Shyu L.-H.Fu Y.-F.Jywe W.-Y.Lee K.-C.Chen J.-J.Wen-Yuh Jywe2022-05-242022-05-242002https://www.scopus.com/inward/record.uri?eid=2-s2.0-0141539256&partnerID=40&md5=e1f842cc792eee7ed579211bae1827bfhttps://scholars.lib.ntu.edu.tw/handle/123456789/612008In this paper, a measurement method based on differential position has been announced. The position can be measured and tracked by using a focusing and symmetric light beam(±1 order diffraction beams) that the profile of the tested surface such as cylinder or sphere can be obtained by using this method. To verify this concept, an experiment is hold with a slanted mirror and a taut-wire. The experimental result shows that the concept in this paper is feasible, and the axis of cylindroids or apex of the spheroid can be traced with a system precision of sub-micrometer.Cylinders (shapes)Diffractive opticsFocusingMicrometersMirrorsPosition measurementSpheresSurface measurementDiffraction laser beam systemSubmicrometerLaser beamsconference paper2-s2.0-0141539256