Black dot in the middle of the beam?

Just put together my first laser the other day. It works great but I noticed it has a black dot in the center of the beam when unfocused. Down below is an image of what it looks like. Is this bad? Should I be concerned?

Sorry for the links. The pictures are huge.

With 3e glass I added a black dot to represent what it looks like with the lens on. My camera cannot see it.

Bare diode

The first image looks photo shopped the second looks like something one the diode window.

That is just a dust particle on the diode window. You can clean the diode window but that could introduce more dust if you don't know how to do it.

Try blow it away first.

I did blow on it to no avail, and yes the first photo is shopped because my camera cannot pick up the black dot with the lens on.

What's the best way to clean the diode window without introducing more dust?

The best way is with canned air that way you are not touching the lens.

Blowing on it with your mouth is not a good idea because no matter how hard you try not to spit any thing out your going to and your saliva will stick on the
lens and make things worse, canned air is really the only way to go here.

If you try wiping it with a dry cloth use a micro fiber cloth only or proper lens cleaning tissues, usually a dry cloth will not do much if the air didn't do anything
but sometimes it will.

So now you are up to a wet cloth and the best thing to use is 100 proof alcohol and why you say because it will cut through a lot of crap and because there
is nothing but alcohol so there is nothing to leave a streak on the lens when it drys up.

If you use something like 70% or even 90% alcohol the other 10% is water and it will leave a streak on the lens as it's drying up.

Even acetone has water in if you bought it from the hardware store and it will leave a streak, now if you can buy pure reagent acetone then that is a good lens cleaner also.

Good luck

I think what Flaminpyro meant was 100 percent alcohol, not 100 proof, as 100 proof alcohol is only 50 percent alcohol.

I have, with success, used a lens cleaner. Nikon makes a good one. But, it requires a delicate touch to say the least!

Or you could take a q-tip with a little bit of lens cleaner for glasses and lightly wipe the lens than lightly wipe it with a dry q-tip. It works really well.

I would NOT use a Q-tip...again. You can trap pieces of the cotton in the window, and in the module threads inside. If you don't see them, and fire up your diode, you're likely to fire up the cotton in your module as well.

Lens cleaning kits are affordable and do a better job. Don't mash in your diode window with a Q-tip.

Thanks for the help everybody, but the dot is still present. I tried alcohol, a few microfiber clothes, and an air compressor. Although the dot does look a bit better, I'm just going to leave it be for now. If I tinker with it any further I fear that I may accidentally damage the laser instead of make it better, which usually happens to me when I tinker lol.