Abstract: The present disclosure provides a method and system for optimizing first-diffraction-order reconstruction of holograms, a device and a medium, and relates to the field of image processing. The method includes: acquiring a target image; determining a target image light field according to the target image; calculating a target diffraction field for the target image light field by performing backward propagation by a set distance; constructing a U-Net network model; and inputting the target diffraction field into a trained U-Net network model to acquire an optimized hologram. The trained U-Net network model is obtained by constructing a U-Net network model and training and optimizing the U-Net network model, thereby continuously improving the quality of the zero-diffraction-order reconstructed image of the initial hologram and finally achieving the effect of optimizing the first-diffraction-order reconstructed image of the hologram.

Abstract: The present invention provides a water-absorbent resin that has excellent water-absorption performance with respect to salt water; a water-blocking agent including the water-absorbent resin; and a method for producing the water-absorbent resin. The water-absorbent resin of the present invention includes a partially neutralized polyacrylic acid having a crosslinked structure and has a swelling height of 3.5 mm/0.5 g or more with respect to 3.3 mass % salt water, as determined under the following measurement conditions. Measurement Conditions for Salt Water Swelling Height 0.5 g of water-absorbent resin particles are sprayed over a circular concave cup having a height of 30 mm and an inner diameter of 80.5 mm. A nonwoven fabric 4 is spread thereon. A circular convex cylinder having an outer diameter of 80 mm is placed on the nonwoven fabric, and 55 g of 3.3 mass % salt water at 20° C. is poured into the circular concave cup.