An Organization Committed to Applied Research
Discovering new, better approaches to interferometry and its applications
Refined Imaging is actively exploring ways to apply X-ray and neutron interferometer to solve problems in the secure supply chain, healthcare, nondestructive evaluation, agriculture, and more.
Probably no one explains how interferometry works better than Prof. Richard Feynman in his popular 1965 lecture on the "Electron Two Slit Experiment".
Even today, this lecture provides valuable insights for interferometry and quantum entanglement.
Since Feynman's lecture, researchers in Switzerland and Japan in 2006 independently developed grating-based interferometry for incoherent X-ray and neutron sources. We performed our first X-ray interferometry at the US Advanced Photon Source in 2011 and were immediately impressed with the data reduction problem. We consulted with an expert at the Laser Interferometer Gravitational-Wave Observatory and jointly developed a new algorithm which we patented [Butler, 2018] and published [Marathe, 2014].
A neutron grating-based interference pattern superimposed upon an additive manufacturing test coupon shows constructive and destructive fringes. The region around the test dot is expanded at right and shows how the fringe moves left-right as the grating optics are moved; Xg is the relative position of one of the grating optics. We are impressed that grating periods and motions on the scale of microns (easy to accomplish) can develop observable interference patterns for X-rays and neutrons with wavelengths on the order of 20 to 200 picometers.
Tomography, with sample rotation, and grating-based interferometry, with stepped grating motion, are easily combined, as shown in this cartoon movie.
Stepping and rotation takes time; is there an alternative to stepping? Yes! NIH researchers developed an algorithm to extract interferometry data from a "single shot", a fringe pattern with a stationary grating. In collaboration with the Advanced Photon Source, we developed software and applied single-shot to take interferometry movies of rapidly evolving samples, such as polymers with flame retardants subjected to extreme heat and almost catching on fire.[Olatinwo, 2016; Olatinwo, 2017].
It sounds like interferometry takes special optics and clean room conditions; is there a way to ruggedize interferometry? Yes! Researchers at the University College of London developed structure illumination; the requirements of the microfabrication optics are much reduced. We have used both micromilling machines and high-resolution polymer additive manufacturing to fabricate optics, and have tested these optics in a machine-room-type environment such the UC Davis McClellan Nuclear Research Center, with a neutron imaging beamline formerly used to image aircraft.
Reﬁned Imaging is developing intellectual property, patents, and trade secrets. Refined Imaging has the exclusive license agreement with LSU for the following patents and provisional patents.
US patent 10,117,629 “Process for More Effective Performance of X-Ray Grating Interferometry at High Energy” with co-inventors Les Butler, Kyungmin Ham, and Warren Johnson, November 6, 2018. RI has an exclusive license agreement for the use of this patent from LSU.
US patent 10,872,708 “Phase Contrast X-ray Interferometry”, with co-inventors J. Dey, N. Bhusal, L. Butler, K. Ham, J. Dowling, V. Singh, December 22, 2020.
Provisional Patent – “Counterfeit Detection and Provenance with Grating Interferometry, Blockchain, and Smart Contracts”, with co-inventors Leslie G. Butler, Michele L. Maasberg, Ian Taylor, Charles C. Hartman, November 2021
Marathe, S., Assoufid, L., Xiao, X., Ham, K., Johnson, W.W. and Butler, L.G., 2014. Improved algorithm for processing grating-based phase contrast interferometry image sets. Review of Scientific Instruments, 85(1), p.013704.
Grizolli, W., Shi, X., Assoufid, L. and Butler, L.G., 2019, January. Wavepy-python package for x-ray grating interferometry with applications in imaging and wavefront characterization. In AIP Conference Proceedings (Vol. 2054, No. 1, p. 060017). AIP Publishing LLC.
Olatinwo, M.B., Ham, K., McCarney, J., Marathe, S., Ge, J., Knapp, G. and Butler, L.G., 2016. Analysis of flame retardancy in polymer blends by synchrotron X-ray K-edge tomography and interferometric phase contrast movies. The Journal of Physical Chemistry B, 120(9), pp.2612-2624.
Olatinwo, M.B., Ham, K., McCarney, J., Marathe, S., Ge, J., Knapp, G. and Butler, L.G., 2017. Recent applications of X-ray grating interferometry imaging to evaluate flame retardancy performance of brominated flame retardant. Polymer Degradation and Stability, 138, pp.1-11.