Measurement of Rayleigh Scattering in Liquids Using Optical Fibers

Abstract

Measurements have been made of Rayleigh scattering in CCl₄ and C₂Cl₄ as a function of wavelength between 6000 Å and 10,600 Å. The scattering loss rate is 25 dB/km for CCl₄ and 68 dB/km for C₂Cl₄ at 6328 A. The scattering loss rate follows a (wavelength)⁻⁴ dependence over the entire spectrum observed. The Rayleigh scattering was measured by placing the liquid sample in a hollow fused-quartz fiber and measuring the light scattered by the liquid through the fiber wall. It appears that this is the first time that the expected (wavelength)⁻⁴ dependence of Rayleigh scattering has actually been observed in liquids over a wide spectral range. This technique is simple and accurate and may be applied to the measurement of the scattering coefficient of any liquid whose index of refraction exceeds the cladding index of refraction (for fused quartz n_D = 1.458).