Laser imagable lithographic printing plate with diazo resin

Coated planar lithographic printing plate comprising a grained, anodized aluminum substrate and coating thereon comprising a diazo resin in admixture with particulate energy absorbing material that will absorb incident radiation and re-radiate it as radiation that will change said diazo resin coating which is imageable with a Crosfield Datrax 760 YAG laser plate maker producing incident laser radiation at 1.06 microns, said grined and anodized substrate having an anodic coating thickness equal to at least the wavelength of said incident laser radiation but not greater than 1.30 microns and being capable of absorbing at least 50% of the laser radiation used for imaging, the topography of said substrate and said particulate material in said coating trapping and converting a substantial portion of said incident laser radiation which passes through said coating without substantially affecting same into radiation that will change said coating.