Thorlabs Continuously Variable ND Filter NDL-25C-4

Thorlabs Rectangular Continuously variable, Reflective (Metallic) ND Filters are ideal for mounting on a transition stage for use as a variable attenuator. Two different versions are offered in both the 10 mm and 25 mm height size that go from 0.04 (uncoated material) to 2.0, or ...Thorlabs Rectangular Continuously variable, Reflective (Metallic) ND Filters are ideal for mounting on a transition stage for use as a variable attenuator. Two different versions are offered in both the 10 mm and 25 mm height size that go from 0.04 (uncoated material) to 2.0, or from 0.04 to 4.0 optical density.

Our rectangular step variable ND filters have a UV Fused Silica glass substrate and are mental (Inconel) coated. The Inconel film is a very hard metallic alloy that is resistant to aging under normal conditions. The Inconel coating will oxidize at elevated temperatures; it is recommended that the Neutral Density filters be used at temperatures below 100° C.

The use of an Inconel coating ensures that the spectral response of these ND filters is very flat from the UV out to the Mid-IR.