R15 Longpass Filter
Isolate deep red wavelengths with minimal transition bandwidth and exceptionally low passband ripple.
- Passband: 643 – 780 nm, 92.2 – 95.8 % T (± 1.8 % ripple)
- Cut-on (T50): ≈ 636 nm
- Edge steepness: ~15 nm (10 → 90 % transition)
- Blocking: < 0.96 % T below 616 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
R15 Hybrid delivers Passband 643 – 780 nm, 92.2 – 95.8 % T (± 1.8 % ripple), Cut-on (T50) ≈ 636 nm, and Edge steepness ~15 nm (10 → 90 % transition).
The hard-oxide coating is built for repeated handling, heat, and cleaning.
Best suited for:
Deep red LED filtering and laser beam conditioning, Cy5 and Alexa 647 fluorescence, precision color separation in flow cytometry, NIR camera preparation, and red-channel reference imaging.
Description
The R15 passes the deep red and near-infrared spectrum from 640 nm onward, with its 50 % cut-on measured at 635.9 nm. The passband averages above 94 % from 640 to 780 nm, peaking at 95.8 % near 734 nm. Blocking averages just 0.2 % from 386 to 624 nm, providing OD 2.7+ suppression of the entire visible spectrum from UV through orange-red. A mild UV shoulder around 380-385 nm shows slightly elevated transmission but stays under 2 %.
Key Advantages
- 636 nm cut-on for deep-red pass - T50 % at 635.9 nm isolates only the deepest visible red and NIR, blocking everything shorter.
- OD 2.7+ visible blocking - Average transmission 0.2 % from 386 to 624 nm provides one of the deepest rejection floors available.
- 95.8 % peak transmission - Passband peaks near 734 nm with uniform response across 140 nm of red-to-NIR bandwidth.
- Hard-oxide durability - Ion-assisted sputtered coating survives heat, 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
- 633 nm HeNe laser emission pass - Blocks residual plasma lines below 633 nm while passing the laser fundamental and longer wavelengths.
- Cy5 & far-red fluorescence - Collects emission from deep-red fluorophores while blocking common excitation lines at 561/594 nm and below.
- LIDAR receiver filtering - Defines the red-NIR detection window for LIDAR systems, rejecting solar background and visible laser scatter.
- Astronomy H-alpha imaging - Passes the 656.3 nm H-alpha line with minimal blue-green sky background contamination.
- Fruit & food sorting - Isolates deep-red reflectance for ripeness and quality assessment in automated sorting lines.
KUPO Optics manufactures the R15 to your exact specifications - from 5 mm prototypes to 450 mm production blanks. Get in touch.
FAQ
R15 FAQ
What is R15 and what is it used for?
R15 is a 635 nm Longpass Filter. The R15 passes the deep red and near-infrared spectrum from 640 nm onward, with its 50 % cut-on measured at 635.9 nm. The passband averages above 94 % from 640 to 780 nm, peaking at 95.8 % near 734 nm. Common uses include 633 nm HeNe laser emission pass, Cy5 & far-red fluorescence, LIDAR receiver filtering, and Astronomy H-alpha imaging.
What are the key optical specs of R15?
Key published specs for R15 include Passband: 643 – 780 nm, 92.2 – 95.8 % T (± 1.8 % ripple); Cut-on (T50): ≈ 636 nm; Edge steepness: ~15 nm (10 → 90 % transition); Blocking: < 0.96 % T below 616 nm (OD ≥ 2); AOI: 0° (normal incidence); custom angles available.
What applications is R15 best suited for?
R15 is commonly used for 633 nm HeNe laser emission pass, Cy5 & far-red fluorescence, LIDAR receiver filtering, and Astronomy H-alpha imaging. 633 nm HeNe laser emission pass - Blocks residual plasma lines below 633 nm while passing the laser fundamental and longer wavelengths.
Can R15 be customized for size, substrate, or coating requirements?
KUPO lists the construction for R15 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 R15?
The published angle of incidence for R15 is 0° (normal incidence); custom angles available. The hard-oxide coating is built for repeated handling, heat, and cleaning.
