In situ retrieval and correction of aberrations in moldless lenses using Fourier ptychography.

Liquid droplets cured at low temperatures or using ultraviolet light are primary approaches for fabricating refractive lenses without molds. Until now the performance of moldless lens fabrication process relied heavily on this step to precisely control the shape of each liquid droplet. Hence, a major hurdle in lenses fabricated from liquid droplets is the large variability of droplet shapes because they are sensitive to small amounts of interfacial forces. The shape of the final droplet critically affects the imaging performance of the lenses and cannot be reversed easily. Here, we aim to overcome this hurdle by performing in situ aberration correction using Fourier ptychography techniques. We demonstrate, for the first time, that computational optics can reverse high amounts of optical aberrations in moldless lenses and achieve high resolution imaging. In terms of imaging resolution, we successfully increased the resolving power of low powered moldless elastomer lenses by almost three-fold, from a numerical aperture of 0.035 to 0.099. The computational approach directly elucidates the spatially varying wavefront aberrations from each lens using the same imaging system. This provides direct feedback of droplet lens fabrication techniques without the need for advanced wavefront correction methods. The application of computational imaging onto moldless lenses, using consumer digital imaging systems, lends itself to the global efforts in decentralising high resolution image intensive scientific tools to the wider community.