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445 lasers power underwater

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Neptuno

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hi, I'm new to the forum, I have a couple of days looking for the different lasers options, really cool site guys.

I decided which laser I want for experiment a bit, but I was wondering if some of you have some experience using blue lasers underwater, I guess is the best spectrum to get the least possible absorption and the further penetration.

I don't know much about the science of it, so no idea what is the power attenuation vs distance in the air, but would be cool some data and also for underwater.

also.. another question is, if I need to use a housing for a 1W laser underwater, do I need to use some special kind of glass, or I can use a regular tempered glass? not sure how the refractions will go with the laser beam and all that power, any thoughts?

thanks very much
:thanks:
 





I can't see the switch on that one, the only lights that I trust underwater are intova lights, the rubber switches do not work because they get pressed in for the pressure and do not work anymore, besides is a bit pricey, in this question, I'm not really interested in the host, I am more interested in how a glass in front of the laser beam will act, I don't have my laser yet, so I can't test that for the moment, I thought maybe some might know, I don't want the glass to crack underwater for the heat for example.
 
If you tip your laser off to one side a bit to prevent any reflection from going back down into the diode, you should be fine with any kind of glass.
Having the laser's beam go back inside will shorten it's life noticeably especially if it is overdriven already.
*edit* There won't really be any heat going into the glass unless you are very high into the infrared part of the spectrum, It would also take quite a high powered laser to overcome the water's ability to cool the glass faster than it would be heated.
 
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Why do you need a lot of laser power under water?

It's gonna be hard to light a match no matter how much power you have... :whistle:

-Trevor
 
hehehehe, well I need to try at least right? lol

Auto, thanks for pointing me out the reflection, but putting the laser in angle will give me more refraction inside the glass, if the glass is lets say 5mm or more thick would be worst, might be interesting to see it tho :)

I might be getting today or tomorrow my diode, maybe from DTR, need to play for a while outside before I do underwater and burn lots of stuff of course...

too bad I don't have a way to measure the attenuation over the distance underwater, would be interesting .

by the way, how does the beam on a laser look without the lenses?? any pics or videos around?
 
I can't help wondering about where to get a 445nm blocking diving mask. :D

This will be a wading activity, there is no simple way to heatsink and switch on/off a laser inside a glass container.
 
Neptuno said:
blue is the last color absorbed by water, being red the first
Click to expand...

Do you have an absorption spectrum to show?

Blue light is about 10 times more likely to be scattered. And unless you're going swimming in the indoor swimming hole at the YMCA, then I think your red light sources will penetrate further under the surface.

Green btw is always an excellent underwater alternative... it is many times brighter than either red or blue!
 
meatball, the red light is the first one absorbed by water, red light underwater is almost useless, if you are bleeding in full sunlight underwater, about 2-3m your blood will be brown, deeper gets darker.
here is the simplest illustration I found Light was cool the drop the m&m example :), blue is the last color absorbed, but either way, I'm going to try with lasers sometime soon.
for example, a laser meter to measure distance underwater is really useless, normally you use green, but well, blue is even better
 
I thought it might be scattering (like in the atmosphere) in which case a red would theoretically go farther, but indeed it is absorption.

water+absorption.gif
 
Both Rayfoss and Odicforce sell waterproof laser DIY hosts. As skeptical as you might be - they certainly pass the "toilet test"

(well actually ,the "bathtub test" - I'm not a barbarian)
 
rhd said:
Both Rayfoss and Odicforce sell waterproof laser DIY hosts. As skeptical as you might be - they certainly pass the "toilet test"

(well actually ,the "bathtub test" - I'm not a barbarian)
Click to expand...

I have one of each, but have not tested them. :)
They look waterproof though, and I may take them to the beach if the summer gets warm enough.
 
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