**6. Conclusions**

In this paper, we reported on a robust interferometric method that can eliminate the measurement error induced by micro-displacement. This method can greatly enhance the anti-interference ability and accuracy by eliminating the measurement error. This method is especially useful for CTE measurement of non-standard samples like dual-material truss structures with high precision requirements. The theoretical analysis indicated that translation did not a ffect the measurement results and that rotation made the measurement results lager. The robust experimental system was designed and built using two plane lenses and a distance measuring interferometer. The experimental results of the aluminum truss structure proved that this method can avoid the translation error and has the potential to eliminate the measurement error caused by rotation. The CTE measurement results of the sample successfully demonstrated the validity of the measurement system.

**Author Contributions:** Conceptualization and methodology, W.L., S.X. and C.Z.; formal analysis, W.L.; experiment and investigation, W.L. and S.X.; writing—original draft preparation, W.L.; writing—review and editing, S.X., M.Z. and G.L.; project administration, G.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors would like to thank Kai Zhang, Renxiu Han, and Tian Lan for their support. The authors also would like to thank Qiang Xu of National University of Defense and CTEhnology Microsystem Laboratory for his support.

**Conflicts of Interest:** The authors declare no conflict of interest.
