| 摘要 |
A lens in a shape of cylinder or head-cut-off cone made of transparent thin film materials with a fine prism-shaped fresnel lens surface formed thereon. The cylindrical lens is manufactured by forming a fine prism-shaped linear fresnel lens surface on a thin transparent film, shaping the film into a cylinder or a frustum of a cone, and connecting both ends of the film so that the fresnel center line forms a horizontal ring.
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