@inproceedings{81b7e4698b394493b5aa90c6b8578404,
title = "Model-free optical surface reconstruction from deflectometry data",
abstract = "Deflectometry is a metrology method able to measure large surface slope ranges that can achieve surface reconstruction accuracy similar to interferometry, making it ideal for freeform metrology. While it is a non-null method, deflectometry previously required a precise model of the unit under test to accurately reconstruct the surface. However, there are times when no such model exists, such as during the grinding phase of an optic. We developed a model-free iterative data processing technique which provides improved deflectometry surface reconstruction of optics when the correct surface model is unknown. The new method iteratively reconstructs the optical surface, leading to a reduction in error in the final reconstructed surface. Software simulations measuring the theoretical performance limitations of the model-free processing technique as well as a real-world test characterizing actual performance were performed. The method was implemented in a deflectometry system and a highly freeform surface was measured and reconstructed using both the iterative technique and a traditional non-iterative technique. The results were compared to a commercial interferometric measurement of the optic. The reconstructed surface departure from interferometric results was reduced from 44.39 μm RMS with traditional non-iterative deflectometry down to 5.20 μm RMS with the model-free technique reported.",
keywords = "Deflectometry, Freeform, Metrology, Model-free",
author = "Graves, {L. R.} and H. Choi and W. Zhao and Oh, {C. J.} and Peng Su and T. Su and Kim, {D. W.}",
note = "Publisher Copyright: {\textcopyright} COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.; Optical Manufacturing and Testing XII 2018 ; Conference date: 20-08-2018 Through 22-08-2018",
year = "2018",
doi = "10.1117/12.2320745",
language = "English (US)",
series = "Proceedings of SPIE - The International Society for Optical Engineering",
publisher = "SPIE",
editor = "Ray Williamson and Kim, {Dae Wook} and Rolf Rascher",
booktitle = "Optical Manufacturing and Testing XII",
}