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UV Bandpass Filters


Available Designs for Standard Bandpass Filters


Open-Faced - The open-faced design includes a substrate with an optical filter coating on one surface. Open-faced filters must be handled with care as the soft filter coating is exposed. Potential damage from moisture, atmospheric contaminants or handling can be reduced by sealing the
filter with a protective fused silica cover, as shown below (available above 190nm only).

Covered / Edge Sealed - Filters above 190nm may be supplied with a fused silica cover for protective purposes. As shown in the diagram, a spacer ring is placed between the substrates to form a small air gap, then the edges are sealed. This design enables the filter to be handled without risk of touching the delicate filter coating. Please note that covering a filter decreases its transmission by 2-3%.

Edge sealing adds approximately 0.010” (0.254mm) to the diameter of the filter. Total thickness for a covered and edge sealed filter is approximately twice that of an open-faced design. Exact dimensions are available from the Optics Sales Department.


Mounted - Open-faced or covered filters (without edge sealant) can be supplied in metal mounting rings, if desired. The rings are constructed from aluminum and are black anodized. Mounting a filter reduces clear aperture and increases the outside diameter as outlined below.

Diameter Information for -N, -B, -W and -VBB Filters


NOTE: Filters are supplied open-faced unless otherwise specified
* 2.0“ Diameter 122-157nm filters are 5mm thick

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