Standard rainbow thermometry connects the scattering angle of the main rainbow maximum, generated by a single droplet, to the droplet’s refractive index and thus to its temperature. Droplet nonsphericity influences the rainbow position and therefore degrades the quality of the droplet-temperature measurement. We propose global rainbow thermometry, which measures the average rainbow position that is created by multiple droplets and from which a mean temperature can be derived. The new technique aims at eliminating the nonsphericity effect. The principle of this method is presented, and a typical recorded image is discussed.
© 1999 Optical Society of America
J. P. A. J. van Beeck, D. Giannoulis, L. Zimmer, and M. L. Riethmuller, "Global rainbow thermometry for droplet-temperature measurement," Opt. Lett. 24, 1696-1698 (1999)