Optical power per area (irradiance) is frequently reported in literature incorrectly or at best vaguely. Researchers applying the same optical power per area may report it orders of magnitude differently. General optics also discussed

The optical power used in optogenetics is frequently reported in vague ways. As such, two researchers may use the exact same optical settings, but report it orders of magnitude separated. This discussion hopes to address some of these inconsistencies, because it is important to discuss how the irradiance was measured so that the process is repeatable.

The optical power (typically in milliWatt (mW)) is reported over the area of stimulation (typically in millimeter (mm)), as that is what drives an opsin to change the membrane permeability and hence the membrane potential.

The following suggested method sections provide a clear way to report on irradiance, both for in-vivo and in-vitro experiments. They both cover general optical considerations of a typical optogenetics setup, including efficiency loss, on/off characteristics, and (for in-vivo) tapered fiber tips.

File Description File Type
Methods Section and Acknowledgement In Vivo In Vivo pdf
Methods Section and Acknowledgement In Vitro In Vitro pdf

ONE Core acknowledgement

Please acknowledge the ONE Core facility in your publications. An appropriate wording would be:

“The Optogenetics and Neural Engineering (ONE) Core at the University of Colorado School of Medicine provided engineering support for this research. The ONE Core is part of the NeuroTechnology Center, funded in part by the School of Medicine and by the National Institute of Neurological Disorders and Stroke of the National Institutes of Health under award number P30NS048154.”