Research and Analysis Report on Grating Ruler Based on Moiré Fringe Principle

To achieve high-precision measurement of micro-displacement, this study takes the Moiré fringe principle as the core and designs and fabricates a modular grating ruler measurement system. The system comprises a light source, a scale grating and an index grating with grating pitches of 1.4mm and 1.6mm respectively, a low-speed motor traction device, a photoresistor sensor, and a 51 single-chip microcomputer (SCM) calculation unit.The experiment adopts the point-by-point measurement method, with each group of measurements repeated 10 times and the average value taken. The results show that the system has an effective measurement range of 120mm, a measurement resolution of 1μm, a repeat positioning accuracy of ±0.5μm, and an average relative error of 7.3%.Boasting advantages such as modular design, easy operation, and controllable cost, the device can provide a reliable solution for micro-displacement measurement in fields like precision manufacturing and optical instruments, and possesses broad application prospects.