ND Filter, Metallic, Optical Crown Glass, 50.8 x 50.8 mm, 2.5 OD

The FBS-ND25 Metallic Neutral Density Filter is a 50.8 x 50.8 mm square Optical Crown Glass Metallic ND Filter with an optical density of 2.5 at 632.8 nm. Our metallic neutral density coatings provide broadband attenuation for low power applications. The coating is deposited on one side of a cost effective B 270 optical glass substrate, providing excellent performance in the visible and near-infrared.

Specifications

Technical Specs

Size
50.8 x 50.8 mm
Wavelength Range
400-1200 nm
Optical Density
2.5
Optical Density Tolerance
±4% @ 632.8 nm
Transmission
0.3% @ 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

Size
50.8 x 50.8 mm
Wavelength Range
400-1200 nm
Optical Density
2.5
Optical Density Tolerance
±4% @ 632.8 nm
Transmission
0.3% @ 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

Resources & Downloads

2D Product Drawings

NEUTRALD-20S.pdf(59.9 kB, PDF)

Other

FBS-ND25 RoHS Certificate(264.7 kB, PDF)
FBS-ND25_ROHS2-2021.pdf(280.2 kB, PDF)

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