| 摘要 |
<p>Apparatus and methods for a two-lens optical system having a focal length that can be readily switched between a first focal length and a second focal length. The system includes first and second multi-element lenses, each of which includes a cavity for a fluid. The first lens has the first focal length in the absence of the fluid in its cavity and the second focal length when the fluid is present in its cavity. The second lens has the second focal length in the absence of the fluid in its cavity and the first focal length when the fluid is present in its cavity. The focal length of the optical system is controlled by controlling which cavity of the two lenses contains the fluid.</p> |
