Long-wave pass filters are newly available

UltraOpto New Product Launch | Longpass Filter, the Core of Spectral Selection with High Transmittance for Long Waves and Deep Cutoff for Short Waves

UltraOpto newly launches the Longpass Filter (LP Filter). As a core fundamental component for optical spectral regulation, it relies on the principle of multi-layer dielectric film interference to achieve precise spectral selection with high transmittance for long waves and deep cutoff for short waves. It features high cutoff steepness, excellent passband transmittance, and customizable cutoff depth. It can completely filter out short-wave stray light interference, efficiently retain long-wave effective signals, and significantly improve the signal-to-noise ratio of optical systems. It is an essential optical component in various fields such as fluorescence detection, machine vision, infrared imaging, and laser systems.

The product supports customized cutoff wavelengths in the full range of 200nm~1650nm, meeting the needs of ultraviolet, visible, and near-infrared full-wave bands; the peak transmittance of the passband can reach more than 95%, the cutoff steepness is <20nm, the maximum cutoff depth is OD6 and above, the cutoff wavelength tolerance is ±1%, and the in-chip deviation is ≤3nm. The spectral selection is precise and sharp, with fast switching from short-wave cutoff to long-wave high transmittance without crosstalk.

Substrates can be flexibly selected as needed. For conventional visible/near-infrared, N-BK7/H-K9L optical glass and B270 float glass are preferred; for ultraviolet/high-power laser scenarios, JGS1/UVFS fused silica can be customized; for the 8-14μm infrared band, special substrates such as silicon, germanium, and zinc selenide are available; sapphire substrates can meet high-temperature resistance and high-end requirements. The size ranges from 2mm×2mm to 100mm×100mm, with circular, square, special-shaped/bar-shaped options available for customization. The thickness can be adjusted from 0.55mm to 6mm, and personalized processes such as drilling and plating positioning marks are supported, adapting to various optical path integration and installation.

It adopts ion beam sputtering/electron beam evaporation + ion-assisted deposition ultra-precision coating technology, alternately depositing high and low refractive index dielectric film layers. The film layers have high density and strong adhesion. For high-power scenarios, laser damage-resistant film systems can be customized, with a laser damage threshold of >5J/cm²@1064nm; the light-transmitting surface is coated with a broadband anti-reflection film, with an average single-sided reflectivity of ≤0.5%, and the edge is coated with a blackened film to suppress stray light. The processing accuracy is strictly controlled throughout the entire process, with an effective light-transmitting aperture of ≥90%, surface quality reaching the high standard of 40/20 MIL. After coating, annealing is performed to eliminate stress, and the film uniformity deviation in mass production is ≤±1%, with excellent consistency.

Before leaving the factory, it undergoes comprehensive testing with ultraviolet-visible-near-infrared spectrophotometers and optical density testers, and passes rigorous tests such as high and low temperature cycles (-40℃~+85℃), constant humidity and heat, film adhesion, and abrasion resistance. The optical performance does not drift under temperature changes, humidity, and slight friction, the film layer does not fall off or get scratched, and the transmittance change rate is ≤1%, adapting to long-term continuous industrial-grade work. It is widely used in various scenarios such as biomedical fluorescence detection, machine vision/industrial defect detection, infrared imaging/night vision systems, laser/cosmetic instruments, optical communication/near-infrared spectral analysis. Mainstream specifications are available in stock, and the cutoff wavelength, substrate, size, and cutoff depth can be customized non-standard. Small-batch sampling is supported, with stable delivery time, providing high-reliability and high-precision long-wave spectral selection solutions for various optical systems.