BH-S20 is tailored for near-UV and violet work. It passes the 400 – 430 nm band at better than 90 % while cutting almost every photon longer than ~440 nm. From 450 nm clear out past 720 nm the curve hugs the baseline below 1 %, with only a gentle rise in the far IR (≈ 18 % by 780 nm) that can be handy for alignment or can be flattened on request.
Key advantages
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High violet throughput – > 90 % transmission across 400 – 430 nm keeps 405 nm diodes and UV-LEDs bright.
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Ultra-steep 440 nm edge – ≈ 8 nm transition cleanly separates violet from the visible spectrum.
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Deep blocking band – < 0.5 % transmission from 450 nm to 720 nm protects sensors, kills stray glow, and reduces heat.
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Optional IR leak – Small, controlled lift above 750 nm can serve as an alignment beacon; zero-leak versions available.
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Hard-oxide durability – Ion-assisted coating resists heat, humidity, solvents, and aggressive wipe-downs.
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Format freedom – KUPO can supply anything from 5 mm chips to 450 mm plates, thickness 0.21 – 3.8 mm, on Borofloat®, soda-lime, Schott D263 T, or Corning Eagle XG glass.
Typical applications
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Fluorescence microscopes & cytometers – Cleanly excite DAPI, Hoechst, and other 405 nm dyes while blocking visible emissions.
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UV-LED curing & lithography – Pass 405 nm light to photoresists while dumping all longer wavelengths that cause substrate heating.
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Machine-vision inspection – Pair with 405 nm LED bars for contrast on anti-counterfeit inks or semiconductor wafers.
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Stage & themed lighting – Create punchy “black-light” effects without visible spill; the mild IR tail aids motion-tracking rigs.
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AR / VR optics – Inject violet graphics or sensor beams without leaking green-red light into the user’s eye path.
Need fast prototypes, odd outlines, or high-volume production? KUPO Optics can coat, dice, and ship BH-S20 to your exact specs—swiftly.
