This paper describes transverse oscillations, within the range 0.2-30 Hz, of the surface of different animal cells: human and frog erythrocytes, human lymphocytes and monocytes, cultured 3T6 fibroblasts, and rat cardiomyocytes. The minimal area of the cell surface which undergoes unidirectional transverse movement is equal to or less than 0.5 x 0.5 microns. The amplitude of the oscillations recorded on larger surface areas is lower than on the smaller ones because of the averaging of solitary oscillations. The oscillation amplitude is different in different cells. The highest amplitude is recorded in human erythrocytes (350-400 nm), the lowest one, in fibroblasts, lymphocytes and monocytes (20-30 nm). The oscillations of the human erythrocyte are suppressed on hypotonic swelling, after hardening of the cell membrane owing to adsorption at the surface of the impermeable dye Heliogen Blue, by treatment of the cell with 0.01% glutaraldehyde, by treatment with 0.5 mM 4-hydroxy-mercurybenzoate, and after crenation caused by 1-2 mM 2,4-dinitrophenol. The amplitude of the surface oscillations is decreased in spectrin deficient erythrocytes obtained from patients with hereditary spherocytosis, which indicates an essential role for spectrin in the rapid oscillations of the erythrocyte surface.

Tapered- and straight-core fiber microlenses of hyperbolic shape are studied with the segmented beam propagation method (Se-BPM). This new formulation extends to a large scale the finite-difference time-domain method for calculating propagation of the wave field in guiding systems. It is based on partitioning an entire computational domain into subdomains along the direction of propagation. The Helmholtz equation can be solved directly for each subdomain, and an iterative procedure is used to propagate the field from one subdomain to another. The Se-BPM is compared with other approaches that are commonly used to analyze straight-core fiber microlen devices in the paraxial approximation. We deal mainly with small-spot-size fiber microlenses where this approximation does not apply. We show that the emergent beam is not Gaussian in the far field. Instead of the usual far-field characterization we propose a near-field characterization of the fiber microlens. This is possible with the near-field scanning optical microscopy technique.

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