| Popis: |
We present an X-ray mirror bender that includes multiple spring actuators that introduce a controlled deformation of the mirror substrate capable of correcting residual figure errors on the mirror, below one nanometer. For usual mirror dimensions, this requires applying correcting forces with resolution and stability in the order of 0.01 N, and a range up to 20 N, depending on the initial figure error of the mirror. To obtain the required stability, the actuators need to compensate intrinsic mechanical instabilities, such as thermal drifts or the limited repeatability of parts that move during the adjustment of the figure. The concept we propose uses weak springs that allow reducing all these effects below noticeable values. Additional considerations on friction and parasitic components of the force are accounted. The system also includes two independent bending actuators with a larger force range to generate the mean elliptic figure of the mirror. Metrology tests of the performances of the system show that the correctors are repeatable within 0.01 N, and reach much higher resolution. A prototype of the bender has been used to correct the figure error of a 500 mm long mirror below one nanometer (root mean square). The agreement to the predicted figure is better than 0.08 nm rms. |
