Absorptive Neutral Density Filters

Newport's absorptive ND filters are precision polished, and offer uniform attenuation over lower power beams across the visible range at an economical price suitable for OEM integration.

Low cost ND filters ideal for OEM integration
Precision polished for demanding research applications
Broadband attenuation, visible to near IR
Absorptive neutral density glass
Permanently marked with optical density
For low power applications

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Description	Compatibility	Price
FR-OD05 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 0.04 OD at 546.1 nm	UNIVERSAL	$30
FR-OD100 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 1.0 OD at 546.1 nm	UNIVERSAL	$30
FR-OD20 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 0.2 OD at 546.1 nm	UNIVERSAL	$30
FR-OD200 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 2.0 OD at 546.1 nm	UNIVERSAL	$30
FR-OD300 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 3.0 OD at 546.1 nm	UNIVERSAL	$30
FR-OD40 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 0.4 OD at 546.1 nm	UNIVERSAL	$30
FR-OD60 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 0.6 OD at 546.1 nm	UNIVERSAL	$30
FR-OD80 Absorptive ND FiltersNeutral Density Filter, Absorptive, 12.7 mm, 0.8 OD at 546.1 nm	UNIVERSAL	$30
FSR-OD05 Absorptive ND FiltersNeutral Density Filter, Absorptive, 25.4 mm, 0.04 OD at 546.1 nm	UNIVERSAL	$40
FSR-OD10 Absorptive ND FiltersNeutral Density Filter, Absorptive, 25.4 mm, 0.1 OD at 546.1 nm	UNIVERSAL	$40

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Features

Absorptive Neutral Density Glass for Low Power Applications

These neutral density filters are made from absorptive glass. This results in a lower cost product that is somewhat less fragile compared to coated metallic ND filters. Absorptive ND filters also reflect far less light toward the source compared with metallic ND Filters, which may be beneficial. Nevertheless stacking a large number of ND filters can still result in excessive undesired reflection due to Fresnel surface reflection. Due to the absorptive nature of the filter glass, use with high power lasers should be avoided. Power levels 1-5 W/cm² are advised.

Spectrally Neutral for Visible Wavelengths

Absorptive glass ND filters are spectrally neutral over the visible spectral region. OD05 to OD40 optical densities are shown.

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.

Finely Control Beam Attenuation

Our absorptive ND filters are available individually or in a set of 9. Filters may be used individually, or combined in series, to obtain any desired density from 0.04 to 4.0. The Ø25.4 mm and 50.8 mm square sizes are permanently marked with the optical density.

Proper Orientation

To prevent unwanted interference from etalon effects, filters should be angled slightly with respect to the incident beam.

Neutral Density Filter Kit

The FS-3 Absorptive Neutral Density Filter Set includes nine 50.8 x 50.8 mm square absorptive neutral density filters The FS-3R Absorptive Neutral Density Filter Set is a set of nine 25.4 mm diameter absorptive neutral density filters. Both offer Optical Densities of OD 0.04, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0 and 3.0, which provide broadband attenuation for the visible to NIR region for power levels less than 30 W/cm². This unique assortment of filters permits easy selection of any desired density from 0 to 8 with 0.1 OD resolution by using individual filters or a combination of no more than two filters. The total filter set range is 0 to 8 OD.