if the laser is concentrated around how concentrated is the beam. How hot does the laser become

Question: if the laser is concentrated around how concentrated is the beam. How hot does the laser become
- Keywords:
  beam,
  hot,
  laser
Asked by sean fraile to David on 23 Jun 2016.
- David Robertson answered on 23 Jun 2016:
  
  We try not to concentrate our laser beams too much because of exactly this problem. If you concentrate them too much then they can damage our mirrors.
  
  Other people use lasers to heat things up a a lot, some of the people I work with use lasers to melt glass, but some people go even hotter. The most extreme example is using lasers to try and create temperatures as hot as the centre of the sun. This is laser driven nuclear fusion. Here is a link to an article about an American system for this http://www.scientificamerican.com/article/high-powered-lasers-deliver-fusion-energy-breakthrough/

Question: if the laser is concentrated around how concentrated is the beam. How hot does the laser become