Absorptive ND Filter, Ø25.4 mm, OD 0.8

Overview

Absorptive neutral density filters use neutral absorbing glass (NG-series colored glass) as the substrate, achieving uniform attenuation through broadband bulk absorption with nearly wavelength-independent behavior across the visible range — reducing intensity while preserving the original spectral shape. Simple, stable, and cost-effective, they are often paired with a double-sided AR coating to lower surface reflection and raise effective transmission. Widely used for imaging brightness control, optical measurement, detector protection, and laboratory intensity adjustment.

Applications

• Broadband beam attenuation
• Laser power / intensity control
• Imaging & detector protection
• Optical measurement & illumination control

Construction & Performance

• Substrate: Neutral Absorbing Glass
• Coating: Uncoated
• Dimensions: Ø25.4 mm
• Thickness: 2.0 mm
• Spectral range: 400–700 nm
• OD: 0.8
• 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.