UV Fused Silica Metallic Neutral Density Filters

Our metallic neutral density coatings provide broadband attenuation for lower power applications. The precision polished UV fused silica substrate, the filters may be used anywhere from 350 to 2000 nm.

Broadband attenuation from 350-2000 nm
Metallic neutral density coating
Low wavefront distortion
UV grade fused silica
For lower power applications
Available in convenient kits

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Description	Compatibility	Size	Optical Density	Optical Density Tolerance	Avail.	Price
FRQ-ND003Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.03 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.03	±2.5% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$46
FRQ-ND01Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.1 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.1	±8% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$73
FRQ-ND02Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.2 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.2	±7% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$73
FRQ-ND03Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.3 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.3	±6% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$73
FRQ-ND04Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.4 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.4	±5% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$73
FRQ-ND05Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.5 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.5	±4% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$73
FRQ-ND06Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.6 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.6	±4% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$81
FRQ-ND07Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.7 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.7	±4% @ 632.8 nm	FREE 2-day shipping on thousands of products on Newport.com Learn More	$81
FRQ-ND08Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.8 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.8	±4% @ 632.8 nm		$81
FRQ-ND09Metallic ND Filter, UV Fused Silica, 25.4 mm, 0.9 OD at 632.8 nm	UNIVERSAL	Ø25.4 mm	0.9	±4% @ 632.8 nm		$81

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Specifications

Wavelength Range
350 - 2000 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
Thickness
3.0 mm
Thickness Tolerance
±0.25 mm
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

Features

Finely Control Beam Attenuation

Typical curve. Actual transmission may vary.

These filters are available individually or in a set of eight. The set consists of a logical assortment of filters packaged in a protective hardwood case. All filters are permanently marked with the optical density and are shipped with a transmission curve. Filters from this product family may be used individually, or combined in series, to obtain any desired density from 0 to 7 in steps of 0.1 OD.

Metallic Coating Properties

Due to the absorptive nature of the metallic coating, use with high-power lasers should be avoided. Power levels less than 30 W/cm² are advised.

For additional attenuators, see Laser Beam Attenuators

Additive Optical Densities

Optical density (OD) is given by the relationship: OD = -log(T) or T = 10^(-OD) where T is transmittance (0≤T≤1). Optical Density, unlike transmittance, is additive. When multiple filters are stacked, the total density is easily found by adding up the densities of each filter in the series. For example to achieve desired transmittance of 8%, first calculate the equivalent density (OD = -log(0.08) = 1.097 ≅ 1.1), then find a combination of filters that adds to the desired number, such as a combination of an OD1 filter and an OD0.1 filter.

UV Fused Silica Substrate

The coating is deposited on one side of an ultra-pure UV grade fused silica substrate providing excellent transmission from the ultraviolet to the near-infrared (350-2000nm). These precision polished substrates have flatness less than 1λ–2λ, resulting in low wavefront distortion for the transmitted beam. The polished second surface is uncoated.

Proper Orientation

To prevent unwanted interference from etalon effects, filters should be angled slightly with respect to the incident beam. To minimize back reflections, the filter should be oriented with the coated metallic surface facing the incident beam. Any light reflected from the uncoated second surface will pass through the metallic coating first, which will greatly attenuate unwanted back reflections.

Neutral Density Filter Kits

The FR-ND UV Fused Silica Metallic Neutral Density Filter Set includes eight, 25.4 mm diameter, UV Fused Silica Metallic ND Filters. The FS-ND UV Fused Silica Metallic Neutral Density Filter Set includes eight, 50.8 x 50.8 mm square, UV Fused Silica Metallic ND Filters. Each kit includes optical densities of 0.03, 0.1, 0.3, 0.5, 1.0, 2.0 and 3.0. 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 NIR. Filter kits provide convenience and cost savings.