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How I Built My First Laser

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How I Built My First Laser

Building you own laser is a rewarding experience. Not only is there a coolness to seeing what you built, but there's the ability to chose and set your own design parameters to your own build.

If you have built other electronics projects, you'll find that building your own isn't that hard to do. If you are good at soldering and have a basic understanding of electronics, odds are very good that you will be successful at it.

As tempting as it was to start out with a 1.6 watt blue laser, I decided to start out simple with a much lower power level, only 100mW (0.1 watts). I chose Green for the color because the bean is so bright and visible.

Getting the laser diode is easy, DTR's Laser Shop had exactly what I needed. The 3.8mm 50mW 520nm green laser diode was well documented telling me what I needed to know about supply current, voltage drop, and power output. While everything varies, at least I had a good idea what to expect. I chose the 520nm Osram PL520 Diode In Copper Module W/Leads & 405-G-2 Lens for $88 (USA).

https://sites.google.com/site/dtrlpf/home/diodes/pl520-520nm-laser-diode

If I wanted to save money and get a bit more power, I could have gone with the 450nm Osram PL450B Diode In Copper Module W/Leads & Three Element Glass Lens $47 (USA)

https://sites.google.com/site/dtrlpf/home/diodes/450nm-pl450-diodes

While tempting, the Green just looks so great, I went with Green for the brightness.



The Heat Sink came from Z-Bolt, "Heat Sink for 12 mm Modules" $20 (USA). After I ordered the heat sink, I did spot it for a few dollars less on another shop, but now I can't find the link to it.

Heat Sink for 12 mm Modules



The design that I used is a modification to a design I saw here on the Laser Pointer Forum. Both D1 and D2 were added just in case I went brain dead and plugged the battery or AC supply in backward. D1 prevents the reverse flow of current and D2 takes the voltage off the other components.



The Datac Prototyping Board # 12-607 turned out to be the ideal size to match the Heat-sink. I did have to enlarge the holes so that the M4-.70x25 metric screws would fit properly. The nylon spacers also had to be opened up a bit too.



The V+ connection is at the top of the image and the V- or ground connection is at the bottom of the image. Any voltage from 12 volts to 15 volts works OK and it might even work down to about 10 volts. The On/Off Switch is the larger switch and the High/Low Power Selection Switch is the smaller switch. Things were getting a bit tight, so I skipped putting in R2 and LED2. Because I wanted to run all sorts of tests on the finished board, I did leave some copper loops that I could attach clip leads to for measurements.



I knew the voltage regulator would be in the way, so I bent it down in front outside of the circuit. In high power mode at 300mA, the hottest thing is the voltage regulator. I measured it at 115 degrees F (46 C) after running for 5 minutes. The heat-sink for the laser measures 89 degrees F (32 C) after 5 minutes. I have yet to test how hot the voltage regulator would be if I leave off the heat sink.



As far as performance I was amazed at how well it did. In low power mode, roughly 55mW, I could light a match and pop black balloons. In full power mode the balloons pop faster and the match lights quicker. Both videos were shot in full power mode.

https://www.youtube.com/watch?v=ZRrG2y5DHEk

https://www.youtube.com/watch?v=lzR-5Mx6XbY


Selecting R3 & R4 Resistors:

A conservative choice would be both set at 12Ω. That would result in a High/Low current of 104mA and 208mA (28mW and 80mW power). Remember all power levels are my best guess based on DTR's Data.

A more liberal approach would use 10Ω resistors for R3 & R4. That would result in a High/Low current of 125mA and 250mA (42mW and 96mW power). This is 50mA higher that the specification for the diode, so the life may be a bit shorter.

A radical approach would be to use 8.2Ω resistors for R3 & R4. That would result in a High/Low current of 152mA and 305mA (55mW and 108mW power). Clearly well beyond the specification and it will shorten the life of the diode, but no one knows by how much.

I started with 8.2Ω resistors, but after testing it for a while, I'm going to switch it so that R4 = 13Ω. That would result in a High/Low current of 152mA and 250mA (55mW and 96mW power). Because the laser burned so well even in low power mode, I decided not to risk making the life too short. It is after all, my first home brew laser and it's a bit like my first love.


Other Things:

C1 is a 1uF Tantalum Capacitor. Like other Tantalum Capacitors is has a polarity, watch out for the + and -. The + lead is longer than the - lead. If you wire the capacitor backward Tantalum Capacitors have been known to explode, so be careful. If you want, you could use a 0.1uF Ceramic Capacitor. The Ceramic Capacitors operate either way and don't explode if put in backward.

The resistors can be either 1/2 watt or 1/4 watt, whatever you like to use.

If you haven't guessed it yet, SW-1 is the On/Off Switch and SW-2 is the High/Low Power Switch.

R1 & R2 and their matching LED1 & LED2 aren't really required for the circuit to work. They are just power indicators. LED1 indicated that power is connected and LED2 shows that power is connected AND the laser is turned on.


What's Next:

I did spot a 3.8mm 300mW 650nm Single Mode Diodes on DTR's Shop. It's only $21 with Copper Module, Leads & Acrylic Lens. It's really tempting to try and see if I could build this really cheap. All Electronics does sell some low cost heat sinks that I might be able to modify... but I may have to wait a bit before my next build. My wife put up with this one, but if I do too much too quickly it's not the laser that will get too hot on me. :beer:


In closing I do want to say that DTR's Shop ROCKS !!! He was VERY helpful and was very prompt in answering my questions. I will be purchasing from him again . . . after my wife calms down. :) I give him 5 out of 5 stars!!!


Bob Diaz
 
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10fenny

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Holy build thread batman! Im still a newb builder and that was a great write up!!! I love those z bolt heat sinks
 
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Thanks !!!

I have a great deal of respect for those who build the handheld flashlight style lasers. However, my building style is to make more of the desktop lab style lasers. The Z-Bold Heat sink (also found at other stores) works VERY well and is easy to put into a design.

I like the fact that after 5 minutes the level of heat around the laser diode is limited. The large heat sink means that I don't have to worry about the cycle time as much as if I used a smaller heat sink.

The only thing about the heat sink is DTR doesn't stock them and I have to go elsewhere. (DTR if you are reading this, hint hint hint... please consider stocking this.)

Here are some additional photos of the heat-sink:








Bob Diaz
 
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Thanks for the link. Like many links, if I don't save it somewhere, I lose it and can't find it again. In my case I plan on more builds and the head-sink is ideal for what I'm doing.


Bob Diaz
 
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Bob, I have a question for you, are you really using the 3 element lens on that or did you change to something else? I noticed you didn't post a beam shot showing the dot. I have a build with the same diode and when I tried the three element lens the splash was terrible so I changed to an acrylic lens with much better results. Do you get the same with the 3 element?

Alan
 
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I used the 405-G-2 Lens and I have no idea how many element lens it is. The "dot" is more of a green line. I'm at work right now, so it will have to wait until I get home to take a shot of it.

For some reason I forgot to grab a shot of the "dot".

While I'd rather see a dot, because the burning power works better than I thought, it's good enough for me.

I'm going to make some minor changes on the build to fix some minor things.

Right now I'm researching lower cost heat sinks for my next build...


Bob Diaz
 
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Oh I see now I misread the beginning of your first post, I see now it says the G-2 lens, that is a single element lens and will give better results with this diode than a 3 element so you made a good choice, you also get a better power output with a G-2.

Alan
 

Pman

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Great job with this and nice writeup. +REP.
Curious as to the total cost of the driver.
Welcome to the forums;)
 
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Great job with this and nice writeup. +REP.
Curious as to the total cost of the driver.
Welcome to the forums;)

The electronics behind this, not counting the laser or heat sink, cost me about $5. I purchase parts in bulk for many projects and get them from All Electronics, an electronics surplus store.

All Electronics | Electronic and Electro-Mechanical Parts and Supplies at Discount Prices


The laser assembly is the most expensive part.


I'm really looking at DTR's 300mW 650nm Single Mode Diode In Copper Module W/Leads & Acrylic Lens only $21. It's VERY tempting to see how cheap I can put something together.

https://sites.google.com/site/dtrlpf/home/diodes/3-8mm-650nm-300mw-diode


I'm trying to get the cost of the heatsink down and have found some interesting possibilities...


$4.49 Aluminum Radiator Heatsink 20x27x32mm for 12mm Laser Diode Module Black:

http://www.amazon.com/Aluminum-Radi..._sbs_hi_1?ie=UTF8&refRID=1R46Z6GR5PN6VWD8RF4F


$4.49 Aluminum Radiator Heatsink 20x27x50mm for 12mm Laser Diode Module Golden

Aluminum Radiator Heatsink 20x27x50mm for 12mm Laser Diode Module Golden - - Amazon.com


$4.00 HeatSink Holder Mount for 12mm laser modules

HeatSink Holder Mount for 12mm laser modules - - Amazon.com


$9.00 Aluminum radiator for laser module heat sink Inner hole 12mm

Aluminum radiator for laser module heat sink Inner hole 12mm - $9.00 : Civil Laser products





Sincerely,


Bob Diaz
 
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crazyspaz

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Nice writeup :) If you wanted, you could extend the 317 with some wires and heatsink it on the lasers heatsink, it would be much cooler that way. Those diodes are one of my top favorites- I need to build with one again. Can't beat the color and brightness. I had one in a stainless steel host that was fantastic, but I sold it a while back :/ Seeing this makes me wish I hadn't :D
 
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DTR

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Awesome write up. Love the build.:beer:

Yea I have stocked heatsinks in the past. I may again in the future. The Z-Bolt style ones are some of the nicer ones out there. A lot of the ones from different companies that just use the set screw make them too large as they have to accommodate the huge tolerance ranges of the old brass 12mm modules that come from China which I have seen range from 11.80mm-12.10mm. That ends up leaving a gap with my 12mm copper modules which are all 11.96mm with a tolerance of +/-0.005mm. The clamp design gives the ability to hold way out of spec brass ones and mine while keeping perfect contact all around.;)
 
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