Re: LED eye damage


Jim Yanik wrote:
"mc" <look@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
news:4o8cg.41394$QU3.18788@xxxxxxxxxxxxxxxxxxxxxx:

It also depends on how CLOSE the light source is,along with it's
intensity,and particular wavelengths.(like UV.)

Light follows the inverse square law.

Light does, but the eye has a lens in it and views a focused image.
As a result, surface brightness is independent of distance. (If the
light source is farther away, it covers a smaller area of the retina.)
So it's a question of losing a lot of your retina or just a little...




Just because the image is focused does not mean the power delivered is the
same.The lens of the eye is not magic.(no gain,either)

Power is not the issue, it's intensity (power / area). Less power
covering proportionately less area gives the same intensity. Moving
farther away just reduces the area of damage.

What you say is true only at a large enough distance so that the source
is imaged to a diffraction-limited spot in your eye. The image area
becomes constant, so reducing power by moving farther away does reduce
the intensity. That's why it's safe to look at the stars, but not at
our own sun.

Mark

.

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