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400nm UV Shortpass Filter
400nm UV Shortpass Filter is an optical filter designed to transmit the light of UV and near UV. Coligh manufactures UV VIS IR shortpass filters.
It has features below:
- High transmission in UAV
- Deep blocking depth from VIS to NIR
- Hard coating
- Substrate Fused Silica JGS1
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UV Shortpass Optical Filter with 400nm Cut-Off Wavelength Description
The 400nm UV Shortpass Filter is an interference optical filter specifically designed to efficiently transmit ultraviolet light (UV-A and near UV) with wavelengths below 400nm, while blocking visible and infrared light with wavelengths above 400nm. It is commonly used to separate UV signals from visible/infrared background, improving the signal-to-noise ratio in imaging and detection systems.
- It achieves an average transmission of ≥92% in the core UV band of 340–400nm, ensuring efficient throughput of weak UV signals.
- With a design of over 40 layers of dielectric interference coatings, it achieves transmission less than 0.1% (T < 0.1%) in the visible to near-infrared range (620–1100nm), effectively eliminating environmental light interference.
- We use JGS1 fused silica as the substrate, suitable for deep UV below 300nm, with a very low thermal expansion coefficient.
- The multilayer dielectric coating is applied by ion-assisted deposition, providing strong durability of the coating layers.
400nm UV Shortpass Filter Technical Datasheet
| Parameter | Specification |
| Cut‑off Wavelength (50% T) | Around 400nm |
| High‑Transmission Band | 340-400nm@Tave>=92% |
| Blocking Region | 620-1100nm |
| Optical Density (OD) | OD >3 (T <0.1 1%) |
| Substrate Materials | Fused Silica JGS1 or White glass |
| Coating Type | Hard first‑surface all‑dielectric |
| Surface Quality | 80-50, 60‑40, 40-20 scratch‑dig (MIL‑PRF‑13830B) |
| Clear Aperture | ≥ 90% of full aperture |
| Available Diameters | Ø25 mm, Ø25mm,Ø32mm, Ø50mm, or custom |
| Thickness | 4.0mm or 1.0mm or custom |
400nm UV Shortpass Filter Applications
- Laser Processing Quality Diagnosis
Plasma emissions during welding contain characteristic spectral lines in the 300–390nm range, but scattered 1064nm pump laser light and thermal radiation from the metal can obscure key signals. The 400nm UV shortpass filter can transmit ultraviolet plasma flashes while blocking thermal noise and pump light above 420nm, improving real-time defect detection rates. - Astronomical Ultraviolet Observation
Extraterrestrial objects emit characteristic spectral lines in the 280–400nm range, but ground-based observation is severely contaminated by atmospheric scattered light above 400nm. The 400nm UV Shortpass Filter can be integrated into the focal plane filter wheel of telescopes to transmit target UV spectra while suppressing sky background light above 420nm. - UV Curing Process Monitoring
Mercury lamps emit effective curing UV light at 365nm and 395nm, but visible and infrared radiation above 400nm can cause substrate overheating and deformation, and do not reflect true curing intensity. The 400nm UV Shortpass Filter transmits curing UV light in the 300–390nm range while blocking ineffective radiation above 420nm, enabling real-time UV intensity feedback to control systems. - Forensic Evidence Detection
Biological traces fluoresce at 450nm under 365nm excitation, but ambient light above 400nm at the scene may obscure weak signals. The 400nm UV Shortpass Filter, integrated into multispectral imaging light sources, allows 365nm excitation light to illuminate evidence. On the camera end, a 400nm filter blocks ambient light to enhance detection contrast.
