Thorlabs FEL1350 Near Infrared Longpass Optical Filter

FEL1350 is a near-infrared longpass optical filter from Thorlabs. It was part of their FEL series of soft-coated longpass filters, designed to transmit longer IR wavelengths while rejecting shorter ones.

📌 Key Specifications

• Filter Type: Longpass filter (transmits wavelengths above a specific cutoff).

• Cut-On Wavelength: 1350 nm — it allows wavelengths longer than ~1350 nm to pass.

• Diameter: Ø1″ (approx. Ø25.4 mm) clear aperture.

• Rejection Band: Designed to block shorter NIR wavelengths (below the cutoff).

• Intended Use: Useful in optical systems where removing light below ~1350 nm is needed (e.g., NIR imaging, spectroscopy).

🧠 Typical Applications

Longpass filters like the FEL1350 are commonly used in:

• NIR imaging setups

• Spectroscopy and photonics experiments

• Systems needing suppression of undesired shorter wavelengths