Northumbria Optical Coatings Ltd

Long Wave Pass

Long Wave Pass filters (also referred to as edge filters) are constructed from stacks of thin layers. They are distinguished by a sharp transition from a zone of rejection to a zone of transmission. The rejection region extends to below 0.3um and the transmission region typically extends to greater than twice the wavelength of the edge position. When ordering it is necessary to specify the required 5% or 50% cut on edge position (the 5% point is measured as an absolute value but the 50% point is measured as 50% of peak transmittance).

Typical Performance

Long_Wave_Pass_Curve.jpg

Typical Characteristics

Available wavelength range (edge position) ~1.3 to 20um
Edge tolerance To customers 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

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