Need waterproof 1.5mw laser built

well there more important things to a laser like the Polarisation and Monochromatic abilities of the light.
in lasers are Mirror that bounce the light off untill it is nearly 100% perfektly alligned,
i guess you can do the same with Glass Fibre, thats why Fibre lasers exist.
but you will loose some of the input.

That is true except that the fiber is not working the same way as it would in a fiber laser. Also, its not so much the properties of the light that matter as much as it is getting it focused into as small of a point as possible and retaining its beam like properties so that it can be directed at the pest with minimal losses from optics.

If you decide to go the fiber route, to preserve beam quality you would have to use a single-mode (TEM00) laser precisely focused into the end of a (very small!) singlemode fiber at a specific conical angle (I've read that microscope objectives in micrometer mounts are often used for this very exacting purpose), then expand/collimate/focus at the other end of the fiber. Quite the project!

I just thought of something else. IF the laser output is polarized, all you have to do is make sure the beam enters through the tank glass (or still water surface) at Brewster's angle (you might go to Sam's Laser FAQ page, or Wiki it to learn about it). At this one angle, polarized laser light oriented correctly, will pass into the tank with almost no loss at all by reflection. Because of refraction though, the beam will bend as it passes into the tank and you will have to figure out the geometry. That way your laser wouldn't have to take a dunk.

One way to check a laser's polarity is to simply aim it at a glass table top at Brewster's angle. Note the amount reflected off the glass. Rotate the laser slowly while maintaining the angle. If the beam is polarized you will notice as you rotate the laser that the amount of light reflecting off the glass will change. At Brewster's angle, when the polarization is horizontal, most if not all of the laser energy will reflect off the glass; when the polarization is vertical, most if not all of the energy will pass through the glass with very little reflection. A nonpolarized laser beam will not show this characteristic. The polarization orientation can then be marked on the laser for future reference.

The laser might then be mounted on a tripod and adjusted so that the beam satisfies two criteria: 1. Properly oriented/polarized beam enters the water (or tank glass) at Brewster's angle. 2. Beam hits target while satisfying the first condition.

Then you simply use a lens between the laser and the tank to focus, and nothing gets wet/shorted/blown up ;-)

Fyi,
T.

If you want to try to maintain a perfect angle with the surface of the water or the side of the tank the whole time that would work great. The issue here is being able to move the beam around and hit different sides of things. While that would be the cheapest way to go about this, it also would be the most difficult to utilize every time. Fiber would be safe for the laser but also the most difficult to make, costly, and sensitive to damage design. A waterproof project box would work well but its also risky if it isn't built exactly perfect. An o-like waterproof 445nm laser might work well but it likely won't be reliable and might not be powerful enough and or duty cycle would probably limit how much you can do at a time.

well with 1-2 mirrors you can keep the laser outside of the tank and keep the beam focused on the spot.

That would be insanely difficult(mostly annoying and time absorbing) to use on a regular basis for tank maintenance.

If the problem isn't very big, and you are strapped for cash just try toasting the buggers from outside the tank without mirrors. It might just work, especially if you use Brewster's angle to reduce losses through the tank. If the problem will require frequent maintenance and getting them from outside the tank fails then I think your best bet is using a waterproofing case or having a laser commissioned.

we have now 4 options:
From outside. +no cost (apart from the laser) -you cant reach everthing +easy
Mirrors. +cheap -difficult to use
Waterprooflaser. -can be kinda chunky -cant reach everything
Fibre. +flexible +easy to use -cost

Still think the best and easiest idea is the project box. I made a drawing of the project. You can get the M140 Diode HERE and the project box HERE.

Cube, that's exactly what I was thinking. The only difference is the main heatsink could nearly fill the box and the module and driver just sit inside the heatsink together so both are heatsinked and you get maximum volume of copper/aluminum inside the box. Aluminum may be better simply because of weight issue. If the box was almost filled with aluminum and the whole thing was thermal epoxied to the box I think it would be pretty damn efficient. Especially if on the outside of the box was a small finned aluminum heatsink that would dissipate heat into the water even better.

The wires exiting the box could easily be placed inside surgical tubing which is super flexible rubber that is very resilient and perfectly waterproof.

The main window may not actually need to be AR coated if we designed the laser to utilize Brewster's angle internally.

If we gave that box to FlaminPyro I am sure he could shorten it down for us as well. All we would need would be like half that length.

The box I chose was the first one that showed up on my search on eBay. There is definitely finned boxes too, so no need for external heatsink. There is a huge amount of aluminum boxes, most of them under $10! ^As for the window, (I'm still a noob when it comes to optics) won't a dicro work? It could be a bit hard to find Brewster's angle when you have a pre-focused beam.

Cube777 said:

The box I chose was the first one that showed up on my search on eBay. There is definitely finned boxes too, so no need for external heatsink. There is a huge amount of aluminum boxes, most of them under $10! ^As for the window, (I'm still a noob when it comes to optics) won't a dicro work? It could be a bit hard to find Brewster's angle when you have a pre-focused beam.

Click to expand...

I was messing with my lasers a while back on a random piece of glass in my room and found Brewster's angle by hand. It was not very difficult to get zero reflection just holding the laser and slowly moving it but it was as easy to lose as it was to get XD. Either way, a dicro would also work. Anything that's AR coated would work. I'm sure something that can be pulled from a Ca$io projector from DTR would work as well.

Yeah, you could buy a box of THIS from DTR for $21 with 2 dicro's. Overall this project could be pretty cheap against using a flashlight! And a hell lot easier!

Exactly, which is why I said this was the best bet IMO. No messing with mirrors every time you want to zap some pests and no messing with the unnecessary complexity and likely high cost of fiber(that may or may not result in a useable laser). Cheap, reliable, easy setup, easy use.

The only easier thing would be to get a waterproof laser from o-like and risk getting a well... piece of crap, which I see happening more often than not, or spending a ton on a higher grade waterproof laser.

And because this laser could be cooled so efficiently you can get a very high power output also. So

:lasergun:

bey-bey pests!

Can I assume you have Googled it and have seen this thread?
The waterproof laser case!

TBH, that is a neat idea but a little too ghetto for my liking and not capable of high output lasers for several reasons.