Micro and nano dual-scale structures fabricated by amplitude modulation in multi-beam laser interference lithography

© 2017 Optical Society of America. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reservedIn this work, an effective method was presented to obtain a specific micro and nano dual-structures by amplitude modulation in multi-beam laser interference lithography (LIL). Moiré effect was applied to generate the amplitude modulation. The specific intensity modulation patterns can be obtained by the control of the parameter settings of incident laser beams. Both the incident angle and azimuth angle asymmetric configurations can cause the amplitude modulation in the interference optic field and the modulation period is determined by the angle offset. A four-beam LIL system was set up to fabricate patterns on photoresist and verify the method. The experimental results are in good agreement with the theoretical analysis

Fabrication of periodically micropatterned magnetite nanoparticles by laser-interference-controlled electrodeposition

This paper introduces a laser-interference-controlled electrochemical deposition method for direct fabrication of periodically micropatterned magnetite (Fe3O4) nanoparticles (NPs). In this work, Fe3O4 NPs were controllably synthesized on the areas where the photoconductive electrode was exposed to the periodically patterned interferometric laser irradiation during the electrodeposition. Thus, the micropattern of Fe3O4 NPs was controlled by interferometric laser pattern, and the crystallization of the particles was controlled by laser interference intensity and electrochemical deposition conditions. The bottom-up electrochemical approach was combined with a top-down laser interference methodology. This maskless method allows for in situ fabrication of periodically patterned magnetite NPs on the microscale by electrodeposition under room temperature and atmospheric pressure conditions. In the experiment, Fe3O4 NPs with the mean grain size below 100 nm in the pattern of 5-lm line array were achieved within the deposition time of 100 s. The experiment results have shown that the proposed method is a one-step approach in fabricating large areas of periodically micropatterned magnetite NPs

Fast Fourier transport analysis of surface structures fabricated by laser interference lithography

This paper presents an FFT (fast Fourier transform) analytical method for the study of surface structures fabricated by laser interference lithography (LIL). In the work, the FFT analytical method combined with Gaussian fitting is used to determine the periods and pattern distributions of surface structures from frequency spectra. For LIL, the processing parameters of incident and azimuth angles can be obtained corresponding to the period and pattern distribution. This work facilitates the detection of micro- and nano-structures, the analysis of pattern distribution in engineering, and the processing error analysis of LIL

Templated assembly of micropatterned Au-Ni nanoparticles on laser interference-structured surfaces by thermal dewetting

This paper introduces a laser-interference-controlled electrochemical deposition method for direct fabrication of periodically micropatterned magnetite (Fe3O4) nanoparticles (NPs). In this work, Fe3O4 NPs were controllably synthesized on the areas where the photoconductive electrode was exposed to the periodically patterned interferometric laser irradiation during the electrodeposition. Thus, the micropattern of Fe3O4 NPs was controlled by interferometric laser pattern, and the crystallization of the particles was controlled by laser interference intensity and electrochemical deposition conditions. The bottom-up electro- chemical approach was combined with a top-down laser interference method- ology. This maskless method allows for in situ fabrication of periodically patterned magnetite NPs on the microscale by electrodeposition under room temperature and atmospheric pressure conditions. In the experiment, Fe3O4 NPs with the mean grain size below 100 nm in the pattern of 5-lm line array were achieved within the deposition time of 100 s. The experiment results have shown that the proposed method is a one-step approach in fabricating large areas of periodically micropatterned magnetite NPs.

Fabrication of three-dimensional Si-Au hierarchical nanostructures by laser interference lithography

This paper reports a method for the fabrication of 3D Si-Au hierarchical nanostructures to improve the optical performances through four-beam laser interference lithography (LIL) and inductively coupled plasma (ICP) etching. The 3D Si-Au hierarchical nanostructures were composed of silicon tapered pillar arrays, Au grids, and Au islands, and they demonstrated wide-angle antireflective properties less than 25% reflection in the entire visible wavelengths. In addition, many special properties could be obtained by displacing the islands and grid of the hierarchical structure with other metal material due to the flexibility of LIL and ICP etching

3D periodic patterns using polarization controlled 3+1 beams interference

In this work, we studied the influence of polarizations in the 3D-light field formed by a multi-beam amplitude interference strategy. The 3D periodic structures are created by 3+1 beams interference. A comparative study using MATLAB simulation has been performed to visualize the effect of diverse polarization modes on the formation of 3D intensity patterns. Based on the multi-beam amplitude interference strategy, varied 3D periodic structures can be designed by tuning the polarization mode of the coherent beams, which provide design ideas for the manufacture of large-area 3D crystal structures

Surface texturing on stainless steel by direct laser interference lithography

A method for the surface texturing of well-designed and high controllable micro dimple structures on stainless steel by direct laser interference lithography (DLIL) is presented. The method offers its innovation that the micro circular dimple structures can be fabricated directly by controlling the process of three-beam laser interference. Different exposure durations have been studied to achieve the optimum value of the dimple diameter and density in order to reduce the friction coefficient of stainless steel. The dry sliding test of friction coefficients were performed by mechanical tester (UMT-TriboLab) under normal loads of 15 N. The results indicate that the micro circular dimple structures with the average dimple diameter of 4.2 μm and density of 23 percent have about 77% reduction of friction coefficient compared with untreated surfaces

Fabrication of cross-scale structures by Moiré effect in laser interference lithography

This paper presents a method for the fabrication of cross-scale structures using the controllable Moiré effect to break through the scale barriers caused by the spatial distribution in a laser interference lithography (LIL) system. The formation principle of macroscopic Moiré gratings in the LIL system was analyzed as partial wavefront interference introduced by optical components. In this work, an additional lens was used in the improved two-beam LIL system to precisely control the size of Moiré gratings, combined with the intrinsic period in the LIL system to form a cross-scale distribution of light intensity. This method provides a way for the fabrication of cross-scale surface structures by single exposure. Through the double-exposure technology, the fabrication of isotropic and anisotropic structures can be achieved flexibly for different applications, such as photonic crystals, self-cleaning surfaces, structural color elements and anti-counterfeiting labels

Vacuum conditions for tunable wettability transition on laser ablated Ti-6Al-4V alloy surfaces

This work investigates the mechanism of the controllable wettability transition on laser ablated Ti-6Al-4V alloy surfaces with the vacuum treatment. The effects of surface morphologies, vacuum conditions and joint mechanisms are discussed. To achieve stable and controllable wettability transitions, the laser ablated Ti-6Al-4V alloy surfaces were placed in a low vacuum environment to adsorb non-polar organic molecules. The sample appeared an unstable wettability transition, which manifested itself as a change in the apparent contact angle (ACA) with time. High vacuum conditions can accelerate the assembly of organic molecules on the sample surface and achieve a stable wettability transition. Furthermore, by varying the surface morphologies of laser ablated Ti-6Al-4V alloy and the adsorption time of organic molecules, stable and controllable wettability transitions can be achieved at high vacuum conditions

Use of atomic force microscopy in UVB-iced chromosome damage provides important bioinformation for cell damage assessment

The chromosomal structure derived from UVB-stimulated HaCaT cells was detected by atomic force microscopy (AFM) to evaluate the effect of UVB irradiation. The results showed that the higher the UVB irradiation dose, the more the cells that had chromosome aberration. At the same time, different representative types of chromosome structural aberrations were investigated. We also revealed damage to both DNA and cells under the corresponding irradiation doses. It was found that the degree of DNA damage was directly proportional to the irradiation dose. The mechanical properties of cells were also changed after UVB irradiation, suggesting that cells experienced a series of chain reactions from inside to outside after irradiation. The high-resolution imaging of chromosome structures by AFM after UVB irradiation enables us to relate the damage between chromosomes, DNA, and cells caused by UVB irradiation and provides specific information on genetic effects