In order to accurately measure the three-dimensional deformations between large photoelectricity measurement equipments

a high-precision optical angular measure method is proposed based on the moiré fringe produced by the double diffraction grating interference. Through collimator to simulate equipment and the fine-tuning mechanical structure to adjust collimator to simulate the torsional flexibility of three-dimensional objects

the measurement experiment is made on the independent foundation platform. Through comparing different design proposal in experiments

use of the scheme of CCD target surface installed in the image surface of parallel light is come to use. The image processing technology of filtering thinning is made used to obtain the stripe width by treating with the collected moiré fringe. According to the changes of stripes width

the torsional flexibility value is work out through the mathematical model. The experiments results show that

when the fine-tuning institution makes the collimator circumgyrate in the field of view of ±7'

the clearer moiré fringe image can be gotten in the scheme. And after the algorithms process

the angle of torsion measuring accuracy is 4.3"(3 ) when the moiré fringe width is 1615~1712 . This method meets the measurement requirements of high-accuracy angle of torsion between equipments

and it lays the foundation to enhance the photoelectric precision of measurement equipment.