| 摘要 |
A roller extruder for manufacturing Fresnel lens angular segments from raw plastic, the roller extruder having a blank roller and a die roller positioned a desired roller clearance from the blank roller, the die roller having two peripheral lens dies with an angular displacement between the lens dies increasing linearly from a die junction at the inside roller edge to approximately one hundred eighty degrees at the outside roller edge, and the die roller having peripheral Fresnel facet dies.
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