An article “An economical “Solar-pumped laser” produces ultra high temperature” shows that solar-pumped-laser realized ultrahigh-temperature which is impossible with simple concentration of sunlight.
The following movie is an experiment of solar-pumped-laser at Tokyo
Institute of Technology in January 2009. Output of laser was 50W. It can drill a hole on a 0.1mm-thick stainless plate easily.
The next movie shows deoxidation of magnesium oxide with
solar-pumped-laser. You will see the smoke from MgO at the instance
when the laser is correctly focused. The output is not enogh for commercial smelting, but deoxidation itself is possible.
[...] ・太陽光励起レーザーで金属板に穴を開ける – The Magnesium Civilization [...]
that is so cool. it’s amazing to see technology at work like this.