The intensity of high-order rainbows for normally incident light
and certain rotation angles of a cylinder with an elliptical cross
section is greatly amplified with respect to the intensity for a
circular cross-sectional cylinder. The amplification is due to a
number of the internal reflections occurring past the critical angle
for total internal reflection, and the effect is especially strong for
odd-order rainbows, beginning with the third order. Experimentally,
the fourth- and the fifth-order rainbows of a nearly elliptical
cross-sectional glass rod were observed and analyzed.
© 1998 Optical Society of America
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