Theoretical study of surface states excitation in one-dimensional photonic crystal by halide perovskite microstructures

In this work we develop the concept of integrated light source based on halide perovskite microwires for Bloch surface waves (BSWs) in one-dimensional photonic crystals. We theoretically study modes supported by a CsPbBr3 microwire placed on the surface of a photonic crystal. The modes with field distribution similar to BSW are observed. We study the coupling of microwire modes with BSWs depending on the geometric parameters of the wire. BSW excitation efficiency exceeding 40% is found for BSW-like modes of microwire. We also examine resonant modes of finite microwire and show that BSW-like modes play a main role in the excitation of BSWs with perovskite radiation. Our research paves the way for the implementation of complete integrated optical setups on the surface of photonic crystals.

Cross correlation of CIELAB color reflectance data from archive photographs and line-scan images of sediment

Archive color photographs—particularly of sites where sediment is no longer available—are an underused resource that potentially contains detailed paleoenvironmental information. To investigate this potential, two sets of digital images were taken, at different times, of loess, glaciolacustrine, and deep-sea sediments. The first image set was taken using standard digital cameras. Lighting conditions and sediment surface preparation varied, in a similar way to characteristics likely to be encountered in archive photographs. The second image set was taken by a high-resolution, line-scan camera with an integrated light source. CIELAB (Commission Internationale de l'Eclairage) color reflectance data were obtained from both image sets and analyzed by cross correlation. Of the three reflectance parameters (L*, a*, and b*), L* reflectance is the most compromised by differences in ambient lighting or moisture content. Textural distinctions appear to be an important factor influencing the cross correlations and produce multiple, relatively weak solutions for the glaciolacustrine sediments, whereas the texturally uniform loess and deep-sea sediments produce a single, best-fit solution. Comparison of a* reflectance records from an undated marine sequence with a chronologically constrained sequence from the same site indicates the potential to apply color reflectance to produce preliminary age models.

Flexible interventional imaging system based on miniaturized X-ray tubes (FlexScan)

In orthopedic hand surgeries C-arms are the standard imaging modalities for procedure and tool guidance. However, the currently used systems have a large footprint and high weight, which can lead to workspace restrictions and difficult positioning of the device at the desired imaging position. The aim of this paper is to present a prototype of a new, flexible, lightweight and small footprint X-ray system, which is capable to create 2D projection images from different orientations. The new design includes a miniaturized Xray tube covered in a custom-made case mounted on a flexible holding arm attached to the standard OR table rail. With that, fast positioning and fixation for the subsequent image acquisition is achieved. A flat panel detector is placed in an adjustable metal sheet construction below the table. For safety aspects an overlay of the X-ray cone beam with an integrated light source visualizes the irradiation area. The acquired images are visualized on a 2-in-1 netbook. A foot pedal initiates the imaging process. A prototype of the free movable miniaturized X-ray system FlexScan was build. Workspace restriction, usability and general imaging needs were simulated and tested. FlexScan has the potential to improve X-ray guided interventions on extremities especially for small private surgery centers. It fulfills the general imaging needs and is capable of producing 2D projection images from different orientations within a small and lightweight setup.