15,518 research outputs found

    Fringe counter for interferometers Patent

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    Digital sensor for counting fringes produced by interferometers with improved sensitivity and one photomultiplier tube to eliminate alignment proble

    Rapidly reconfigurable slow-light system based on off-resonant Raman absorption

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    We present a slow-light system based on dual Raman absorption resonances in warm rubidium vapor. Each Raman absorption resonance is produced by a control beam in an off-resonant Λ system. This system combines all optical control of the Raman absorption and the low-dispersion broadening properties of the double Lorentzian absorption slow light. The bandwidth, group delay, and central frequency of the slow-light system can all be tuned dynamically by changing the properties of the control beam. We demonstrate multiple pulse delays with low distortion and show that such a system has fast switching dynamics and thus fast reconfiguration rates

    Wide-angle flat field telescope

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    Described is an unobscured three mirror wide angle telescopic imaging system comprised of an input baffle which provides a 20 deg (Y axis) x 30 deg (X axis) field of view, a primary mirror having a convex spherical surface, a secondary mirror having a concave ellipsoidal reflecting surface, a tertiary mirror having a concave spherical reflecting surface. The mirrors comprise mirror elements which are offset segments of parent mirrors whose axes and vertices commonly lie on the system's optical axis. An iris diaphragm forming an aperture stop is located between the secondary and tertiary mirror with its center also being coincident with the optical axis and being further located at the beam waist of input light beams reflected from the primary and secondary mirror surfaces. At the system focus following the tertiary mirror is located a flat detector which may be, for example, a TV imaging tube or a photographic film. When desirable, a spectral transmission filter is placed in front of the detector in close proximity thereto

    Imaging Studies of photodamage and self-healing in disperse orange 11 dye-doped PMMA

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    We report on optical imaging studies of self-healing after laser-induced photodamage in disperse orange 11 dye doped into poly(methyl methacrylate) (PMMA) polymer. In particular, the high spatial-contrast image of the damage track made by a line focus pump laser allows the recovery rates to be measured as a function of burn dose using the relationship between transverse distance and pump intensity profile. The time evolution of the damaged population results in an intensity-independent time constant of {\tau} = 490\pm23 min, in agreement with independent measurements of the time evolution of amplified spontaneous emission. Also observed is a damage threshold above which the material does not fully recover.Comment: 5 pages, 8 figure

    High spectral resolution time-resolved optical spectroscopy of V893 Sco

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    We present high resolution time-resolved optical spectra of the high inclination short orbital period dwarf nova V893 Sco. We performed spectral analysis through radial velocity measurements, Doppler mapping, and ratioed Doppler maps. Our results indicate that V893 Sco's accretion disk is dissimilar to WZ Sge's accretion disk, and does not fit any of the current accretion disk models. We derive the system parameters M1 and i, and present evidence for V893 Sco as a very young cataclysmic variable and an ER UMa star. We advance the hypothesis that all ER UMa stars may be newly formed cataclysmic variables.Comment: 23 pages (total), 8 figures, accepted by Ap

    The Costs of Broken Windows Policing: Twenty Years and Counting

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    Enforcing a Wall of Separation Between Big Business and State: Protection from Monopolies in State Constitutions

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    The goal of this Note is not to convince the reader to care more about regulatory monopolies than private ones. In fact, it is not to talk about private antitrust law at all. Instead, the goal is to put today’s concern with monopolies in historical perspective. Part I traces the history of the antimonopoly spirit in the United States starting with the English tradition that was highly influential on the Founders. This Note then demonstrates that today’s concern with private monopolies comes from a shift that took place during the progressive era. In Part II, this Note highlights the role state constitutional claims can have in protecting rights, as explained by Justice William Brennan. Finally, in Part III, this Note provides a blueprint for how state antimonopoly provisions may be used to target state-created monopolies in practice and reclaim America’s Founding antimonopoly spirit

    Gang Policing: The Post Stop-and-Frisk Justification for Profile-Based Policing

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