Total-reflection-based microscope compatible with X-ray and visible light for sample positioning

Sample positioning in X-ray imaging is often technically demanding and involves radiation exposure to the sample. For easier and damage-free positioning, the integration of a visible-light microscope is an effective and widely adopted approach. However, such visible-light microscopes require careful calibration of the objective optic against the X-ray microscope, which introduces additional challenges. To address this issue, we propose a simple total-reflection-based microscope compatible with X-rays and visible light using a Wolter mirror which functions as both X-ray condenser optic and visible-light objective optic. Calibrating our visible-light microscope requires only simple adjustment of an optical lens and three planar mirrors, while no adjustment of the objective optic. We constructed our proposed system for a soft X-ray ptychography system and successfully demonstrated the simple calibration of the visible-light microscope, which was then applied to position a biological sample without delivering a radiation dose.