| 摘要 |
<p>[Problem] To implement a small, inexpensive, highly telecentric, high-performance imaging lens with a long back focal length and small F-number. [Solution] An imaging lens (1) is provided with the following lenses, in order from the object side: a negative first lens (L1); a positive second lens (L2); a negative third lens (L3); a positive fourth lens (L4); and a positive fifth lens (L5). An aperture is disposed between the image-side surface of the first lens (L1) and the object-side surface of the third lens (L3). The index of refraction (Nd3) and Abbe number (vd3) of the material constituting the third lens (L3) at the d-line thereof satisfy relations (1) and (2). (1) Nd3 < 1.75 (2) vd3 < 35</p> |
