The backscattered intensity from a dense distribution of latex microspheres is measured near the retroreflection direction. It is shown that a sharp peak appears in the retroreflection direction when the volume density is above 1%. The angular width of this peak is much smaller than (wavelength)/(particle size) and cannot be explained by Mie theory, double-passage effects, or radiative-transfer theory. When the particle size D is less than the wavelength λw, a small peak appears at the retroreflection direction. When D is 2–4 times greater than λw, the peak becomes large as the density increases. When D is many times greater than λw, the sharp peak at the retroreflection direction is superimposed upon the Mie-scattering pattern. The angular width of the peak is of the order of (a wavelength)/(a mean free path).
© 1984 Optical Society of America
Original Manuscript: June 23, 1983
Manuscript Accepted: April 17, 1984
Published: August 1, 1984
Yasuo Kuga and Akira Ishimaru, "Retroreflectance from a dense distribution of spherical particles," J. Opt. Soc. Am. A 1, 831-835 (1984)