H-K9L Reflective ND Filter, 50.0 × 50.0 mm, OD 0.1

Overview

Reflective neutral density filters use high-quality K9 (BK7-equivalent) optical glass coated with a precisely controlled metallic reflective film (e.g. protected silver or aluminum). Attenuation is achieved primarily by reflection rather than bulk absorption, so absorbed energy is minimal — greatly reducing heating and thermal-lensing and yielding a higher laser-induced damage threshold. This makes them especially suitable for CW, high-power, and ultrafast laser systems. The broadband metallic coating (400–1100 nm) provides flat spectral attenuation across the visible to near-infrared.

Applications

• CW & high-power laser attenuation
• Ultrafast laser power balancing
• Energy calibration & beam sampling
• Detector protection

Construction & Performance

• Substrate: H-K9L (BK7-equivalent)
• Coating: Metallic Coating (HR@400-1100 nm)
• Dimensions: 50.0 × 50.0 mm
• Thickness: 2.0 mm
• Spectral range: 400–1100 nm
• OD: 0.1
• Clear aperture: >90%
• Parallelism: 5 arcmin
• Surface quality: 80-50
• Surface flatness: λ/2 @ 633 nm

Storage & Handling

For optimal performance, store and use at 25 °C and 40–60% relative humidity. If the surface becomes contaminated, clean gently with ≥99% alcohol and lint-free lens tissue; never use coarse cloth, water, or abrasive cleaners, which may damage the optic.