| 摘要 |
<p>The invention is part of the technical field of special lenses and relates in particular to an improved Fresnel lens, as well as to a method and mold for manufacturing it. The technical problem to be solved is to provide a Fresnel lens of high efficiency and which may be manufactured in mass-production work also by means of a simple molding process. The Fresnel lens (8), as viewed in cross-section, has a face (3) formed with a plurality of spirally arrranged teeth (4), each whereof includes a light ray (5) refracting portion (4a) and a connection flank (4b) to the next adjacent refractive portion, in each tooth (4) the angle included between any such refractive portions (4a) and the adjoining connection flank (4b) being less than 90 DEG .</p> |
