First 405nm...Question about safety.

I just got the $9 Ebay pen, and the dot on it looks very strange. I only looked at it for a second at a distance of ~20 feet on a white wall inside. I can't even see the dot outside in daylight. Other than maybe 3 seconds of exposure total (I put it away after) I haven't used it, but it almost feels like my eyes are hurting. I wonder if that's just psychological.

Anyway, like I said it doesn't seem that bright. And the dot looks very strange to my eye. I took a picture of it, and it looks normal, so I'm wondering if my eyes just have a strange response to near-UV light.

Is this normal? Is 405nm like 808nm in that I need to be extra special?

Thanks for any answers.

EDIT: I'll be testing the output tomorrow, and we'll see how many mW it is.

If it was a $9 pen, it's probably not more than 20mw tops. You should always observe proper eye safety with any laser, but diffuse reflections at that distance shouldn't have posed much of a hazard.

This is common for the 405nm wavelength, some people's brains process the color differently, i know i regularly experience this with every power of 405nm i own, hence it is my very least favorite wavelength and i have no desire to purchase it in burning powers.

I think that may be it. I get massive headaches whenever I turn it on. Even if I'm not looking at the dot (which looks super funky and grainy). Oh, and I can see the beam at night...I think this might be pretty powerful.

Ya, I had hoped I wasn't the only one :crackup:

Just tested it - at 35mW

I actually noticed this with my 405 build. I get dull headaches after playing with mine for a little bit.

I think I get a headache because the dot is so hard for my eyes to focus... even on a black diffuse surface. I have to put my glasses on and observe the dot to actually see that it's a small round dot. Without glasses the dot looks like it's a 1.5" splotch of blurry light... it's weird.

For the record, I can see the beam on my pointer when shining it in a dark room or the night sky.
At 65mA my beam should only be 40mW as well. On high power (~180mW) the beam can be seen even in lit rooms.
I'm not surprised it's 35mW if you can see the beam.

Yes mine gimmie a headache too. Minor, but noticeable. I think its your eyes vain attempts to focus on it over and over. To me the dot looks looks like how lights look when I take my glasses off. Kinda like a quarter sized round snow flake of purpleness.

Chromatic aberration is why it's fuzzy (for most of us, our eyes are optimized to focus on red to green wavelengths, as we have highest acuity with these wavelengths); eyestrain and squinting from trying to focus on 405nm is my guess for the cause of the headaches.

Lasers at 405nm and shorter (farther into UV) are best for messing with fluorescing objects. Try pointing it at a dayglow orange object or things that are made to glow in the dark. Even dayglow post-it notes light up really well.

Not only is it difficult for the human eye to focus at those frequencies, the more UV, the more the lens and Vitreous humor in your eyes will "haze" from secondary florescence.

what I see when my blu ray is focused is a small dot with a circle of like 6 dots surrounding it, the circumfrence of the dots is like a size of a dime. is this normal?

Canuke said:

Chromatic aberration is why it's fuzzy (for most of us, our eyes are optimized to focus on red to green wavelengths, as we have highest acuity with these wavelengths); eyestrain and squinting from trying to focus on 405nm is my guess for the cause of the headaches.

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I agree

When I first got mine I also got headaches but I learned to stop trying to focus on the dot and I don't get them anymore

genius5th said:

what I see when my blu ray is focused is a small dot with a circle of like 6 dots surrounding it, the circumfrence of the dots is like a size of a dime. is this normal?

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Absolutely. Really, since the advent of 405nm in the hobby, one of the first questions people have is "Why does the dot look so strange? And why do my eyes hurt? Is this causing damage to my eyes?"

As was mentioned above, what goes on is, the 'feedback loop' in your eyes (kind of like 'contrast detect autofocus' in cameras) just can't get the dot of 405 into a 'comfortable' focus zone, because of the fact that this is just at the edge of our vision. Essentially we see 405 at a really low resolution, and our brains aren't used to that, and keep trying to focus our eyes, to try and bring that dot into a cleaner, smaller, clearer space that we "expect".

This constant attempt to focus and converge that dot, causes both eyestrain and ocular muscle strain. It's not optical damage from the 405 light itself, it's just your eyes "working too hard".

And for the other folks asking - yes, this is absolutely positively normal for everyone to see it as a splashy pattern, a fuzzy pattern, or a broad dot with a halo. We actually use some similar "violet" indicator lights on runways in aviation, and I noticed this "wow, the violet ones are so blurry all the time" phenomenon years before I owned or saw a 405nm laser. I even noticed it when I was a kid.

So it is normal, and it's not hurting you, there's nothing wrong with your eyes. It's just hard to see.

thanks for the info, its really strange how different people see blu ray in other ways
almost like a rorschach test

I love 405nm. Great fluorescent effects and fantastic for burning. Just don't try to hard to focus on the spot!