Fully functional waterproof laser - with gifs!

[sellersmd]

So I started a thread in March of this year about building some waterproof laser hosts to take scuba diving.

To recap the previous thread, I bought a couple of waterproof flashlights built for scuba diving, gutted them, mailed them to mrcrouse to custom mill a couple of heat sinks, and then bought diodes/drivers/lenses from DTR and called it a day.

In May, I took one of my new toys to Playa Del Carmen, Mexico to test out in the Caribbean. I got scared of a leak killing a nice laser, so I opted to take the guts out and dive with the empty host just to be EXTRA sure that the host wouldn't leak. And it didn't. So that is good. Didn't get to test it, but I got some peace of mind out of the deal.

I don't get to dive terribly often (due to both work and living in west Texas). I did, however, get to dive yesterday, and was brave enough to take a laser down with me. I was diving in Balmorhea State Park in Balmorhea, TX. It is a spring-fed 'lake' with a maximum depth of around 20 feet and a year-round water temperature of about 62 degrees F.

First things first. Air temperature was 46 degrees F and it was just COLD all around, so I didn't dive for too too long. But I did manage to use the laser. It did not leak, and it worked brilliantly. I was really surprised to notice that fish chase the dot readily.

WARNING - LARGE, SLOW LOADING GIFS BELOW. CLICK LINKS FOR FASTER LOADS

In full sun, the dot is visible, but the beam is not:

Link to gifv: DIY Scuba Laser- Full Sun

In the shade under a setting sun, however, you can see a visible beam:

Link to gifv: DIY Scuba Laser - Setting sun

Sorry for just 2 poor quality gifs. Between the cold water and trying to scuba dive, hold the camera, and use the laser all at the same time, it is the best quality I could muster.

Long story short, I am calling the project a success, and may well be building more in the future. It'll also be a nice laser to use on land in times of bad weather. I'd be happy to answer any questions anyone has, and thanks for taking a look.

 

[Ricker]

Wow, that's too awesome, bud! +1 to you! I wouldn't think the fish would chase the beam/dot around either! It's just like shooting fish in a barrel... with a laser.

 

[Laser Chick]

Very nice, thanks for posting this!

 

[HTPOW]

wow so amazing,Is the fish will chase the laser ? Lasers can be used to attract the attention of the fish and then catch fish?

 

[RedCowboy]

Very interesting, those fish must think it's something to eat.

 

[Koff]

Lead them to fish trap. hehe

 

[Benm]

This is kinda nice. Personally i keep it to snorkeling where a waterproof laser could be nice, but i have numerous fans who are into scuba diving, who might be interested in something like this.

I wonder how it will fare when you get down to typical scuba depths of around 100 feet. Many things designed to be waterproof in pool depths don't do that well with repeated exposure to more depth, but if this does, it would make a pretty cool thing for divers.

What the exact effect on the fish is i don't know (guess they aren't catfish), but i doubt i would seriously harm them.

 

[sellersmd]

This is kinda nice. Personally i keep it to snorkeling where a waterproof laser could be nice, but i have numerous fans who are into scuba diving, who might be interested in something like this.

I wonder how it will fare when you get down to typical scuba depths of around 100 feet. Many things designed to be waterproof in pool depths don't do that well with repeated exposure to more depth, but if this does, it would make a pretty cool thing for divers.

What the exact effect on the fish is i don't know (guess they aren't catfish), but i doubt i would seriously harm them.

Thanks for the kind words. In regards to depth, the waterproof flashlight I started with was rated to 50 meters (164 feet) and was intended for recreational scuba diving. I didn't do anything to impair the structural integrity of the host, so I have no qualms with taking it down to 100 feet. My depth tests in Playa Del Carmen were down to 70 feet. I didn't have the electronics inside, but I did have some paper towels, which should have felt at least damp after 3+ hours of scuba diving if any water was getting in.

In regards to effects on fish, I don't have strong evidence either way, but it didn't seem to affect fish at all aside from getting their attention. My main use for it will be pointing out things to my dive buddy, so I think it will work perfectly for that.

I CAN NOT WAIT to take it on a night dive. Although I am a bit scared of what critters it might attract in the ocean at night.

 

[Ricker]

I was going to say that but forgot, the biggest issue in scuba diving is pointing something out to a partner, that will be so darn nice to have a pair for that exact purpose!

 

[sellersmd]

I was going to say that but forgot, the biggest issue in scuba diving is pointing something out to a partner, that will be so darn nice to have a pair for that exact purpose!

That is exactly why I built them - I dive with my girlfriend, and we'll be cruising along and I will see something neat and try desperately to point it out to her. I usually get shrugged shoulders as a response. I'm hoping with this I'll have more luck.

 

[Lifetime17]

Hi,
Now that's impressive you are actually herding those fish with the beam. You did very well multitasking my friend. This is a refreshing thread under water laser vids with wildlife. You could probable herd them into a container if you wanted them for an aquarium. Just a thought , but the concept of a waterproof build is awesome.Post a thread of the build, like you said it would be prefect for camping or emergency use in inclement weather. WOW !!

Rich

 

[Benm]

That is exactly why I built them - I dive with my girlfriend, and we'll be cruising along and I will see something neat and try desperately to point it out to her. I usually get shrugged shoulders as a response. I'm hoping with this I'll have more luck.

I bet you will - it's pretty great for pointing things out under water where you cannot communicate verbally.

I'm not really sure how visible it will be under practical conditions, and if diving at greater depth i'd actually suggest using a red laser instead: As the water above you filters out more and more red light, the overal image just becomes more blue. Red would stand out more in such circumstances.

On the other hand, when you get deep enough in murky water to lose all red daylight you'd probably have a torch on you which could be used to point out things... though that would probably not work for finding a pygmee seahorse in a shitload of similarly colored coral

 

[sellersmd]

I bet you will - it's pretty great for pointing things out under water where you cannot communicate verbally.

I'm not really sure how visible it will be under practical conditions, and if diving at greater depth i'd actually suggest using a red laser instead: As the water above you filters out more and more red light, the overal image just becomes more blue. Red would stand out more in such circumstances.

On the other hand, when you get deep enough in murky water to lose all red daylight you'd probably have a torch on you which could be used to point out things... though that would probably not work for finding a pygmee seahorse in a shitload of similarly colored coral

I toyed back and forth with what wavelength and output to use for quite a while. I agree with you that reds are the first to go as depth increases, so that color likely would have stood out the most at greater depth.

I guess the reason I chose the 520nm is due to 'perceived brightness.' Essentially, given equal intensities, the human eye perceives green as brighter than other wavelengths. I got that information from Characteristics of Visual Perception: Brightness.

I also wasn't sure what output I wanted, as I knew I wouldn't have access to safety glasses underwater. I opted for around 100mW.