• Beamsplitter Coating on Front Surface: 700 - 1100 nm
• AR Coating on Back Surface: 700 - 1100 nm
• UV Fused Silica Substrate
• 30 arcmin Wedged Back Surface to Minimize Ghosting

This Ø1" Thorlabs' UV Fused Silica Broadband Beamsplitter for NIR light provide a split ratio of 70:30 when used with light incident at 45°. A dielectric coating is used for long-term stability. This plate beamsplitter utilizes a UV-grade fused silica substrate, which offers high transmission deep into the UV (down to 185 nm), good homogeneity, and a lower coefficient of thermal expansion than N-BK7. In addition, UV fused silica exhibits virtually no laser-induced fluorescence (as measured at 193 nm), making it an ideal choice for applications from the UV to the near IR.

To help reduce unwanted interference effects caused by the interaction of light reflected from the front and back surfaces of the optic, two features have been added to this round broadband plate beamsplitter. First, an antireflection coating, which is designed for the same operating wavelength range as the beamsplitter coating on the front surface, has been deposited onto the back surface. Approximately 4% of the light incident at 45° on an uncoated substrate will be reflected; by applying an AR coating to the back side of the beamsplitter, this percentage is reduced to an average of less than 1% over the entire operating range of the coating. Second, the back surface of the round beamsplitter has a 30 arcmin wedge; therefore the fraction of light that does get reflected from this AR-coated surface will diverge. The edge of the round plate beamsplitter is engraved with the item number and an arrow pointing to the AR-coated surface indicating the direction of light propagation.

• Split Ratio (T:R): 70:30
• Diameter: 1"
• Diameter Tolerance: +0.0 mm / -0.2 mm
• Thickness: 5 mm
• Center Thickness Tolerance: ±0.4 mm
• Substrate: UV Fused Silica
• Damage Threshold: N/A
• Coating on Surface 1: 700 - 1100 nm Beamsplitter Coating for 45° Incidence
• Coating on Surface 2: Broadband AR Coating for 700 - 1100 nm (R_avg < 1% within Wavelength Range)
• Wedge Angle: 30 arcmin
• Clear Aperture: >90% of Central Diameter
• Surface Flatness: ?/10 @ 635 nm Over the Clear Aperture
• Splitter Ratio Tolerance: ±8%
• Polarization Relationship: |Ts-Tp| < 35% and |Rs-Rp| < 35%
• Surface Quality: 20-10 (Scratch/Dig)
• Durability: MIL-M-13508C, MIL-C-675C, MIL-C-14806