Measurement method for large aperture angle incomplete spherical surface stitching based on confocal focusing

In traditional stitching measurements, the central sub-aperture is usually used as the reference and is not suitable for incomplete spherical surfaces without central sub-aperture. The measurement of each sub-aperture requires manual readjusting the position and attitude of the measured component, resulting in low measurement accuracy and low measurement efficiency. In response to this issue, this study proposed a method based on confocal focusing for large aperture angle incomplete spherical surface stitching measurement. Automatically and accurately determine the position of the common focus through confocal focusing technology, the positioning accuracy of the measured component is improved. A sub-aperture stitching model was built, coordinate mapping rotation algorithm and overlapping area error compensation algorithm were applied to the surface shape of each sub-aperture, achieving stitching measurement of large aperture angle incomplete spherical surfaces. Finally, the confocal interference stitching measurement system was built to carry out stitching experiments of sphere and large aperture angle incomplete spherical surface. The stitching experimental results indicated that the method increases the measurement accuracy of PV by 2.2 times, increases the measurement accuracy of RMS by 2.3 times, and increases the measurement efficiency by 1.6 times. Therefore, this method provides a high-precision measurement method for detecting large aperture angle spherical surface shape.