Sparse scanning Hartmann wavefront sensor

We propose a sparse scanning Hartmann wavefront sensor (SS-HWFS), which decouples the dynamic range and spatial resolution that used to be traded off in a conventional HWFS by removing its arrayed architecture. In addition, the SS-HWFS applies the compressed sensing (CS) reconstruction and is able to restore the wavefront with a sparsely-chosen acquisition. In the SS-HWFS, a collimated beam as the reference is incident on the sample, which is then sparsely scanned over by a pinhole. The wavefront slopes are measured by tracking the diffraction spots recorded by an imaging sensor behind the pinhole. The wavefront is then reconstructed by assuming sparsity in the Zernike domain, which is frequently used for aberration analysis. Compared with traditional Hartmann wavefront sensors (HWFS), the SS-HWFS could achieve high spatial resolution, extensive dynamic range, extended aperture, and compressed acquisition simultaneously, which is a great benefit for the non-null testing of static optical components. Our sparse scanning wavefront measurement scheme is applicable not only for the HWFS but also for the Shack–Hartmann wavefront sensor (SHWFS). Wavefront measurement of a free-form lens is performed to demonstrate the capability of our proposed method.