Why do Blue LED llights look blurry?

[GilmoreD]

Some of the coolest Christmas lights (I think) are the Blue LED versions. Why is it that when you see Blue LEDs or Blue lighted lettering, it looks blurry?
I figured if anyone would know... it would be a CPF'er.
Thanks in advance,
Dave

 

[VanIsleDSM]

Can't give you a really technical explanation.. but I know that the eye has the most trouble focusing on blue light.

 

[bitslammer]

Here's a nice quick explanation.

http://www.codinghorror.com/blog/archives/000337.html

 

[Ken_McE]

In addition to the focus issue Bitslammer brought up, the distribution of color sensors in the eye is not uniform. The center of the eye (the fovea) is the part that handles our clearest, sharpest, high resolution seeing. It is rich in red and green sensors but has few blue receptors. Thus, we are simply not designed to see blue/violet as sharply as the longer wave colors.

 

[Alan B]

Also, If I remember correctly, Blue focusses a little in front of the retina, so it is not quite as sharp.

-- Alan

 

[PhotonWrangler]

In addition to all of the other great information offered above, blue LEDs are operating close enough to the UV spectrum to cause your corneas to fluoresce a little bit, contributing to the haze. (I just verified that in a mirror with a blue LED).