Long pass filters are precision optical components that transmit wavelengths longer than a defined cut-on point while blocking shorter wavelengths. Designed for demanding scientific and industrial use, these filters deliver high transmission, steep spectral edges, and robust environmental stability.
SOT long pass filters are widely used in biomedical imaging, fingerprint recognition, color measurement, and environmental monitoring, where accurate wavelength selection is essential. Standard models cover common VIS–NIR ranges, and custom designs are available to meet specific spectral and mechanical requirements.
Key Features
- High Transmission – Excellent throughput above the cut-on wavelength with minimal loss
- Broad Wavelength Coverage – Standard cut-on options from 335 nm to 1600 nm
- Customizable Specifications – OD level, cut-on wavelength, and passband tailored to your needs
- High Durability – Qualified to adhesion, abrasion, and environmental standards
- Versatile Applications – Biomedical imaging, digital imaging, biometrics, and environmental sensing
Spectrum Transmission
Standard transmission curves provide high passband transmission with strong out-of-band blocking. If a standard model does not meet your system needs, custom spectral designs can be produced for specific cut-on wavelengths, bandwidths, and OD targets.
Coating Quality & Environmental Reliability
All long pass filters are tested to stringent standards:
- Adhesion (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 with no defects
- Solvent Resistance – Stable after acetone and alcohol exposure
- Salt Spray – 100 h at 35 °C, 5% salt concentration with no degradation
Standard Specifications
| Model | Cut-on Wavelength (nm) | Transmittance | Wavelength Range (nm) | Optical Density |
|---|---|---|---|---|
| NH-LP335 | 335 ± 5 | T ≥ 90% | 340–500 | OD ≥ 3 @ 200–320 |
| NH-LP400 | 400 ± 5 | T ≥ 90% | 410–1100 | OD ≥ 3 @ 350–380 |
| NH-LP410 | 410 ± 5 | T ≥ 90% | 420–1100 | OD ≥ 3 @ 350–390 |
| NH-LP420 | 420 ± 5 | T ≥ 90% | 430–1100 | OD ≥ 3 @ 350–410 |
Additional models and custom specifications are available upon request.
Typical Applications
- Biomedical Imaging – Suppress background light to enhance diagnostic contrast
- Fingerprint Recognition & Biometrics – Improve feature-to-background contrast
- Digital Imaging & Color Measurement – Accurate color separation and imaging fidelity
- Environmental Monitoring – Selective wavelength filtering for sensing applications