Laser done laser’d itself…
Ouch!
Look like the ray was focusing straight on the mirror. mirror and lens are easy to find on ebay, but maybe you need a laser tube too.
Check out http://lightobject.com they have the parts and other things. Plus the forum is very helpful.
I would be surprised if you needed a new tube if it burnt through the mirror 
However you can get replacements off e-Bay for both. The mirror in your photo looks to be metal evaporated onto glass - probably not robust enough for a laser cutter. Go for a Silicon or Molybdenum lens.
I have just read about using the disk out of an old 3.5" hard drive to cut circles out of that can be used as mirrors and they are double sided and get you a good few out of one disk. Not sure if it is worth messing but if anybody is on a tight budget might be worth a look.