B6809 Dual-Band Filter

The B6809 passes the blue-to-green spectrum with its 50 % cut-off measured at 541 nm. Transmission averages above 90 % from 415 to 530 nm, peaking at 93.3 % near 475 nm, providing wide coverage across the blue-to-green window. Beyond the transition edge, the filter suppresses transmission to below 1 % by 558 nm and maintains sub-0.5 % blocking on average from 558 nm to 780 nm – a clean, deep rejection floor across the yellow-to-NIR region.

Key Advantages

• Precise 541 nm cut-off – T50 % measured at 541.1 nm with a transition that drops to < 1 % within 17 nm, cleanly separating the blue-green passband from yellow and longer wavelengths.
• High-throughput passband – Average transmission above 90 % across 415–530 nm with a 93.3 % peak, minimizing signal loss across the full blue-to-green range.
• Broadband blocking – Sub-0.5 % average transmission from 558 nm to 780 nm, ensuring reliable rejection of yellow, orange, red, and NIR wavelengths.
• Hard-oxide durability – Ion-assisted sputtered hard coating withstands heat, humidity, solvents, and frequent cleaning cycles.
• Custom formats – Round, square, or free-form blanks from 5 mm to 450 mm, thickness 0.21–3.8 mm, on Borofloat, soda-lime, Schott D263 T, or Corning Eagle XG substrates.

Typical Applications

• Fluorescence excitation filtering – Passes the full excitation band for GFP and FITC variants while blocking yellow-green emission wavelengths above 540 nm.
• Multi-channel microscopy – Defines a blue-to-green detection channel in multi-color imaging systems, preventing cross-talk with yellow or red fluorescence channels.
• Laser line clean-up – Removes broadband background from 488–532 nm laser sources, passing only spectrally pure emission below the cut-off.
• Machine vision – Isolates blue-green LED illumination in high-contrast inspection systems requiring rejection of yellow and red ambient light.
• Architectural & stage lighting – Produces a pure green wash from broadband sources with no yellow, orange, or warm-tone contamination.

Need a 550 nm shortpass tailored to your optical path? KUPO Optics provides rapid prototyping and volume production to your exact size, shape, and substrate specifications.