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  2. Diffraction - Wikipedia

    en.wikipedia.org/wiki/Diffraction

    A diffraction pattern of a red laser beam projected onto a plate after passing through a small circular aperture in another plate. Diffraction is the deviation of waves from straight-line propagation without any change in their energy due to an obstacle or through an aperture.

  3. Annulus (firestop) - Wikipedia

    en.wikipedia.org/wiki/Annulus_(firestop)

    Sprinkler branch pipe through-penetration with plastic sleeve - missing firestop in concrete fire separation. The space between the sleeve and the pipe is the annulus or annular space. The annulus, or annular space, is the space between a penetrant and anything that surrounds it, such as the sides of an opening or a sleeve, as the case may be. [1]

  4. Dynamical theory of diffraction - Wikipedia

    en.wikipedia.org/.../Dynamical_theory_of_diffraction

    There is a gap between the dispersion surfaces in which no travelling waves are allowed. For a non-absorbing crystal, the reflection curve shows a range of total reflection, the so-called Darwin plateau. Regarding the quantum mechanical energy of the system, this leads to the band gap structure which is commonly well known for electrons.

  5. Diffraction from slits - Wikipedia

    en.wikipedia.org/wiki/Diffraction_from_slits

    Because diffraction is the result of addition of all waves (of given wavelength) along all unobstructed paths, the usual procedure is to consider the contribution of an infinitesimally small neighborhood around a certain path (this contribution is usually called a wavelet) and then integrate over all paths (= add all wavelets) from the source to the detector (or given point on a screen).

  6. Ground-penetrating radar - Wikipedia

    en.wikipedia.org/wiki/Ground-penetrating_radar

    It is a non-intrusive method of surveying the sub-surface to investigate underground utilities such as concrete, asphalt, metals, pipes, cables or masonry. [1] This nondestructive method uses electromagnetic radiation in the microwave band ( UHF / VHF frequencies) of the radio spectrum , and detects the reflected signals from subsurface structures.

  7. Line-of-sight propagation - Wikipedia

    en.wikipedia.org/wiki/Line-of-sight_propagation

    Objects within the Fresnel zone can disturb line of sight propagation even if they do not block the geometric line between antennas. Low-powered microwave transmitters can be foiled by tree branches, or even heavy rain or snow. The presence of objects not in the direct line-of-sight can cause diffraction effects that disrupt radio transmissions.

  8. Optics - Wikipedia

    en.wikipedia.org/wiki/Optics

    In general, light that is passing through an aperture will experience diffraction and the best images that can be created (as described in diffraction-limited optics) appear as a central spot with surrounding bright rings, separated by dark nulls; this pattern is known as an Airy pattern, and the central bright lobe as an Airy disk. [69]

  9. Beamline - Wikipedia

    en.wikipedia.org/wiki/Beamline

    In particle accelerators the beamline is usually housed in a tunnel and/or underground, cased inside a concrete housing for shielding purposes. The beamline is usually a cylindrical metal pipe, typically called a beam pipe, and/or a drift tube, evacuated to a high vacuum so there are few gas molecules in the path for the beam of accelerated particles to hit, which otherwise could scatter them ...