Abstract: A projection curtain is provided in the present invention. The projection curtain at least comprises a reflective layer and one of a colored layer, a diffusion layer, and a Fresnel lens layer. The Fresnel lens layer is a spherical Fresnel lens layer or an aspherical Fresnel lens layer. The Fresnel lens layer comprises a plurality of annular protrusions protruding from a plane, the plurality of annular protrusions are arranged in circular bands. A cross-sectional shape of each annular protrusion along a cross section perpendicular to the plane is a triangular shape or a multi-step shape or a free surface shape. The width of one side of each cross-sectional shape parallel to the plane gradually changes, and gradual change of the cross-sectional shape and the width thereof determines light gathering characteristics of the spherical Fresnel lens layer or the aspherical Fresnel lens layer. A surface of each annular protrusion has scattered microstructures.

Abstract: The present invention provides a preparation method of (5-fluoro-2,3-dihydrobenzofuran-4-yl)methylamine or a salt thereof, which uses 4-fluoro-3-methylphenol as the starting material, and is carried out through the steps of bromination, O-alkylation, cyclization, bromination, azidation or ammonolysis, and reduction. The reaction route of the present invention has simple synthesis process, convenient operation, high yield, and is environmentally friendly. The prepared (5-fluoro-2,3-dihydrobenzofuran-4-yl)methylamine can be used as an intermediate in pharmaceuticals and fine chemicals.