The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of E acc $ 25 MV͞m at a quality factor Q 0 $ 5 3 10 9 . The design goal for the cavities of the TESLA Test Facility (TTF) linac was set to the more moderate value of E acc $ 15 MV͞m. In a first series of 27 industrially produced TTF cavities the average gradient at Q 0 5 3 10 9 was measured to be 20.1 6 6.2 MV͞m, excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities, additional quality control measures were introduced, in particular, an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electronbeam welds. The average gradient of these cavities at Q 0 5 3 10 9 amounts to 25.0 6 3.2 MV͞m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication, and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing research and development towards higher gradients is briefly addressed.

Pico projectors are the latest technology to prove that big things often do come in small packages. These tiny projectors are embedded in mobile devices to provide large-screen displays that can be viewed from anywhere. This paper describes Microvision's PicoP® display engine, a biaxial MEMS scanning laser projection technology. It's amazing what we carry in our pockets these days. From cell phones to iPods to PDAs, we have at our fingertips connectivity with friends and colleagues around the world, libraries of text, music, photos, videos and more. Unfortunately, the displays that we use to view all this information are also small; they are flat-panel screens with just a few square inches of display area. No wonder that projectors that display large images from within hand-held electronic devices-pico projectors-are drawing so much attention in the tech world. With pico projectors, you can project a full-size image onto whatever is near at hand, whether it be the wall, your shirt, or a piece of paper. Pico projectors represent a core enabling technology for the future growth of portable devices.

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Multiple‐receiver MF radar returns from the mesosphere are used to investigate the relationship between spaced antenna (SA), radar interferometry (RI), and imaging Doppler interferometry (IDI) wind estimation techniques. Our results show that frequency‐domain (RI and IDI) and time‐domain (SA) techniques yield almost identical results under high SNR conditions suitable for SA full correlation analysis (FCA).

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