The white light interferometer stitching measurement stage design for the X-ray mirror

Abstract The X-ray mirror surface requires high spatial resolution image measurement, a task for which the white light interferometer stitching method is most commonly used in the X-ray optical measurement lab. The measurement stage design, a crucial part of this method, includes two linear axes and two rotation axes, each with specific travel ranges. The 1200 mm travel range axis is the X axis, and the 390 mm travel range axis is the Y axis. The measurement head travel range is 390 mm along the Z axis. The rotation axes are the X-axis and the Y-axis, and each rotation range is ± 1.5 degrees. The accuracy of the rotation axes is 2.87 x10 −3 degrees. The linear axes stage X, Y, and Z-axis scales accuracy ±1 µm for up to 1 m. In this study, the measurement head is ZYGO Nexview NX2, which has one rotation axis to the Y-axis. The Nexview NX2 measurement sensor array pixels are 1000 * 1000 and 1X objective head with an 8.69 * 8.69 mm field of view. Thus, each pixel’s spatial resolution is about 8.69 μm for the white light interferometer stitching measurement with 1X objective. Therefore, the stage linear direction accuracy is good enough to support the different snapshot images for stitching.