My new DIY red laser

[The Lightning Stalker]

Where did you get that focusing optic? That nooks pretty neat. I tried to remove the focus
from a GGW drive the other day, but unfortunately it broke in the process. It had a stepper
motor drive anyway, so I would've had to make a driver to use it.

The rings around the dot are probably spherical aberration. See this thread:
http://laserpointerforums.com/f38/very-srange-beam-pattern-405nm-74359.html. Keep looking and maybe you will find an aspehric.
I hope you can get back up and running, it looks like quite the laser.

 

[alessnilsen]

I got it from a CD RW/DVD ROM drive, Samsung TS-H492. The only stepper motor I found is for move the whole optic block around the CD axis.

Here you can find a photo of it:

And here, the focusing block:

The focusing block have a voice coil and some magnets, when I put some electricity into it, the lens move up or down, being more or less close to the LD, adjusting the focus. The adjust circuit is a simple voltage controller, using a 7805 to limit the tension, a 2N2222 transistor and a precision trimpot to adjust, nothing complicated.

 

[The Lightning Stalker]

Oh, okay. I thought it was motorized. The GGW drives actually have a secondary focusing mechanism
ahead of the objective that is driven by a tiny stepper motor. It has a threaded shaft with an ultra fine
thread pitch, almost like a micrometer.

 

[alessnilsen]

I have never looked inside a blu-ray drive, so, if you say this, I believe! But is strange to have a stepper motor controlling the objective lens focus.

I'll keep searching for a aspheric lens to make a little and cute dot instead of this ugly rings. But I'm happy with the result!

 

[Pman]

IF nothing else look at how much you are learning from all of this

 

[alessnilsen]

Yes! 11 LD's dead, but now I have a fully working driver, for first time, I was able to get all the power of the LD's. :evil:

Other question, in all DVD burners sleds I observed the use of a concave lens, like this:

LD -> concave lens + difraction grating -> mirrors and beam splitters -> collimating lens -> objective lens.

Why the concave lens (I know because it make things feels away) are used here?

 

[The Lightning Stalker]

I'm not 100% sure on this, but I believe it partially corrects the spherical aberration. It's not as good as using an aspheric, though.

 

[alessnilsen]

Thanks for all! Today my new fake 500mW laser arrived, when I put the bean in that lens, it forms many circles, with sure, is spherical aberrations, this lens has pros and cons:

Pros:
Very short focus distance, to use it, you need to place it very close to the laser diode, this will collimate almost all the output from LD, making it more efficient (good for burning objects).
Easy to get, almost all cd/dvd drives have one.

Cons:
Since is a coated lens, dirty and grass can danificate it easy, so, is fragile.
Is a spherical lens, it has spherical aberration, if you don't correct it, you won't be able to get a single, clear, tiny dot/beam, the beam/dot I got is very ugly!

About my driver, thanks! I don't know why LM337 doesn't work! I'll replace the LM337 with a LM317 or similar IC in my first laser.

And, alright, thanks for the compliments!

 

[alessnilsen]

This is my new build! Now complete, with electrical focus adjust, a 400mA driver and a 100uF capacitor for protection. Is very good for burning! Thanks to this forum!

A little relay to switch the 400mA to the driver:

The focusing head, using the original focus system of the DVD-RW:

Here the laser working

Unfocused beam (see the rings from the lens):

Here focused:

Portable? I think no!

And here, the LD! From a GSA-H50N

Thanks for your help!

 

[alessnilsen]

Hi! After some experiments with lenses/LD's and drivers, I decided to build my definitive red laser, It will work with a LG GSA-H55N laser diode, running on 400mA and with a 12V power supply.

I like to see the lasers mounted in square heatsinks, seems more powerful, like lab lasers. I decided to start with a 10x10x5cm MDF box, a DVD-RW collimating lens and a tailcap of a dead laser, this is what I done:

Here is the ugly beam that I got, I don't know, every lens I use forms those rings.

Here some beam shots around the sky.

I'll keep searching for a lens with short focal lenght and aspherical.

 

[The Lightning Stalker]

Nice work once again, Mr. nilsen

 

[crazyspaz]

Awesome! Glad you got everything working. I enjoy seeing your builds, they are very unique! Most people just stick a dvd burner diode in an Altoids tin or something lame like that.

Also, in pic 7 of your box build, the resistors look very very close to the screw holding your regulator to the heatsink- if they touch the screw, they will have contact with the back of the regulator, which will short. May want to add a little piece of electrical tape there, or maybe some glue.