R2918 Longpass Filter
Isolate pure red light with exceptional edge steepness and broad passband transmission flatness.
- Passband: 614 – 780 nm, 91.1 – 95.4 % T (± 2.2 % ripple)
- Cut-on (T50): ≈ 605 nm
- Edge steepness: ~18 nm (10 → 90 % transition)
- Blocking: < 0.92 % T below 584 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
R2918 Hybrid delivers Passband 614 – 780 nm, 91.1 – 95.4 % T (± 2.2 % ripple), Cut-on (T50) ≈ 605 nm, and Edge steepness ~18 nm (10 → 90 % transition).
The hard-oxide coating is built for repeated handling, heat, and cleaning.
Best suited for:
Red LED and laser systems, mCherry and Cy5 fluorescence, deep color separation, infrared camera pre-filtering, and red-channel imaging in multiplexed detection arrays.
Description
The R2918 passes the red and near-infrared spectrum with its 50 % cut-on at 604.7 nm. Transmission averages above 94 % from 610 to 780 nm, peaking at 95.4 % near 692 nm. The blocking floor is exceptionally deep at 0.2 % average from 380 to 593 nm, providing OD 2.7+ rejection of the entire visible spectrum from UV through yellow-orange. This filter sits between the 600 nm and 615 nm longpass models, offering a precise cut-on for red-channel applications.
Key Advantages
- 605 nm cut-on for precise red pass - T50 % at 604.7 nm offers a red-onset position between the O16412 (599 nm) and R2613 (614 nm).
- Ultra-deep 0.2 % blocking - OD 2.7+ rejection from 380 to 593 nm, matching the deepest blocking in the series.
- 95.4 % peak with > 94 % average - Flat, high-throughput passband across 170 nm of red-to-NIR bandwidth.
- Hard-oxide durability - Ion-assisted sputtered coating withstands thermal cycling, humidity, and aggressive 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
- Red fluorophore collection - Passes Texas Red, mCherry, and tdTomato emission while blocking 561/594 nm excitation lines.
- Machine vision red-channel - Defines a pure red-NIR detection window for inspection systems using 610+ nm illumination.
- Solar red-NIR analysis - Isolates the red and NIR portion of the solar spectrum for photovoltaic performance characterization.
- Medical diagnostic imaging - Passes the red-NIR tissue transparency window for pulse oximetry and spectroscopic analysis.
- Stage & event lighting - Produces deep red and NIR washes with absolutely no orange, yellow, or blue contamination.
Need the R2918 in a specific size or substrate? KUPO Optics provides rapid prototyping and production-scale manufacturing.
FAQ
R2918 FAQ
What is R2918 and what is it used for?
R2918 is a 606 nm Longpass Filter. The R2918 passes the red and near-infrared spectrum with its 50 % cut-on at 604.7 nm. Transmission averages above 94 % from 610 to 780 nm, peaking at 95.4 % near 692 nm. Common uses include Red fluorophore collection, Machine vision red-channel, Solar red-NIR analysis, and Medical diagnostic imaging.
What are the key optical specs of R2918?
Key published specs for R2918 include Passband: 614 – 780 nm, 91.1 – 95.4 % T (± 2.2 % ripple); Cut-on (T50): ≈ 605 nm; Edge steepness: ~18 nm (10 → 90 % transition); Blocking: < 0.92 % T below 584 nm (OD ≥ 2); AOI: 0° (normal incidence); custom angles available.
What applications is R2918 best suited for?
R2918 is commonly used for Red fluorophore collection, Machine vision red-channel, Solar red-NIR analysis, and Medical diagnostic imaging. Red fluorophore collection - Passes Texas Red, mCherry, and tdTomato emission while blocking 561/594 nm excitation lines.
Can R2918 be customized for size, substrate, or coating requirements?
KUPO lists the construction for R2918 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 R2918?
The published angle of incidence for R2918 is 0° (normal incidence); custom angles available. The hard-oxide coating is built for repeated handling, heat, and cleaning.
