Quasi-elastic Light Scattering for Studying the Motion of Flagellated Microorganisms

Abstract

Quasi-elastic laser scattering has been used to study the motion of flagellated algae. Our experimental approach differs from standard laser velocimetry and appears to be most effective in studying the motion of elongated microorganisms whose size is greater than a wavelength and which execute complex rototranslatory motions. By using a radiofrequency field to orient the samples, flagellar beating and rotation frequencies have been measured by direct detection, while the swimming speed distribution has been measured by heterodyne detection. Flagellar beating measurement is also possible in unoriented samples; we report flagellar beating lines for some species of flagellated algae.