Luminescence of bandpass dichroic filters within their transmission band can result in misinterpretation of experimental data

In this paper, we considered the autoluminescence of three IR bandpass dichroic filters, occurring in their transmission bands under excitation in visible, as a potential source of erroneous interpretation of experimental results. An interference filter with the transmission band centered at 1270 nm, used for the detection of singlet oxygen phosphorescence, and two other IR filters with the transmission bands centered at 1064 and 1047 nm were under study. All three filters were shown to emit noticeable luminescence within their transmission bands under excitation at 405, 440, 510, and 660 nm. The determined luminescence decay times varied from 0.1 to >20 μs and depended on the excitation wavelength. The results obtained suggest that this potential parasitic luminescence should be carefully taken into account in experiments with low-intensity luminescence signals because its underestimation can corrupt the interpretation of the experimental data.