Help!How to clean laser pointer lens

I got my laser about two years ago, recently，there were some little black dot at the pattern , I guess there was something that block the laser lens,now the question is : how can I clean it, I don't wanna buy another one since it was sent by my girl friend...
BTW,the laser my girlfriend sent to me is from here , you can just refer from it.Thanks~

Welllllll.... if that's the same laser she paid probably about $250 to much for it....

Now to the point. What do you think the material on the lens is?
There is a pretty good chance it is burned into the lens.
I sometimes use high grade alcohol and I've heard of others using compressed/canned air.

Knowing what substance is on the lens will greatly help us in helping you.

Here's the do's and don'ts of cleaning a lens...

Don'ts:
-touch with bare hands
-use Q-tips (cotton will end up on your lens)
-use Kleenex (cotton will end up on your lens)
-use paper towels (cotton will end up on your lens)
-use <97% alcohol (that other 3-5% is usually oil and will end up smudging your lens)

Do's:
-use nitrile or powderless latex gloves (or be very careful not to touch the lens)
-use >97% (preferrably >99%) acetone, methanol, or isopropyl alcohol (acetone preferred, then methanol)
-get a very clean wash bottle to apply the solvent and allow to air-dry

P.S.
what type of lens is it? if cleaning it doesnt work you can send it to me for cleaning, just pay shipping (p.m. me) also post a pic of this black dot you're talking about

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