A high speed and high precision displacement measurement method based on double grating scales was presented

and the signal’s switching and merge of double grating scales was discussed based on the analysis of measuring theory of grating scale. By analysis of the subdivision error of Moire fringe

the error of the count impulse’s switch process was decreased. A signal process circuit was designed using the programmable logic device-FPGA

and the feasibility of method was proved through the logical and timing simulation by the design software of FPGA. Experimental results show that while the maximum allowable moving speed of grating is grater than 1 m/s

the measurement resolution is 10 nm. It can satisfy the system requirements of high speed and high precision displacement measurement.