Sunday, February 23, 2014

Violet Blue Laser Pointer Build Part 4

Violet Blue Laser Pointer Build Part 4

Finished Product:

At last, we have a handheld, easily portable, blue/violet laser pointer. It runs on a single nine volt battery, has tunable output, a momentary switch for easy use, an external SPST switch to keep it from lighting up your pocket, an internal master power switch to make extra sure, and it's all in a very attractive black metal case!

Tuning the collimator was both easier and harder than expected. To dial it in, you simply move the threaded lens assembly around until you get the finest dot the optics will allow. Sadly, it's not the best collimator, and beam divergence is quite obvious at a range of fifty feet or so. Better collimation would do wonders for this unit, and might even yield enough light concentration power to pop balloons and light matches.

The blue beam is clearly visible in the night sky, and pointing to stars is easy and fun with this laser. Even with the beam convergence issue, the dot is remarkably bright at several hundred feet, which is plenty far to point out stars, tease animals, and play with at concerts.

When I light it up in public places, it's fun to watch people look around for the source. If the area is dim at all, then the visible beam points right to me, so keeping it on continually is a dead giveaway. In daylight, its source is much harder to find, but it's also a little less noticeable in the first place, with ambient light washing the dot out a little. Green lasers are excellent for this sort of fun as well.

Second Thoughts:

Obviously, I'd like to have been more cautious with our first Blu-Ray laser diode. Doing it right the first time would have saved us at least two weeks and $50. Still, this was a relatively inexpensive project, and if I hadn't been comfortable with the time and monetary investments, I wouldn't have chased it in the first place. If you take my experience in counsel and preserve your own diode because if it, so much the better.

These blue lasers are really, strikingly bright. I feel constrained to warn again that eye safety precautions are a must. Eric and I were careful never to power the laser unexpectedly, and to always indicate to one another where it would be pointed. When even the reflection of the dot on the wall seemed unreasonable to look at, we didn't. We could have been more careful by wearing laser-specific eye protection, and perhaps we should have, but we didn't want to spend more money on goggles that we might never use again. It probably goes without saying; if you build one of these, keep it away from kids and others with poor impulse control.

Eric and I missed out on a big opportunity to make this thing cooler than we had at first imagined. A few days after our Blu-Ray laser project was complete, I was cruising Ebay to see what kinds of blue laser items were available there. I found a seller who apparently orders in PS3 Laser Lens Assemblies, extracts the diode, and then sells the diodes on Ebay as his own product. The photo in his auction exactly matched the appearance of my diodes still in their metal mounts from the PS3 lens assembly, and I was curious. When I emailed him asking if it was a diode from a PS3 Laser Lens Assembly, I must have hit a nerve, because he never answered. I did find his website through his auction page though, and here it is, Indigo Lasers (Defunct Link removed. -Ed).

I'm not linking to Indigo Lasers to shame him in any way. I think that it's great to see the entrepreneurial spirit in action, though he could be a little more forthcoming about his parts sourcing. I'm linking because he's created some interesting technical schematics of the laser diodes. This page in particular (also dead link -Ed) piqued my interest, because it shows the pin outs for all of the lasers in that part; Blue, Red, and Infra-Red!

Had Eric and I realized that our diode was capable of emitting three laser colors, we surely would have incorporated more than one into our circuit, and given at least the red one a switch. As it stands, we can go back and rework it, but it may be wisest to leave this one as is and start a new one for a more integrated laser experience. We can make a better go of it the second time, and then we'll have two!

I would like to post a snippet of Indigo Laser's pin out map, and doing so would surely be within fair use guidelines, but the fellow running that site seems secretive enough and already worried about his documents being stolen. (He's overlaid a clear photo over the real one on the site to discourage people taking a copy. Didn't stop me, shouldn't stop you.)

Instead of posting part of his schematic and sending him into Red Alert mode, I'll simply describe the pin out here. Lay the diode on a flat surface in front of you, with the diode's pins facing you. The perimeter of the diode is round, but it has a flat edge. Roll it so that the diode's flat edge meets the flat surface and lays still. Now you're looking at the five pins like a pentagram, with one in the middle at the top. Number the pins 1-5, starting with the bottom left corner and moving around the pins clockwise.

Pin 1: (Bottom Left-Hand corner) - Infra-Red Laser +
Pin 2: (Left and Center) - Blue Laser +
Pin 3: (Top Center) - GROUND -
Pin 4: (Right and Center) - Red Laser +
Pin 5: (Bottom Right-Hand corner) - Photo diode (used for power regulation when connected)

Final Thoughts:

This was a really fun project. I've known Eric for something like fifteen years now, and I was actually glad that I wouldn't be able to get it done on my own. When we finished the project, we took our wives to a nice dinner. We've both got great wives. (Hi honey!)

Speaking of wives, Crystal was reading through one of my drafts of this write up, and she said that it seemed that not many people would be able to pull this project off. I really have to disagree with her there.

For one thing, Eric and I really made it harder than it had to be, both by designing our own circuit, and also by letting things get out of hand with our first diode. Sam's Laser FAQ is the definitive online resource for all things laser related, and Sam's even got pre-designed circuits you can build straight from given specs there. (There's also a special section at Sam's that's all about Blu-Ray diodes that I seem to have missed when I was researching. Or maybe it's new?) And as for the power snafu, Eric and I really knew better. We even joked while we were doing it that it wouldn't be a surprise if we fried the diode. Sure enough, we did.

If you're thinking about building your own blue laser pointer, I would suggest the following:
  • Know how to solder. This isn't a hard project where soldering is concerned, but you should at least know how first.
  • Don't worry about making yours look like mine, or anyone else's. Focus on the parts and objects around you that could be a case, or a switch, or whatever.
  • Find a friend who's interested and have fun with it. Hopefully, your friend will be able to help out when your skills aren't quite where they could be.
  • Take your time. No need to get sloppy and ruin your hardware.
  • Follow the tips above about not burning out your diode.
  • Don't forget that your safety is paramount. Don't be careless.
Last of all, have fun with this great project.

No comments:

Post a Comment