Abstract: A method of making optical performs from which optical fibers are drawn after collapsing of the preform, which comprises depositing by a vapor-phase reaction a plurality of layers on the inner surface of a support tube and controlling the temperature profile around the perimeter of the support so that the thickness of the deposit varies between at least one maximum and at least one minimum. Upon collapse of the support this gives rise to a core having a noncircular cross section.

Abstract: The device consists of a transparent container, partly filled with a ferromagnetic fluid surrounding a bubble of a transparent liquid. By an external magnetic field the ferromagnetic fluid is displaced within the container and moves the bubble making it pass between a light source and a light sensitive element.

Abstract: The connector ensures the alignment between the two fibres ends (9, 10) thanks to the force exerted by a locally generated magnetic field (5, 6, 7, 8) on a ferromagnetic fluid placed between the side fibre surface and a small tube (1) with a diameter greater than fibre diameter.

Abstract: A body transparent to laser radiation, such as an optical fiber or a preform thereof in the process of manufacture, is transluminated by a monochromatic beam of a frequency in the THz range split off from a composite laser beam with two closely spaced frequencies produced by the Zeeman effect. Another monochromatic beam of the second laser frequency bypasses the transparent body and is photoelectrically recombined with the first beam to provide an electrical measuring wave at a beat frequency in the MHz range differing in phase from an electrical reference wave of the same beat frequency, similarly derived from the original laser beam, to an extent determined by the refractive index and the thickness of the transluminated body. Two or more phase comparisons are made with different angles of incidence of the transluminating beam and their results are compared for an arithmetic determination of refractive index and thickness.

Abstract: A drum for winding up filamentary material, such as optical fibers, has a generally cylindrical unitary flangeless hollow body of airtight and somewhat resilient polymeric material inflated under a fractional gauge pressure through a valve in one of its end walls. A bore in each end wall, centered on the cylinder axis, enables the drum to be coupled with a driving mechanism.

Abstract: An optical fiber, being drawn from a preform and wound upon a reel, passes between parallel plates of a capacitor connected in a measuring circuit which, from the capacitance variations due to changes in fiber diameter, controls a reel-driving motor to minimize these variations. The capacitor may have a constant charge, as by having one of its plates made of an electret, in which case the capacitance variations are determined from voltage changes. A calculator connected to the measuring circuit translates these variations into numerical values representing the fiber diameter which can be visually displayed.