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A nano-displacement measurement system with duo-gratings is analyzed by using optics theory,a math- ematic model for the system is established,and the characteristic of laser Moirésignals is studied through CAD simu- lation.To improve signal sensitivity and positioning accuracy,two methods of precision positioning are brought for- ward:differential Moirépositioning method and modified Moirépositioning method.A compound control system for precision positioning is set up by combining these 2 Moiréalignment methods,in which the modified Moiréalignment technique is used for coarse alignment and the differential Moiréalignment technique is used for fine alignment,and the system obtains positioning accuracy of±10 nm in±500μm positioning range with shot response time.
A nano-displacement measurement system with duo-gratings is analyzed by using optics theory, a math-ematic model for the system is established, and the characteristic of laser Moirésignals is studied through CAD simulations. Improve signal sensitivity and positioning accuracy, Two methods of precision positioning are brought for-ward: differential Moirépositioning method and modified Moirépositioning method. A compound control system for precision positioning is set up by combining these 2 Moiréalignment methods, in which the modified Moiréalignment technique is used for coarse alignment and the differential Moiréalignment technique is used for fine alignment, and the system Directions positioning of ± 10 nm in ± 500 μm positioning range with shot response time.