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Color
glass filters |
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We
use color filters from various suppliers, mainly from Schott, Germany.
These materials have different transmission and absorption properties
and are used for broadband spectral filtering. These are used as long
pass and band pass filters. They are much less expensive than coated
filters. |
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Heat filters |
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Heat filters are short pass filters which
transmit the visible light and absorb the IR radiation, thus not
allowing the "heat" to pass through. We use Schott filters like KG1,
KG3, KG5 etc. These can also be "toughened" if required. |
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Absorbing glass Neutral density
filters |
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Neutral density (ND) filters are gray in color.
They absorb the light and give a uniform response in the visible
region. They reduce the amount of light passing through the system.
They can be manufactured to different optical densities. NG1, NG3, NG4 etc
are some of the Schott glasses used for this purpose. |
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Coated neutral density filters |
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These are similar to the above mentioned ND
filters but instead of color glass filters, these filters are made by
coating Inconel or Nichrome on optical glass. |
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Dichroic filters |
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These are coated filters which transmit one
part of the spectrum and reflect another. For e.g, they can transmit
the visible and reflect the IR region (Hot mirrors) or they can reflect
the visible and transmit the IR (Cold mirrors). Used at Normal
incidence and also 45°. |
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