Integrating Sphere - Materials

Materials

The optical properties of the lining of the sphere greatly affect its accuracy. Different coatings must be used at visible, infrared and ultraviolet wavelengths. High-powered illumination sources may heat or damage the coating, so an integrating sphere will be rated for a maximum level of incident power. Various coating materials are used. Early experimenters used a deposit of magnesium oxide. Barium sulfate has a usefully flat reflectance over the visible spectrum. Finely-deposited gold is used for infrared measurements. Various proprietary PTFE compounds are also used for visible light measurements.

The theory of the integrating sphere assumes a uniform inside surface. Openings where light can exit or enter, normally called ports, that are used for detectors and sources must be small, less than about 5% of the surface area of the sphere, for the theoretical assumptions to be valid. Unused ports should therefor have matching plugs, with the interior surface of the plug coated with the same material as the rest of the sphere. Baffles are normally inserted in the sphere to block the direct path of light from a source to a detector, since this light will have non-uniform distribution.

Read more about this topic:  Integrating Sphere

Famous quotes containing the word materials:

    The competent leader of men cares little for the niceties of other peoples’ characters: he cares much—everything—for the exterior uses to which they may be put.... These are men to be moved. How should he move them? He supplies the power; others simply the materials on which that power operates.
    Woodrow Wilson (1856–1924)

    In how few words, for instance, the Greeks would have told the story of Abelard and Heloise, making but a sentence of our classical dictionary.... We moderns, on the other hand, collect only the raw materials of biography and history, “memoirs to serve for a history,” which is but materials to serve for a mythology.
    Henry David Thoreau (1817–1862)

    Realism to be effective must be a matter of selection. ... genius chooses its materials with a view to their beauty and effectiveness; mere talent copies what it thinks is nature, only to find it has been deceived by the external grossness of things.
    Julia Marlowe (1866–1950)