Angle measurement based on in-line digital holographic reconstruction

Using digital holography technology to reconstruct the optical information of the calibrated grating, the grating pattern can be magnified without an optical lens. This greatly reduces the volume and complexity of the image angular displacement measurement device. This paper proposes an angular displacement measurement technology based on in-line digital holographic reconstruction. The wavefront recording of the calibrated grating holographic interference fringes can be realized in a small volume; the wavefront is reconstructed via algorithm, then the coded information on the calibrated grating is recognized based on the reconstructed light wave. The recognition and angle calculation of coded lines was successful in an experiment on 1024 period calibrated circular gratings, and 1.24 '' measurement resolution is achieved by the subdivision algorithm. This study may represent a workable foundation for future small-volume and high-resolution angular displacement measurement technology.