Newbie question!

JFK · Jan 27, 2015

Hello all, this is my first post about my first DIY project.

I have bought a 2W Copper 445nm M140 Blue Laser Module W/X-Drive & 405-G-2 Glass Lens.

I have still not received my heatsink so I have test it 1sec and let it cool down 1min for each tests.

My question is : is it possible to get a slim sharp "infinite" straight beam with this setting ?

Because for now, I have not find the right "focus" of the lense.
The beam is always a "cone".

Thank you for your reply.

DTR · Jan 27, 2015

Not sure what you mean by cone? You should be able to in a few seconds focus the spot on the wall. These are higher power multimode diodes so the spot size is elongated instead of a perfect dot of that is what you mean.

Should look like this.:beer:

BowtieGuy · Jan 27, 2015

No, it won't be possible, depending on what you mean by a slim and straight beam. The M140 is a multi mode beam, and is never going to give you a traditional "dot", especially set at infinity.
The beam is going to be rectangular, with a bar, or as some say, "bat wings" going through it.
You are wise not to run it for more than a couple seconds without a heatsink, I know it's hard to wait on parts, but your diode will appreciate it. Also trying to focus while it's only on for a real short time is very difficult.

Edit: DTR beat me to it, damn slow typing.

JFK · Jan 28, 2015

Hello,

I have done small shot outside to infinite to compare the beam to my Chinese green laser.
And for now, it's not an "infinite" beam, the diameter increase hugely.
Well, I will wait the heatsink and termal paste and come back to you.

Attached, this is what I call "straight "infinite" line beam", what is the right name for that ? (Sorry I'm not English native)

The second attached photo is the heatsink that I have choose.
What do you think about it ? Is it enough ?

Tx.

JFK · Jan 28, 2015

Hello,

For what I have understand from now, the beam is rectangular because it's a multi mode diode.
Noticed !

My question is following the two drawings that I have made :
Is it possible to get a straight beam (see previouse post) unlike a "focalised" with this module ?
I'd like to point the stars to explain to my friends what to see with my telescope.

BowtieGuy · Jan 28, 2015

That heatsink will work, but it isn't very large. Is it going to be installed in a host that could possibly add to it's heatsinking ability?
I've also seen some of that style heatsink not having a good snug fitting 12mm bore for the module, and thus not transfering the heat very well.

I personally would not use a 2W blue laser for star pointing. IMO, It's way too powerful, and will damage your night vision, not to mention 2W pointing in the sky could be very dangerous.
I would stick to a low power green, or even red.

Edit: As far as focusing, it's going to look just about like the photo that DTR posted.

BTW - Welcome to LPF! :beer:

iroquois · Jan 28, 2015

The line instead of point could me eliminated by two anamorphic prisms right? not that i know ones that can fit in a laser pointer case.

and how about thermal grease / compound to 'snug fit' to the heatsink?

BowtieGuy · Jan 28, 2015

Thermal compound (grease) will help if the gap is small, maybe a couple thousanths of an inch. If the gap is any larger, I would use other methods of filling the gap, such as aluminum or copper foil.

iroquois · Jan 28, 2015

Thousands of an inch? Anywhere I can see some data on this? If it isn't good for fitting the tiny gaps between a supposed 12mm module and a 12mm heatsink hole, then I don't think it would work for say the heatsink on a CPU or thermistor to metal like in 3d printers, but its used for it.

Thanks for the idea about aluminum and copper foil. but won't it tear when trying to push the module in the heatsink hole for a tight fit?

BowtieGuy · Jan 28, 2015

Yep, thousanths of an inch. You can use it with much larger gaps but it won't work nearly as well. I'm just saying that these are optimum conditions, guys here probably use it every day to fill larger gaps.

Here is a recent thread that covers a lot of related ideas. (see post #2) http://laserpointerforums.com/f44/liquid-heatsink-material-91896.html#post1335146

Also, this is the "Arctic Silver" site. Check the thickness they refer to when determining the coverage area.

Edit: In the instructions section (How to apply thermal compound): "Stock processors and/or heatsinks with normal surface irregularities will require a layer 0.003" to 0.005" thick as shown below to fill the
resultant gaps. (Equal to the thickness of about 1 sheet of standard weight paper.)"

JFK · Jan 29, 2015

Hello,

Thank you for your precisions.
Following the drawing of the heatsink, the gap will be around 0.05mm.
Well, finally with the screw, it will touch on a side and at the other side it will be 0.1mm.

JFK · Feb 8, 2015

Hi All,

I have finally receive the heatsink, and mounted it with Artic Silver 5.
So now, I can "shot" more than a sec.

My question is :
Why it's impossible to get a clean slim beam ?
Look at the attached photo, I'm at 1.5m to the wood board.
There is a big "splash"on top of the dot (1).
And another more upper (2).
At night pointing the sky, impossible to get a nice slim beam... (compared to my green laser)

Did the module is defective ? The lense is defective ?

Thank you in advance.
Regards.

DTR · Feb 9, 2015

Yea 1 and 2 are not a problem but the line though the output should not be there. Could be a small speck of dust got on the optics. Can you unfocus it all the way and get a picture of the output. Either way these diodes are multimode so they don't have the low divergence of a 532 DPSS module so nothing will change the way it looks in the night sky.

JFK · Feb 9, 2015

Hello!
Thank you for the reply.
By "un focus all the way" do you mean, remove the lense?
Tx

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