Patent ID: 7327518

Claim:
A method for attenuating the power of a laser beam from an initial level to a lower target level, the method comprising the steps of: separating the laser beam into first and second beams plane-polarized in respectively first and second planes in respectively first and second orientations; synchronously rotating the polarization plane of each said first and second plane-polarized beams to respectively third and fourth orientations different from said first and second orientations; separating each of said polarization-rotated first and second beams into first and second portions plane-polarized in respectively said first and second orientations; combining said first portion of said polarization-rotated first beam with said second portion of said polarization-rotated second beam; and combining said second portion of said polarization-rotated first beam with said first portion of said polarization-rotated second beam, with one of said combined beams defining an attenuated output beam and wherein the amount which the polarization plane of said first and second plane-polarized beams is rotated is selected so that the power of the attenuated output beam corresponds to the target level and will remain substantially at that target level even if the initial polarization state of the laser beam varies.