Narrow bandpass filters are precision optical components designed to transmit a very narrow wavelength range while effectively blocking all other wavelengths. They are essential in applications where spectral purity and signal accuracy are critical, including laser systems, spectroscopy, optical communication, and scientific instrumentation.
SOT narrow bandpass filters combine high transmittance, deep blocking, and low temperature sensitivity, ensuring consistent performance even in demanding environments. A broad selection of standard wavelengths from UV to IR is available, with extensive customization to meet specific system requirements.
Key Features
- High Transmission Efficiency – Up to ≥90% transmission at the passband
- Strong Out-of-Band Blocking – OD ≥ 3 for excellent stray-light suppression
- Low Temperature Shift – Stable spectral performance across wide temperature ranges
- High Precision Bandwidths – Narrow FWHM for accurate wavelength selection
- Fully Customizable – CWL, FWHM, OD, and substrate options available
Spectrum Transmission
Standard models provide narrow passbands with steep spectral edges for precise wavelength isolation. If standard offerings do not meet your needs, custom spectral designs can be developed based on your target wavelength, bandwidth, and blocking requirements.
Coating Quality & Environmental Reliability
All narrow bandpass filters are tested according to strict military and industrial standards:
- Adhesion Test (MIL-C-675C) – No blistering or peeling after repeated tape removal
- Thermal Cycling – −62 °C to +71 °C with no coating detachment
- Abrasion Resistance (MIL-C-675C / CCC-C-440) – No surface damage after 25 cycles at 1.0 lb load
- Humidity Resistance – 95–100% RH at 49 °C for 24 h without defects
- Solvent Resistance – Stable after acetone and alcohol exposure
- Salt Spray Test – 100 h at 35 °C, 5% salt concentration with no degradation
Standard Specifications
| Model | CWL (nm) | Transmittance | FWHM (nm) | Optical Density | Notes |
|---|---|---|---|---|---|
| NH-BP250 | 250 ±5 | ≥70% | 10–20 | OD ≥3 @ 300–400 | Standard |
| NH-BP315 | 315 ±2 | ≥70% | 10–20 | OD ≥3 @ 300–400 | Customizable |
| NH-BP375 | 375 ±2 | ≥90% | 10–20 | OD ≥3 @ 300–1100 | High precision |
| NH-BP405 | 405 ±2 | ≥90% | 10–20 | OD ≥3 @ 350–1100 | Common wavelength |
| NH-BP532 | 532 ±3 | ≥90% | 10–20 | OD ≥3 @ 350–1100 | Laser optics |
| NH-BP650 | 650 ±3 | ≥90% | 10–20 | OD ≥3 @ 350–1100 | Imaging |
| NH-BP850 | 850 ±3 | ≥90% | 10–20 | OD ≥3 @ 350–1100 | NIR |
| NH-BP940 | 940 ±3 | ≥90% | 10–20 | OD ≥3 @ 350–1100 | IR sensing |
| NH-BP1680 | 1680 ±10 | ≥90% | 10–20 | OD ≥3 @ 800–3000 | IR |
| NH-BP2500 | 2500 ±2 | ≥90% | 10–20 | OD ≥3 @ 800–3000 | IR |
Additional wavelengths and bandwidths available upon request.
Typical Applications
- Laser Systems – Spectral purification and wavelength isolation
- Spectroscopy – Accurate spectral line selection
- Industrial & Scientific Research – Precision optical measurements
- Astronomical Imaging – Reject light pollution and isolate emission lines
- Optical Communication – Channel selection and noise reduction