The common description of the eye's red cone sensitivity is wrong

Discussion in 'Eye-Care' started by David Jonsson, Jan 15, 2007.

  1. All sources I have found describe the eye's red cone sensitivity as the
    one here
    http://hyperphysics.phy-astr.gsu.edu/hbase/vision/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
     
    David Jonsson, Jan 15, 2007
    #1
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  2. David Jonsson

    Salmon Egg Guest

    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 1.06┬Ám.
    Nevertheless, there were some photo-surfaces that were responding weakly to
    the neodymium radiation.

    Bill
    -- Fermez le Bush
     
    Salmon Egg, Jan 15, 2007
    #2
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