Abstract: Methods and apparatus for detecting defects, such as air lines, in optical waveguide fibers are provided. The methods and apparatus employ scattered light interference signals produced by a fiber clad measurement system that transversely illuminates a fiber with a laser beam. Defects in the fiber produce characteristic peaks in the frequency spectrum of the scattered light signal. By filtering the scattered light signal to remove (a) the components associated with the fiber clad measurement system and (b) the fundamental component associated with the fiber, the defect-related components in the scattered light signal which represent defects in the associated fiber are determined. Once the presence of these defect-related components is determined, a defect detection output pulse is generated for each such event. The defect detection methods are also incorporated in an overall system for drawing and inspecting the optical lightguide fibers.

Abstract: A low cost radio frequency identification tag is provided for attaching to and identifying objects such as, for example, a passenger's luggage. The tag is programmed to contain information such as the origin, destination, and name of a passenger accompanying the luggage. This information is programmed into the tag at the time when the customer checks his or her luggage at a terminal. The tag includes an integrated circuit with all radio and data functions incorporated onto this integrated circuit, and an antenna for radio communication. The integrated circuit in the tag is suitably powered from the incident radio frequency energy provided by a interrogator while the tag is located in the radiation pattern of this interrogator. The luggage tag is assembled inexpensively by packaging the integrated circuit between paper or plastic substrates on which printed identifying information is also added at the point of check-in at the terminal.

Abstract: An antenna design for a tag operating in an radio frequency identification system minimizes the influence of reflecting surfaces upon the antenna radiation pattern. The antenna advantageously provides near uniform performance when the tag is in varying proximity to different metal reflecting surfaces. The antenna operates as a quarter wave patch antenna and is constructed from a rectangular metal patch separated from a larger metallic plane. This metallic plane serves as the reference ground plane for a circuit attached to the antenna, with a direct short between the patch and the ground plane along one edge of the patch. The dimensions of the metal patch are selected such that one quarter of a wavelength of incident radiation forms a standing wave on the antenna. A careful choice of dielectric material and lateral dimensions determine the bandwidth of the antenna.

Abstract: In a radio frequency identification communication system, a communication protocol advantageously controls communication between an interrogator and one or more identifying labels or read/write tags. This protocol is configurable in two modes in which a read/write tag can be expected to operate. In the first mode, a rapid transfer of a limited amount of data takes place between the interrogator and one or more tags. In the second mode, a slower or less time critical transfer of a large quantity of data in a packet format takes place. In this second mode, a communication to the other tags causes these tags to remain "silent" so that they do not corrupt the data transfer in progress. The interrogator automatically determines the quantity of data and the correct mode in which to operate. Either mode can be initiated on successive communication periods by the communication protocol.

Abstract: The diameters of successive axial portions of an optical fiber being drawn are monitored and controlled by an optical measuring technique in such manner as to eliminate the effects of occasional, anomalous measurements or "dropouts". Measurement validity is tested by comparing, with a maximum allowable value, the difference between each successive diameter measurement and a standard for diameter measurement validity. Some examples of such a standard are provided. In addition, two embodiments of fiber monitoring systems are disclosed, as well as an overall monitoring and control system for fiber diameters.