Violet Blue Laser Pointer Build Part 2

Violet Blue Laser Pointer Build Part 2

Oh, one more thing:

Your visual safety is the most important factor to consider when undertaking a project of this kind. Please be cautious around lasers, and never allow a laser beam the remotest possibility of passing near or into an eye. I strongly recommend reading the "Laser Safety" portion of Sam's Laser FAQ. Also, parts of this project involved cutting and grinding metal, both of which create flying metal shards. Eye protection when operating cutting and griding equipment is an absolute imperative. 

Further, the post, posts, documents, text, photos, and any other media that are part of this series documents only my own project, and should not be regarded as advice to you. You undertake any project completely at your own risk. 

That said, here we go.

Project Execution, Take 1:

The PS3 Laser Lens assembly shipped from Monaco, of all places. It took far longer to arrive than I had anticipated, and the company I ordered it from was unresponsive to my requests for updates. I was literally one day from filing a charge back on it with my credit card company when it arrived.

The nondescript white box had me a little nervous at first. How could I know that I actually had a Blu-Ray component here? I would just have to carry on and find out when I power it up. But I couldn't power it up until I had it disassembled.

The lens assembly cover came off easily, and it was neat to see all of the laser lenses arrayed inside. Some of them were mounted on coils that could be moved around with small magnetic braces around them (coincidentally, this is also how the armature in your hard drive moves the read/write heads around on the platters).

The laser diode can be seen on the far left side of this photo, sitting horizontally with its soldered metal brace being the two metal points at the far left of the assembly. The laser is aimed through an initial lens block, and then through a splitter block, where the beam is apparently divided, perhaps by wavelength frequency (beam color).

The sheer number of lenses in this assembly impressed me. I've harvested laser diodes from CD burners and DVD drives, and they usually have very simple lensing compared to this. I suspect that blue lasers being a relatively new technology, the diodes aren't yet advanced enough to give quite the right beam properties straight from the component, and the beam needs a lot of work before it's ready for use in reading media. Thus, the extensive lensing.

It seemed to me that all of those cool lenses might be useful at some point, so when I got the diode free of the assembly chassis, I set the rest aside for more work at some future date.

This is a shot of the laser in its chassis, removed from the main lens assembly. The through hole ribbon cable connector was removed by locking a corner of the diode chassis into the desk vise, and then using copper solder wick to remove the solder and get the pins free so that the connector could slide off of them.

Below is a simple current limiting circuit we built to test things out with. We decided to start with high values of resistance and slowly ramp down to find where the diode would begin to light, and then lase. Once we had our ballpark, we would put a potentiometer on the circuit to help with fine tuning.

This was an early test circuit. I don't know resistor color bars on sight, but it doesn't really matter, because this one got the laser diode to glow like a dim LED, but it was nowhere near lasing. At any rate, it's good to see some of the breadboarding and testing process. You can add up the resistor values for yourself if you like.

This next photo is important to me, because it illustrates our first big mistake. What you'll see here is the laser diode, now removed from its metal housing, and put into the collimator sleeve (also metal, but thick and round). The original red laser was press-fit into the collimator sleeve. It was so snug in the sleeve that pressing it back out damaged the red laser diode can. I was loathe to damage the blue laser diode can by trying to fully press it into the sleeve, so instead I got it in as snug and straight as I could with my thumbnail and then hot glued it down.

Failing to press-fit the diode into the collimator sleeve was a mistake because the diode is intended to use the surrounding metal housing to sink heat away from itself. Without this precious thermal management, the diode is likely to fail even under normal operating power.

Further, the groove in which the diode is seated when it is press-fit is designed to align the diode can so that the beam travels into the collimator lens at as close to the ideal 90 degrees as possible. Simply placing it on the groove, or only pressing it in partway leaves the diode can both misaligned and physically further from the collimator lens than intended, leading to inefficient use of the light source and making beam tuning as intended impossible.

Our first powered tests produced only a dim LED glow from the diode, but as we ramped up power by decreasing resistance in our test circuit, we quickly brought the diode from a dim glow, to a bright glow, to dim lasing, to bright lasing.

We were so excited to see lasing that we turned off the lights in the room and took photos of the blue laser on a wall, but it's a classic "you had to be there" moment; the photos themselves are unspectacular. I won't post photos of a black background with a bright blue dot here for the sake of your sanity.

By this point, Eric had a good idea of the power range needed for the driver circuit, and he grew quiet as he thought about different design options. I left him to it and began work on the case for the laser.

So it's a black metal pen case. I pulled out the foam inserts and stared at it for a while to try to conceptualize the best way of mounting the laser guts inside. Once I felt I had an idea, I took the parts I had at hand and put them into the case to see if they'd fit as visualized. I didn't have a power circuit yet, so I arranged everything, leaving a big gap in the middle and asked Eric if he could commit to his circuit fitting there. He felt that the space provided would be ample, so I got to work on the cutting and drilling that the case would require.

You can see the dot I made on the case with a silver sharpie. To determine the right location for the hole, I simply popped in the collimator and lined it up with the natural front curve of the case. Where the lens ended up is where I needed my hole. I started the hole with a 1/16" drill bit, and then used an Irwin Unibit to step the hole up to 5/16" or so. I then used a Dremel grinding stone to deburr the hole.

Ergonomics are a factor with a laser pointer, so the momentary switch was next. Toward the front of the unit, next to the laser aperture seemed to make sense, so I made an outline for cutting to place the switch. The switch handily came with a collar (which, in a rare moment of brilliance, I had been smart enough to save), so all I needed to install it was the right sized square hole.

I traced the smaller, inner collar size onto the outside of the case with the sharpie and used that as my cutting template. I didn't worry too much about keeping it neat, as the larger, upper collar would cover any small sharpie fudges I made.

Dremel Note 1: Here I'll note that if you don't have a Dremel in your shop, you should really prioritize getting a good one for regular use.

My first "rotary tool" was a Black & Decker Dremel knock off, which I thought would be a good investment rather than a real Dremel because it took a VersaPak battery, along with several other tools I had at the time. Boy, did Black & Decker teach me a lesson. Dust Buster, yes. All other tools, no. They were right to kill off the VersaPak line, but it's too bad that I was suckered into buying any of that garbage in the first place.

Lesson learned. I buy quality tools now. My drills (well, one is an electric screwdriver) are DeWalts, and my Dremels are really Dremels.

Dremel Note 2: If you plan to do any kind of material cutting with Dremel's pressed sand cutting discs, make sure you keep a lot of the discs on hand. They shatter before they flex, and the shattering is just as soon induced by looking at them funny while in use as smashing them with a hammer. This makes eye protection doubly important, as cutting wheel chunks are relatively large, sharp and heavy, and the rotational speed launching them yields incredible velocity in flight. Goggles stop them easily enough, but you don't want your corneas doing that job for sure.

Part 3 Tomorrow!

Violet Blue Laser Pointer Build Part 1

(Editor's Note: This appeared on an Entrepreneurship Website that I used to own. It's been at least six years since Eric and I built this (it was posted in 2008), and we remain in touch, and this remains a treasured experience. Since the old entrepreneurship blog no longer exists, I'm posting this technical and fun, but very very long build log here at Phischkneght Extended. Probably with some very light editing. Also, since this post is huge, I'll post it here as three or four parts. Hopefully there are more to come. Cheers. Feb. 2014)

The end of the Blu-Ray/HD-DVD format war (Blu-Ray won, if you haven't been following along) signals the beginning of two changes:

1. For a very limited time, HD-DVD players will be available at prices far below commodity value. Dead, unsupported tech never fares well in the mass marketplace.
2. Over the long term, Blu-Ray hardware will follow the natural downward price curve that all consumer commodity tech shows over its life.

When Crystal and I got married in 1999, she wouldn't let me add a DVD player to our gift registry because she couldn't imagine anyone buying us a $500 video player. Today if you watch retail spaces carefully, you can buy a cheap DVD player for $20 or so. It seems extraordinary, but for a tech item, it's a perfectly typical curve. (For a much more radical example, compare 1999's 500MB hard drive for $150 to today's (2008)1TB hard drive for $200. That's 2,000 times the storage space for $50 more, less than ten years later.)
The practical upshot of the two points above is that from here on out, blue lasers are increasingly in the realm of economical hacking projects.

Practicality/Conception:

I make it my general policy not to get involved in the annual Black Friday madness. Once in a while I make an exception, like when I managed to buy The Orange Box at Best Buy for $25 last year (the cake is a lie, Mr. Freeman). 2007's pre-Black Friday hoopla included a press release from Wal-Mart that they'd be offering limited stock of a certain model of HD-DVD player for under $100. I was itching for a project at the time, and my green laser seemed to be getting a bit long in the tooth, so I decided to look into creating a blue laser pointer with an HD-DVD laser diode. 

The response of my fellow Mefites to the laser question was mediocre, but it did yield a link to this video, which, strangely enough, had been posted the same day I asked my question. It's a very cheesy video, and the creator of the laser pointer in it shows gross disregard for both his own safety and for the health of his laser diode. But the video did serve as an extremely useful idea seeder:

1. It confirmed to me that a blue laser diode could be harvested and used in a project.
   
2. It showed that the diode could be driven by a nine volt battery.
3. It showed that at its core, the project could involve a very simple power circuit (though the nice tuning regulated circuit we ended up with is much more complex).
4. It illustrated a source for the laser diode component that I had not (but should have) thought of.
5. It provided a pin out for the blue laser portion of the laser diode.
6. I was worried about beam collimation, and this video answered that concern very nicely, with a collimator hacked off of a separately purchased red laser.

I've criticized the video more than once now, and I should explain why:

1. The phaser casing isn't as portable as I wanted my final product to be. Oh, and it's tacky. I like Star Trek, but that's just not slick enough for me. 
2. The video talks about extracting the diode from the laser lens assembly, but does not illustrate how this was done. I found that it's not terribly difficult, but it is a rather delicate process at the point where the diode needs to be extracted from its own little mounting chassis.
3. The video didn't provide the pin out for the non-blue laser contacts on the diode (more on this later).
4. The video does not show how the laser diode is secured to the front portion of the collimator assembly. From the video, it looks as if it was done with hot glue, which would negate much of the heat sinking abilities of the collimator assembly, leading to the diode overheating and burning out.
5. The guy in the video uses one resistor in serial with the nine volt battery to the diode, never mentioning the value of the resistor or why he used that value.
6. Getting the collimator off of the sacrificial red laser was non-trivial, and it nearly ruined the red laser diode. Not such a big deal, but a mention would have been nice.
7. The video dialog did not point out that the laser was likely running in the top of its power range, meaning that it would be very sensitive to overheating even with proper heat sinking. My guess is that if his "laser phaser" has had much use at all, the laser diode is in the late stages of progressively burning out by now.
8. He makes no mention of eye safety where lasers are involved.

As mentioned in the above list, I realized that buying an entire HD-DVD box would be entirely unnecessary for sourcing a blue laser diode. Those active in the game console modding scene know that parts can be sourced for replacement for just about any current gaming system, including the PlayStation 3 (which of course, uses a Blu-Ray laser as its primary media reader). It seemed like such a no brainer, and I should have thought of it on my own. After heading on over to a couple of my favorite online console parts dealers, I found the PS3 laser lens assembly that I would end up buying.

Now that I knew that I could source the critical blue laser diode component, I began to get excited. I'd been seeing Sonar Blu-Ray pointers, walkthroughs on building your own (non-blue) laser pointers (Used to have a ref link to Magus Lasers here, but the site is dead and Google offers no replacement -Ed Feb2014), the ThinkGeek blue laser pointers, and even Wicked Lasers, (where, even today at this writing, you can buy the above Sonar Blu-Ray pointer for a ridiculous $2,000) for months by this time.

Now it was starting to look like my turn.

But first, I needed to make sure that I could pull off this project. Crystal was unlikely to let me spend $50-$70 on a blue laser diode if the odds weren't good that I could get the project off the ground.

Late Conceptualization, Preparation:

I'm mostly a real-world, practical use guy. My electronics theory skills are weak, so my first call was to my good friend, Eric Widdison. Eric walked away from Utah State University a few years back with a Master's degree in Electrical Engineering. Eric isn't that good at basic math, and he can't solder worth a darn, but I knew that he would be my go-to guy for this project. (I should mention here that Eric is a terrific sport, and his advanced math skills are superlative.)

My main concern for this project at this point was creating the driver circuit to power the laser diode. I knew that this part of the project would be critical to overall success. A bad driver circuit would fail to bring the diode to lasing state, burn it out quickly or slowly, or perhaps a combination of those. I explained the project and the need for help with the power circuit to Eric, he said that he felt confident that he could help me make it work.

With Eric on board, I ordered the PS3 laser lens assembly and the red laser mentioned in the Laser Phaser video for the collimator. I also spent a week or so thinking about the various components I had on hand and gathering up the ones I felt might be useful to the project.


Late Preparation, Early Execution:

Eric and I worked out a good night for him to come over and start the project with me, and on a chilly Tuesday night, we found ourselves at my work bench with all kinds of fun hardware at hand and no idea where to start.

We quickly decided to pick what our case would be. I had gathered several containers for the purpose, including Altoid tins, some other plastic mint cases, and a pill bottle or two. Most of the potential cases that I had chosen were determined to be too small for this project and had to be eliminated from the running.

We settled on a metal case with a foam insert...much like a fancy pen would arrive in. In fact, it's the case my green pen laser came in when I ordered it years ago. The case was a little larger than we felt ideal, but better too big than too small in this instance.

It was good that we settled on our case early, because we needed to begin thinking about component quantity, size, and placement right away. These were our main component criteria:

• A laser pointer should have a momentary switch. Easy to turn on, but the default state is off.
• It should also have a hard master switch that will ensure the laser is never accidentally powered on.
• It would be nice to have the option of tuning output power, possibly via a potentiometer.
• The power circuit we would build would have to fit inside the case.
• The battery would have to fit inside the case.
• The laser collimator housing (with the laser diode inside) would have to fit inside the case.

With those criteria in mind, we picked through my parts collection and found a momentary switch I harvested from the packaging that a dinosaur toy came in for my son a couple of Christmases ago, an SPST (Single Pole, Single Throw) switch from an ATX power supply, a nine volt battery with a power connector, and the collimator I had already purchased for this project.

With everything else assembled, I got out the PS3 laser lens assembly box, which had arrived that day, and prepared to begin work on it.

(Part Two will be posted tomorrow!)