Hi, just joined. Looking to build a laser for a scuba diving project

[minimalmayhem]

Hi,
I'm in the UK and during our covid lockdown can't go diving so instead I've cooked up an idea to build a tool to help measure distances of up to 15 meters along the line laid in underwater caves - for when I can go diving again.

I'm hoping to find some tips/guidance on how to put together the light sources for my project from people who know what they're doing...so far I've pretty much destroyed four ebay laser pointer pens working things out and have realised I could do with some help from people who know what they're doing!

Fwiw, my project is based on having two light sources a fixed distance apart (I'm told green lasers seem to work well in the murky waters I dive in). One diver holds this 'target' at one end of a line and another holds a device with a camera, pressure sensor and compass at the other end. The camera records the image and some software on a raspberry pi calculates the distance based on how far apart the light sources appear to be (further away they look closer together).

I'm all good with the software/hardware for the camera end of things and have it all housed in a big old diving torch. The target is proving more tricky - I have a big torch that can house the lasers (it is about 8cm/3" across and 13cm/5" deep), but choosing modules and building electronics to go with it is harder than I expected. Ideally I want the lasers to flash say every 0.5 seconds or so because that makes it easier to identify them in the software (in a dark cave divers bring a lot of light and I expect our torches might confuse the software...I am writing it so it is fairly basic!)

I've had a look around the forums and it seems like most people are building lasers that would be much more powerful than I expect I'll need. I'm guessing I want something <1W but don't know for sure until I get in the water and try it out.

Grateful for any pointers (see what I did there?) on modules, drivers or the electronics for the flashing control.
Thanks

 

[Snecho]

It's a cool project for sure, but aren't there already ready built devices for diving that measure distance? They use two converging beams that have a set angle that calculate the length of something based of where the two dots land.

Maybe your application is for extremely tight spaces?

 

[minimalmayhem]

It's a cool project for sure, but aren't there already ready built devices for diving that measure distance? They use two converging beams that have a set angle that calculate the length of something based of where the two dots land.

Maybe your application is for extremely tight spaces?

not super tight spaces...I've not seen or heard of the devices you mention, but to be honest, even if they do exist...where's the fun in buying one when you can spend hours learning image recognition software development and burning your fingers as you relearn how to solder ?
The only other devices I've heard of are one that is attached to the line directly and has a kind of roller that spins as you swim forwards (number of revolutions → distance) and someone who built something with a propeller to measure distance.