<5mW Green Laser for Humpback Whale Research

I tried posting this one to the general forum, but didn't get any responses. Hopefully this is a more appropriate place for this, and someone will be able to help me out.

I am a graduate student, studying humpback whales off the coast of California. For part of my thesis, I am measuring the width of the flukes (tail) of these whales. To do this, I plan to attach two parallel lasers (of a known distance apart) to a camera, then to use the distance between the two dots in the photo to calculate the width of the flukes.

So, I am looking for recommendations of laser pointers that will show up in full daylight (just the dots, not the beams). Because I will be pointing these lasers at animals, they have to be <5mW. I would prefer a constant on/off switch, and it would be helpful if it was waterproof/shockproof as I will be using it on a boat. Does anyone have any suggestions for me?

I've been looking at the Z-bolt BTG-10G, but my funding is limited and I would prefer something cheaper if I could find it. I appreciate any advice or info you guys can give me.

Hmm.... You won't be able to see a 5mW green very well in the daylight (especially off a whale's fluke). If you are pointing at their tails, I see no reason to stick with <5mW.
A 50mW should be adequate for your needs, however getting them precisely lined up will be quite the challenge.
I recommend 2 of these:
www.rayfoss.com
One problem you may run into is that most green lasers have a duty cycle that you must respect or you can possibly overheat the laser and kill it.
The only 532nm lasers I know of with an unlimited run time are Lab-style lasers (with active cooling).

I don't think you can get the Whales to chase the beams and dots like cats do.........

robertkoa said:

I don't think you can get the Whales to chase the beams and dots like cats do.........

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Would be hilarious to watch though.

Lase

Lase said:

Would be hilarious to watch though.

Lase

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Whales are so cute when they chase the dot on the surface of the Ocean....

WARNING : Never play "laser tag " with Whales within 1060 feet of Ocean Liners, Fishing Vessels, etc.

LZTN - 532nm 100mW Smallest Green Laser Pointer for day time use

blakegriffin said:

LZTN - 532nm 100mW Smallest Green Laser Pointer for day time use

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Did you read the OP?
Not so sure about this recommendation. :thinking: I have had several and they have very little in the way of a heatsink. Not a good laser to keep on for extended times, the 10440 batt diesfast, and that laser is harder to aim with the tiny host.

Don't you also need to know the precise distance from the laser to the whales tail?

I don't think this idea is going to work. Because there are going to be too many variables.

I assume you want to do something like this....

Perhaps distance calibration would be possible by adding a third centred dot so the distance between the 3 would only be possible at known/plotted distances from a steroscopic imaging device(s).
The three lasers would NEED to be lab style units with continuous duty cycles allowed. And on a boat in open seas cooling shouldn't be much of an issue while water tightness and anti-corrosion would be a much greater a problem.(go with the brass hardware when possible.)
Under 5mw green on the open ocean would be near useless. Bright sun, reflections, ambient colour of the water, absorbtion rates, etc. all make that waaaay under spec.
With care, a higher power should be much more suitable while only slightly more dangerous. Two power levels per laser unit would be better. Do the sighting with possibly the centre dot on at, say, 50mw and the two flanking units at 5mw (so you can see the orientation from your viewpoint) but when you press a button to trigger a "picture" or image capture it causes all three lasers to pump up to 100mw for a brief time for the purposes of catching the three dots on the image.
The more dots you can project the more accurate your calculations would be on your imaging though as the potential for having one fall on a wave different to the others is pretty high. You might think of looking into motion capture technology/theory for their tips on reliably capturing real time 3D data. They usually use IR but the theory should transfer fairly easily.

Just a thought.

I think you guys are missing the point...

He doesn't want to use angled lasers and trig to find the width. He just wants to put two lasers parallel to each other a few inches apart so that the dots will be the same distances apart on the whales tail far away. Then once he takes a picture he will see the two dots and use them as a scale to measure the tail.

So what you need are two 50mw green laser modules, a heatsink for each, a battery pack, and some way to finely adjust the allignment (screws or something). Then just aim it at a target a few hundred feet away with marks the exact distance apart as the lasers are and adjust the lasers until it lines up.

Just make sure the whale's tail is pointed directly at you and not at any angle or your result wont be accurate.

"Just make sure the whale's tail is pointed directly at you and not at any angle or your result wont be accurate. "

That's one of the things that I was taking into consideration before I wrote up a reply. The chances of being almost 90 degrees in line with a swimming whale is so low that you might as well count it as not happening.
And the chances of spotting a swimming whale, lining up your equipment, on a tossing boat, at that perfect angle, then projecting the two dots on a tail from a constantly changing distance at the perfect time that the tail is visible and seeing the result is, for the most part, impossible.
Some sort of photography or more likely, digital imaging is going to be necessary.
If you are going to design and build something to do that reliably and effectively then take it a little further and include the extras to do the job more reliably, efficiently, and under far more conditions than those "ideal" ones.
Or in other words, plan for the real life conditions. Heavy seas, whales at all angles, tails only partially visible, boat moving in all 3 planes of motion while working, etc.
The best way to do that would be with 3D imaging. A second digital camera shouldn't be a stretch after going through everything to get a first one. Then as the distance between the two parts of the 3D imager(cameras) would be a known value making all the other calculations simple. A single dot would be simple to calculate in 3D space at the time of an image. Basic math.(The kind that computers are great for.) Then another dot on each side of that at known distances would allow for very precise measurements at any distance.
And even if the tail isn't directly lased an image including the dots on the water within a few feet of the tail would probably be good enough for transposition of the measure.

Just taking a few things, not directly stated, but implied, into consideration.