Subaperture stitching interferometry based on digital holography

• A subaperture stitching interferometry based on digital holography is provided to measure the deformation of spherical surface.
• The experiments demonstrate the feasibility and effectiveness of the proposed interferometry.
• The phase aberration caused by position errors of each subaperture measurement are effectively compensated by method of numerical parametric lens.
• The relative alignment errors of adjacent subapertures are eliminated with the iterative process of stitching optimization.

A novel subaperture stitching interferometry based on digital holography is developed to measure the deformation of spherical surfaces. The subaperture measurement is performed by off-axis digital holography on single exposure. Then, the subaperture phase maps are obtained by digital holographic reconstruction, in which the phase aberration caused by position errors of each subaperture measurement is effectively compensated by the method of numerical parametric lens. After that, the full aperture phase map is retrieved by a subaperture stitching algorithm, in which the relative alignment errors of adjacent subapertures are eliminated with an iterative process of stitching optimization. The experiments demonstrate the feasibility and effectiveness of the proposed interferometry, which provides a rapid and robust way to measure spherical surfaces with high resolution and precision. A practical example is given to demonstrate the performance of this method. The stitching result shows good agreement with the full-aperture result.