What Types of lasers would travel farthest in water? 2

[Stgeorgeskid]

I have a science project on lasers and i need to do two things, 1) find three lasers, each different wavelengths, and 2) test them in a scientific method and also create a Hypothesis. I am looking for any guidance as to where i can find verifyed research on the subject and if any one knows, where to buy lasers. By the way, i am not posting HW.

 

[DaveVikingPE]

Try Edmund Scientific,

http://www.edsci.com/,

they've got EVERYTHING you'll need.

 

[111121]

The three most common lasers used in the metals industry are the CO2 laser (wavelength 10.6 micron), the Nd:YAG laser (1.06 micron)and the Diode laser (0.81/0.94 Micron).

Lasers are used in combination with water for industrial metal cutting eg Hybrid Laser/Water Jet, but info on beam travel through water unless coupled with fibre optics will be difficult to find.

Laser manufacturers include: Rofin Sinar, Trumph, Fanuc, PRC, Convergent, Prima, Panasonic, Mitsubishi and Wegmann Baasel.

References can be sought through the Laser Institute of America

http://www.laserinstitute.org

TJA

 

[cgwilson2]

I know that Harbor Branch Oceanographic was doing some reseach on the subject for use of coastal processes monitoring and might have some information on the subject.

http://www.hboi.edu

 

[nornrich]

Stgeorgeskid,

Just a guess, but I seem to remember reading somewhere that the US Navy has the ability to communicate with submerged submarines through Ultra Low Frequency (ULF). The lower the frequency the better the signal transmits through the water. Using this assumption the lower wavelength lasers would probably work the best.

Rich...


Richard Nornhold, PE
nornrich@redrose.net

 

[GregLocock]

Good guess, but not in this case. The absorption of visual light by water is well known (clue: what colour is it underwater?).

You do realise that you are extrapolating a trend across wavelengths by a factor of 10^9 or more?

Cheers

Greg Locock

 

[kenvlach]

In various types of spectroscopy used in Quantitative Analysis (chemistry), for penetrating water (a common solvent), the trend is UV (best), violet, blue, green…IR (~worthless). So lowest wavelength, highest frequency is best.
So, Greg, Rich is right about lower wavelength but got there by faulty logic -- frequency is inversely proportional to wavelength: f = c/&[ignore]lambda[/ignore];.

Of the lasers in ‘Characteristics of Laser Sources’ in CRC Handbook of Chemistry and Physics, 79th Edn., the 10 best for penetrating water are
1. Argon (Ar₂), ~125 nm wavelength (UV),
2. Krypton (Kr₂), ~145 nm,
3. Fluoride (F₂), ~155 nm,
4. Hydrogen (H₂), ~165 nm,
5. Xenon (Xe₂), ~175 nm,
6. Argon-chloride (ArCl), ~180 nm,
7. Argon-fluoride (ArF), ~195 nm,
8. Krypton-chloride (KrCl), ~220 nm,
9. Krypton-fluoride (KrF), 249 nm,
10. Chloride (Cl₂), ~255 nm.

Also, 2 common types of possible interest:
Nitrogen ion (N₂+), 420 nm (violet),
Argon ion (Ar+), 488 nm (blue-green).

Hope this helps,
Ken

 

[GregLocock]

"So lowest wavelength, highest frequency is best."

The exact opposite of what Richard said!

Cheers

Greg Locock

 

[chubPE]

Wow Greg, imagine that. A PE wrong.....


wow

 

[GregLocock]

Oh, another illusion shattered.

Actually I just reread Rich's post. The confusion comes about because he wrote

" The lower the frequency the better the signal transmits through the water. Using this assumption the lower wavelength lasers would probably work the best."

Lower wavelength does not imply lower frequency, rather the reverse.




Cheers

Greg Locock

 

[wsmith]

Most underwater optical imaging and communications systems use green laser - about 530 nm. Under ideal conditions you can exceed 1000 m range, but high turbidity can cut range to a fraction of this. In addition to choosing the laser itself, you need to select a light detector - for underwater imaging generally a streak tube or microchannel plate intensifier is used with a CCD camera.

 

[Micanopy]

In the 1970s we used to use green lasers for long distance (100m) levelling under water. As the laser showed up you could just take a height from the laser beam with a tape measure. Herriot Watt University, Edinburgh, Scotland were the developers of this technology. They gave a paper on it to The Underwater Association. You might try The Society for Underwater Technology (SUT.

 

[canyoncruz]

ANY Green alser......and old KTP doubled Solid State Diode Pumped (SSDP) laser, a Ti Saphire SSDp laser, one of the newer solid state green lasers....you can find cheap ones from several chinese companies........CASIX being one of them.

Have worked on thses types of prjocts before. In reality onlly goos in the deep blue, close to shore, this light is a plantin magnets, which in turn call the food chain to attention