Shack-Hartmann (SH) wavefront sensing is widely applied to astronomical observations with its fast and accurate measurement. However, due to the computational nature of SH that the input beam is segmented to provide local wavefront slopes, the sampling density of the sub-apertures and the calculation accuracy of each sub-focal spot's centroid have great influence on the wavefront reconstruction accuracy. Therefore, it is usually difficult to achieve high resolution wavefront reconstruction for dark stars in the astronomical observations with insufficient light intensity.
View Article and Find Full Text PDFThis paper proposes a single-shot high robustness wavefront sensing method based on deep-learning for wavefront distortion measurement in high power lasers. This method could achieve fast and robust wavefront retrieval by using a single-shot near-field profile image and trained network. The deep-learning network uses fully-skip cross connections to extract and integrate multi-scale feature maps from various layers and stages, which improves the wavefront retrieval speed and enhances the robustness of the method.
View Article and Find Full Text PDFWe report a novel, to the best of our knowledge, mode-tunable optical vortex generation method based on a mirror curvature dynamically controlled Z-shaped resonant cavity, a mode conversion beamline, and a reference laser beamline. By changing the mirror curvature of an intra-cavity deformable mirror (DM) at a certain pumping voltage and current, various Hermite-Gaussian (HG) mode beams were obtained in the Z-shaped resonant cavity of a laser diode pumped Yb:CALGO laser. The vortex beams were realized finally by using an external cavity astigmatism converter.
View Article and Find Full Text PDFA shear-joint deformable mirror (DM) is important in the high-power laser systems such as the National Ignition Facility (NIF). In this paper, the print-through high-frequency aberration (PT-HIFA) that arises from adhesive curing and is corresponding to the actuator array is reported to exist in the initial surface shape of a lab-made shear-joint NIF DM. Meanwhile, experimental results show that the PT-HIFA has a great modulation on the laser intensity.
View Article and Find Full Text PDFIn a well-manufactured deformable mirror (DM), the temperature-induced distortion (TID) has been reported exist on the surface shape of the DM, when the working environment temperature is not equal to that of the manufacturing environment. The DM could not effectively correct this actuator-corresponding TID and the correction ability of the DM would be limited. In this paper, the the TID's essential mechanism is analyzed systematically based on the thermal stress characteristics.
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