Our partner Andover Corp.

Standard long wave pass filters

from Andover

Long wave pass filters provide a sharp cutoff below a particular wavelength. Often used for order sorting, they isolate broad regions of the spectrum, simultaneously providing high transmission of desired energy, and deep rejection of unwanted energy.

Constructed of hard, durable first-surface dielectric coatings on optical-quality IRtransmitting substrates, these filters will withstand normal cleaning and handling associated with any high-quality optical component.

For convenience, we offer the filters in two standard sizes: 25mm and 50mm dia. In addition, we offer custom sizes and shapes, as well as custom optical characteristics. Contact our expoert on the right for a quotation.

  • Useful for isolating broad spectral regions
  • Constructed of hard, durable first-surface coatings
  • Available in standard and custom wavelengths


General Specifications
Thickness 1.0±0.2 mm
Diameter Tolerance +0/-0.1 mm
Min. Clear Aperture 90% of outside dimension
Substrate Material Silicon or Germanium
Flatness 3-5 waves at cut-on W/L
24-hour Humidity per MIL-C-48497A
Operating Temperature -62 °C to +71 °C
Parallelism <10 arc minutes
Transmission (Ave) >85% from 1.05 x cut-on to 2.0 x cut-on
Rejection (Ave) <0.1%
Slope <7% (12% for 1.05 μm filter)
Optional Mounted in threaded ring - contact our expert on the right for thread sizes

Standart Long Pass Filters

  Size, Shape & Part Number  
5% point cut-on W/L 25 mm Ø 50 mm Ø

1.05 μm ± 0.04 μm 1.05ILP-25 1.05ILP-50
1.65 μm ± 0.07 μm 1.65ILP-25 1.65ILP-50
2.40 μm ± 0.09 μm 2.40ILP-25 2.40ILP-50
3.60 μm ± 0.14 μm 3.60ILP-25 3.60ILP-50
4.50 μm ± 0.18 μm 4.50ILP-25 4.50ILP-50
7.30 μm ± 0.29 μm 7.30ILP-25 7.30ILP-50

Custom IR Long Wave Pass Filters

Andover can design and fabricate long pass and short pass filters to suit your particular requirements. Every phase of the process is performed in-house, including thin-film coating design, mechanical design, substrate fabrication and coating, inspection, and environmental testing.

We can coat a variety of substrate materials, including Germanium, Sapphire, Silicon, Zinc Sulfide, and Zinc Selenide.

Contact our expert on the right for a quotation, whether it is for prototype quantities, or production quantities.

 Custom Long Pass Filters

  Size, Shape & Part Number  
5% point cut-on W/L 25 mm Ø 50 mm Ø

0.1 μm - 2.1 μm IRLWP08-25 IRLWP08-50
2.2 μm - 5.0 μm IRLWP10-25 IRLWP10-50
5.1 μm - 7.0 μm IRLWP12-25 IRLWP12-50
7.1 μm - 11.0 μm IRLWP14-25 IRLWP14-50


Order Sorting
FTIR Spectroscopy
Thermal Imaging


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