Large aperture telescope for advanced lidar system

The final optical design for a space-borne light detection and ranging lidar mission is presented, in response to the European Space Agency “Advanced lidar concepts” proposal for use of a differential absorption lidar system to measure water vapor distribution in atmosphere at 935.5 nm. The telescope adopts a double afocal concept i.e., four reflections with two mirrors using a lightweight and large aperture primary mirror. It is derived from a feasibility study that compares several different optical configurations, taking into account parameters such as cost, dimensions, complexity, and technological feasibility. The final telescope optical design is described in detail, highlighting a trade-off with other solutions and its optical tolerances.