The Planck mission of the European Space Agency (ESA) is designed to image the anisotropies of the Cosmic Background Radiation Field over the whole sky. To achieve this aim, sophisticated reflectors are used as part of the Planck telescope receiving system. The system consists of secondary and primary reflectors which are sections of two different ellipsoids of revolution with mean diameters of...

Surface-emitting lasers with an external cavity delivering a diffraction-limited beam have shown the potential to outperform edge-emitting devices in applications demanding high brightness (emitted intensity per unit solid angle), like pumping of doped fiber amplifiers or frequency doubling [1]–[3]. Due to the large mode size, the VECSEL concept is powerscalable by expanding the pumped area and...

Pure and fresh water is being scarce day by day. Although Bangladesh is a riverine country, pure drinking potable water is not a cheap commodity. Most of the people in the cities boil water to drink, and people of the villages take tube-well’s water directly, which might have high amount of heavy metal like arsenic. Solar still is a cheap and very useful renewable technology, which can be used ...

In order to optimize space laser communication networking, the 2:1 transmissions for all reflectors on a multi-address transceiver can be removed. However, without transmissions, exhibit doubled optical coupling effect in rotation, which reduces numerical calculation precision of attitudes reflectors’ lines-of-sight (LOS). present study, using Snell’s law reflection and Euler’s theorem, mathema...

background: understanding the learning styles of medical students can drive the institutions to adapt instructional materials to enhance students’ learning of knowledge and skills. this study explored the learning styles of undergraduate medical students, comparing gender variations in terms of their significant preferences. materials and methods: a cross-sectional observational study was perfo...

We consider passive synthetic aperture imaging where a single moving receiver antenna records signals that are generated by distant unknown noise sources and backscattered by one or several reflectors. The reflectors can be imaged by migrating the autocorrelation functions of the received signals. We compare this passive synthetic aperture imaging with the usual, active synthetic aperture imagi...

We present ultrawide flat-band reflectors enabled with multilevel resonant leaky-mode structures. The reflectors are designed using particle swarm optimization. We show that three-level silicon-on-insulator structures provide bandwidths of approximately 840 nm for TE polarization and approximately 835 nm for TM polarization, across which reflectance is greater than 99% and 97.5%, respectively. ...

In this work, we study theoretically the operation of long surface acoustic wave reflectors, comprising a large number of electrodes, at the fundamental and second harmonic frequencies on the 128 LiNbO3 substrate for various electrode thicknesses and metallization ratios. Numerical simulations utilizing tailored test structures and time gating indicate that the reflectivity of the second-harmon...

We propose and analyze a new type of a resonator in an annular geometry that is based on a single defect surrounded by radial Bragg reflectors on both sides. We show that the conditions for efficient mode confinement are different from those of the conventional Bragg waveguiding in a rectangular geometry. A simple and intuitive approach to the design of optimal radial Bragg reflectors is propos...