Newbie attempting first laser and am stumped

[shaku22]

Hi all!

So I've started my first project using a 658 nm 200 mW diode from aixiz. It's been a great learning experience and I've pulled a lot of useful information from this forum. Before I jump into my problem I'll explain my setup a little so you guys will have something to work with.

I also used his housing shown here. For the driver I decided to use the simple power mosfet linear current regulator circuit shown here http://laserpointerforums.com/f51/simple-linear-mosfet-dimming-circuit-pwm-70812.html. The driver is fed by a wall transformer rated for 9V & 210 mA. Things were going great as I made sure to fine tune my circuit correctly and tested it with a dummy load before adding the $40 diode to the mix. To make sure I was pulling the right amount of current (~230 mA) I added a 1.1 Ohm resistor in series with my dummy load and measured a voltage drop of 0.254 V.

With everything working I added the diode (with the aixiz housing) to the mix. After putting on proper safety glasses and turning it on I measured 230 mA being pulled. Since all was good in Ohm's land I moved the lens around till I was able to get a small bar/dot shape at a sweet spot 5 or so inches in front of the laser.

Now on to the brick wall that I've hit. After trying to burn a white piece of paper burn with no success, I tried a black piece from a magazine with no success, so then I tried a piece of a thin black trashbag with no success. :cryyy: I've tried all three at various distances 1 inch to 10 inches at various lens focuses with no success. I believe my problem to either be a bad diode or my focused sweet spot isn't really a focused sweet spot. Any ideas?

 

[daawood123]

Unfocus your laser, so it is basketball sized on the wall, and stick whatever it is you want to burn in the part that looks the thinnest, you should use smoke to help looking for this "sweet spot". If it still doesnt work, then either your batteries are messed or your laser isnt very high powered. HTH

 

[shaku22]

Okay. I unfocused the laser till I got a small basketball/large tennis ball shape on the wall about 12 inches away. The circle is very hard to see with my glasses on and moonlight coming in through some windows on my garage door. Is this normal?

I then found the most concentrated spot, a round dot, about 1 inch from the housing. Testing the black thin trash bag piece still yielded no burning.

I'm not using batteries. I am using a wall transformer and pulling directly from an outlet.

The diode is seeing 230 mA of current so with a 0.95 W/A efficiency that yields 219 mW. Can a diode be dead but still pull it's typical current rating?

 

[daawood123]

If you mean normal correction glasses, then it is very unusual that you have difficulty seeing this. If you mean laser safety glasses, then its perfectly normal. Try using 6v to power the laser, if you have a driver then it should be fine. 4 aa or aaa batteries will provide this. Then try again. If you cannot see the beam at night with laser glasses off, then your laser is probably dead.

 

[shaku22]

I mean laser safety glasses that cover the 650 nm range.

The 9 Volt supply is dropping to 8.5 Volts because I've maxed out its 210 mA current rating and the driver is forcing it to output 230 mA.

I'll see if I can get a 6 V power supply and/or will need to get a thing to plug some batteries into. There is a 2.5V drop across the diode.

If by beam, you mean a red line drawn from the aixiz module to the point of contact, then I can see no beam with or without glasses. Putting some smoke in the path of the beam barely illuminates it. I guess I need to order another diode.

 

[shaku22]

New 650 diode came in. Soldered it up and it works amazingly!

Seems the previous diode partially died at some point along the process.

 

[HitShane]

First time I have ever seen this show up, when I clicked on your first link to the module...
I wonder why your link is to aixiz.net and not aixiz.com

 

[shaku22]

idk. Just now noticed that now. Maybe aixiz purchased both domains.