Lawrence Berkeley National Laboratory
Lateral shearing interferometry for high-NA EUV wavefront metrology
- Author(s): Zhu, W
- Miyakawa, R
- Chen, L
- Naulleau, P
- et al.
Published Web Locationhttps://doi.org/10.1117/12.2501989
Copyright © 2018 SPIE. We present a lateral shearing interferometer suitable for high-NA EUV wavefront metrology. In this interferometer, a geometric model is used to accurately characterize and predict systematic errors that come from performing interferometry at high NA. This interferometer is compatible with various optical geometries, including systems where the image plane is tilted with respect to the optical axis, as in the Berkeley MET5. Simulation results show that the systematic errors in tilted geometries can be reduced by aligning the shearing interferometer grating and detector parallel to the image plane. Subsequent residual errors can be removed by linear fitting.