High levels of excitation light intensity (such as that transmitted by Chroma ET-series excitation filters) could, under some circumstances, lead to rapid photobleaching or phototoxic damage to the sample, and/or high levels of autofluorescent signal.

The use of neutral density (ND) filters in the excitation light path may be required to minimize these effects. Furthermore, the use of a range of multiple ND filters can allow for application- or sample-specific customization of excitation light intensities to maximize signal-to-noise.

See the 22000 Series.