Making my First Laser...

So, I've been interested in lasers for a while and I've decided to make a simple one for an interesting summer project. I'm no electrician, but I have messed with electronics a bit.

I've looked around on these forums (and youtube) but I'm not able to find a guide showing which each part does and how they work together. Maybe it's just me...

Help would be appreciated! I know most of you have done this for a while. =)

Thanks,
-Zachary

I've looked around quite a bit and discovered some very interesting information. I also have a couple of questions. So, here goes...

I found a camping flashlight that we haven't used in a while, so I decided to use it as a host for my laser.



I plan to use a lava drive, so I need minimal voltage for a red diode. I'm looking into Li-ion batteries that are 3.7 volts...so I would only need one right? That would mean I have more space for the electronics since I want to cut part of the flashlight off as shown here...



Is it a good design? Enough room for an Axiz module, diode, lava driver and the heatsink? I have a feeling it will because of the ability to fit everything in a pen host, but I'm still not sure because of the height room.

I'm not sure where I'm going to get the diode from...I don't feel like paying for one when I could probably get some somewhere around here. We have a broken dvd player, so I might just use that..or look on freecycle for some broken player/burners.

Next question...
I didn't understand which way to connect the driver to the switch to the battery. I searched for it using the search engine (yay!) and I found an answer on the last post of a thread called http://laserpointerforums.com/f50/how-do-i-install-switch-36046.html ...not sure if this is correct though. =/

Thank you for your help,
-Zachary

I'm not sure what you are trying to ask. A switch simply goes in series with the battery.

I understand...but what I didn't understand was where to place the switch. This article kind of confused me by saying that "the switch MUST be placed between the battery and the driver, NEVER between the driver and the laser diode!" While thinking about this some more, I figured that the switch placement inside the flashlight is correct. What about the space inside the host, is that sufficient?

depends alot on the power rating you intend. doesnt look like a host that will emit heat very well, so probably best to keep it <100mw. im sure its possible to fit a laser in there, but you may need or want more space since it's your first build. I have a class 4 laser running off one 18650, the question is whether you need as large a voltage, and if you tuned it down using a resistor or whatever, there could be large heat losses, and like i mentioned it looks like the rubber coating will keep alot of heat in.

So, you're saying that a 3.7 volt bat is to much voltage for a lava drive? I should just use a regular AA then, right? I understood that the lava drive emits less heat then the rkcstr drive.

-Zachary

Im not too sure about technicalitys like that, but i know what you put in must come out lol. If you put in that much power you need ways to disperse the heat that results. I dont believe the driver will actually affect the output of the battery, will it? Think they control current through resistors, not sure, but the excess energy used by a resistor gets turned to heat.

If you're talking about a Flexdrive from Dr.Lava then 3.7V is plenty to power any of the common diodes we use in pointers. It is a buck/boost driver that allows a diode to be powered if it requires more volts than the supply, in the case of BluRays around 5V, or less volts than the supply, in the case of typical reds, around 2.5V. So one 3.7V battery is plenty. What you need to consider is the capacity of the battery and how long it will last. Flexdrives are very efficient and do not heat as much as most linear drivers.

However, it is the heat from your diode that is usually the problem, not the driver. You need to ensure you have a heatsink of sufficient mass to absorb excess heat from the diode. If the mass is small, it will heat quickly and you will have to limit your, 'on', time with increased, 'off', time to allow the heat to dissipate. A larger heatsink will heat slower and lengthen your, 'on', time with reduced, 'off', time. This is called the, 'duty cycle'. Even a large heatsink will overheat in time if you keep putting energy into it and this is why PC heatsinks increase their surface area by having fins to help dissipate the heat to the air. Having fins on a handheld laser is not always practical and generally a moderate mass of aluminium or other metal is chosen and regulates the heat. A rubber insulated handheld laser will not be able to dissipate heat very well and is not the best choice. Not a problem for a first build though and choosing a conservative output is not a bad thing as you will be able to enjoy your photons for longer anyway.

For more information on the Flexdrive please read this thread - http://laserpointerforums.com/f64/lava-micro-flexdrive-driver-lavadrive2-fits-pens-22502.html

If you maintain a sensible limit on power, and you won't usually get too much out of a freebie harvested diode from a random DVD drive, then you probably don't need to worry about a heatsink at all. I would get your bits together; Aixiz module; diode; driver and battery; and build your setup without the host first to understand how it all goes together. Then you can think of how to fit it all into a host of your choice.

You will also need a a couple of other essentials. If you want to set your current correctly, (once you have a diode of known specifications), you will need a, "Dummy Test Load", (RCKSTR explains his here but you can make your own or search in the, "Pro Shop", section for more - Test Load KIT (AKA Dummy load, unassembled) - $5.75 : rkcstr.com, Micro-Drive and laser diode electronics)

... And above all things you will need eye protection that covers the wavelength you are working with. If you're not sure then ask on this but searching will throw up plenty of leads for research.

It's a great feeling when you first see the special light but remember that safety comes first! Enjoy...

I hope that gets you started...

M

Personally, I wouldn't choose to work with that torch as a starting-point - for a first build it's often better to start off with something tried and tested, and the rubberised feel isn't practical - it prevents heat transfer to the air. How were you planning on making the heatsink?

Many people start off with (and indeed, may continue to use) a laser built in one of these torches:

DealExtreme: $11.88 5W Luxeon Lumiled 3-AAA MXDL Flashlight

They are cheap, but for their price the quality is good, and they offer plenty of volume for the driver and heat-sink. Jayrob's builds are really impressive too.

If you want to continue and use that torch, you'll either want to make the heat-sink for yourself, or measure the space available and work out a shape, then send the dimensions off to be made elsewhere. A "cut through" diagram is really useful once you've taken the required measurements, and will help you work out how you're going to use the space available.

In terms of the electronics, I'm afraid Fonduman's understanding is limited. Drivers can do two things - they can take too much voltage, but the right current, and waste the extra energy as heat (this is a linear regulator - LM317, 1117, "Groove", Rkcstr, and one of Lava's drivers), or they can take a higher or lower voltage, at a lower or higher current respectively, store the energy, then release it in a controlled way to the diode (this is a buck, boost, or buck-boost regulator - LM3410, "Spark", One/two of Lava's designs). Both methods have advantages and disadvantages (main ones being cost, current limit, stability, efficiency and temperature).

The reason you have to cut the supply rather than the output on one of Lava's drivers, as you described in #4, is essentially that the driver's process of storing and releasing the energy in a controlled way is vulnerable, and when there is no current on the output, it damages itself.

Wow, that is very inexpensive! Thank you for the suggestion. =) I really liked Jayrob's build using this host:

DealExtreme: $10.90 C6 DIY Cree LED Flashlight Full Casing/Shell with Driver Pill (2*CR123A/1*18650)

I might use it, or use my original host, either way I was still wanting to build the heatsink myself. For the heatsink, I'm thinking of getting either a copper pipe or a thick copper rod and drilling a hole through it for the Aixis Module.

To create my own test load, I'll just use 3 1N4001 diodes and a 1 ohm resistor in series.

Thank you for all your help..feel free to give me more. =]

-Zachary

Tagg said:

Wow, that is very inexpensive! Thank you for the suggestion. =) I really liked Jayrob's build using this host:

DealExtreme: $10.90 C6 DIY Cree LED Flashlight Full Casing/Shell with Driver Pill (2*CR123A/1*18650)

I might use it, or use my original host, either way I was still wanting to build the heatsink myself. For the heatsink, I'm thinking of getting either a copper pipe or a thick copper rod and drilling a hole through it for the Aixis Module.

To create my own test load, I'll just use 3 1N4001 diodes and a 1 ohm resistor in series.

Thank you for all your help..feel free to give me more. =]

-Zachary

Click to expand...

I genuinely think you have enough for now! :na: Go play!

More pics as you progress please.

M

charliebruce said:

In terms of the electronics, I'm afraid Fonduman's understanding is limited. Drivers can do two things - they can take too much voltage, but the right current, and waste the extra energy as heat (this is a linear regulator - LM317, 1117, "Groove", Rkcstr, and one of Lava's drivers), or they can take a higher or lower voltage, at a lower or higher current respectively, store the energy, then release it in a controlled way to the diode (this is a buck, boost, or buck-boost regulator - LM3410, "Spark", One/two of Lava's designs). Both methods have advantages and disadvantages (main ones being cost, current limit, stability, efficiency and temperature).

The reason you have to cut the supply rather than the output on one of Lava's drivers, as you described in #4, is essentially that the driver's process of storing and releasing the energy in a controlled way is vulnerable, and when there is no current on the output, it damages itself.

Click to expand...

ah, you mean like a capacitor? that makes sense, once its charged the battery just stops giving out more current. although im sure its more complicated than just a capacitor lol

For capacitor read inductor. Similar(ish), but not the same. Back EMF, (Electro Magnetic Force), and oscillators I believe.

M

Buck converter - Wikipedia, the free encyclopedia explains the basic concept of changing (in this case, reducing) voltages using an inductor. It's a good read if you're interested in electronics, but will take effort on the part of the reader.

I think I have the general idea, if i remember correctly it involves inducing current in many loops with few loops or vice versa, to convert from high voltage low current to low current high voltage or vice versa.

edit:nvm i remembered thats a transformer lol

Ok, so I have a table with my supplies and sources in the attached .pdf file...

I went over my expected total of $50, so does anyone know of any other places to get any parts on my chart for less? :undecided:

Thank you,
-Zachary

EDIT: Is there any place where I could find a 445nm sled instead of a 405nm sled for the same price, or will that not be in a sled since 445nm is not "blu-ray"? If I can't, could I get a 445nm diode for $9?