Metallic ND Filter, UV Fused Silica, 25.4 mm, 2.5 OD at 632.8 nm

The FRQ-ND25 UV Fused Silica Metallic Neutral Density Filter is a 25.4 mm diameter UV Fused Silica Metallic ND Filter with an optical density of 2.5 at 632.8 nm. Our metallic neutral density coatings provide broadband attenuation for lower power applications. The coating is deposited on one side of an ultra-pure UV grade fused silica substrate providing excellent transmission from the UV to near-infrared. All filters are permanently marked with the optical density.

Specifications

Technical Specs

Size
Ø25.4 mm
Wavelength Range
350 - 2000 nm
Optical Density
2.5
Optical Density Tolerance
±4% @ 632.8 nm
Transmission
0.3% @ 632.8 nm
Angle of Incidence
0°
Material
UV grade fused silica or equivalent
Damage Threshold
30 W/cm² CW, typical; not recommended for pulsed laser use
Size Tolerance
±0.25 mm
Thickness
3.0 mm
Thickness Tolerance
±0.25 mm

Surface Flatness
≤1λ at 632.8 nm over the clear aperture
Surface Quality
60-40 scratch-dig
Clear Aperture
≥central 80% of dimensions
Wedge
≤3 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
Ø25.4 mm
Wavelength Range
350 - 2000 nm
Optical Density
2.5
Optical Density Tolerance
±4% @ 632.8 nm
Transmission
0.3% @ 632.8 nm
Angle of Incidence
0°
Material
UV grade fused silica or equivalent
Damage Threshold
30 W/cm² CW, typical; not recommended for pulsed laser use
Size Tolerance
±0.25 mm
Thickness
3.0 mm
Thickness Tolerance
±0.25 mm

Surface Flatness
≤1λ at 632.8 nm over the clear aperture
Surface Quality
60-40 scratch-dig
Clear Aperture
≥central 80% of dimensions
Wedge
≤3 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

Drawings And Cad

FBR-NDXX-S(62 kB, PDF)

Other

FRQ-ND25 RoHS Certificate(264.7 kB, PDF)
FRQ-ND25_ROHS2-2021.pdf(280.5 kB, PDF)

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Compatible

Description	Compatibility	Price
FH-1ROptical Filter Mount, Stackable, 1.0 in. Diameter Optics	UNIVERSAL	$42
U100-A3KMirror Mount, ULTIMA^®, Clear Edge, 1.0 in., 3 Locking Knobs	UNIVERSAL	$181
FH-1SOptical Filter Holder, Drop-in, 25.4 mm Optics	UNIVERSAL	$87

Frequently Purchased Together

Description	Compatibility	Price
FRQ-ND20Metallic ND Filter, UV Fused Silica, 25.4 mm, 2.0 OD at 632.8 nm	UNIVERSAL	$71
FRQ-ND30Metallic ND Filter, UV Fused Silica, 25.4 mm, 3.0 OD at 632.8 nm	UNIVERSAL	$71
FRQ-ND10Metallic ND Filter, UV Fused Silica, 25.4 mm, 1.0 OD at 632.8 nm	UNIVERSAL	$71
FRQ-ND15Metallic ND Filter, UV Fused Silica, 25.4 mm, 1.5 OD at 632.8 nm	UNIVERSAL	$71