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  4. Neutral Density Filters
  5. Optical Crown Glass Metallic ND Filters
  6. FBR-ND04

ND Filter, Metallic, Optical Crown Glass, 25.4 mm, 0.4 OD at 632.8 nm

  • Size
    Ø25.4 mm
  • Wavelength Range
    400-1200 nm
  • Optical Density
    0.4
  • Optical Density Tolerance
    ±5% @ 632.8 nm
  • Transmission
    39.8% @ 632.8 nm
  • Angle of Incidence
    0°
  • Material
    B270 Optical Crown Glass or Equivalent
  • Damage Threshold
    30 W/cm2 CW, typical; not recommended for pulsed laser use
  • Size Tolerance
    +0/-0.50 mm
  • Thickness
    3.0 mm
  • Thickness Tolerance
    ±0.25 mm
  • Surface Flatness
    ≤5λ at 632.8 nm over the clear aperture
  • Surface Quality
    60-40 scratch-dig
  • Clear Aperture
    ≥central 80% of dimensions
  • Wedge
    ≤5 arc min
  • Chamfers
    0.25–0.76 mm face width
  • Chamfers Angle Tolerance
    45° ±15°
  • Durability
    MIL-C-48497A, adhesion, humidity, moderate abrasion, and solubility requirements
  • Cleaning
    See How to Clean Optics
Other