Compare Model Drawings, CAD & Specs Size Optical Density Availability Price
Ø100.0 mm 0 - 1
Ø100.0 mm 0 - 2
Ø100.0 mm 0 - 4
Ø25.0 mm 0 - 1
Ø25.0 mm 0 - 2
Ø25.0 mm 0 - 4
Ø50.0 mm 0 - 1
Ø50.0 mm 0 - 2
Ø50.0 mm 0 - 4


  • Wavelength Range
    250-2500 nm
  • Material
    UV grade fused silica
  • Size Tolerance
    +0/-0.3 mm
  • Thickness
    2.0 mm
  • Thickness Tolerance
    ±0.25 mm
  • Surface Flatness
  • Surface Quality
    80-50 scratch-dig
  • Wedge
    ≤ 20 arc sec
  • Chamfers
    0.2-0.3 mm face width
  • Chamfers Angle Tolerance
    45° ±15°
  • Durability
    Metalized area MIL-M-13508C, AR coated area MIL-C-675, moderate abrasion
  • Inside Diameter
    7.5 mm
  • Cleaning


Finely Control Beam Attenuation

These variable neutral density filters allow convenient adjustment of beam attenuation by simply rotating the filter. Optical density varies linearly with rotation angle across a 270° range from 0 up to the chosen maximum of OD1, OD2, or OD4. An arbitrary transmitted beam power may then be obtained easily using the angular markings to rotating the variable ND filter to the specific corresponding angle. Due to this linearity in density, the rotation may even be motorized to produce a precise logarithmic sweep in the transmitted beam power.

Wide Wavelength Range

Fused silica substrate for these ND filters allows the transparency from 250-2500 nm range.

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.

Filter Mounting

We offer a variety of rotary mounts for the variable neutral density filter. Please check out the accessories section below for recommendations. Shown is model FR-CV-75 compact circular variable ND filter mount.

Model FR-CV-75 Circular Variable Neutral Density Filter/Beamsplitter Mount.