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Sapphire and glass ball lenses
Ball
lenses have very low spherical aberration and so focus
and collimate light very accurately; a sapphire ball
has only 23% of the aberration of an equivalent BK7
planoconvex lens over the same aperture. Ball lenses
are available economically at very high precision and
are simple to mount. Sapphire can be used from 170nm
to 5.3µm and has exceptional hardness, strength
and temperature resistance. Ball lenses are ideal for
focusing light into fibres, fibre coupling, emitters
and detectors.
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