Help with different types of fixed focus lenses?????

[Hyrule571]

Hey, new here, FIRST POST LOL...

bought one of those laser pens from ebay, i bought one that was $8.98, the one that you see all over the pages ---> 405nm 5mW Blue Laser pointer.

Its a fixed focus and its visible from 1000meters... does that mean when i click it on the beam will stay that diameter and not expand or whatever and become no longer visible until after 1000meters or what? IDK how that all works. I know its some cheap 5mW laser and i know theres ones 100 times better but im a rookie i love lasers =] IM FIRIN' MUH LAZOORRR LOL (help me out)... oh is 405nm like... blue-violet? right?

 

[Bluefan]

Hi and welcome to the forum! feel free to introduce yourself in the welcome section.

The beam will diverge, depending on the laser this can be very fast or diffraction limited, the best possible. After 1000m the dot is probably about 1 meter in size for a normal pointer. 405nm is violet and not very visible, but because of fluorescence in for example wite paper the dot may appear more blue.

5mW pointers are known to be overspec, so please use some laser safety eyewear!

 

[Hyrule571]

Awesome, just need a bit more detailed info in where you said...

"The beam will diverge, depending on the laser this can be very fast or diffraction limited, the best possible."

thats what i didnt really get. So 405nm isnt really visible? =[ Why? Could animals see it, like pigeons or something? (NOT saying that im about to blind a pigeon NOOO i love animals and im a safety freak, no pointing in peeps' eyes lolz..) is 405nm still cool though? Like can it be seen still as blue 50% of the time? Please help im a starter and i love lasers =]

 

[udanis]

1.So 405nm isnt really visible?
2.is 405nm still cool though?
3Like can it be seen still as blue 50% of the time?

405nm is visible, but not as visible to 532nm. Our eyes are most sensitive to between 500nm and 600nm

405nm is cool. Your eyes can't focus on the dot though but you can make various things glow with it because it is so close to uv light. If you hit any glow in the dark objects with it the really glow good!

I like 405nm, but thats me. 445nm is still way cooler though

 

[Kevlar]

Here are a couple of diagrams that show the different spectrum's and their visibility to the human eye. 405nm is borderline UV.

 

[Hyrule571]

ARE YOU KIDDING ME!!?!?! whoa... thats... kewl... alright! well thanks haha kewlio.. thanks for everything, last question, do different wavelengths affect how reflective they are on various surfaces? thx! oh! and is it ever possible to have a black or white laser? lol ok done asking just help me out witht hose two n im done! =]

 

[Kevlar]

ARE YOU KIDDING ME!!?!?! whoa... thats... kewl... alright! well thanks haha kewlio.. thanks for everything, last question, do different wavelengths affect how reflective they are on various surfaces? thx!

Yes, a good example would be black lights and how they affect different colors, same with your 405nm laser. That is one of the fun things with that wavelength. My kid has a glow in the dark drawing pad that uses a weak UV black light to fluoresce the GITD pad, but my 405nm laser does it much better!!

There is actually a list on this forum with all kinds of different materials that are fluorescent, like urine.

oh! and is it ever possible to have a black or white laser? lol ok done asking just help me out witht hose two n im done! =]

I don't think black but definitely white. Search for white fusion on this forum and let me know what you think?

 

[Hyrule571]

sweet, THX!

 

[Hyrule571]

OK i got my laser!!!!! Wow my first OFFICIALLY COOL laser lolz... a got a 5mW 405nm laser and its SWEEEET =] all my friends are like wow thats sick bro n stuff like that, sweet stuff... but i tell them this is nothing, this ones 5mW, theres ones that are a whole WATT+... so yeah anyways i got a last question... How can i test how far this thing can go, AND which AAA batteries would be best? Some original energizer/duracell batteries, or advanced energizer batteries, or ultimate lithium batteries (all AAAx2), which is best?