Fabrication of Gratings for Neutron and X-ray Interferometry with the Ability to Adjust the Period in Real-Time*

We describe the development of a neutron and x-ray transmission grating whose period can be adjusted in near real-time to serve as a suitable source grating for far field interferometry. Our DynAmic ReconfIgUrable Source grating (DARIUS) is fabricated on a silicon platform by patterning and etching microchannels to create a microfluidic device. DARIUS will allow for selectively infilling the microfluidic channels with an x-ray/neutron absorbing fluid to reconfigure the effective grating period on demand. This method enables neutron and/or x-ray beam modulation in real-time. We will report on the initial prototype DARIUS which is comprised of 128 active microchannels etched in silicon with a 20 µm period and 125 µm depth. We will provide details on the fabrication and scaling up to a final device consisting of two gratings patterned on both sides of the wafer, with an active area of 51.2 mm × 51.2 mm and 2,560 channels on each side. The dual-sided DARIUS will be used for dynamic tuning of the effective transmission grating period from 20 µm to 20,000 µm. We also will report progress on wafer-scale bonding to seal the channels with open access ports for selective filling and draining the opaque fluid.