Underwater lasers

[3D diver]

Researchers are using calibrated lasers to size fish in stereo video setups. Two lasers in parallel with a known distance apart can be used as a scale bar for accurately sizing many animals in such a scenario. I am unsure of the specs of the underwater lasers they use, but I think it should be a different spectrum than red lest it be absorbed within a few feet.

Interesting...I'd like to read more about that. I shoot a little 3D myself:

 

[Sam Miller III]

Under water lasers have been around for about 25-30 years

The Russian "Sea Bear" spear gun of the 1980 (?) or 1990s offered a laser sight for their guns...you might find one on E bay

I mounted am laser in a small UW light case when the lasers first appeared on the market (purchased the laser for $120.00)..worked but not well

Back to the drawing board...

SDM

 

[smellzlikefish]

Interesting...I'd like to read more about that. I shoot a little 3D myself:

I never would have guessed that from your name...

The idea behind using stereo cameras is similar to creating 3-D video, except they are utilizing computer programs to extract data such as fish size, swimming speed, etc. You can do a lot more with two cameras than just one!

Check this link out: ScienceDirect.com - Aquacultural Engineering - Extracting fish size using dual underwater cameras

 

[3D diver]

I never would have guessed that from your name...

The idea behind using stereo cameras is similar to creating 3-D video, except they are utilizing computer programs to extract data such as fish size, swimming speed, etc. You can do a lot more with two cameras than just one!

Check this link out: ScienceDirect.com - Aquacultural Engineering - Extracting fish size using dual underwater cameras

Subtle is my middle name...

I spent a little time Googling the subject and scanned a couple of articles. Interesting, but, in the end, not a whole lot of fun.

I like the idea of using 3 colored lasers with a beam spreader as video lights to control the color ballance of the resulting light source. Doubt that's practical, though...

 

[Jerry_]

Was thinking about them as a way marker, this assumes however that the beam would be visible for about 50-100m, even in non-optimal conditions.

 

[smellzlikefish]

Lasers are just light, so I'd imagine in poor vis conditions the laser would only go as far as your vision would take you.

 

[Jerry_]

Laser is a beam of coherent light, so I would guess it reachesmore far than what the diver has an impression what his depth of view is.

It all depends on how much energy the beams loses when it hits a floating particle.

This is what I was interested to know from the OP: if I have a (let's say) real 50mW green laser, and a level of x particles by cm3, what far will it reach.
Whatbis the influence if I only use a red laser, or if I change to 100mW.

Would be nice if the OP could contribute. Also would be good for the OP if he would take some lead in the discussion, or let us know whether he is just waiting to collect ideas.

 

[miketsp]

Can we have enough power to use as a knife replacement - for cutting fishing line and nets at close distances (<1cm)?

Or maybe tight beam and accurate pointing to use as a long-range signalling device - to flash aircraft or choppers if we're lost at sea during daytime? This would probably need a flashing mode to attract attention.

I don't think I'd carry one just to use as an UW pointer. Just one more item to wash and clean after the dive.

 

[Jerry_]

@mikestp

You want to replace the lead weights by batteries

 

[underwaterlasers]

Haven't used, but I am interested in the subject.

Would be nice to get some info on the type of lasers and power used/proposed and how far they reach in "troubled water"

So, to not upset the government, you cannot sell anything above 5 milli-Watts to the general public. This is not unreasonable for use underwater. Even in somewhat cloudy water, the beam travels a atleast 50 feet or more. For very heavy cloudy water they may not go more than a few feet. But Ocean water they would travel quite far.

Depending on the intended use, for instance, signaling other divers, the higher the power the better. But then you have to start filling out paperwork to the government to verify that you sold the higher power lasers to "professional" end users.

So powers that can be easily obtained for packaging inside the existing housing size that I have made some prototypes with: 10mW, 20mW, 30mW Higher powers could be contracted with the manufacturers.

As for uses, the main use I would envision is for signaling other divers. However, it seems most of the people I talk to mention stimulating the fish and other underwater creatures.

They can also be used as illumination devices for cave diving or "murky water diving". I also envisioned an adapter to turn the device from a laser pointer to "spread the beam" so it works more as an illuinator. I have seen one of these "laser illuminators" on the market as well....marketed for cave diving.

I have seen other underwater laser manufacturers claim, "shark deterrent" but in recent discussions with some people, this seems to be a non-scientific or verified claim, furthermore, it will be hard to remember you're holding a laser when a shark is coming at you....

---------- Post Merged at 11:56 AM ---------- Previous Post was at 11:51 AM ----------

Sorry, but what would you do with one? Point at stuff? Get fish to chase the dot?

Not (entirely) a facitious question.

This is a question pretty much every diver asks, which is why I decided to post. It seems that no one I talk to has even considered using them or really has any idea what they would use them for other than to stimulate activity in fish while snorkeling or diving.

so here are the uses: Make fish chase your laser beam. Signal other divers, illumination, strap to your spear gun and use for aiming. Those are the big ones I have always thought would be cool to use a laser for, but it doesn't seem there is a huge interest....

---------- Post Merged at 11:58 AM ---------- Previous Post was at 11:51 AM ----------

Well the power generator required for laser weapons would sink you quickly to the ocean floor.

the company I used to work for is currently working with the navy to make "above water" laser cannons.

---------- Post Merged at 12:03 PM ---------- Previous Post was at 11:51 AM ----------

From personal experience (and several posts on Scuba Board) red lasers don’t work very well in water, even with good visibility.

Reportedly green lasers are better, but I have no personal experience, and they are (or at least used to be) significantly more expensive.

What color are your prototypes?

To see more discussions you might want to plug the following into Google, or your search engine of choice:

I have made green 532nm @ 5mW power. The green wavelength is the most sensitive to the human eye, so is the best combination of human perception versus transmission through the water. The blue wavelength between 405 and 455 nm is the best transmission through water. So for signaling to and underwater detector is the optimal wavelength. Depending on the application it could be argued that underwater lasers should be "blue", however, when the human eye is the intended "detector" I have concluded that green, (532nm), would be prefered. however, long term, if I think there is enough interest I would offer both. I will try that search you mention