Long-pass infrared filters, unlike semiconductor filters, are constructed from stacks of thin layers. OD 3 rejection in the suppression range is not as high as it is with semiconductor filters, but it has the advantage of free choice of slope position.

• Edge position:
  Each wavelength between 1 µm and 20 µm (at a transmission of 5%)
• Transmission:
  60% – 80% in the passband, 0.1% or less in the cut-off region. The cut-off region extends to the x-ray range. The passband extends to at least double the edge wavelength.
• Size:
  Standard filters have a diametre of 25.4 mm and an aperture of >21 mm. Other sizes are available upon request. Square designs starting at 2 mm x 2 mm and round IR long-pass filters with a diametre of up to 100 mm can also be produced.