The circular gradient neutral density filter provides linear attenuation of transmitted light through absorption and reflection, effective from the visible to near-infrared spectral range. The optical density changes linearly within a 0°–270° sector. By rotating the filter, the attenuation level can be easily adjusted. This filter can also function as a variable beam splitter. All other regions of the filter are coated with a broadband anti-reflection coating for the visible range to reduce light loss and suppress ghosting. The Ni-Cr-Fe coating serves as the attenuating layer; however, due to the absorptive nature of the metal film, the filter is not suitable for high-power laser applications.
Constructed with high-quality H-K9 optical glass substrate, the circular gradient neutral density filter meets general laboratory requirements. It performs optimally in the 450–700 nm wavelength range and may exhibit slight light loss when used across the broader 400–1100 nm range.
The relationship between optical density (OD) and transmittance (T) is given by: T% = 10^(-OD) × 100, or OD = log₁₀(1 / T)
The circular adjustable neutral density filter is mounted on a holder with a rotating axis, allowing 360° rotation with angle markings in 2° increments. The filter uses a circular element made of high-quality H-K9L optical glass, with one side coated with a NiCrFe broadband attenuating metal film. This reflective and partially absorptive coating enables linear attenuation of transmitted light across a 0–270° rotation range, effective from the visible to near-infrared region. Due to the absorptive nature of the metal coating, the filter is not suitable for high-power laser applications. The base of each filter mount features an M6 threaded hole, compatible with Ø12.7 mm post assemblies.
360° rotatable with 2° minimum graduation
Optical material: H-K9L
Coating: One side coated with NiCrFe broadband attenuating metal film, reflective with partial absorption
M6 threaded hole at the base, compatible with Ø12.7 mm post systems
