Introduction: | Metallized Reflective ND Filter is made of UV fused silica substrates, with very thin aluminum coating + protection layer, or Nickel coating deposited on single surface. The filter allows broadband light 200-2500nm designed to pass as specified transmission ratio, others will be reflected. Typical transmission ratios are T50:R50 and T70:R30 for protected-aluminum reflection ND filter, and T25%(OD0.6),T10%(OD1),T1%(OD2) and T0.1%(OD3) for nickel-coated reflective ND filter.
The UV fused silica substrate used in these filters exhibits high transmission and virtually no laser-induced fluorescence, as measured at 193 nm, making it an ideal choice for applications from the UV to the near IR. While the spectral range's lower limit of 200 nm is limited by the absorption of the light by the substrate, UV fused silica provides good transmission up to 2.1 µm, and thus the upper limit of 1200 nm is dependent on the increased opacity of the nickel coating. |