Broadband tunability of gain-flattened quantum well semiconductor lasers with an external grating

Quantum well lasers are shown to exhibit flattened broadband gain spectra at a particular pumping condition. The gain requirement for a grating-tuned external cavity configuration is examined and applied to a semiconductor quantum well laser with an optimized length of gain region. The predicted very broadband tunability of quantum well lasers is confirmed experimentally by grating-tuning of uncoated lasers over 85 nm, with single longitudinal mode output power exceeding 200 mW

Ralph: A Visible/Infrared Imager for the New Horizons Pluto/Kuiper Belt Mission

The New Horizons instrument named Ralph is a visible/near infrared multi-spectral imager and a short wavelength infrared spectral imager. It is one of the core instruments on New Horizons, NASA's first mission to the Pluto/Charon system and the Kuiper Belt. Ralph combines panchromatic and color imaging capabilities with IR imaging spectroscopy. Its primary purpose is to map the surface geology and composition of these objects, but it will also be used for atmospheric studies and to map the surface temperature. It is a compact, low-mass (10.5 kg), power efficient (7.1 W peak), and robust instrument with good sensitivity and excellent imaging characteristics. Other than a door opened once in flight, it has no moving parts. These characteristics and its high degree of redundancy make Ralph ideally suited to this long-duration flyby reconnaissance mission.Comment: 18 pages, 15 figures, 4 tables; To appear in a special volume of Space Science Reviews on the New Horizons missio

Decolonising imperial heroes:Britain and France

The heroes of the British and French empires stood at the vanguard of the vibrant cultures of imperialism that emerged in Europe in the second half of the nineteenth century. Yet imperial heroes did not disappear after 1945 as British and French flags were lowered around the world. On the contrary, their reputations underwent a variety of metamorphoses in both the former metropoles and the former colonies. The introduction to this special issue of the Journal of Imperial and Commonwealth History presents an overview of the changing history and historiography of imperial heroes half a century after the end of empire