mixed lathanum - magnesium aluminates , their production process and lasers using these aluminates . these lasers comprise two flash lamps for longitudinally pumping a bar of an aluminate of formula la 1 - x nd x mg y al 11 o 18 + y , x and y being numbers such that o & lt ; x ≦ 0 . 2 and o & lt ; y & lt ; 1 , preferably with y ranging from 0 . 5 to 0 . 55 , emitting in the infrared , mirrors for amplifying the light emitted by the bar and a polarizing prism for passing the amplified light beam outside the laser .