Page 2 of 2 FirstFirst 12
Results 11 to 17 of 17

Thread: "photopic-scotopic vision"

  1. #11
    Join Date
    Jan 2007
    Location
    Florida
    Posts
    4,382

    Default

    Yeah, a chart like that would definitely be cool
    Because some people run 635 instead of 660 and an argon 488 instead of diode 473 etc

    It'd have to be objective though--because some people see different than others -possibly different levels of color perception. I know one guy who looked at one picture here and said "it all looks white" (different colored lasers) he says he's color-blind though and there may be different levels in different people. It'd make for an interesting experiment though. Several lasers with analog blanking ,a power meter and a group of people should be all that'd be needed-- maybe at the next SELEM

    A chart something like this?:

    nM Multiplier

    405 X3.7
    457 X2.9
    488 X2.4
    532 X1 (using the 532 as the ref rather than the std 555nm due to laser wavelength available)
    635 X2.2
    650 X2.5
    660 X2.9
    (I just pulled these number out of the air for demonstration puposes only!)
    Last edited by steve-o; 04-12-2007 at 11:30.

  2. #12
    Join Date
    Apr 2006
    Location
    Orlando, FL - USA
    Posts
    1,741

    Default

    Hi guys,

    Just a quick note here. I hope I can shed some light (no pun intended) on this subject.

    Basically the cones (color-sensing organs in your eye) are what make up the PHOTOPIC curve. The rods (black-and-white and peripheral vision sensing organs) are what make up SCOTOPIC curve. The scotopic curve shows a shift toward the blue which happens with "night vision". Basically what it means is that, with VERY low light conditions, the black-and-white sensing organs of your eye are more sensitive to blue(er) light. Maybe evolution (or God) crafted our vision like that because there is more blue(er) light available at nigh with starlight and such...

    Some people have looked at these curves and tried to imply that, well, since laser shows happen in a darkened environment, maybe we should be using the SCOTOPIC curve instead of the PHOTOPIC curve to figure out vision response? There is a really simple rule to apply. If you are perceiving color, then it's PHOTOPIC.

    Note that there is new research being done into lighting with induction lamps and so called SCOTOPIC-ENHANCED theory is starting to be considered. Personally, I don't buy it... but no doubt more vision research will happen and maybe some hybrid curve will come out of it. Still, I have my doubts...

    Best regards,

    William Benner


  3. #13
    Join Date
    Jan 2007
    Location
    Florida
    Posts
    4,382

    Default

    Thanks William,
    Rods and cones--I should have remembered. My cat can see a red laser. I believe some animals have primarily rods for nocturnal hunting. I wonder what the laser looks like to him? White I guess?

  4. #14
    Join Date
    Dec 2006
    Location
    Pflugerville, TX, USA
    Posts
    1,977

    Default

    Cats call it pffttmeow.

  5. #15
    Join Date
    Jan 2007
    Location
    Florida
    Posts
    4,382

    Default

    .

  6. #16
    Join Date
    Mar 2007
    Location
    Rotorua New Zealand
    Posts
    528

    Default

    I seem to remember from 'old army' days as a medic that there was a 'fluid' called 'visual purple' by which the eye became far more sensitive to the low levels of light at night. This visual purple is easily destroyed after a flash of bright light and it takes time to reform. That is why you have trouble seeing in the dark if you get a flash. We had to keep one eye covered in the event of an explosion. Note aircraft cockpit lights are red that doesn't screw up visual purple in the eye !! This has nothing to do with lasers but the discussion bought it back to me.
    Cheers
    Ray
    NZ

  7. #17
    Join Date
    Jan 2007
    Location
    Florida
    Posts
    4,382

    Default

    These 2 charts are completely different. Does anybody know of an "official" or standardized one?
    Attached Thumbnails Attached Thumbnails eye color senitivity.JPG  

    eye snsitivity.jpg  


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •