Abstract: A two-stage optical imaging system which is capable of operating in the infra red and which is compact, the system comprising an objective generally in the form of a Cassegrain system with primary and secondary mirrors A, B together with a relay C which may be reflective, refractive or refractive and diffractive, the relay C being located co-axially between the primary and secondary mirrors A, B.

Abstract: The method and apparatus for decreasing thread switch latency in a multithread processor stores instructions for an active thread in a primary instruction queue, and stores instructions for a dormant thread in a thread switch instruction queue. The active thread is the thread currently being processed by the multithread processor, while the dormant thread is a thread not currently being executed by the multithread processor. During execution of the active thread, instructions are dispatched from the primary instruction queue for processing. When a thread switch occurs, instructions are dispatched from the thread switch instruction queue for execution. Simultaneously, instructions stored in the thread switch instruction queue are transferred to the primary instruction queue. In this manner, the thread switch latency resulting from the amount of time to refill the primary instruction queue with instructions of the dormant thread is eliminated.

Abstract: A head-up display 10 comprises a display device 11 for generating information to be presented to an operator 15 in superimposition with his forward view of the outside world 16, via an off-axis reflectively-powered combiner optic 14 for effecting said superimposition and a relay optic 12, 18 between the display device 11 and the combiner optic 14. The relay optic 12, 18 forms an intermediate image 13 of the displayed information in advance of the combiner optic 14 and the combiner optic 14 collimates the intermediate image for delivery to the operator 15 and re-images the aperture stop formed by the relay optic 12, 18 as an exit pupil at the operator's eye position 20. The relay optic 12, 18 comprises a relay lens 12 and an axis deviation arrangement 18, having a pair of surfaces A, B preferably formed of holograms which are mutually inclined at an acute angle each surface A, B being both transmissive and reflective according to the angle of incidence of light thereon.

Abstract: A piper liner laminate and method of making a pipe including this liner are disclosed herein. The liner comprises a central layer preferably of either polyethylene or polypropylene sandwiched between first and second layers of fibrous material, for example polyester mat, which are laminated together preferably by a mechanical bond. Constructed in this manner, the liner, which is especially suitable for sewer pipe, provides a reliable barrier preventing corrosive chemicals from penetrating therethrough and into the wall of the pipe.