We present an optical scheme to encode and decode 2 bits of information into different orbital angular momentum (OAM) states of a paraxial optical beam. Our device generates the four light angular momentum states of order ±2 and ±4 by spin-to-orbital angular momentum conversion in a triangular optical loop arrangement. The switching among the four OAM states is obtained by changing the polariza...

In order to expand the area of use of the beam tracing method, the beam tracing with the refraction method (BTR) was developed. The BTR is best suited for acoustic and hydro-acoustic simulation of non-homogenous environments. The BTR can trace the refraction as well as the reflection of the sound wave, using triangular beams. The geometry of the scene in the BTR is based on triangle meshes rath...

We report the testing of a high gradient electron accelerator with a photonic-band-gap (PBG) structure. The photonic-band-gap structure confines a fundamental TM(01)-like accelerating mode, but does not support higher-order modes (HOM). The absence of HOM is a major advantage of the PBG accelerator, since it suppresses dangerous beam instabilities caused by wakefields. The PBG structure was des...

Comprehensive beam tracing method is a simulation method that calculates refraction as well as reflection of sound. Due to the non-linear nature of Snell’s law, refraction (in contrast to reflection) is not a linear transformation. Because of this triangular beams used in comprehensive beam tracing simulation lose focus after refraction. In this paper the problem of non-linearity of refraction ...

We demonstrate a coherent atomic beam splitter for metastable helium atoms, based on the diffraction of atomic matter waves from a blazed phase grating. The beam splitter is created by driving the two transitions of a three-level V system with differentially detuned standing light waves that have a relative spatial phase shift of pi/2. The light f ields create a potential that is approximately ...

The importance of the beam and its engineering applications is obvious, and it undergoes different kinds of loading. Such loading may cause cracks in the beam. Crack depth and location are the main parameters for the vibration analysis of such beams. These cracks and their locations effect on the shapes and values of the beam frequency. So it becomes very important to monitor the changes in the...

By using one of the definitions of the Bernoulli numbers, we prove that they solve particular odd and even lower triangular Toeplitz (l.t.T.) systems of equations. In a paper Ramanujan writes down a sparse lower triangular system solved by Bernoulli numbers; we observe that such system is equivalent to a sparse l.t.T. system. The attempt to obtain the sparse l.t.T. Ramanujan system from the l.t...

in this paper, some elementary operations on triangular fuzzynumbers (tfns) are defined. we also define some operations on triangularfuzzy matrices (tfms) such as trace and triangular fuzzy determinant(tfd). using elementary operations, some important properties of tfms arepresented. the concept of adjoints on tfm is discussed and some of theirproperties are. some special types of tfms (e.g. pu...

Recent years have seen a great potential of the focused ion beam (FIB) technology for the nanometer-scale patterning of a freestanding two-dimensional (2D) layer. Experimentally determined sputtering yields of the perforation process can be quantitatively explained using the binary collision theory. The main peculiarity of the interaction between the ion beams and the suspended 2D material lies...