Northumbria Optical Coatings Ltd

Narrow Bandpass

Narrow bandpass filters are designed to isolate a narrow region of the infra-red spectrum. This is accomplished using a complex process of constructive and destructive interference. Narrow band pass filters have bandwidths (measured at half-peak transmittance levels) less than 6% of the centre of wavelength value. When ordering, the bandwidth can be expressed as a percentage of the centre wavelength, or can be given in microns. The filters exhibit high peak transmission (typically greater than 60%) combined with high attenuation levels outside the passband (typically less than 0.1%).

Typical Performance

Narrow_Band_Pass_Curve.jpg

Typical Characteristics

Available wavelength range ~2 to 20um
Tolerance on CWL To customers requirements, but standard tolerances are typically +/-0.3% for a 1% bandwidth filter to +/-1% for a 6% bandwidth filter
Peak transmittance Typically >60% (depending on wavelength and bandwidth)
Available bandwidths Typically 0.9% to 6%
Blocking (attenuation) Typically <0.1 % from 0.3 micron to far infrared

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