What is the longest wavelength ever seen by the human eye?

[Grebulous]

I've gotten curious about how the human eye's sensitivity to long wavelengths drops off. What's the longest wavelength anybody has ever seen? I know there is nonzero (but very low) sensitivity to 800+ nm light, but does anybody know the extreme long wavelength limit of human vision?

 

[kgbgru]

My mouse has a 852 nm laser and I can just barely see a faint red when I stare into it.

 

[jim mcnamara]

See this article:
http://www.iscc.org/jubilee2006/abstracts/JakabAbstract.pdf

Humans have a lot of alleles for the cone (color) pigments, some rare ones extend the visible spectrum slightly. This also results in a very few women having tetrachromatic color vision, and it is also the root cause of color blindness. Rod cell pigments do not absorb longer wavelengths - google for the Purkinje effect - so they probably do not extend vision in the direction you are interested in.

Note: there is an optical problem with extending the range of visible wavelengths - an image that is correctly focused on the fovea (cone cells) for 500nm light willl not be focused well at 1000nm, assuming humans could see 1000nm light which they cannot, AFAIK.

See this for the 'five site rule' on the origins and evolution of color vision in mammals
http://mbe.oxfordjournals.org/cgi/content/abstract/15/5/560