Ultra-narrowband optical interference filter with a 1650.96 nm center wavelength (CWL), a 0.8 nm full-width at half-maximum (FWHM), and wide-range OD4 out-of-band blocking from 300 nm to 1800 nm. This is a multi-cavity filter with transmission that is greater than 90% at 1650.96 nm. This ultra-narrowband filter is coated on a 2 mm thick fused silica substrate and mounted in a 25.4 mm (+0/-0.2 mm) diameter, 5 mm (± 0.1 mm) thick anodized aluminum ring. Alluxa ultra-narrow bandpass filters have the highest transmission and narrowest bandwidths currently available. And because they are hard-coated using our innovative SIRRUS? plasma deposition process, all Alluxa optical filters are highly durable and resistant to laser damage. Contact us for custom sizing options.