| 摘要 |
<p>A lens element (20) is formed from a monolithic unit having two sections (36A, 39A) aligned on an optical axis. A selected one of the sections has an axial gradient refractive index, and the other has a homogeneous refractive index. The axial gradient index material may be selected such the third order spherical aberration of the element is zero. The axial gradient index material may be selected such that similarly constructed elements having shape factors between about 0 and 2.0 also have zero third order spherical aberration. The refractive index preferably varies as a non-linear function of at least distance along the optical axis. An element is formed from a material having an axial gradient dispersion. Shape factor and dispersion gradient may be selected such that the element is achromatic.</p> |
