Variable optical null based on a yawing CGH for measuring high-departure acylindrical surface

To address this problem, we analyze the departure of off-axis acylindrical subapertures, and propose a measurement strategy by yawing the cylinder null. When the cylinder null is yawed with different angles, variable mounts of acylindrical wavefronts are generated to compensate most of the aberrations for different off-axis subapertures.

Thus, the fringe densities are drastically reduced within the vertical dynamic range of interferometers. To connect all subaperture together, we also propose an acylindrical stitching approach. Experimental results demonstrate that an acylindrical lens with a departure of up to 81μm from the best-fitting cylinder can be measured using the proposed method.