A design for a 100-nm bandwidth Raman amplifier is presented. The pumped with eight, 130-mW lasers wavelengths ranging from 1416 to 1502 nm. peak-to-peak gain ripple 1.1 dB. new model was developed this that includes pump-to-pump and signal-to-signal interactions in addition double Rayleigh scattering amplified spontaneous emission. An understanding of the among these various effects essential design. These modeling results are based on measurements physical characteristics transmission fiber.

This paper proposes an absolute phase retrieval method for complex object measurement based on quantized phase-coding and connected region labeling. A specific code sequence is embedded into of three coded fringes. Connected regions different codes are labeled assigned with 3-digit-codes combining the current period its neighbors. Wrapped phase, more than 36 periods, can be restored reference to sequence. Experimental results verify capability proposed measure multiple isolated objects.

Abstract Distributed energy sources, for example the ambient broadband vibrations, are of great importance development Internet Things. However, multistable vibrational harvesters, increasing number stable equilibrium states to broaden working frequency bands is very difficult. Here we present a poly-stable harvesting approach capable achieving an exponentially growing maximum states. Unlike traditional harvesters relying on external static magnetic field, nonlinear dynamical behaviours...

A robust and rapid camera calibration method is essential in vision measurement. This paper proposes a using 2.5-D coding target that requires just single captured image capable of identifying the intrinsic extrinsic parameters system simultaneously. The consists four fixed planes to which coded patterns are attached. prevent ill condition arises Zhang's method, they provide different homography matrices at same time. cameras calculated geometric constraints feature circles on each plane....

Single-pixel imaging (SPI), which is generally based on computational imaging, has the advantages of a wide bandwidth and ability to image objects beyond visual field. However, major challenge in developing SPI large number illumination patterns that are required. Unlike traditional relies random measurement patterns, method proposed this letter involves two-step phase shift reduces greatly required patterns. Theoretical analysis shows 6724 reconstruct 128 × 128-pixel whose peak...

Rayleigh crosstalk caused by the double reflection of a signal is investigated in long systems consisting distributed Raman amplifiers. A simple equation for crosstalk-to-signal ratio presented and it shown that bidirectional pumping reduces crosstalk. Power penalties arising from are evaluated using Gaussian model.

Vibrational energy harvesters, which are generally based on a single cantilever beam, mainly effective for excitations perpendicular to the beam. However, typical ambient vibrations of multifrequency and multidirectional. To achieve full harvesting vibrational in multiple directions, this letter proposes multidirectional harvester utilizing multimodal double-branched beam that has four natural frequencies below 22 Hz. Comparison experiments different directions demonstrate an improvement...

Machine vision techniques, including camera calibration methods, are of great importance for the development vision-based measurements. However, in multi-camera rapidly constructing accurate geometric relationships among different coordinates is very difficult. Herein, we present a method capable calibrating intrinsic and extrinsic parameters four cameras using only single captured image per camera. Unlike Zhang's method, which relies on multiple images to calibrate cameras, uses multi-plane...

In practical application environments, objects are rarely stationary, which makes it difficult to image dynamic with conventional single-pixel imaging (SI) techniques. this paper, a rotationally synchronized (RS-SI) method is proposed object in rotation. The modulation pattern rotates sync the rapidly rotating object, and center of rotation ensured be line illumination pattern. Then, RS-SI reconstruction algorithm used reconstruct by collecting light reflected from object's surface. This...

In this study, to enhance the output performance of a contact-separation mode triboelectric nanogenerator (TENG), zinc oxide nanorod (ZnO NR) film with piezoelectric properties was integrated into Polydimethylsiloxane (PDMS) as dielectric layer. The working mechanism PDMS-ZnO NR-based TENG theoretically analyzed in two stages: charge transfer during contact electrification on material surface and movement electrostatic induction process. characteristics were investigated compared those...

A compound eye has the advantages of a large field view, high sensitivity, and compact structure, showing that it can be applicable for 3D object detection. In this work, an artificial system is developed detection, consisting layer lenslets prism-like beam-steering lens. calibration method system, with which correspondences between incident light rays relevant image points obtained precisely using active pattern at multiple positions. Theoretically, patterns two positions are sufficient...

For conventional camera calibration methods, well-focused images are necessary to detect features accurately. However, this requirement causes practical inconveniences image acquisition for long- and short-distance photogrammetry. In study, three active phase-shift circular grating (PCG) arrays used as patterns. The PCGs' centers regarded feature points that can be accurately extracted by ellipse fitting of 2π-phase even though patterns substantially blurred. the experiments, Gaussian...

This paper presents an innovative seat suspension with variable stiffness and damping (VSVD) via magnetorheological fluid dampers to enhance ride comfort. The VSVD is developed based on structure springs in series units, its principles of vibration attenuation are evaluated theoretically. proposed then manufactured tested. test results illustrate that the equivalent power (Is = 2.0 A current) increased 186% (Id 1.0 A) raised 520% compared no current applied. evaluation vibration-attenuation...

The compound eye of insects has many excellent characteristics. Directional navigation is one the important features eye, which able to quickly and accurately determine orientation an objects. Therefore, bionic curved have great potential in detecting target. However, there a serious non-linear relationship between target image obtained by wide field view (FOV), effective model not been established detect In this paper, method for proposed, combines virtual cylinder with neural network. To...

As a computational technology, single-pixel microscopic imaging (SPMI) transfers the target’s spatial information into temporal dimension. The traditional focusing method of before evaluation is not applicable to SPMI system. We propose grating-free autofocus strategy derived from physical mechanism optical defocus. Maximizing amplitude just one high-frequency point in spectrum all that needed achieve fast with Accordingly, only four patterns need be cyclically projected, enabling efficient...