Auto-collimation angular measurement method based on moiré fringe

Combining the imaging grating method,the roll measurement based on moire fringe and the auto-collimation angular measurement,A method is proposed to measure the platform prism rotation angles through measuring the width of moire fringe by means of grating pair between main grating image and indicating grating.The relationships of the platform prism revolution angle,the angle of gratings and the width of moire fringe are established.Different from traditional counting ones,the width of moire fringe is gotten by image processing.The experimental result shows that the contrasts of moire fringe images received are distinct and can realize the demands of moire fringe image processing.The measuring error is better than 0.2 arc second within 7 arc minute range compared with 0.2 are second autocollimator.