Abstract: An optical fiber communication system according to the invention comprises an optical fiber filter that can be manufactured at low cost and that can be conveniently incorporated into the system, substantially like a conventional fiber jumper. The filter comprises a length L of axially uniform optical fiber selected to have substantially no loss (e.g., <1 dB) at a wavelength .lambda..sub.1, and to have relatively high loss (e.g., >20 dB) at a wavelength .lambda..sub.2. The length L will typically be less than 100 m. In one embodiment the optical fiber is a single mode optical fiber at .lambda..sub.1 (e.g., 1.3 .mu.m) that does not have a guided mode at .lambda..sub.2 (e.g., 1.55 .mu.m). In another embodiment the fiber contains a dopant that does substantially not absorb radiation of wavelength .lambda..sub.1, but substantially absorbs at .lambda..sub.2. In the second embodiment, .lambda..sub.1 can be greater than .lambda..sub.2.

Abstract: A spinnerette for the spinning of fibres has a rectangular frame with an upper flange for connection to a jet assembly and a lower planar apertured plate for the passage of spinning dope, the apertured plate being formed with its spinning holes and then electron beam welded into the bottom of the frame from the outside.

Abstract: A spinning cell for producing lyocell fibre by spinning a solution of cellulose in an organic solvent through an air gap into a spin bath has nozzles to create a cross-draught through the air gap.

Abstract: A relatively low cost, battery powered golf swing training and practice device by which a golfer may ascertain various characteristics, such as club head speed and elapsed swing time, regarding the swing of his golf club. The present training and practice device is both compact and lightweight to advantageously permit portable operation at in and out-of-doors locations. The present device includes a unique photodetector and light trap system arranged to reliably sense the movement of a golfer's club head during a backswing and downswing. The operation of the present device is controlled by a microprocessor, so that information regarding a golfer's swing can be efficiently computed and accurately indicated at an associated printer and/or digital display.

Abstract: A golf swing training and practice device by which a golfer may ascertain various characteristics, such as clubhead speed and elapsed swing time, regarding the swing of his golf club. The present training and practice device comprises a portable, battery or AC powered apparatus for accurately measuring, computing, and displaying both the elapsed time to complete the golfer's swing and the speed by which a golfer's clubhead is moved through a measuring zone. The measuring zone is established by the optical axes of a pair of photodetectors or the like, that are mounted within a detector head. Unlike conventional golf training or practice apparatus, the photodetectors of the present invention are responsive to ambient light. The photodetectors are disposed in parallel alignment with one another, so as to receive respective horizontal and parallel beams of light, whereby to define the measuring zone therebetween.