First laser build, advice welcome

[firelight]

Hello all, I'm looking to construct my first laser build. I'm new here (obviously) and I've done quite a bit of looking around on the site to see what other people are doing. I was thinking I would start my building career with a 405nm laser in the 100mw range. It seems like a reasonable place to start. :yh:

I've seen people do various things and start with various materials, so I wanted to ask if anyone had some opinions about the various options I have, I will elaborate below...

I have seen there are plenty of units on ebay with the lens and diode already set in the module with the driver attached, basically only needing a host. However, I would like to buy all the parts individually and assemble the diode, module lens, as well as do the soldering and such on my own. This way, if (or when) I make a mistake, I can do so with a relatively low power and cheap component, rather than ordering something that is already assembled, and then breaking an expensive component when I try making something a bit more powerful in the future.

On to the questions, and thank you for staying with me through this :thinking:

1) is there any benefit to harvesting a diode from a sled like this one: PHR-803T Laser Sleds for 405nm Laser diode Extraction | eBay
as opposed to just ordering the diode by itself, such as this one:
New 100mW 405nm Blue-Violet blu-ray Laser Diode | eBay

2) I'm seeing a lot of drivers for the 405nm lasers with push button on/off switches like these: 405nm 100-300mw Laser Diode Driver Reverse protection | eBay
if I chose to set the module and driver in say a flashlight host that has it's own on off switch, is it best to just secure the push button on the driver down permanently and then use the host's on/off switch? Alternatively, is there someplace I can get a driver without a button for a 405nm 100mw range laser, or perhaps plans to build one from parts?

3) Heatsinking. There seems to be a lot of conflicting information out there, or at least it seems that way to a newbie like me, so will I need a heatsink for a 100mw laser? I don't plan on running the laser for long periods of time. Is there any "rule of thumb" for when you need to start considering using a heatsink?

4) Host. I have seen several different hosts for low power builds, which are just hollow laser pointer shells on ebay. I realize these offer no room for heatsinks. I have also seen many people make their own custom heatsinks for hosts that were originally flashlights. I have access to a lathe, and if/when I make a more powerful laser I will use a larger host with a custom heatsink, but for now (assuming I continue and make a ~100mw laser) do I need a larger host, and custom heatsink, or is a narrow laser pointer host suitable?

Thanks again for all your help, any comments/advice would be greatly appreciated, if not, I suppose I'll just venture off and try it myself, I guess at some point you just need to jump in and go for it.

As a pre-emptive message: I know many veterans are concerned about newbies not taking safety seriously. I I have saftey goggles for the proper wavelength, and if I move into other colors I will get suitable protection.

Thanks again! :thanks:

 

[Wolfman29]

So I will do my best to answer all your questions in order! But first, welcome to the forums! We were all noobs once, I was a noob just in November or something like that. Anyway, it's a fun hobby!

1) Generally speaking, harvesting a diode from a sled makes the process that much cheaper. I know on HighTechDealz (a reputable, Texas-based laser store, which is great and cheap) that the harvested diodes are always 5-8$ more expensive than the sleds in which they come. That said, there is a reason they are more expensive: there is always a chance of killing a diode during extraction, so having it pre-extracted costs money.

However, I would always suggest extracting them yourself, as long as you think you can do it. I have a crappy Radioshack soldering iron and just everyday pliers, etc. and I can do it just fine. All it takes is a bit of finesse and precautions.

2) In the event that you buy a driver with a push button already on the board, well... I wouldn't buy it. It's not necessarily bad, I just don't like that style, and I usually prefer to use the ones that don't have that. However, some people *do* like those, and so, if you don't want to use the button, just heat up the solder joints attaching the button the board with your soldering iron and remove the button by desoldering it. Then, just bring the two solder blobs from the desolder and there you have it - always on. That way, you can use the flashlight button switch instead of the driver one.

Regarding building your own drivers - always a brilliant idea. However, if you want to make a hand-held, you are going to need to understand the inner-workings of the LM317/LM1117 driver well enough to make it small enough to fit in a host. Further, you can just buy and do some solder modifications of other drivers like jib77's LM1117 driver (change out the resistors to be two 5.5Ohm resistors or close to that instead of two 1 Ohm resistors). You can also buy boost drivers, but those are a bit more costly and are a bit harder to configure and set, too.

3) Yeah. I know what you mean. I *always* have a nice heatsink for my builds, though. I make my own heatsinks (WITHOUT A LATHE?) out of copper or aluminum rod stock. Even low-powered diodes heat-up, and they will need some heatsinking, even if it's not very much. But, the more the merrier. All more heatsinking will do for you is extend your possible duty-cycle (my ~80mW 405 build has essentially no duty cycle).

4) I wouldn't suggest using a hollow laser pointer shell from eBay for a first build. First of all, they offer very little room for heatsinks, as you mentioned. Secondly, they make for very difficult builds because the components are so narrow and hard to get to. Third... why get a pen laser when you can have an awesome, beastly, club-you-over-the-head laser TORCH? Those are more fun, offer more room for drivers and heatsinks, can run much longer, and they just look cooler (in my opinion).

I would really suggest using something the Cree Aurora C6 host if you can - it's a popular host, has lots of internal room in the head, and has enough room for two 16340 li-ion batteries (enough to give you the voltage necessary for even a home-made driver).

Anyway, if you have any more questions, go ahead and ask

And once again, welcome to the forums!

 

[firelight]

Wow! Thanks for the response, that does wonders for clearing up some of my concerns. I just want to get familiar with the process of building something from parts, so if and when I move on to bigger (and pricier) stuff I can avoid expensive mistakes.

Yes, I think you are right about the host, I was just thinking modifying a flashlight might be a little troublesome, but I'm not stranger to hacking and bodging until things work out. I was considering making my own host for a higher power build down the road, aluminum rods aren't that expensive, and If I milled it myself, then I can have exactly as much space as I want or need. Besides which I figured I could just set the entire module in one big chunk of aluminum in the front of a custom host, which ought to suck out a lot of heat.

I only have two more questions though, first, you said

I make my own heatsinks (WITHOUT A LATHE?) out of copper or aluminum rod stock

Do you just buy some metal rod and drill out an appropriate size hole for the module?

Second,

You can also buy boost drivers, but those are a bit more costly and are a bit harder to configure and set, too

I've read of people using different types of drivers (boost, micro, ect) but I'm afraid I don't really know the difference. If you would be so kind, could you elaborate a bit for me? or point me in the direction of a thread that already explains it?

Thanks again for all your help, you are a great endorsement of the welcoming and helpful nature of the forum.

 

[Wolfman29]

Alright, to your fir4st question:

I basically bought copper rod stock and drilled a hole in it, yes (using ever increasing bit sizes so it's an easy job). Then I put the heatsink *on* my handdrill (around a screw, through that hole) and then put a bolt on the end... that way, I have a makeshift lathe! I then use a file and a dremel to get it down to size for said host. Finally, I use my handdrill and a tap to make a set-screw so everything fits securely.

Regarding drivers....

Micro drivers are sort of just a style or nickname. They don't actually mean anything, aside from being small, I suppose. However, there are three main types of drivers that we use.

The first and the simplest is the linear driver. The linear driver limits the current by turning the remaining power into heat and then dissipating it. Unfortunately, these require about 2.5V overhead in voltage, in addition to the voltage required for the diode. So that means that you need a lot of voltage... which is alright, if you are using multiple cells.

The second most complex and fairly common is the buck driver. The buck driver is actually very efficient. What it does is converts voltage to extra current (via Ohm's Law) so that the current draw of the power source is lower than the current output, but the voltage source must have a higher voltage than that required by the diode. Generally, these are 80-95% efficient, which is pretty damn good. I use these all the time, because most of my builds are two-cell builds. It makes for extraordinarily long battery life.

The third, and most complex, of the drivers we use around here are boost drivers. Boost drivers essentially "boost" the voltage to a higher level so that the voltage required for the diode can be met. That means that, if you have 2V of input and your diode requires 4.5V to run, the boost driver will draw extra current from the source and convert it to voltage (via Ohm's law, again). This means that the current draw on the source is higher than output, but the voltage draw on the source is lower than output.

I guess there is a fourth: the buck/boost. This is our favorite type, because it means you can use any voltage source and run efficiently! It just combines the effects of a buck driver and a boost driver, meaning it will draw current in whatever proportion is necessary to maintain the output voltage/current required.

And no problem. I got lots of help when I was new, I figured I would pass it along.

 

[Morgan]

If you mean, "Microboost", this is a boost only driver manufactured by a member called Dr.Lava and was specifically tailored to drive high power bluray diodes up to 12x, (circa 700mW max), "Flexdrive", is also made by Dr.Lava and is a buck/boost driver well suited to most other diodes. Both are specifically designed for very well regulated outputs without even the tiniest of voltage spikes to keep your laser diodes shining brightly. You may have seen others mentioned but these are dedicated high end laser diode drivers.

There are other drivers available but the most important thing, regardless of which type of driver you go for, (linear, buck, boost, buck/boost... ), is that it is properly regulated. Many of the drivers you can buy online, (particularly from general flashlight sellers based in China), are really designed for high power LEDs and can put your laser diodes at risk. The use of these LED drivers has become more common since the availability of the extremist laser diodes that really don't seem to be affected by any sort of abuse, (read 445nm here!), but they are not the best type to get started with.

My advice would be to start from first principles and build yourself a simple linear driver like the DDL, (a LM317T based driver), and go from there. It may be tricky to fit one into a flashlight host, (and power it!), but it'll get you a laser that works well as a test bed. Check out the guide in my sig for useful info and a link to the DDL instructions. Heatsinking a 100mW bluray LD built into an Aixiz module, for example, would always be advised by most but not a deal breaker if you observe a sensible duty cycle.

Enjoy your stay with us too and keep us updated with your building. We love pictures here!

M


@ Wolfman29 - Which are the buck only drivers you refer to? Are these an internet purchase? I've been out of touch for a bit so I may have missed them.

 

[Wolfman29]

Yes - they are LED drivers, in fact. I am no believer that we can't use LED drivers for our LDs. All you need is a cap on the LD's pins and you are ready to go. In fact, I have a great LED driver that I have running my PHR without a cap and it is extraordinarily stable (has a built in tantalum). I get these kinds of things from DealExtreme and DinoDirect.

 

[firelight]

Also, open to anyone, I've seen some information on "test loads" mainly with higher power lasers. What are test loads, and when should they be used? Thanks again for understanding my general nooby-ness. :thinking:

 

[Wolfman29]

Test loads are essentially laser diode simulations so drivers can "set." Because laser diodes are very fragile things, it is best not to use an untested driver on a laser diode. As such, we stick laser drivers to test loads, which are comprised of a certain amount of rectifier diodes (such as 1N4001 diodes) and a 1 Ohm resistor in order to test 1) whether or not the driver is outputting enough current in order to power the diode (we set up the number of 1N4001 diodes so that the Vftotal is equal to that of a LD we are simulating, i.e. 4x 1N4001 diodes has about 2.8Vf, which is close to a red LOC diode) and 2) so that we can make sure that our driver is outputting constant current that is low enough for our diode to handle.

This way, the diode is safe when we plug it in! So we *always* use test loads.

 

[Morgan]

Hmmm, I'm not so sure I trust these LED drivers myself. I haven't heard any reports of failures with the 445s, (but then again, I'm not sure just what you have to do to kill one of those! Time was when the mere mention of direct driving from a battery would have you instantly flamed!), but if you want to risk a delicate and pricey 12x bluray then be my guest. Personally, I won't be running my expensive LDs with them. Yes they may work but in my opinion, you get what you pay for. Having said this, the community experience will show if these drivers are any better than they used to be.

Each to their own though... Variety be the spice of life.

Think I'll check out the, "Driver Compilation Thread", for a catch up...

(Testloads are also covered in the guide in my sig. )

M

 

[firelight]

Hello again, so I have some updates. I've ordered some parts, and I have some additional questions. I ordered a 6x br laser diode rated at around 200mw, Threshold current is listed as ~33mA(~3.6V) whereas operation voltage is ~5.1V @ 190mA. I also orderd a rkcstr microdrive, and a rkcstr test load kit. I plan on milling my own heat sink depending on the host I get, but that's where I'm stuck. I see a lot of other people have built BR lasers with a host that supports a single 3.7V Li-ion battery. However, as stated on the rkcstr web page

Input voltages of at least 3V up to 15V, where your input must be at least 2.25V + Vf of your diode

. So, if I am correct in my thinking, the diode has an operational voltage of 5.1V, which means I should input around 7.35V which would mean I should use a host that can support 2 3.7V Li-Ion batteries?

First of all, please go over my thinking, and point out any flaws you see please :thanks: Secondly, if that all seems well and dandy, does anyone have some advice for a good host that will hold 2 batteries as well as an aixiz module set in a custom heatsink (I can make the heatsink as big or small as it needs to be to fit the host, just so long as I can fit the module, driver and two batteries in it.

Thanks again! :yh:

 

[rhd]

Your understanding is correct. The rkcstr driver is linear, and has a "dropout" of 2.25V. So you need to supply it with (basically) 2x lithium ion cells.

If you're making your own heatsink, you've got all the flexibility in the world. A good trick is to search for 18650 flashlights on cheap chinese gadget sites. Generally, anything that can take an 18650 will take 2x 16340 (cr123) batteries.

Good luck!

 

[Wolfman29]

Yeah. WHen people build BRs with a single cell, they have to use boost drivers.

 

[firelight]

Thanks again, and one last question for now...
The V3 microdrive has a max current output of ~440mA. I don't plan on pushing it all the way to it's limits but if I'm running it at ~7V input should I be thinking about a heat sink for the driver, and if so, what is the best way to set the driver in a heat sink? Again, I do have access to a lathe and scrap aluminum as well as rotary tools drills sanders grinder ect, so making most any shape heatsink isn't really out of the question.

Thanks again for all the help, it's been great so far, I would definitely be doing a lot more (potentially costly) trial and error without everyone's help. :thanks:

 

[Wolfman29]

For that low power of a build (not *that* low power, but not insanely high, either), heat sinking of the drive is only slightly necessary. What I would do is find where the main IC and the main resistors are on that driver (I am not familiar with that driver, so I don't know), get some scrap aluminum to fit over them (about two or three mlilimeters thick?) and then Arctic Silver them to the IC and the resistors. That will keep it sufficiently cool for respectable duty cycles.

 

[123splat]

Bump, just to subscribe to the thread. Lots of good info here in plain, simple terms, along with links to other very good info.

Welcome and good luck Firelight. You are in good hands.