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UV Bandpass Filter 254nm CWL 13nm BW 25mmdia Mounted

Only 5 left in stock
SKU: 254FIA25
More Information
Diameter (mm) 25
Thickness (mm) 6
Avg. Blocking OD 4
Avg. Blocking Range 200nm to 1200nm
Blocking OD OD4
Blocking Type Metallic
CWL(nm) 254
Mounted/Unmounted Mounted
Peak Transmission (%) >15%

Our mounted range UV interference filters 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. 

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.

Mounted Filters

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)
<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)

Unmounted Filters


Thickness (mm):
CWL Tolerance (nm):
HBW Tolerance (nm):
Optimum Operating temperature:
Surface Quality:
Usable Temperature Limits:

25.0mm ± 0.2 
35.0mm ± 0.2
2mm +/-0.2
<0.01% (OD4) @ 200nm to 1200nm 
± 3nm
± 3nm
-50°C to +80°C

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