A laser system comprising: - a seed laser; and - an optical amplification subsystem, receiving an output of said seed laser and providing an amplified laser output, said optical amplification subsystem comprising: - a first plurality of amplifier assemblies arranged in parallel, each amplifier assembly of said first plurality of amplifier assemblies including a second plurality of optical amplifiers arranged in parallel; - the output of said seed laser being split and fed to each amplifier assembly of said first plurality of amplifier assemblies; - the input of each amplifier assembly of the first plurality of amplifier assemblies being split and fed to each optical amplifier of the second plurality of optical amplifiers; - for each amplifier assembly of the first plurality of amplifier assemblies: a combiner adapted to combine the outputs of the second plurality of optical amplifiers and providing a first amplified laser output; - a combiner adapted to combine the outputs of the first plurality of amplifier assemblies and providing said amplified laser output; - a first phase control circuitry associated to each amplifier assembly of the first plurality of amplifier assemblies, said first phase control circuitry including a first phase modulating means, a first intensity sensor which measures said amplified laser outputs, and a first phase control logic circuitry which receives an output from said first intensity sensor; wherein - each amplifier assembly of said first plurality of amplifier assemblies also comprises a second phase control circuitry including a second phase modulating means, a second intensity sensor which measures the first amplified laser output of said second plurality of optical amplifiers, and a second phase control logic circuitry which receives an output from said second intensity sensor; and wherein - said first phase control circuitry is adapted to sequentially vary the phase of each amplifier assembly of said first plurality of optical amplifiers and selects the phase of each amplifier assembly of said first plurality of optical amplifiers which produces the maximum intensity of said amplified laser output; and - said second phase control circuitry is adapted to sequentially vary the phase of each optical amplifiers of said second plurality of optical amplifiers and selects the phase of each optical amplifiers of said second plurality of optical amplifiers which produces the maximum intensity of first amplified laser output as sensed by said second intensity sensor. - a seed laser; and - an optical amplification subsystem, receiving an output of said seed laser and providing an amplified laser output, said optical amplification subsystem comprising: - a first plurality of amplifier assemblies arranged in parallel, each amplifier assembly of said first plurality of amplifier assemblies including a second plurality of optical amplifiers arranged in parallel; - the output of said seed laser being split and fed to each amplifier assembly of said first plurality of amplifier assemblies; - the input of each amplifier assembly of the first plurality of amplifier assemblies being split and fed to each optical amplifier of the second plurality of optical amplifiers; - for each amplifier assembly of the first plurality of amplifier assemblies: a combiner adapted to combine the outputs of the second plurality of optical amplifiers and providing a first amplified laser output; - a combiner adapted to combine the outputs of the first plurality of amplifier assemblies and providing said amplified laser output; - a first phase control circuitry associated to each amplifier assembly of the first plurality of amplifier assemblies, said first phase control circuitry including a first phase modulating means, a first intensity sensor which measures said amplified laser outputs, and a first phase control logic circuitry which receives an output from said first intensity sensor; wherein - each amplifier assembly of said first plurality of amplifier assemblies also comprises a second phase control circuitry including a second phase modulating means, a second intensity sensor which measures the first amplified laser output of said second plurality of optical amplifiers, and a second phase control logic circuitry which receives an output from said second intensity sensor; and wherein - said first phase control circuitry is adapted to sequentially vary the phase of each amplifier assembly of said first plurality of optical amplifiers and selects the phase of each amplifier assembly of said first plurality of optical amplifiers which produces the maximum intensity of said amplified laser output; and - said second phase control circuitry is adapted to sequentially vary the phase of each optical amplifiers of said second plurality of optical amplifiers and selects the phase of each optical amplifiers of said second plurality of optical amplifiers which produces the maximum intensity of first amplified laser output as sensed by said second intensity sensor.