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Figure 7
(a) As the mirror system is cooled from 295 to 77 K the mirror contracts, resulting in a height error in the tangential plane of approximately −7000 nm. As the undulator K value increases from 1 to 3 the contraction continues because the mirror temperature is in the negative CTE regime of silicon. (b) To a first-order approximation, the slope error of the mirror in the tangential plane is a constant −0.6 µrad for cool-down and all evaluated undulator K values. In both plots the manifold–substrate interface is at the far left (x = −150 mm), the beam center is at x = 0 and curves are given for the linear horizontal polarization mode of the undulator. |
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