| 摘要 |
Optical apparatus for modifying a radiation beam, the apparatus including a variable focus lens (1) comprising a first fluid (A) and a second fluid (B) wherein the fluids are immiscible and are separated from each other by a fluid meniscus (6; 106; 206; 306) which is configurable into a configuration which is arranged to modify a predetermined vergence of an input radiation beam (15; 32; 33) and a focus control system. The optical apparatus is characterised in that the apparatus comprises a first redirector arranged to redirect the radiation beam, after having passed once through the fluid meniscus, back towards the fluid meniscus, and a second redirector arranged to further redirect the radiation beam, after having passed twice through the meniscus, back towards the fluid meniscus, wherein the configuration is arranged to further modify the vergence of the radiation beam following each of the redirections, the further modifications being arranged to provide the variable focus lens with an amplified focal power. |
