Laser powder bed fusion (LPBF) has broad application prospects due to its high fabrication accuracy and excellent performance, but the dynamic mechanical properties of LPBF components are relatively low defects melt track such as protrusions depressions, whose generation mechanisms remain unclear. In this work, we investigate correlation between ex situ in high-speed, high-resolution characterization. We correlate protrusion at starting position with droplet ejection behaviour backward...

Vaporization of alloying elements is an important phenomenon during laser powder bed fusion (LPBF), especially in the interaction with difficult-to-form materials containing volatile element as main element, which has a significant effect on chemical composition, microstructure and mechanical properties. However, mechanisms typical vaporization, such explosion, its influence forming quality are not fully understood. Here, based situ high-speed high-resolution imaging, we observe explosion...

To suppress the influence of aerosols scattering on double-edge detection technique and achieve high-accuracy measurement wind field throughout troposphere to lower stratosphere, an ultraviolet 355 nm Rayleigh–Brillouin Doppler lidar technology based a dual-pass dual Fabry–Perot interferometer (FPI) is proposed. The speed principle this analyzed, formulas for radial error caused by random noise bias Mie signal contamination are derived. Based principle, structure system designed. Combining...

Y-In₂O₃ hollow nanocubes show enhanced triethylamine gas sensing properties, with a high response and an ultra-fast response-recovery speed.

Two-dimensional (2D) van der Waals materials and related heterostructures have shown a wide variety of novel electronic optoelectronic properties. However, key challenge in fully realizing their potential is general lack manufacturing techniques capable producing desired at large scale. Here, we demonstrate highly scalable direct-laser-writing approach to fabricating in-plane two-dimensional In2Se3 nanolayers. This derives from an optically activated solid–solid phase transition that leads...

A method for optimal design of a multilayer diffractive optical element (MLDOE) dual-wide-waveband systems is presented with consideration polychromatic integral diffraction efficiency (PIDE) and the weight factors PIDE each waveband. The process simulation MLDOE in mid-wave long-wave IR are described, comparison MLDOEs different wavelength pairs determined by methods given. This can make more rational reasonable give better result than that conventional method.

The effect of manufacturing errors on diffraction efficiency for multilayer diffractive optical elements (MLDOEs) used in imaging systems is discussed this paper. relationship and depth-scaling are analyzed two different cases: the relative change same sign opposite sign. For first condition, corresponding decreases more slowly. periodic width also evaluated. When major coexist, magnitude decrease MLDOEs. result can be analyzing effects

The mathematical analytic models of the relationship between depth-scaling error and diffraction efficiency/polychromatic integral efficiency (PIDE) for multilayer diffractive optical elements (MLDOEs) with oblique incidence are presented. A method optimal design MLDOEs consideration comprehensive PIDE working within a range incident angle is established. effect on in visible wavelength analyzed. For 0-20°, maximum 98.24%, relative -6.55%. conclusion provide theoretical basis determination...

In infrared optical systems, the narcissus effect for diffractive surfaces should be calculated with specific diffraction orders based on efficiency. It is shown in this work that order of maximum efficiency varies change incident angle and wavelength backward-traced flux. Meanwhile, yni, which paraxial evaluation criterion intensity a refractive surface, modified considering when ray passes through surfaces, practical example has been given. The analysis can used to calculate control...

The influence of narcissus effect for multilayer diffractive optical elements (MLDOEs) is evaluated from the viewpoint diffraction efficiency and intensity. A modified paraxial evaluation criterion reflected radiation MLDOEs has been deduced. practical 8-12 μm IR system designed with one two-layer element given to illustrate distribution incident energy among various orders in waveband. intensities two surfaces have calculated those that maximum efficiency. This method can be used process...

A method to get balanced output power of a current-controlled in-line semiconductor laser based on REC technique is investigated. By mapping the contour lines P-I diagram this tunable into wavelength-current map, maximum and tuning curve obtained. Numerical studies are carried under linear quadratic relations, as well an experiment measurement. Results shows it's feasible find obtain working currents for lasers.

This paper changed temperature conditions to simulate by finite element software.We can observe the simulation results of BLDC (brushless director current motor) stator resistance.Then we applied formula calculate resistance.At last, measuring resistance different temperatures high box, could contrast above results.We got conclusions that had characters more convenient, simple, accurate than method.

Oblique incidence is the general working state for multilayer diffractive optical elements (MLDOEs) in an imaging system. The polychromatic integral diffraction efficiency (PIDE) very sensitive to incident angle. Therefore, it necessary analyze effect of tilt error on efficiency/PIDE with oblique incidence. theoretical model relationship between and presented, analyzed. analysis comprehensive PIDE a certain range angles MLDOEs established. simulation results showed that angle incidence,...

The analysis model of comprehensive polychromatic integral diffraction efficiency (PIDE) multilayer diffractive optical elements (MLDOEs) working within a range incident angle was established. Based on the special characteristics achromatism and athermalization MLDOEs, an infrared dual-band system with double-layer DOEs in 3.7 μm~4.8 μm 7.7 μm~9.5 wavebands designed. effective focal length is 200 mm, F # 2. cooled plane array 320×256 pixel pitch 30 μm. MTF higher than 0.66 0.54 at frequency...

The multiwavelength laser array (MLA) with fine wavelength tunability is demonstrated experimentally. studied MLA has good single-longitudinal-mode performance, and the side-mode suppression ratio (SMSR) even reaches 62.1 dB. Meanwhile, range of can be tuned to 25.003 nm 63 channels 50 GHz spacing. All lasers are within a deviation <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mo>±</mml:mo> </mml:mrow> <mml:mn>0.02</mml:mn>...

In this paper, the effect of relative microstructure heights error on diffraction efficiency multilayer diffractive optical elements (MLDOEs) is considered. Based relationship and height, analysis result height MLDOEs for 8-14μm far infrared system was present. It shown that over whole waveband above 98.94% double-layer DOEs when two are equal both controlled within ±2%. However, drops quickly changed in opposite sign. The can be used analyzing effects working system.