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  2. 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.

  3. 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 ...

  4. Selected area diffraction - Wikipedia

    en.wikipedia.org/wiki/Selected_area_diffraction

    Since the spacing between atoms in crystals is about a hundred times larger, the electrons are diffracted on the crystal lattice, acting as a diffraction grating. Due to the diffraction, part of the electrons is scattered at particular angles (diffracted beams), while others pass through the sample without changing their direction (transmitted ...

  5. Echelle grating - Wikipedia

    en.wikipedia.org/wiki/Echelle_grating

    An echelle grating (from French échelle, meaning "ladder") is a type of diffraction grating characterised by a relatively low groove density, but a groove shape which is optimized for use at high incidence angles and therefore in high diffraction orders. Higher diffraction orders allow for increased dispersion (spacing) of spectral features at ...

  6. 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 ...

  7. Diffraction grating - Wikipedia

    en.wikipedia.org/wiki/Diffraction_grating

    A blazed diffraction grating reflecting only the green portion of the spectrum from a room's fluorescent lighting. For a diffraction grating, the relationship between the grating spacing (i.e., the distance between adjacent grating grooves or slits), the angle of the wave (light) incidence to the grating, and the diffracted wave from the grating is known as the grating equation.

  8. 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.

  9. Effective medium approximations - Wikipedia

    en.wikipedia.org/wiki/Effective_medium...

    There are many different effective medium approximations, [5] each of them being more or less accurate in distinct conditions. Nevertheless, they all assume that the macroscopic system is homogeneous and, typical of all mean field theories, they fail to predict the properties of a multiphase medium close to the percolation threshold due to the absence of long-range correlations or critical ...