Short wave pass filters are distinguished by a sharp transition from a zone of transmission to a zone of rejection. The rejection region typically extends to the far infrared but can be limited for filters with edge positions below 2um.
When ordering it is necessary to specify the 5% or 50% cut off edge position (the 5% point is measured as an absolute value but the 50% point is measured as 50% of peak transmittance).
Typical Characteristics of Short Wave Pass Filters
| Available wavelength range (edge position) | ~1 to 20 um |
| Edge tolerance |
To customer requirements, from +/-1% but standard tolerance +/-4%
|
| Average transmittance | Typically >75% (depending on wavelength) |
| Cut on slope | Typically < 5% |
| Blocking (attenuation) | Typically <0.1% to 0.3 micron. |
Northumbria Optical Coatings Ltd (NOC) was established in 1995, specializing in the design and manufacture of Infrared Optical Filters and Coatings, covering the spectral range 1.5μm – 20.0μm. Before 1995 NOC operated as a business unit for Rolls Royce International Research & Development based in Newcastle upon Tyne. NOC offers competitively priced standard and non-standard filters which are used in many applications including environmental monitoring, analysis and control of gaseous effluent, analysis of vehicle exhaust gases, ozone layer monitoring, night vision systems and space applications. Contact EOC for more information.