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  2. Grating - Wikipedia

    en.wikipedia.org/wiki/Grating

    The grating profile is the function of the reflectance or transmittance perpendicular to the lines. This function is generally a square wave, in that every transition between lines is abrupt. A grating can be defined by six parameters: Spatial frequency is the number of cycles occupying a particular distance (e.g. 10 line pairs per millimeter ...

  3. Blazed grating - Wikipedia

    en.wikipedia.org/wiki/Blazed_grating

    A special form of a blazed grating is the echelle grating. It is characterized by particularly large blaze angle (>45°). Therefore, the light hits the short legs of the triangular grating lines instead of the long legs. Echelle gratings are mostly manufactured with larger line spacing but are optimized for higher diffraction orders.

  4. Grating lobes - Wikipedia

    en.wikipedia.org/wiki/Grating_lobes

    A typical radiation pattern of phased arrays whose inter-element spacing is greater than half a wavelength, hence the radiation pattern has grating lobes.. For discrete aperture antennas (such as phased arrays) in which the element spacing is greater than a half wavelength, a spatial aliasing effect allows plane waves incident to the array from visible angles other than the desired direction ...

  5. Heating system - Wikipedia

    en.wikipedia.org/wiki/Heating_system

    Distributed heating systems: These systems generate heat in the space they are to heat, without extensive duct systems. Examples include electric space heaters, fireplaces, and solar heating. [3] Heat pumps: They can be used for heating and cooling, transferring heat using refrigerant and electricity, making them more efficient than other ...

  6. Negative thermal expansion - Wikipedia

    en.wikipedia.org/wiki/Negative_thermal_expansion

    Negative thermal expansion (NTE) is an unusual physicochemical process in which some materials contract upon heating, rather than expand as most other materials do. The most well-known material with NTE is water at 0 to 3.98 °C.

  7. X-ray spectroscopy - Wikipedia

    en.wikipedia.org/wiki/X-ray_spectroscopy

    Usually X-ray diffraction in spectrometers is achieved on crystals, but in Grating spectrometers, the X-rays emerging from a sample must pass a source-defining slit, then optical elements (mirrors and/or gratings) disperse them by diffraction according to their wavelength and, finally, a detector is placed at their focal points.

  8. Talbot effect - Wikipedia

    en.wikipedia.org/wiki/Talbot_effect

    Due to the quantum mechanical wave nature of particles, diffraction effects have also been observed with atoms—effects which are similar to those in the case of light. . Chapman et al. carried out an experiment in which a collimated beam of sodium atoms was passed through two diffraction gratings (the second used as a mask) to observe the Talbot effect and measure the Talbot length

  9. Thermochemistry - Wikipedia

    en.wikipedia.org/wiki/Thermochemistry

    Thermochemistry is the study of the heat energy which is associated with chemical reactions and/or phase changes such as melting and boiling. A reaction may release or absorb energy, and a phase change may do the same. Thermochemistry focuses on the energy exchange between a system and its surroundings in the form of heat. Thermochemistry is ...