We subsequently obtained the spot images of a part of the mirrors using a slit size of . For this measurement, the distance between the mirrors and the detector was 12,000 mm. Figure 13 shows the spot image obtained with a slit size of at a scan angle of 123.6 deg, and Fig. 14 shows the projection of the spot image onto the Dy axis. The HPD of the spot image was 0.38 arc min. The HPD of the spot image in the case of slit size (0.61 arc min) was larger than that of the case (0.38 arc min) for the same scan angle. In the measurement, the image blurring could be caused by defocusing due to the short distance between the mirror and the detector. The effect of the defocusing is estimated to be , where is the height of the mirror, is the incident angle of the mirror, is the distance between the mirror and the detector, and is the focal length of the mirror. From the configuration of the mirror, the effect of the defocusing at the distance of 8406 mm was estimated to cause a point spread of 0.1 mm on the detector. This can be converted to 0.04 arc min, which is insufficient to explain the discrepancy of the HPD between the slit sizes of and . In Fig. 10, the peak position of the image in the Dy direction changes along the Dz direction. In sliced profiles along the Dz direction, the peak positions of the profile at a Dz of 4 (arc min) differed from the peak position at a Dz of 4.5 (arc min) by . This is roughly consistent with the blurring of the image in comparison with that of the case. The difference between the sliced images along the Dz direction implies that the angle between the two stages of the mirror was slightly misaligned. Possible reasons for the misalignment include deformation due to misalignment of the alignment bars, imperfection of the shape of the CFRP substrate in the circumferential direction, and nonuniformity of the epoxy thickness in the replication. We need to study each of these elements to achieve improvement of the imaging performance.