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  2. 1951 USAF resolution test chart - Wikipedia

    en.wikipedia.org/wiki/1951_USAF_resolution_test...

    These 54 elements are provided in a standardized series of logarithmic steps in the spatial frequency range from 0.250 to 912.3 line pairs per millimeter (lp/mm). The series of elements spans the range of resolution of the unaided eye, down to the diffraction limits of conventional light microscopy.

  3. Spontaneous parametric down-conversion - Wikipedia

    en.wikipedia.org/wiki/Spontaneous_parametric...

    Schematic of SPDC process. Note that conservation laws are with respect to energy and momentum inside the crystal.. Spontaneous parametric down-conversion (also known as SPDC, parametric fluorescence or parametric scattering) is a nonlinear instant optical process that converts one photon of higher energy (namely, a pump photon) into a pair of photons (namely, a signal photon, and an idler ...

  4. U.S. Route 30 in Indiana - Wikipedia

    en.wikipedia.org/wiki/U.S._Route_30_in_Indiana

    U.S. Route 30 (US 30) is a part of the United States Numbered Highway System that runs from Astoria, Oregon, to Atlantic City, New Jersey.In Indiana, the route runs from the Illinois state line at Dyer to the Ohio state line east of Fort Wayne and New Haven.

  5. Leading lights - Wikipedia

    en.wikipedia.org/wiki/Leading_lights

    Leading lights, also known as range lights in the United States, are a pair of light beacons used in navigation [2] to indicate a safe passage for vessels entering a shallow or dangerous channel; they may also be used for position fixing.

  6. .30-06 Springfield - Wikipedia

    en.wikipedia.org/wiki/.30-06_Springfield

    The .30-06 Springfield cartridge (pronounced "thirty-aught-six" / ˈ θ ɜːr t i ɔː t s ɪ k s /), 7.62×63mm in metric notation, and called the .30 Gov't '06 by Winchester, [5] was introduced to the United States Army in 1906 and later standardized; it remained in military use until the late 1970s.

  7. Ring flash - Wikipedia

    en.wikipedia.org/wiki/Ring_flash

    A ring flash is a circular light that is often operated with a camera lens in the center to take photographs. Unlike point light sources , a ring flash can illuminate a subject with minimal shadows by closely and evenly surrounding the optical axis of the camera lens.

  8. U.S. Route 30 in Pennsylvania - Wikipedia

    en.wikipedia.org/wiki/U.S._Route_30_in_Pennsylvania

    The Amtrak line diverges to the south east of here. The route splits into a one-way pair, with two lanes in each direction, as it reaches Gap and comes to an intersection with the eastern terminus of PA 772. US 30 continues along the one-way pair, with both directions rejoining at a junction with the northern terminus of PA 41.

  9. Illuminance - Wikipedia

    en.wikipedia.org/wiki/Illuminance

    Illuminance diagram with units and terminology. In photometry, illuminance is the total luminous flux incident on a surface, per unit area. [1] It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. [2]