On 1/15/07 12:34 AM, in article
(E-Mail Removed) om, "David Jonsson"
<(E-Mail Removed)> wrote:
> All sources I have found describe the eye's red cone sensitivity as the
> one here
> http://hyperphysics.phy-astr.gsu.edu...colcon.html#c1
> The description is wrong.
> Here it is somewhat better but the graph is cut for red and green where
> violet begins
> http://en.wikipedia.org/wiki/Cone_cell
>
> Almost all people know that to achieve violet one needs to add blue
> light with red. This means that the red cone has sensitivity in the
> violet domain. Why have the medical people missed this? Computer
> science and television has used this since decades.
>
> Please update your web pages.
>
> David
>
Even the excellent Wickipedia article leaves some things out.
Not long after diode lasers were first announced, some laser diodes were
made where I worked. While I do not remember their wavelength it was
somewhere near 860nm well past the end of the graphs presented in the
references above.
These diodes had to operated cold at liquid hydrogen temperatures. With a
dark adapted eye, we could look into the dewar to see dim flashes of light
from the laser. The laser HAD to be pulsed to reach threshold. The
impression was that of orange light. My guess is that the tails of the
responses, small as they are, extend well into the near infrared. The orange
color indicates that least two sets of cones respond.
The same extended low level response at long wavelengths is also present in
photomultiplier cathodes. Of the old line photo-surfaces, only the S-1
material had published response to neodymium radiation at 1.06µm.
Nevertheless, there were some photo-surfaces that were responding weakly to
the neodymium radiation.
Bill
-- Fermez le Bush
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