| 摘要 |
Methods and systems are disclosed relating to low f/# lens with desirable imaging characteristics. In certain embodiments, the lens may include an aspheric surface and a Fresnel surface to produce one or more of the following characteristics: a large aperture; a wide field of view; a low spherical aberration and coma; a low field curvature; a monotonic field curvature for both tangential and sagittal planes; and significant but monotonic distortion. A variety of design forms may be used to accomplish the foregoing results including without limitation: an aspheric surface with a Fresnel asphere; a Forbes aspheric surface with a Fresnel asphere; an aspheric surface with a curved, 2-figure Fresnel lens; a Forbes aspheric surface with a curved, 2-figure Fresnel lens; and wide Fresnel zones. The lens may be a single element lens or a multi-element system including a thin field flattener or a negative lens for lateral color collection. |
