Research on the Application of Vortex Beam in Ptychography

Ptychography is a coherent diffraction technology, which is not limited by sample size and has the advantages of high imaging quality, strong portability,
and low stability requirements for optical platform. It has been experimentally confirmed in the visible light domain, X-ray and other different frequency
bands. The ptychography system has a wide application prospect in the fields of microimaging, three-dimensional morphology measurement and information
security. However, many researches on ptychography are still in the preliminary theoretical stage and there is none research on its combination with vortex
beam, and the key parameters affecting the imaging performance are still not to be studied. This thesis first briefly introduces the research background, significance, the basic concepts, development and application of ptychography and vortex beam. Then, it introduces the theoretical basis supporting its use, including computer-generated hologram (CGH), beam steering and the computing algorithm of ptychography. On this basis, this thesis presents the following innovative research:
An optical ptychography set-up, with a spatial light modulator as the core device, is designed to facilitate the flexible production of different types of optical
probe, such as the generation of conventional beams and vortex beams; flexible adjustment of the order and defocus of vortex beams, etc., so as to realize their
experimental exploration. Experiments show that vortex beams have a higher imaging quality in ptychography, and the topological charge number and defocus of vortices also affect the reconstruction quality of the samples to a certain extent. Therefore, these parameters can be adjusted according to the experimental requirements to achieve the best recovery quality of information about the samples in the actual experimental operation.