## 3 Experimental Verification  
As shown in Figure 11, the experimental setup for verifying the assembly process of the grazing incidence focusing mirror is constructed. At the bottom is a 45-degree flat mirror, which is used to turn the parallel light emitted from the parallel light source from the horizontal direction to the vertical direction; the base of the platform is a fixed support subsystem, which mainly contains various mechanisms for adjusting and fixing the front spider to move horizontally and centrally; the upper part is a precision adjustment subsystem, which is the most crucial device for the assembly and adjustment device, and mainly consists of six circumferential uniformly arranged motion modules and a two-dimensional moving platform below, in which three of the six motion modules are connected to a piezoelectric actuator mechanism for precision adjustment of the spatial attitude of the mirror, and three of them are used as counterweights to reduce the influence of weight on the mirror's surface shape accuracy; at the top is the spot monitoring subsystem, which mainly includes a large travelling module that can move along the vertical direction, a motorised five-degree-of-freedom adjustment stage, and a spot analyser, which is used to adapt to the precision adjustment of the focal length of the mirror, to ensure that the focused spot is accurately imaged in the image plane of the spot analyser; and on the left side is the transfer arm, which is used for the initial transfer and placement work of the  
Figure 10: (**a**) Effect of adhesive curing on the surface shape of the mirror; (**b**) Analysis of the accuracy of the surface shape of the mirror due to adhesive curing. \begin{table}
\begin{tabular}{c c} \hline \hline
**Assembly Process** & **Angular Resolution** \\ \hline Standard surface (error-free) & \(1.23^{\prime\prime}\) \\ Standard surface with NURBS surface interpolation (error-free) & \(1.51^{\prime\prime}\) \\ Pre-assembly (with surface shape error) & \(48.64^{\prime\prime}\) \\ During assembly (three-hanging-point) & \(51.37^{\prime\prime}\) \\ During assembly (six-hanging-point) & \(49.50^{\prime\prime}\) \\ Post-assembly (after adhesive curing) & \(52.23^{\prime\prime}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The angular resolution under different conditions. mirror. The schematic diagram of the optical path of this experimental setup is shown in Figure 12.  
The gravity effect experiments are carried out in the three-hanging-point and six-hanging-point modes, respectively, and the operation steps are slightly different; in the six-hanging-point suspension mode, the other three-hanging-point are counterweights, and each counterweight is 1/6 of the weight of the mirror itself. All the hanging points are evenly distributed, and the hanging plate is made of stainless steel of uniform size, which is connected to the motion module evenly distributed in the circumferential direction above through the hanging rope, and the hanging plate is connected to the mirror by double-sided adhesive. To ensure that the force of the hanging points is uniform in the assembly process, the hanging points are located at the same height relative to the mirror. The direction of the tension of the hanging rope is vertically upward, so in the process of bonding the hanging plate to the outer surface of the mirror, all the hanging points should be adjusted to a uniform corresponding position first, and then the upper motion module should be slowly moved to the outer surface of the mirror, so that the hanging points are just external to the outer side of the mirror, and then three of the hanging points should be slowly adjusted to adjust the spatial position of the mirror. The mirror under the two hanging-point methods is shown in Figure 13, the process of adjusting the experimental setup is shown in Figure 14, and the imaging quality of the focused spot is shown in Figure 15.  
Figure 11: Experimental setup for grazing incidence focusing mirror assembly.