Phase Gratings for ORNL HFIR and SNS Neutron Imaging Interferometers

The Oak Ridge National Laboratory (ORNL) Neutron Imaging Facility will build a Talbot- Lau interferometer for advanced imaging projects, including inspection of additive manufactured components- This SBIR seeks to enhance the ORNL interferometer with novel optics, enabling the interferometer to operate in both Talbot-Lau and the recently invented far-field mode- Dual-mode operation is an ORNL goal- Refined Imaging will microfabricate the high-aspect ratio phase grating optics needed for far-field interferometry- The advantages of far-field over Talbot-Lau are: (1) a two- fold efficiency increase in the use of the neutron flux and (2) a larger scan range of interferometry autocorrelation scattering lengths- Conversely, Tablot-Lau excels at differential phase contrast imaging- In Phase 1, Refined Imaging will explore three microfabrication strategies for high-aspect ratio neutron phase gratings: (1) Double-sided nickel-on-graphite, (2) double-sided nickel-on-silicon, and (3) thin-film photoresists for silicon-on-silicon structures- An optics expert from Sandia National Laboratory will assist with grating design- NIST and NIH researchers have demonstrated the dual application of phase gratings in both neutron and X-ray applications-The commercial application of this SBIR project is extensionof far-field interferometry from the ORNL neutron beamline into lab X-ray sources operating at high energy, well above the typical 90 kV used today- We anticipate the ORNL neutron far-field interferometer will develop a customer base of additive manufacturers- As that customer base grows, it will outpace the available beamtime at ORNL, hence the need for high-energy X-ray far-field interferometers for NDE- The other application of far-field will be medicals; the technology that efficiently uses neutrons at ORNL beamlines translates into low X-ray dose to the patient in a CT scanner-