L-, M-, and N-Band Infrared Filters

L-, M-, and N-Band Infrared Filters
L-, M-, and N-Band Filters from Andover Corporation are mid- to long-wave infrared filters designed for spaceborne and airborne imaging systems, including CubeSats, SmallSats, and surveillance platforms. These filters span wavelengths from approximately 3000nm to 12350nm, covering the L-band (3–4 µm), M-band (4.5–5.5 µm), and N-band (7.5–13 µm). Each band supports distinct sensing applications across thermal infrared and atmospheric windows.
L- and M-Band Filters are commonly used in aircraft surveillance, satellite navigation, and weather monitoring, where precise discrimination of mid-IR signatures is critical. These filters are fabricated for optimal performance with cooled infrared sensors, offering high transmission in the target band and OD3 blocking outside of it.
N-Band Filters excel in the far-infrared domain, where hot thermal features—such as volcanic activity and industrial heat sources—can be detected with high contrast. Designed for use with both cooled and uncooled microbolometers, they offer consistent performance across platforms. When cooled from room temperature to liquid nitrogen temperatures (-196°C), a wavelength shift of approximately 1% is expected, and accounted for during design. These filters are especially suited to applications requiring isolation of narrow spectral regions, including thermal IR astronomy and remote sensing.
Contact Us for Information on N-Band Filters
All filters are manufactured on single substrates with durable coating systems and are available in custom sizes to meet the demands of mission-specific payloads and research instrumentation.
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- Emission Line: FIR Broadband, N-Band
- Parallelism: < 10 arc minutes
- Bandwidth (FWHM): 4000
- Transmission: > 80 % Ave
- Blocking: < 0.1 % (avg) UV to 17 microns
- Size: 25.0 Ø +0.0 / -0.2
- Thickness: 1.0 ±0.2
- Scratch-Dig: 80/50
- Clear Aperture: 22mm dia.
- Flatness: 5λ or better at λ of Interest
- Filter Type: -
- Substrate Material: Ge
- Emission Line: FIR Broadband, N-Band
- Parallelism: < 10 arc minutes
- Bandwidth (FWHM): 4000
- Transmission: > 80 % Ave
- Blocking: < 0.1 % (avg) UV to 17 microns
- Size: 50.0 Ø +0.0 / -0.2
- Thickness: 1.0 ±0.2
- Scratch-Dig: 80/50
- Clear Aperture: 45mm Ø min
- Flatness: 5λ or better at λ of Interest
- Filter Type: -
- Substrate Material: Ge
- Emission Line: SWIR, L and M-Band
- Parallelism: < 10 arc minutes
- Bandwidth (FWHM): 2000
- Transmission: 80% (avg)
- Blocking: T(avg) <0.1 UV to 11000nm
- Size: 12.5 Ø +0.0 / -0.2
- Thickness: 1.00 ±0.2
- Scratch-Dig: 80/50
- Clear Aperture: 10mm Ø min
- Flatness: 5λ or better at λ of Interest
- Filter Type: --
- Substrate Material: Silicon
- Emission Line: SWIR, L and M-Band
- Parallelism: < 10 arc minutes
- Bandwidth (FWHM): 2000
- Transmission: 80% (avg)
- Blocking: T(avg) <0.1 UV to 11000nm
- Size: 25.0 Ø +0.0 / -0.2
- Thickness: 1.00 ±0.2
- Scratch-Dig: 80/50
- Clear Aperture: 22mm dia.
- Flatness: 5λ or better at λ of Interest
- Filter Type: -
- Substrate Material: Silicon
- Emission Line: SWIR, L and M-Band
- Parallelism: < 10 arc minutes
- Bandwidth (FWHM): 2000
- Transmission: 80% (avg)
- Blocking: T(avg) <0.1 UV to 11000nm
- Size: 50.0 +0.0 / -0.2
- Thickness: 1.00 ±0.2
- Scratch-Dig: 80/50
- Clear Aperture: 45mm Ø min
- Flatness: 5λ or better at λ of Interest
- Filter Type: --
- Substrate Material: Silicon