Simple interferometric fringe stabilization by charge-coupled-device-based feedback control.
A method for producing stabilized interference patterns for ultraviolet interference lithography using a CCD camera as the detector element is described. Intensity data obtained from the CCD element are filtered in software to minimize speckle and detector noise effects as well as to determine the relative phase of the interfering beams. A control signal is then issued to correct the fringe drift. The system allows rapid reconfiguration of the lithography setup with minimum realignment of optical components.
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