Neutral Density Filters
Reflective Neutral Density (ND) Filters
Neutral Density filters or ND filters provide a linear spectral transmission across the visible region. They control light intensity without selectively absorbing energies at specific wavelengths. They are, therefore, generally used to attenuate the intensity of a beam of light over a broad spectral region. This property is often required to prevent saturation or damage to a wide variety of detectors and even the human eye.
Reflective ND filters are available in optical density of 0.3, 0.5, 0.6, 0.9, 1.0, 1.3, 1.5, 2.0, 2.5 and 3.0. Stack several ND filters together, and the total density is the sum of the density of each filter in the stack, permitting the creation of neutral density filters with custom optical densities.