Advances in ptychographical coherent diffractive imaging

Extracting quantitative image information from coherent diffraction measurements remains challenging due to problems such as slow convergence of iterative phase retrieval algorithms, questionable uniqueness of the resulting images, and common requirements of compactness of the specimens. These difficulties are overcome by combining iterative phase retrieval with ptychography, i.e., the use of multiple diffraction measurements probing several overlapping regions of the specimen. While promising results of ptychographical coherent diffractive imaging have been achieved the technique has been limited by requiring precise knowledge of the illumination. We present advances of the reconstruction algorithm, which allow unsupervised deconvolution of the illuminating probe and the complex-valued optical transmission function of the specimen. We have performed measurements using both visible light and x-rays, demonstrating sub-50nm resolution.