| abstract |
The newly discovered retinal ganglion cell photoreceptor melanopsin absent in the central fovea of the eye but distributed throughout the remaining human retinal body provides both non-visual biological/physiological input inducing circadian entrainment, and visual input affecting perceived brightness; this perceived brightness is not the object brightness commonly associated with luminance and perceived color of an object in central view, but the perception of brightness of a whole space or task background. Discussed are improvements to circadian lighting systems based on melanopsin stimulation whereby ambient and/or device background lighting may be temporally tuned over a range of prescribed color temperatures from a first subset of lighting having a higher melanopic content to a second subset of lighting having a lower melanopic content or vice versa in accordance with a desired circadian cycle, and in a manner where net light output is of a constant perceived brightness and color throughout temporal tuning. |