Abstract: Apparatus for analysing the optical properties of a transparent object (118) comprises a light source, an analyser cell comprising a body of solid transparent material (110) having a cavity (112) formed therein for receiving the object (118) to be analysed, and arranged so as to allow a light beam from the light source to pass through the object (118), said body (110) having an entrance surface (114) through which the light beam enters the cell from the ambient medium and an exit surface (116) through which the light beam leaves the cell, and analysing means for analysing the light beam after passage through the object (118), and is characterised in that the cavity (112) in the analyser cell is of substantially circular section in at least the region through which the light beam passes in use.

Abstract: A method of sensing optically properties of an approximately cylindrical object, such as an optical fibre or optical fibre preform, which diffracts the illuminating beam into a plurality of beam portions each corresponding to its respective diffraction order, comprising the steps of illuminating the object with an illuminating beam substantially perpendicular to the axis of the object, moving an aperture so as to discriminate a beam portion exiting from the object and corresponding to a selected diffraction order, and detecting said beam portion.

Abstract: An apparatus for measuring the geometry of an optical fibre having at least one coating, the apparatus comprising a container for containing a coated optical fibre in a fluid, means for directing light transversely through the fibre in the container and means for permitting light deviated at the coating interfaces or surfaces to exit the container whereby the light can be detected by a light detecting means by substantially dark field illumination. The invention also provides a method of measuring the geometry of an optical fibre having at least one coating the method comprising the steps of: (a) disposing the coated optical fibre in a fluid; (b) directing incident light transversely through the coated fibre; and (c) detecting transmitted light from the coated fibre which is deviated at the coating interfaces or surfaces so as to detect the coating(s) by substantially dark field illumination.

Abstract: Cleaving of an optical fibre (2) is achieved by bringing a fibre cleaving blade (3) into lateral contact with such a fibre. Undue intrusion of the blade into the fibre during prior art cleaving processes can damage the fibre so as to detract from the quality of the resulting cleaved fibre end surfaces. Improvemets in the quality of the resulting end surfaces can be obtained in relation to prior art techniques by superimposing a relatively small amplitude vibratory component on a relatively steady movement of the blade towards the fibre. This can also enable the conventional use of a backing anvil at the cleaving location to be dispensed with, thereby removing danger of contamination from the anvil.