| 摘要 |
An optical cell 5 comprising at least one telescope 10, where the cell 5 is configured such that light makes at least one transit through the telescope 10 in a forward direction and a reverse direction before exiting from the cell 5. The telescope 10 is preferably a folded/reflector telescope 10, comprising a first retro-reflector 15 and at least one positively optically powered surface 20 and the optical cell 5 preferably comprises at least one counter reflector 30, wherein the reflectors define a cavity between them, at least one input 40 for allowing light into the cavity and at least one output 45 for light to exit the cavity. The cell is optionally configured to support helical modes by providing a tangential component to the input beam angle. The cell may, but is not limited to, be a resonator or cavity. |
