785nm notch filter precisely blocks near-infrared laser for Raman imaging optical lenses.

The 785 nm notch filter is a band-rejection filter that achieves deep blocking with an OD6 or higher cutoff around the center wavelength of 785 nm (typical stopband approximately 766–804 nm, bandwidth ≈39 nm), attenuating laser light in this band to <0.0001%, while maintaining high transmission of >93% in the 350–742 nm and 828–1600 nm bands. It employs an ultraviolet fused silica substrate and an interference design with over 108 dielectric layers, with a thickness of only 2 mm (3.5 mm with housing), surface quality 60-40, wavefront error <λ/4, and can withstand a laser damage threshold of 1 J/cm² (532 nm, 10 ns). It also features an arrow mark indicating the preferred orientation to suppress stray light.

Main Applications:

• Raman Spectroscopy: Blocks 785 nm excitation light while simultaneously collecting both Stokes and anti-Stokes low wavenumber signals, with a measurable range as low as 10 cm⁻¹.

• Fluorescence Imaging: Eliminates laser scattering to improve signal-to-noise ratio.

• Laser Protection: Selectively blocks near-infrared laser light while maintaining high transmission in the visible and longer wavelength bands.

• Multispectral Systems: Prevents source crosstalk and enables precise band imaging.

Common Specifications:

• Standard Sizes: Ø25 mm, Ø50 mm, thickness 2–5 mm.

• Stopband OD: Options from OD3 to OD6, customizable bandwidth of 15–50 nm.

• Passband Ripple: <±1%, cutoff transition <2 nm.

• Operating Temperature: -40 °C to +180 °C, with durable and humidity-resistant coatings.