Laser not strong enough

[glsf91]

I'am building a laser engraver.
I bought a red laser LPC-836. I'am using this housing: Housing Gehäuse mit Linse und Feder für TO-18 / 5.6mm laser diodes Laser Diode | eBay
I also bought a 660nm 300-400mW CW Red Laser Diode ML101U29-25.
I use as a driver LM2596S DC-DC Constant Current and Voltage Adjustable Module LED Driver.
Voltage and current (300ma) is ok.

I can focus the spot but I can see some red (diffusing) around it. The distance to the paper is about 10cm.

I also tried the driver circuit with the LM317 from this forum. http://laserpointerforums.com/f67/laser-driver-can-done-rog8811-87507.html. Same result.

Both diodes are not strong enough to burn some paper. But according to other engraver blogs this should work.
The only think I did not do is press the diode in the housing completely to the end. I left it out for about 1-1,5mm. This because it is easier to remove it from the housing when necessary.
Can this cause the weakness ?
Or can this be caused by the lens.

So what can be wrong ?

 

[rhd]

You may have killed your diode by using an improper Chinese LED driver on a laser diode. That's not just a LED driver, it's a dirt cheap one with a low frequency IC. It's probably crazy ripply.

 

[The Lightning Stalker]

I'm not sure an LPC can burn white paper,
even when focused. It can burn dark print
easily when focused, though. 300mA is a
little low. Those modules are also not the
best. Try the copper module from DTR, and
put it in a heatsink such as this one.

There are also better lens options. How are
you focusing it?

http://laserpointerforums.com/f39/fs-12x30mm-module-heatsink-blocks-93282.html

 

[glsf91]

There are also better lens options. How are
you focusing it?

I focus with the screw at the front of the housing.

 

[alessnilsen]

I have some LPC-815 lasers, I'll try to burn some white paper, this should tell if there's something wrong with your laser.

----- EDIT -----

I tried, but nothing, I used my 250mW laser focused into the white paper, but no signals of burning!

You need to go into a lower wavelength, like 445nm or 405nm, this is what my 450nm laser did to the paper.

With less power, you should be able to write to the paper without burning it like I did. :yh:

 

[The Lightning Stalker]

I focus with the screw at the front of the housing.

And? What is the beam shape when it is "focused"?

 

[glsf91]

And? What is the beam shape when it is "focused"?

Just a small spot. But still there is some red around it. See first picture.

 

[The Lightning Stalker]

Okay, well that is part of the problem.
This is not focused. This is what is
called "focused" to infinity. This is
where the laser is a thin line that very
gradually widens as it gets farther from
the source. At least I think that is what
you are describing. It is a bit unclear.

Focused is when the beam is an hourglass,
or pear shape and there is a tiny focal
point a few cm in front of the lens, after
which it quickly diverges. To get that,
unthread the lens until the focal point is
4-5cm from the aperture.

Get a copper module from DTR, put it in the
heatsink I linked to in post #3, increase
the current to 500mA, and focus the laser
as above, in that order, and you should be
burning stuff, providing the diode was not
damaged up until this point.