Coherent, focus-corrected imaging of optical fiber facets using a single-pixel detector

A novel imaging technique that produces accurate amplitude and phase images of an optical fiber facet using only a phase-only liquid-crystal on silicon (LCOS) spatial light modulator (SLM) and a single-pixel detector is presented. The system can take images in two orthogonal polarizations and so provides a powerful tool for modal characterization of multimode fibers, which is of increasing importance due to their burgeoning use in telecommunications and medical applications. This technique first uses a simulated annealing algorithm to compute a hologram that collects light from a small region of the fiber facet. Next, the fiber facet is automatically brought into focus using adaptive aberration correction on the SLM. Finally, a common-path interferometer is created using the SLM, and the phase of the optical field at each pixel is determined. Finally, high-definition amplitude and phase images of a ring-core refractive index fiber are presented as a proof-of-principle demonstration of the technique

Anisotropy characteristics of element composition in Upper Triassic "Chang 8" shale in Jiyuan district of Ordos Basin, China: Microscopic evidence for the existence of predominant fracture zone

This study quantified the anisotropy of element composition in Upper Triassic "Chang 8" shale in Jiyuan district of Ordos Basin, China and provided the microscopic evidence for the existence of dominant fracture zone. Element quantification was carried out ensuring both observational resolution and sample representativeness. Results show that for shale slices in two directions which are 45 degrees (225 degrees) and 0 degrees (180 degrees /360 degrees), the distribution of elements is significantly different from that in other directions. The minimum of element contents often occurs in 45 degrees (225 degrees) and the maximum of element contents often occurs in 0 degrees (180 degrees/360 degrees). The brittleness parameter value stays at a high level from 0 degrees (180 degrees/360 degrees) to 22.5 degrees (202.5 degrees). The maximum value occurs in 0 degrees (180 degrees/360 degrees), and the minimum value occurs in 45 degrees (225 degrees) which has obvious significance in shale stimulation. The conclusion proved that the existence of predominant fracture zone in shale has the microscopic evidence in micro-scale brittle minerals