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Thread: Nominal Ocular Damage Distance...

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    Default Nominal Ocular Damage Distance...

    Nominal Ocular Dazzle Distance is a new concept by Craig Williamson of DSTL_Porton Down and Leon McLin of the US Air Force 711th Human Performance Wing.

    The proposed concept, gives a more accurate view of what happens when performing a task while a portion of the eye is illuminated, and while the fluid in the eye and surface of the retina is scattering laser light. This scattered light can greatly affect visual acuity elsewhere in the eye.
    What NODD does different is it helps estimate what the laser "Dazzle" does to visual acuity off axis to the laser strike.

    NODD is also dependent on the angle of beam entry to the eye, as well as the angle to the viewing target such as a runway threshold.

    The results of this calculation might surprise most of the naysayers who think even low power pointers cannot possibly interrupt a pilot's task during approach or at high altitude flight. This paper is the first published means to help determine a qualitative level of visual field disruption in a meaningful way.

    Stray Light and Veiling Glare matter....

    More to come.

    Steve

    Reference Citation:

    Craig A. Williamson and Leon N. McLin, "Nominal ocular dazzle distance (NODD)," Appl. Opt. 54, 1564-1572 (2015)

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    Interested !
    Cheers

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    More information and evidence based theories in this area are always appreciated.

    Thanks!

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    I can see this being a potential nightmare for laser show producers / users though. Legislators in Europe will probably jump on this as an excuse to ban or restrict audience scanning to levels below the NODD. They're some in the UK who are rumoured to have already proposed a reduction in exposure levels for audience scanning because it might dazzle club users and cause tripping accidents. Ultimate bullshit in my opinion. I've yet to see anyone in a club staggering around dazzled from a laser, and I've seen levels at several hundred MPE (illegal, not eye safe of course and not my doing). In fact blinders and strobes are far more disorientating, and alcohol away from lighting causes most accidents. This to my mind can only be bad for the industry, and if it does affect audience scanning legislation, will only cause more and more clubs to go underground and scan at illegal levels.

    I'm also missing something here as I fail to see it's usefulness to the aviation industry in any event. Pointing lasers at aircraft is already illegal so having a safe NODD distance isn't really going to change that. Legal users can't generally operate near airports and affected areas are notified and approved so pilots can avoid them. Illegal users aren't going to measure their distance from the runway when illegally shining lasers at aircraft and in fact, in may have the opposite effect in that it may give them a defence in that their lawyers can claim they were outside of the NODD so the pilot wouldn't have been affected in any event, thereby either alleviating the conviction or reducing the penalty if it's strict liability.

    I just can't see any good to come out of this for either the industry or for pilots.

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    well good or bad it's published and i tend to agree that it will be misused in every way possible
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

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    This is an interesting development.

    I have a corollary complaint. What is the reason for allowing police and other emergency vehicles to use dazzling levels of blue light (red for ambulances) aimed into oncoming traffic? I know that it is necessary for them to be seen. I understand that in some circumstances more light intensity may be needed. But, the new LED lights are DANGEROUS! The number of vehicles that pass these lights every night number in the thousands. The intensity is so high that it requires me to try to avert my view from the road and the blue ones interfere with dark adaption. I suspect that no standard exists for these emergency, monochromatic lights. These need to be turned down or replaced. But, here we go.. watch out for those laser pointers.

  7. #7
    mixedgas's Avatar
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    Planters,
    +

    Our Governor (Ohio) had the lights toned down on state highway vehicles and the state police cars.
    +
    The salt trucks are using a really effective green,yellow,white led scheme. They now have a bright/dim switch on the salt trucks, as the green/yellow scheme was too good. The green and yellow leds were picked for scotopic and photopic peaks of the eye, and are HIGHLY effective. Whomever paid the extra for the custom green/yellow blinker is a hero in my book.
    +
    You know right away a state plow is ahead of you in the winter...
    +
    https://www.youtube.com/watch?v=Ea-a7DxEy6o
    +
    https://www.youtube.com/watch?v=X5G2Ya0ZaJ0
    +
    Snow truck/car collisions are probably WAY down compared to the old, dim, all amber scheme.

    +
    IMHO The new, ALL BLUE Ohio State Trooper Leds (seem to be near 445-450 nm) are too dim in Ohio... They added a few red leds to the rear of the car that are usually dimmer then the tail lights.
    +
    So much for Federal standards..
    +
    Steve
    Last edited by mixedgas; 02-02-2016 at 10:52.
    Qui habet Christos, habet Vitam!
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