scholarly journals Design and Fabrication of Dual-Scale Broadband Antireflective Structures on Metal Surfaces by Using Nanosecond and Femtosecond Lasers

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 20
Author(s):  
Rui Lou ◽  
Guodong Zhang ◽  
Guangying Li ◽  
Xuelong Li ◽  
Qing Liu ◽  
...  
Keyword(s):  
Metal Surface ◽  
Sample Surface ◽  
Morphological Characterization ◽  
Nanosecond Laser ◽  
Nanoscale Structures ◽  
Broadband Absorption ◽  
Hemispherical Reflectance ◽  
Average Reflectance ◽  
Potential Applications ◽  
Dual Scale

Antireflective surfaces, with their great potential applications, have attracted tremendous attention and have been the subject of extensive research in recent years. However, due to the significant optical impedance mismatch between a metal surface and free space, it is still a challenging issue to realize ultralow reflectance on a metal surface. To address this issue, we propose a two-step strategy for constructing antireflective structures on a Ti-6Al-4V (TC4) surface using nanosecond and femtosecond pulsed lasers in combination. By controlling the parameters of the nanosecond laser, microgrooves are first scratched on the TC4 surface to reduce the interface reflection. Then, the femtosecond laser is focused onto the sample surface with orthogonal scanning to induce deep air holes and nanoscale structures, which effectively enhances the broadband absorption. The antireflection mechanism of the dual-scale structures is discussed regarding morphological characterization and hemispherical reflectance measurements. Finally, the modified sample surface covered with micro-nano hybrid structures is characterized by an average reflectance of 3.1% over the wavelengths ranging from 250 nm to 2250 nm.

scholarly journals Antireflective and Superhydrophilic Structure on Graphite Written by Femtosecond Laser

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 236
Author(s):  
Rui Lou ◽  
Guangying Li ◽  
Xu Wang ◽  
Wenfu Zhang ◽  
Yishan Wang ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Near Infrared ◽  
High Efficiency ◽  
Electronic Devices ◽  
Sample Surface ◽  
Graphite Surface ◽  
Hazardous Substances ◽  
Functional Surface ◽  
Nano Structures ◽  
Average Reflectance

Antireflection and superhydrophilicity performance are desirable for improving the properties of electronic devices. Here, we experimentally provide a strategy of femtosecond laser preparation to create micro-nanostructures on the graphite surface in an air environment. The modified graphite surface is covered with abundant micro-nano structures, and its average reflectance is measured to be 2.7% in the ultraviolet, visible and near-infrared regions (250 to 2250 nm). The wettability transformation of the surface from hydrophilicity to superhydrophilicity is realized. Besides, graphene oxide (GO) and graphene are proved to be formed on the sample surface. This micro-nanostructuring method, which demonstrates features of high efficiency, high controllability, and hazardous substances zero discharge, exhibits the application for functional surface.

Broadband absorption of nanostructured stainless steel surface fabricated by nanosecond laser irradiation

2020 ◽  
Vol 31 (17) ◽  
pp. 175301
Author(s):  
Md Abu Taher ◽  
Sajin Ponnan ◽  
Hiteswar Prasad ◽  
Desai Narayana Rao ◽  
Sri Ram G Naraharisetty
Keyword(s):  
Stainless Steel ◽  
Laser Irradiation ◽  
Steel Surface ◽  
Nanosecond Laser ◽  
Stainless Steel Surface ◽  
Broadband Absorption

scholarly journals Analysis of QualitySpec Trek Reflectance from Vertical Profiles of Taiga Snowpack

Geosciences ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 404 ◽  
Author(s):  
Leena Leppänen ◽  
Anna Kontu
Keyword(s):  
Grain Size ◽  
Surface Area ◽  
Near Infrared ◽  
Sample Surface ◽  
Short Wave ◽  
Optical Remote Sensing ◽  
Mass Ratio ◽  
Data Set ◽  
Hemispherical Reflectance ◽  
Snow Microstructure

Snow microstructure is an important factor for microwave and optical remote sensing of snow. One parameter used to describe it is the specific surface area (SSA), which is defined as the surface-area-to-mass ratio of snow grains. Reflectance at near infrared (NIR) and short-wave infrared (SWIR) wavelengths is sensitive to grain size and therefore also to SSA through the theoretical relationship between SSA and optical equivalent grain size. To observe SSA, the IceCube measures the hemispherical reflectance of a 1310 nm laser diode from the snow sample surface. The recently developed hand-held QualitySpec Trek (QST) instrument measures the almost bidirectional spectral reflectance in the range of 350–2500 nm with direct contact to the object. The geometry is similar to the Contact Probe, which was previously used successfully for snow measurements. The collected data set includes five snow pit measurements made using both IceCube and QST in a taiga snowpack in spring 2017 in Sodankylä, Finland. In this study, the correlation between SSA and a ratio of 1260 nm reflectance to differentiate between 1260 nm and 1160 nm reflectances is researched. The correlation coefficient varied between 0.85 and 0.98, which demonstrates an empirical linear relationship between SSA and reflectance observations of QST.

Formation of microstructure on liquid metal surface under nanosecond laser ablation

2010 ◽  
Author(s):  
Alexei N. Panchenko ◽  
Nadezhda M. Bulgakova ◽  
Alexei E. Tel'minov ◽  
Mikhail A. Shulepov
Keyword(s):  
Laser Ablation ◽  
Liquid Metal ◽  
Metal Surface ◽  
Nanosecond Laser ◽  
Nanosecond Laser Ablation ◽  
Liquid Metal Surface

Morphological Characterization of Elastin-Mimetic Block Copolymers Utilizing Cryo- and Cryoetch-HRSEM

2003 ◽  
Vol 9 (3) ◽  
pp. 171-182 ◽  
Author(s):  
Elizabeth R. Wright ◽  
Vincent P. Conticello ◽  
Robert P. Apkarian
Keyword(s):  
Block Copolymers ◽  
High Vacuum ◽  
Three Dimensional ◽  
Sample Surface ◽  
Morphological Characterization ◽  
High Concentration ◽  
Micellar Aggregates ◽  
Hydrogel Network ◽  
Resolution Level

Elastin-mimetic block copolymers were produced by genetic engineering. Genetically driven synthesis permitted control of the final physiochemical characteristics of the block copolymers. We designed BB and BAB block copolymers in which the A-block was hydrophilic and the B-block was hydrophobic. By designing the copolymers in this manner, it was proposed that they would self-assemble into micellar aggregates that, at high concentration, would form thermoreversible hydrogels. To analyze the three-dimensional fine surface morphology of the copolymers, to the resolution level of a few nanometers, we employed cryo-HRSEM. This method provided vast expanses of the specimen in its frozen hydrated state for survey. In our initial cryo-HRSEM studies, we observed the protein filaments and micelles surrounded by lakes of vitreous ice. Upon examination at low and intermediate magnifications, there was an extensive honeycomb-like filamentous network. To delineate the fine morphology of the hydrogel network at high magnification and to greater depths, we cryoetched away unbound water from the sample surface, in high vacuum, prior to chromium deposition. By using this technique, we were able to visualize for characterization purposes the fine fibril networks formed from the micellar aggregates over the surface of the hydrogel.

Experimental Research of Boiling Heat Transfer Phenomena on Metal Surface in State of Low Gravitational Acceleration Field Between 0g and 1g

2011 ◽  
Author(s):  
Eiji Nemoto ◽  
Tomohiro Saitoh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Stainless Steel ◽  
Liquid Nitrogen ◽  
Metal Surface ◽  
Boiling Heat Transfer ◽  
Sample Surface ◽  
Gravitational Acceleration ◽  
Maximum Heat ◽  
Acceleration Field

The paper deals with the characteristics of boiling heat transfer phenomena on the metal surfaces where gravitational acceleration between 0g and 1g acts. To conduct the experiment in the field where the gravitational acceleration between 1g and 0g acted accurately, we produced the Atwood machine that was able to obtain the fixed gravitational acceleration field known by physics well. The metallic materials used by the experiment were brass, stainless steel, aluminum, copper and these materials were processed to 10mm in the diameter, and we put these samples in liquid nitrogen and experimented on the boiling phenomenon. As a result, it has been understood that there is the feature shown next in boiling heat transfer phenomena on the metal surface in gravitational acceleration field between 0g and 1g. (1) When brass, copper, stainless steel, and aluminum of the sample were put in the liquid nitrogen, the temperature differentiation coefficient on the sample surface showed the tendency to decrease in proportion to gravitational acceleration changed from 1g into 0g. (2) In boiling heat flux curve in these metals (brass, stainless steel, aluminum and copper), it was clarified for gravitational acceleration 1g to indicate maximum heat flux value qmax.

Broadband low-frequency acoustic absorber based on a metaporous composite

2022 ◽  
Author(s):  
Jia-Hao Xu ◽  
Xing-Feng Zhu ◽  
Di-Chao Chen ◽  
Qi Wei ◽  
Da-Jian Wu
Keyword(s):  
Acoustic Waves ◽  
High Efficiency ◽  
Low Frequency ◽  
Frequency Noise ◽  
Sound Waves ◽  
Broadband Absorption ◽  
Trapped Mode ◽  
Potential Applications ◽  
Simulation And Experiment ◽  
Interest In Research

Abstract Broadband absorption of low-frequency sound waves via a deep subwavelength structure is of great and ongoing interest in research and engineering. Here, we numerically and experimentally present a design of a broadband low-frequency absorber based on an acoustic metaporous composite (AMC). The AMC absorber is constructed by embedding a single metamaterial resonator into a porous layer. The finite element simulations show that a high absorption (absorptance A > 0.8) can be achieved within a broad frequency range (from 290 Hz to 1074 Hz), while the thickness of AMC is 1/13 of the corresponding wavelength at 290 Hz. The broadband and high-efficiency performances of the absorber are attributed to the coupling between the two resonant absorptions and the trapped mode. A good agreement between the numerical simulation and experiment is obtained. Moreover, the high broadband absorption can be maintained under random incident acoustic waves. The proposed absorber provides potential applications in low-frequency noise reduction especially when limited space is demanded.

Metal surface coloration by oxide periodic structures formed with nanosecond laser pulses

2017 ◽  
Vol 96 ◽  
pp. 63-67 ◽  
Author(s):  
Vadim Veiko ◽  
Yulia Karlagina ◽  
Mikhail Moskvin ◽  
Vladimir Mikhailovskii ◽  
Galina Odintsova ◽  
...  
Keyword(s):  
Metal Surface ◽  
Periodic Structures ◽  
Laser Pulses ◽  
Nanosecond Laser ◽  
Nanosecond Laser Pulses

scholarly journals Nano-acoustic resonator with ultralong phonon lifetime

Science ◽  
2020 ◽  
Vol 370 (6518) ◽  
pp. 840-843
Author(s):  
Gregory S. MacCabe ◽  
Hengjiang Ren ◽  
Jie Luo ◽  
Justin D. Cohen ◽  
Hengyun Zhou ◽  
...  
Keyword(s):  
Quantum Noise ◽  
Microwave Frequency ◽  
Coherence Time ◽  
Acoustic Resonator ◽  
Nanoscale Structures ◽  
Acoustic Cavity ◽  
Collapse Models ◽  
Potential Applications ◽  
Phonon Lifetime ◽  
Millikelvin Temperatures

The energy damping time in a mechanical resonator is critical to many precision metrology applications, such as timekeeping and force measurements. We present measurements of the phonon lifetime of a microwave-frequency, nanoscale silicon acoustic cavity incorporating a phononic bandgap acoustic shield. Using pulsed laser light to excite a colocalized optical mode of the cavity, we measured the internal acoustic modes with single-phonon sensitivity down to millikelvin temperatures, yielding a phonon lifetime of up to τph,0≈1.5 seconds (quality factor Q=5×1010) and a coherence time of τcoh,0≈130 microseconds for bandgap-shielded cavities. These acoustically engineered nanoscale structures provide a window into the material origins of quantum noise and have potential applications ranging from tests of various collapse models of quantum mechanics to miniature quantum memory elements in hybrid superconducting quantum circuits.

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