Abstract: An optical fiber flaw detection apparatus for detecting white light emitted through a sidewall of an optical fiber and methods of detecting the flaw are disclosed. One embodiment of the apparatus includes a detector located adjacent the fiber and processing circuitry to amplify and convert a signal produced to recognize flaws. A second embodiment includes a plurality of view systems oriented about the fiber and a mechanism to rapid draw fiber through the systems in addition to the detector. Each system is an optical assembly for collecting and directing the light. One method includes the steps of introducing the light into the fiber, detecting the light, and determining on-line the nature of the flaw. A second method includes the steps of heating a preform to a temperature sufficient to draw fiber, drawing fiber, and detecting the emitted light. The draw temperature is sufficient to transmit the light along the fiber.

Abstract: A method an apparatus for continuously producing optical waveguide fiber and preforms. A continuous supply of core cane is provided to a walled deposition chamber upon which glass soot is deposited to form a soot preform. The preform is passed through an aligned drying, consolidation and draw chambers from which an optical fiber may be drawn. In one embodiment, a plurality of burners are positioned at different radial distances from a longitudinal axis of the cane in the deposition chamber. One or more environmental seal(s) are provided to prevent process gasses or contaminants from flowing into or between the chambers.

Abstract: A method and apparatus for automated manufacturing of optical fiber. According to one embodiment of the invention, an automated conveyor system automatically moves spools of optical fiber from one manufacturing process step to another. The spools are preferably mounted on pallets which circuit around on a plurality of non-interconnected track segments. The segments may include, for example, a segment transporting spools from draw, one or more test segments, and a shipping segment. Data-containing devices are mounted to the spool or pallet and allow data to be uploaded, downloaded and transferred as the fiber on the spool is processed and tested.

Abstract: An apparatus and method for coating an optical wave guide fiber with a liquid polymer coating includes pressurizing a chamber with a process fluid and venting the process fluid along, and in a direction opposite the direction of travel of, the incoming fiber, to strip particles from the incoming fiber before the particles enter the die assembly.

Abstract: A system for monitoring the position of a fiber (13) during drawing is provided. The system includes a beam (25) of radiation which is directed at the fiber (13), a Ronchi ruling (50) having a spatial frequency .omega..sub.M which modulates light scattered from the fiber (13), a lens system (27) having a positive focal length, and a detector (31) located in the back focal plane of the lens system. By arranging the components of the system in this manner, the distance between the fiber (13) and the Ronchi ruling (50) is a linear function of the spatial frequency .omega..sub.D of the modulated light at the detector (29). Various procedures can be used to determine .omega..sub.D, a preferred one being shown in FIG. 9.

Abstract: A method for monitoring the thickness of a hermetic coating on an optical waveguide fiber is provided in which an interference pattern is produced by illuminating the fiber with a laser beam. A spatial frequency spectrum is generated for the interference pattern and a first component of that spectrum, corresponding to the outside diameter of the fiber, is identified. The magnitude of this component is inversely related to the thickness of the coating, i.e., the magnitude decreases as the coating thickness increases, and thus this magnitude can be used to monitor the thickness of the coating during, for example, the coating process. Effects of fluctuations in the power of the laser beam and/or movement of the fiber relative to that beam can be minimized by normalizing the magnitude of the first component by the magnitude of the DC component of the spatial frequency spectrum.

Abstract: A method and apparatus for non-destructive analysis of canes and preforms which contain "striae" in which the cane or preform is transversely illuminated with a beam of light at a wavelength which is long enough to substantially eliminate the effect of striae resulting from variations in dopant concentration.

Abstract: A method for measuring the diameter of a transparent filament is provided which is substantially insensitive to ellipticity of the filament. The method comprises using an interference technique to measure the filament diameter at two locations which are spaced apart by an amount such that a plot of diameter versus angle of rotation for an elliptical filament calculated at the first location is approximately 90.degree. out of phase from the same plot calculated at the second location. Due to the phase difference, the average of the two measurements is substantially insensitive to ellipticity. For measurement apparatus comprising one laser and two detectors and for optical waveguide fibers having a cladding composed of fused silica, the two locations can be about 123.degree. apart. In other embodiments, a method for characterizing the non-circularity of a filament is provided. Apparatus for practicing the foregoing methods is also disclosed.

Abstract: Methods for deteting defects, such as, holes or voids, in optical waveguide fibers are provided. The methods employ far-field interference patterns produced by transversely illuminating the fiber with a laser beam. Holes in the fiber produce a characteristic peak in the spatial frequency spectrum of the interference pattern which subdivides into two peaks which migrate in opposite directions as a hole grows in size. Holes also produce a characteristic increase in the total power of the interference pattern, the amount of the increase being a linear function of the size of the hole for holes having a diameter less than about 60% of the diameter of the fiber. The hole detection methods are incorporated in an overall system for controlling the drawing of optical waveguide fibers.

Abstract: Methods and apparatus for determining the curvature of a surface by use of multiple discrete triangulation sensors are described. Robustness in the face of an extreme manufacturing environment is achieved by placing a triangulation light source and a detector at a remote, environmentally controlled location. Light is relayed from the remote source to each sensor head by a single mode optical fiber, which then projects a spot onto the surface under consideration. An image of the spot is formed in each sensor head, and is relayed back to the remote detector by a coherent bundle of fibers. Range to the surface at each sensor head is inferred by the position of each image as relayed by the coherent bundles, while curvature of the surface is determined by comparing ranges as measured at each sensor head. The optics contained in each sensor head are adapted to work well with specular, diffuse, opaque or transparent surfaces.