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Our range of UV interference filters come in mounted and unmounted options. They are used to isolate and transmit a specified narrow wavelength and reflect all other incident wavelengths in the ultra-violet and visible spectrum.

These high-quality ultraviolet interference bandpass filters are available from 214nm-320nm in various bandwidths to meet a range of UV instrument requirements such as fluorescence imaging and UV sterilisation applications.

Typically, our mounted filters are 3-7 cavity and in most cases, blocking is metal dielectric from 200nm to FIR (3000+nm) at OD4. Our unmounted filters have aerospace paint blackened edges.

All our interference bandpass filters are supplied with a transmission curve; ASCII files are available on request. Filters are available on short lead times directly from stock, or as custom products designed to fit your specific application. For more information, please contact our technical sales team with your requirements.

Diameter & Aperture (mm):

Thickness (mm):

CWL Tolerance (nm):
HBW Tolerance (nm):
Optimum Operating temperature:
Edge Treatment:
Edge Marking Format:

Surface Quality:
Usable Temperature Limits:
Design Type:

12.5mm ± 0.1 (8.5mm aperture)
25.0mm ± 0.1 (21mm aperture)
50.0mm ± 0.1 (46mm aperture)
6.1mm +/-0.2
<0.01% (OD4) @ 200nm to 3000nm (for filters with CWL 1600nm upwards)
<0.01% (OD4) @ 200nm to 2000nm (for all other filters)
± 20% of FWHM
± 20% of FWHM
Mounted in black anodized aluminium ring
In most cases {Knight Optical Part#} - {KOLTD} - arrow in direction of light path
-50°C to +80°C
Typical 3 cavity design
All filters are scribed and hermetically sealed to ensure maximum long-term stability
(Information sheet on scribed interference filters)

Knight Optical can provide custom dimensions to above 100mm, please contact our sales team with your specification.


Dielectrically blocked filters are available for increased performance.
Stock filters can be supplied in pre-mounted threaded rings.
Other bespoke sizes to your specification either mounted or un-mounted.
Unmounted interference filters available, sealed around edges with high quality aerospace paint.
Small one-off or small batch quantity for new projects at very competitive prices and normally delivered within 6 weeks.
Alternative imperial sizes are available at short notice, normally within 1-2 weeks.
12.7mm dia: 8.7mm dia aperture
25.4mm dia: 21.4mm dia aperture
50.8mm dia: 46.8mm dia aperture

Information sheet: Interference filter terminology

Information sheet: Scribed interference filters

9 Items

Name CWL(nm) Peak Transmission (%) FWHM Diameter (mm) Thickness (mm) Mounted/Unmounted Blocking Type Avg. Blocking Range Avg. Blocking OD Price Buy
214FIB12 pdf 214 14 14 12.5 6.1 Mounted Silver 200nm to 1150nm 4
214FIB25 pdf 214 14 14 25 6.1 Mounted Silver 200nm to 1150nm 4
220FIB12 pdf 220 16 14 12.5 6.1 Mounted Silver 200nm to 1150nm 4
254FIB12 pdf 254.7 17 14 12.5 6.1 Mounted Silver 200nm to 1150nm 4
280FIB12 pdf 280 17 14 12.5 6.1 Mounted Silver 200nm to 1150nm 4
300FIB25 pdf 300 25 14 25 6.1 Mounted Silver 200nm to 1150nm 4
310FIB25 pdf 310 20 14 25 6.1 Mounted Silver 200nm to 1150nm 4
320FIB12 pdf 320 30 14 12.5 6.1 Mounted Silver 200nm to 1150nm 4
320FIB25 pdf 320 25 14 25 6.1 Mounted Silver 200nm to 1150nm 4

9 Items


UV Interference Bandpass Filters

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