Full-field neutron microscopy based on refractive optics

Abstract

Placing a compound refractive lens (CRL) as an objective in a neutron beam generates new possibilities for 2D and 3D nondestructive mapping of the structure, strain and magnetic domains within extended objects. A condenser setup is introduced that allows correction for the lateral chromatic aberration. More generally, for full‐field microscopy the loss in performance caused by the chromatic aberration can be more than offset by introducing arrays of CRLs and exploiting the fact that the field of view can be much larger than the physical aperture of the CRL. Comments are made on the manufacture of such devices. The potential use is illustrated by comparisons between state‐of‐the‐art instrumentation and suggested approaches for bright‐field microscopy, small‐angle neutron scattering microscopy, grain mapping and mapping of stresses. Options are discussed for depth‐resolved imaging inspired by confocal light microscopy. Finally, experimental demonstrations are given of some of the basic properties of neutron full‐field imaging for a single CRL.

Geometrical-optics formalism to model contrast in dark-field X-ray microscopy

“…Parts of this presentation may be relevant for other X-raydiffraction-based methods to facilitate interpretation of microstructural mapping; opportunities also exist in neutron microscopy (Leemreize et al, 2019). In particular, Bragg coherent diffraction imaging (BCDI) and the related ptychography method also probe one diffraction vector to acquire a high-resolution 3D map of the shape and internal displacements in micrometre-sized isolated particles (Chapman & Nugent, 2010;Miao et al, 2015;Pfeifer et al, 2006;Yau et al, 2017;Chamard et al, 2015).…”

Revisiting Neutron Propagation-Based Phase-Contrast Imaging and Tomography: Use of Phase Retrieval to Amplify the Effective Degree of Brilliance

“…This study has been restricted to positive defocus , since free-space propagation is utilized as the mechanism for phase contrast. However, as briefly mentioned earlier in the paper, negative defoci will be accessible if an imaging system is interposed between the sample and the detector, e.g., in possible future applications of the method of this paper to neutron microscopy [104,105] using compound refractive lenses [106,107]. For such systems, the requirement for b to be positive, so as to avoid a division-by-zero divergence in the Fourier filter given in Eq.…”

Neutron ghost imaging

“…(iv) High-resolution neutron microscopy is notoriously difficult (conventional imaging is currently limited to a resolution of about 10 μm [35]), with research being conducted into efficient scintillator materials [36] to reduce scintillator thickness (and thus increase spatial resolution) without sacrificing detected neutron flux. Neutron microscopy through compound refractive lenses is also being explored [37][38][39][40] and, while promising, does not yet provide resolutions matching conventional imaging.…”