Dual-pass filter delivering vivid blue (410 – 495 nm) and bright NIR (740 – 760 nm) while crushing green-to-red light for maximum contrast.
B6809 offers two clear, high-throughput windows—one in the blue (≈ 400 – 495 nm) and another in the
near-infrared (≈ 740 – 760 nm)—while forcing the entire green-to-deep-red band down to detector-noise levels.
Transmission tops 90 % by 410 nm, holds a flat 92 – 94 % plateau through about 490 nm, then crashes below 1 %
just past 515 nm. After a dark trough through 520 – 700 nm the curve rockets above 90 % near 745 nm, peaks
around 755 nm, and tapers to ~40 % at 780 nm. Ion-assisted hard-oxide coatings shrug off heat, humidity, and
solvents, and KUPO can shift edges, suppress ripples, supply 45 ° AOI versions, or cut large-format plates in
as little as two weeks.
Typical applications: dual-channel fluorescence (blue excitation + far-red detection), machine-vision
lighting with NIR reference beams, AR/VR waveguide injection, magenta stage lighting mixes, and spectroscopy
setups needing both 450 nm pumps and 755 nm reference lines.
B6809 lets two colours through—bright blue (about 400 – 495 nm) and a narrow near-infrared band (about 740 – 760 nm)—while it blocks almost everything in between. Light in the blue region reaches more than 90 % transmission from roughly 410 nm to 490 nm. Just beyond 510 nm the curve drops steeply to below 1 % and stays there throughout the green and red (520 – 700 nm). It rises again above 90 % near 745 nm, peaks near 755 nm, then slowly tails off toward 780 nm. You get a clean blue signal, a deep mid-band notch, and a strong NIR window for alignment or dual-channel sensing.
Key advantages
Bright blue passband – More than 90 % transmission across 410 – 495 nm for curing, inspection, or fluorescence excitation.
Strong mid-band blocking – Less than 0.5 % transmission from 520 – 700 nm removes green and red flare, boosting contrast.
Built-in NIR window – About 90 % transmission at 740 – 760 nm for easy alignment or a second sensing channel.
Steep cut-on / cut-off edges – About 10 nm transition keeps colours separate and prevents bleed-through.
Rugged hard-oxide coating – Resists heat, humidity, solvents, and frequent cleaning.
Quick custom options – Shift edges, flatten ripples, supply 45 ° AOI versions, or scale up to large plates in two weeks or less.
Typical applications
Dual-channel fluorescence – Blue light excites CFP or FITC, while the NIR band collects far-red probes; the green-red block cuts autofluorescence.
Machine vision & metrology – Combine sharp blue lighting with an NIR reference beam for 3-D profiling or mixed-material inspection.
AR / VR waveguides – Feed blue graphics and NIR eye-tracking signals into the combiner without leaking green or red.
Stage & architectural lighting – Create saturated magenta washes (blue + far-red) with no unwanted green spill.
Spectroscopy & Raman – Cleanly separate a 450 nm pump and a 755 nm reference line for stable baselines.
Need tiny chips, odd shapes, or volume supply? KUPO Optics can prototype and ship B6809 in sizes from 10 mm slivers to 300 mm plates—fast.