@ kevinmassey
if your using it for diving you might wanna pick a color more visable than 405nm. i would use green just cause the beam would be crazy bright and you probly could see the point and you can also get keychain greens that run off 1 AAA
Agreed. I would also pick something less than 110mA because I wouldn't want to dive wearing safety glasses either.
@ MECHANICal engineer
Hey Awlego,
I have had the same thoughts about this build as you. My purpose for an underwater laser would be to mount it to my speargun for diving. I can't find any build on this site that uses any depth-rated host.
First off, I don't know your uses for the laser, but 5mW (especially red) ain't really going to produce a visible dot underwater in the daytime unless you are within 5' or even closer. You are going the right route by choosing blue. As kevin stated, green may be a better choice since it really stands out against a blue (ocean) background. Our eyes are able to spot bright green very well underwater. Here is a chart for absorption. This kind of shows how crappy a red laser would be. For distance, light blue in open ocean and green near the coast. For overall- my choice is green.
Note: The depth of the water doesn't matter, it is is distance from the laser to the object. My diving budies couldn't understand this because you don't see reds past 5'.
To answer your question - the host you are using is similar to a light I have used for lobster diving in the keys. The switch may give you some problems contacting like mine did, but try and see. Some of my friends have used that light for years. For underwater use, the plastic housing shouldn't melt, but the lens may be plastic (like mine was). I am not sure how long lasting a high power laser would be going through it (leaving a burn mark?), but other people can answer that if it's plastic. These are some hosts I have looked at for this build.
Just FYI on lasers with fish, they sometimes freak out when they see one with some high mW's. So you don't want to put one on a jewfish or shark unless you want some real excitement underwater!
If I was actually diving with it, I would try to use a green 5mW module. This is because, as you stated, green would be the most visible. I wouldn't want to used a high powered module for the sake of my eyes. I don't think safety glasses would fit under my scuba mask, and I doubt anyone makes a laser scuba mask. As for pointing at fish, I think this would be a bad idea... I follow the "look, but don't touch" diving philosophy
That's different of course if you're fishing using it for a speargun.
Now that I've replied, I'll update my progress:
So while waiting for my blu-ray, I found a cheapo red laser in a drawer at my house and decided to take it apart. After extracting the diode, battery, and switch (no driver??? see note) I made a trip to Radioshack to buy a reed switch. They didn't have a reed switch, but they did have a reed relay, which is basically the same thing, only with a coil wrapped around it so the switch could be triggered electronically as well as physically.
I soldered the diode to the new switch and then attached the switch and the other side of the diode to the battery. The result is a laser that turns on whenever a magnet comes near the reed relay. I superglued a small neodymium magnet to the inside part of the physical switch on the dive light, so that it comes near the relay when I flip it to the "on" position. I put the flashlight all back together and voila! it worked! I promptly took a hot shower with lots of steam and tested my new waterproof laser. It worked great and even the far less than 5mW red beam was very visible in the steam.
My only complaint with the setup is that the beam power flickers. I believe that this has something to do with the reed relay. When I used a normal momentary switch to test my soldering connections, the power was stable. I think that, being a relay, it wasn't really designed to be used as a normal switch. Something is odd, but I can't really figure it out... sometimes the power is stable, other times it flickers. Whatever the case, it definitely turns on and off with the small magnet coming close to the switch, and as a proof of concept I am satisfied.
I plan on buying a true reed switch sometime soon and seeing how that works.
Also, I tried using various strengths of magnets, so it's having too much or too little magnetic force on the reed relay.
***Note***
This laser came with no driver. It uses a CR2032 battery, which according to wikipedia has a relatively low stable current. Is this just a bad design in a cheapo laser pointer, or are they using the special battery so they don't need a driver? Anyways, for the sake of my build, and since it's a cheap laser I don't care about, I will keep their circuit
If anybody wants pictures, let me know and take some when I get a chance. (though there won't be any of the beam as, while the laser is waterproof, the camera is not
)
-Awlego
