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. 2021 Nov 18;12:769586. doi: 10.3389/fphys.2021.769586

Table 1.

Values in this table indicate the approximate irradiance required from different light sources at the sample to image Ca2+ or activate ChR2.

Light sources Wavelength (typical) (nm) Illumination optics (typical) Irradiance
Light emitting diodes/ Xe lamps 400–700 Macro/microscope objective 10 mW mm-2 Funken et al., 2019, 2020
Continuous wave laser (single photon) 400–700 Microscope (1 μm × 1 μm spot) 5–10 μW μm-2 Centonze and White, 1998
Ultrashort pulsed laser (two photon) 700–1100 Microscope (1 μm × 1 μm spot) 5–10 mW μm-2 Bush et al., 2007

The wavelengths are chosen to represent common voltage/ Ca2+ fluorescent indicators and optogenetic applications.