Because of its unique combination of thermal and chemical stability, low thermal expansion and high optical transparency in a wide spectral range, synthetic diamond is becoming the most popular material for optical windows in high-power CO 2 lasers and gyrotrons.
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These have a maximum amount of parallax due to eye movement, equal to the size of the optical window, at close range, diminishing to a minimal amount at the set distance ( somewhere around a desired target range of 25 50 yards ).
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The success of this approach to cancer treatment rests on the existence of an'optical window'in which biological tissue ( i . e ., healthy cells ) are completely transparent at the wavelength of the laser light, while nanoparticles are highly absorbing at the same wavelength.
34.
Collimator sights have had uses as a small arms sight for low light situations ( such as twilight or " room clearing " operations ) since there is no intervening optical window that can block the light, allowing the use of both eyes with a relatively un-obstructed field of view.
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The secondary is typically suspended by X-shaped struts ( sometimes called a " spider " ) in the path of light between the source and the primary, but can be mounted on other types of mounts or optical elements such as optical windows, or diffraction spikes radiating from bright stars seen in astronomical images.
