Northumbria Optical Coatings Ltd

Wide Bandpass

Wide bandpass filters are designed to isolate a very wide spectral band. They are classified by having bandwidths (measured at half peak transmittance levels) greater than 13%. When ordering, it is necessary to specify the 5% cut on/cut off transmission points or the 50% cut on/cut off transmission points (the 5% points are measured as absolute values but the 50% points are measured as 50% of peak transmittance). The filters exhibit high average transmission in the passband (typically greater than 70%) and very low transmission levels outside the passband (typically less than 0.1 %). This type of filter is particularly useful for isolating the 3-5um or 8-12um atmospheric windows and finds widespread use in thermal imaging/human body sensor applications.

Typical Performance


Typical Characteristics

Available wavelength range ~1.5 to 20um
Cut on / off tolerance To customers requirements, from +/-1%. Standard tolerances are typically +/-4% for a 3-5um or 8-12um wide bandwidth filter.
Average transmittance Typically >70%
Blocking (attenuation) Typically <0.1 % from 0.3 micron to far infrared.

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