead to the results given in the output files. The code was written in Fortran-77 and tested on PCs and DEC Workstations.

Directory content:
- readme (2.6 K) --- a readme file nearly equivalent to this page
- homn.dat (0.7 K) --- input data file
- h4_3q2a.for (143.4 K) --- Fortran code
- h-test.dat (5.8 K) --- test output file
- hom-test.res (7.2 K) --- test output file
Parameters:

nterms: number of terms in Eqs. for efficiency factors

nalphas: number of angles for incident radiation.

(values of the parameters can be changed in the beginning of the file h4_3q2a.for)

Values of other parameters are specified in the input file homn.dat. A discription of the parameters is given at the very beginning of the code's text.
Restrictions:

c2 = ri*(2*pi/wvl)*(d/2) <= 135 (?) for prolate spheroids

<= 100 (?) for oblate spheroids

(d - the focus distance of a spheroid)

nterms =~ 1.2 * cdabs(c2) + 8 ( + ~30 if ksi0 > 2).

nalphas <= 91
Recommended values:

refractive index: k <= 1/2*n (?)

eps: 1e-15 for prolate spheroids

1e-15 for oblate spheroids

eps1: 1e-3 ÷ 1e-6
Publications:
- Voshchinnikov N.V., Farafonov V.G.
  Optical properties of spheroidal particles,
  Astrophys. Space Sci. 1993. V. 204. P. 19-86.
- Voshchinnikov N.V.
  Electromagnetic scattering by homogeneous and coated spheroids:
  calculations using the separation of variables method,
  J. Quant. Spectrosc. Radiat. Transfer 1996. V. 55. P. 627-636.
- Farafonov V.G., Voshchinnikov N.V., Somsikov V.V.
  Light scattering by a core-mantle spheroidal particle,
  Applied Optics 1996. V. 35. P. 5412-5426.
Questions, more information, new versions:
Dr. Nikolai Voshchinnikov
Astronomical Institute
St. Petersburg University
St. Petersburg-Peterhof
198904 Russia
e-mail: nvv@aispbu.spb.su

The development of the new approach and the code was financially
supported by a grant of the Volkswagen Foundation (Germany) and partly by the "Universities of Russia - Fundamental Researches" program (Russia).

Created by V.I.
Last modified: 20/01/99, V.I.

nterms:	number of terms in Eqs. for efficiency factors
nalphas:	number of angles for incident radiation.

c2 = ri(2pi/wvl)*(d/2)	<= 135 (?) for prolate spheroids
	<= 100 (?) for oblate spheroids

refractive index:	k <= 1/2*n (?)
eps:	1e-15 for prolate spheroids
	1e-15 for oblate spheroids
eps1:	1e-3 ÷ 1e-6

Light scattering by spheroidal particles treated with the separation of variables method

Program hom_c (version 4.3q2a)

Light scattering by spheroidal particles
treated with the separation of variables method