BH-L20 Longpass Filter
Deliver orange-to-infrared light with stable passband and excellent suppression of green and shorter wavelengths.
- Passband: 565 – 780 nm, 91.3 – 95.5 % T (± 2.1 % ripple)
- Cut-on (T50): ≈ 553 nm
- Edge steepness: ~28 nm (10 → 90 % transition)
- Blocking: < 0.93 % T below 509 nm (OD ≥ 2)
- AOI: 0° (normal incidence); custom angles available
- Construction: Ion-assisted hard-oxide; 5 – 450 mm shapes, 0.21 – 3.8 mm thick
- Custom options: Edge tuning, ripple smoothing, 45° AOI, rapid prototypes
Learn more
BH-L20 Hybrid delivers Passband 565 – 780 nm, 91.3 – 95.5 % T (± 2.1 % ripple), Cut-on (T50) ≈ 553 nm, and Edge steepness ~28 nm (10 → 90 % transition).
The hard-oxide coating is built for repeated handling, heat, and cleaning.
Best suited for:
Orange and red LED filtering, RFP and mCherry fluorescence, warm-tone stage and accent lighting, sodium-line isolation, and broad spectral imaging requiring effective green and blue suppression.
Description
The BH-L20 passes the warm-visible and near-infrared spectrum with its 50 % cut-on at 552.7 nm. The passband runs from 561 to 780 nm with average transmission above 94 %, peaking at 95.5 % near 762 nm. Blocking holds below 1 % from 380 to 530 nm, suppressing UV, violet, blue, and cyan with OD 2+ rejection. The transition spans roughly 30 nm from 531 to 560 nm, providing a clean divide between the cool and warm halves of the visible spectrum.
Key Advantages
- 553 nm cut-on at the warm/cool divide - T50 % at 552.7 nm provides a natural spectral boundary, passing yellow through NIR while blocking blue-green.
- > 94 % average from 561 to 780 nm - Over 220 nm of flat, high-throughput passband covering yellow, orange, red, and NIR.
- OD 2+ blocking to 530 nm - Average transmission under 0.5 % from 380 to 530 nm, thoroughly rejecting the cool-visible spectrum.
- Hard-oxide durability - Ion-assisted sputtered coating survives thermal stress, humidity, solvents, and repeated cleaning.
- 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
- 532 nm laser blocking - Rejects 532 nm Nd:YAG laser excitation while passing all fluorescence emission above 555 nm.
- Warm-tone fluorescence collection - Collects emission from YFP, TRITC, Texas Red, and mCherry while blocking blue-green excitation channels.
- Agricultural & vegetation sensing - Captures yellow, red-edge, and NIR reflectance bands for crop health and stress monitoring.
- Color-temperature correction - Removes cool blue-green content from broadband sources to warm the illumination for imaging or lighting.
- Theatrical lighting - Creates warm amber-through-red-through-NIR washes with no cool-tone leakage for stage design.
KUPO Optics builds the BH-L20 to your exact specifications - rapid prototyping and volume production available. Contact us.
FAQ
BH-L20 FAQ
What is BH-L20 and what is it used for?
BH-L20 is a 555 nm Longpass Filter. The BH-L20 passes the warm-visible and near-infrared spectrum with its 50 % cut-on at 552.7 nm. The passband runs from 561 to 780 nm with average transmission above 94 %, peaking at 95.5 % near 762 nm. Common uses include 532 nm laser blocking, Warm-tone fluorescence collection, Agricultural & vegetation sensing, and Color-temperature correction.
What are the key optical specs of BH-L20?
Key published specs for BH-L20 include Passband: 565 – 780 nm, 91.3 – 95.5 % T (± 2.1 % ripple); Cut-on (T50): ≈ 553 nm; Edge steepness: ~28 nm (10 → 90 % transition); Blocking: < 0.93 % T below 509 nm (OD ≥ 2); AOI: 0° (normal incidence); custom angles available.
What applications is BH-L20 best suited for?
BH-L20 is commonly used for 532 nm laser blocking, Warm-tone fluorescence collection, Agricultural & vegetation sensing, and Color-temperature correction. 532 nm laser blocking - Rejects 532 nm Nd:YAG laser excitation while passing all fluorescence emission above 555 nm.
Can BH-L20 be customized for size, substrate, or coating requirements?
KUPO lists the construction for BH-L20 as Ion-assisted hard-oxide; 5 – 450 mm shapes, 0.21 – 3.8 mm thick. Published custom options include Edge tuning, ripple smoothing, 45° AOI, rapid prototypes. 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.
What should I know about angle of incidence and durability for BH-L20?
The published angle of incidence for BH-L20 is 0° (normal incidence); custom angles available. The hard-oxide coating is built for repeated handling, heat, and cleaning.
