Methods, for use with a laser ablation or drilling process, which achieve depth-controlled removal of composite-layered work-piece material by real-time feedback of ablation plasma spectral features. The methods employ the use of electric, magnetic or combined fields in the region of the laser ablation plume to direct the ablated material. Specifically, the electric, magnetic or combined fields cause the ablated material to be widely dispersed, concentrated in a target region, or accelerated along a selected axis for optical or physical sampling, analysis and laser feedback control. The methods may be used with any laser drilling, welding or marking process and are particularly applicable to laser micro-machining. The described methods may be effectively used with ferrous and non-ferrous metals and non-metallic work-pieces. The two primary benefits of these methods are the ability to drill or ablate to a controlled depth, and to provide controlled removal of ablation debris from the ablation site. An ancillary benefit of the described methods is that they facilitate ablated materials analysis and characterization by optical and/or mass spectroscopy.