| 摘要 |
<p>In an infrared wide-angle single lens which is in a form of a positive meniscus lens, the following conditional expressions (1) through (6) are satisfied: (1) -50.0 th < r1 < -3.5 th (2) -5 th < r2 < -1.1 th (3) 2 < n < 4.5 (4) 0.1 f < d < 0.8 f (5) 0.5 f < bf < 1.5 f (6) 0.5 f < th < 2f where, an aperture stop (S) being disposed between an object plane (O) and a first surface (A1), d is the distance between the aperture stop and the first surface, th is the lens thickness, bf is the backfocus, r1 is the radius of curvature of the first surface, r2 is the radius of curvature of a second surface (A2), n is the refractive index of a vitric material at a wavelength of 10 mu m, and f is the focal length. <IMAGE></p> |
