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
James A. Lock, Charles L. Adler, Bradley R. Stone, and Patrick D. Zajak, "Amplification of High-Order Rainbows of a Cylinder with an Elliptical Cross Section," Appl. Opt. 37, 1527-1533 (1998)