UV Fused Silica Metallic Neutral Density Filters
  • Broadband attenuation, UV to near IR
  • Metallic neutral density coating
  • Low wavefront distortion
  • UV grade fused silica
  • For lower power applications
  • Custom sizes and densities available upon request

Product Description

Metallic neutral density filters 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 ultraviolet to the near-infrared. The substrates for these filters are precision polished to a flatness ≤2 lambda. The second polished side is uncoated.

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.

Our assortment of filters permits easy creation of any desired density from 0 to 8 with 0.1 OD resolution by using individual filters or combinations of filters. When creating custom densities by stacking filters, consideration must be given to surface reflections.

Optical density (OD) is defined by the relationship:
OD = -log(T) or T = 10-OD

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.

To discuss your specific requirements, please call 508-528-4411 to speak directly to one of our Technical Sales Engineers, or email us at filters.sales@newport.com.

Ordering Information

at 632.8 nm
in Filter
Model 25.4 mm
Model 50.8 x
50.8 mm
0.263.10% FRQ-ND02FSQ-ND02
0.439.80% FRQ-ND04FSQ-ND04
0.625.10% FRQ-ND06FSQ-ND06
0.720.00% FRQ-ND07FSQ-ND07
0.815.80% FRQ-ND08FSQ-ND08
0.912.60% FRQ-ND09FSQ-ND09
1.53.20% FRQ-ND15FSQ-ND15
2.50.30% FRQ-ND25FSQ-ND25
4.00.01% FRQ-ND40FSQ-ND40
Set of Metallic Neutral Density FiltersFR-NDFS-ND


MaterialUV grade fused silica
Surface Flatness - 25.4 mm Round≤1 lambda at 632.8 nm over the clear aperture
Surface Flatness - 50.8 mm Square≤2 lambda at 632.8 nm over the clear aperture
Clear Aperture≥central 80% of dimensions
Surface QualityE/E (60-40) per MIL-F-48616
Dimensions±0.25 mm
Thickness3.0 ±0.25 mm
Wedge≤3 arc min
Chamfers0.25–0.76 mm face width x 45° ±15°
Angle of Incidence
Optical Density at 632.8 nm0.03 ±2.5%, 0.1 ±8%, 0.2 ±7%, 0.3 ±6%, 0.4 ±5%, and ±4% for 0.5 to 4.0 OD
DurabilityMIL-C-48497A, adhesion, humidity, moderate abrasion, and solubility requirements
CleaningNon-abrasive method, acetone or isopropyl alcohol on lens tissue recommended
Laser Damage Threshold30 W/cm2 CW, typical; not recommended for pulsed laser use