doubt about 405nm visibility

hello guys, i have read lot of things about visibility of 405nm light..
if you are not lucky one you can get some diode which will be less than 405nm and it seems to be nearly invisible..
my question is if there is any type {kind} of violet diode which will guarantee 405nm and even more??? or iis it really unpredictable and random??

thanx

just freaking make yourself or buy yourself one of these

http://www.laserpointerforums.com/forums/YaBB.pl?num=1224130203/0#4

you'll say holy crap that looooooks BAAAAAAAAAAD SA

Yes, it is random, and varies from diode to diode. Some diodes have an average of 407nm, but it will be pure luck whether you get 415nm or not. Most blu-ray lasers range from 395nm-415nm.

Buy a few diodes, and use the brightest one.  This is going to be a LOT cheaper than asking a company to make you one (by a couple figures).

EDIT: I can see mine pretty well. It's equivalent to about 15mW of green in brightness, at least to me. The beam looks a LOT fatter, though.

-Mark

well, if the blue ray is able to look like 15mw greenie so i think there is nothing to worry about... 15 mw green is quiet good and if it will be blue {violet} it could be awesome

john_lawson said:

just freaking make yourself or buy yourself one of these

http://www.laserpointerforums.com/forums/YaBB.pl?num=1224130203/0#4

you'll say holy crap that looooooks BAAAAAAAAAAD SA

Click to expand...

Hey, thanks John!  [smiley=happy.gif]

But I don't think that’s what he's talking about, although I do agree, buy one and you will be happy to see the beam!  The 70mW does burn very well, and you can even feel it on your skin focused to infinity, not focused for burning (then it burns the heck out of you).   But that's ok if I never sell them, because I plan on giving at least one away for a Christmas present.  Plus I don't mind having a couple extra blu-ray lasers!  

It's said that these lasers vary +/- 5nm, so some could be 400nm, and some could be 410nm.  Some people can't hardly see the dot at all at 400, and they probably wouldn't be able to see it much better at 410nm.  Daguin showed me a pair he built I believe one was 145mW and the other was 115mW (correct me if I'm wrong Dave) and the 115mW looked noticeably brighter.  But it is luck of the draw, and there's no way to acquire a LD one nm or another, unless you know someone that has a whole bunch and doesn't mind testing each one for you (would help if they had a spectrometer) and get you the one that appears brightest.  

Last night was foggy, and man, nice violet beam to the sky looked just about as bright as a 5mW green on a clear night.  
You can also see the dot in the night about as far as you can see a 5-10mW red.  

But yes, the visibility of the blu-ray isn't particularly good since it is at the very edge of our human eye's visible spectrum.  And of coarse 473nm is much more visible.  

In my experience, the visibility of blu-rays depends both on the diodes actual output frequency, and on the eyes of the person observing. For me, all my blu-rays consistently have a brighter beam than any of my reds. While this is how I perceive it, others may perceive it differently..

milantheone said:

well, if the blue ray is able to look like 15mw greenie so i think there is nothing to worry about... 15 mw green is quiet good and if it will be blue {violet} it could be awesome

Click to expand...

Well, I have a high wavelength diode. It's all the luck of the draw, and I got lucky. I've heard that at 400nm, you can barely see the beam, if at all. Also, it depends on individual perception.

-Mark

Shorter wave is better for fluorescence though, so it's not all bad.Smidsy got an abnormally short wave one which you couldn't even see the dot of.Higher wavelength has less chance of giving you cancer though

I'm pretty sure it has to be completely UV to give you cancer, but Switch probably studies up on it, considering how much he brings it up. ;D Some people would prefer more fluorescence. You can't see the beam as well, but about half of the white stuff you shine it on is fluorescent. Which would be a lot brighter. You should study up on the data sheets for different diodes. Some have an average of about 407.5nm.