A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Thank you for reading principles of optics electromagnetic theory of propagation interference and diffraction of light. As you may know, people have search hundreds times for their favorite novels like this principles of optics electromagnetic theory of propagation interference and diffraction of light, but end up in harmful downloads. Rather than enjoying a good book with a cup of coffee in the afternoon, instead they are facing with some infectious bugs inside their computer.

Principles Of Optics Electromagnetic Theory Of Propagation Interference And Diffraction Of Light

Fogging occurs when moisture condensation takes the form of accumulated droplets with diameters larger than 190 nm or half of the shortest wavelength (380 nm) of visible light. This problem may be effectively addressed by changing the affinity of a material’s surface for water, which can be accomplished via two approaches: i) the superhydrophilic approach, with a water contact angle (CA) less than 5°, and ii) the superhydrophobic approach, with a water CA greater than 150°, and extremely low CA hysteresis. To date, all techniques reported belong to the former category, as they are intended for applications in optical transparent coatings. A well-known example is the use of photocatalytic TiO2 nanoparticle coatings that become superhydrophilic under UV irradiation. Very recently, a capillary effect was skillfully adopted to achieve superhydrophilic properties by constructing 3D nanoporous structures from layer-by-layer assembled nanoparticles. The key to these two “wet”-style antifogging strategies is for micrometer-sized fog drops to rapidly spread into a uniform thin film, which can prevent light scattering and reflection from nucleated droplets. Optical transparency is not an intrinsic property of antifogging coatings even though recently developed antifogging coatings are almost transparent, and the transparency could be achieved by further tuning the nanoparticle size and film thickness. To our knowledge, the antifogging coatings may also be applied to many fields that do not require optical transparency, including, for example, paints for inhibiting swelling and peeling issues and metal surfaces for preventing corrosion. These types of issues, which are caused by adsorption of moisture, are hard to solve by the superhydrophilic approach because of its inherently “wet” nature. Thus, a “dry”-style antifogging strategy, which consists of a novel superhydrophobic technique that can prevent moisture or microscale fog drops from nucleating on a surface, is desired. Recent bionic researches have revealed that the self-cleaning ability of lotus leaves and the striking ability of a water-strider’s legs to walk on water can be attributed to the ideal superhydrophobicity of their surfaces, induced by special microand nanostructures. To date, the biomimetic fabrication of superhydrophobic microand/or nanostructures has attracted considerable interest, and these types of materials can be used for such applications as self-cleaning coatings and stain-resistant textiles. Although a superhydrophobic technique inspired by lotus leaves is expected to be able to solve such fogging problems because the water droplets can not remain on the surface, there are no reports of such antifogging coatings. Very recently, researchers from General Motors have reported that the surfaces of lotus leaves become wet with moisture because the size of the fog drops are at the microscale—so small that they can be easily trapped in the interspaces among micropapillae. Thus, lotuslike surface microstructures are unsuitable for superhydrophobic antifogging coatings, and a new inspiration from nature is desired for solving this problem. In this communication, we report a novel, biological, superhydrophobic antifogging strategy. It was found that the compound eyes of the mosquito C. pipiens possess ideal superhydrophobic properties that provide an effective protective mechanism for maintaining clear vision in a humid habitat. Our research indicates that this unique property is attributed to the smart design of elaborate microand nanostructures: hexagonally non-close-packed (ncp) nipples at the nanoscale prevent microscale fog drops from condensing on the ommatidia surface, and hexagonally close-packed (hcp) ommatidia at the microscale could efficiently prevent fog drops from being trapped in the voids between the ommatidia. We also fabricated artificial compound eyes by using soft lithography and investigated the effects of microand nanostructures on the surface hydrophobicity. These findings could be used to develop novel superhydrophobic antifogging coatings in the near future. It is known that mosquitoes possess excellent vision, which they exploit to locate various resources such as mates, hosts, and resting sites in a watery and dim habitat. To better understand such remarkable abilities, we first investigated the interaction between moisture and the eye surface. An ultrasonic humidifier was used to regulate the relative humidity of the atmosphere and mimic a mist composed of numerous tiny water droplets with diameters less than 10 lm. As the fog was C O M M U N IC A IO N

The dry-style antifogging properties of mosquito compound eyes and artificial analogues prepared by soft lithography: a superhydrophobic state with high adhesive force

/pdf/nanopore-based-fourth-generation-dna-sequencing-technology-2cavwwctne.pdf

Nanopore-based Fourth-generation DNA Sequencing Technology

We demonstrate a controllable electromagnetic wave reflector/absorber for different polarizations with metamaterial involving electromagnetic resonant structures coupled with diodes. Through biasing at different voltages to turn ON and OFF the diodes, we are able to switch the structure between nearly total reflection and total absorption of a particularly polarized incident wave. By arranging orthogonally orientated resonant cells, the metamaterial can react to different polarized waves by selectively biasing the corresponding diodes. Both numerical simulations and microwave measurements have verified the performance.

Switchable metamaterial reflector/absorber for different polarized electromagnetic waves

Considering the necessity of alignment in practical applications of photolithography, distribution of complex amplitude of moire fringe patterns that are produced in superposition of two gratings is analyzed in the viewpoint of Fourier Optics and the relationship between fringes and properties of these two gratings is concluded by means of an analysis model. The rule of one-dimensional gratings (1D-gratings) is extended to other form of the gratings which have quasi-periodic repetitive structures. Especially, moire fringes generated by the two superposed 1D-gratings (used in alignment of lithography) can be expressed by an arithmetical operation of two vectors which include enough information about these 1D-gratings. Numerical analyses regarding the moire model and its application in the alignment process of lithography are carried out. Our computational analyses results show that the moire fringes of the two extended gratings can be refined as a transformed fringe pattern of two standard 1D-gratings. Finally, the results also make it out that the fringes which have magnified periods versus that of two 1D-gratings are highly sensitive to relative shift of two gratings thus might be applicable in alignment of lithography or correlated fields.

Fourier-based analysis of moiré fringe patterns of superposed gratings in alignment of nanolithography.

In this paper, we report the design, analysis, and simulation of a novel quadrupleband metamaterial absorber at microwave frequencies. The absorber is composed of delicate periodic patterned structures and a metallic background plane, which are separated by a dielectric substrate. By manipulating the periodic patterned structures, nearly perfect absorption can be obtained at four specific resonance frequencies. Moreover, the significantly high absorptions of quadruple peaks are insensitive to polarization independence, and the influence of the incident angle on the absorption for both TE and TM modes was also analyzed. To explain the absorption mechanism of the suggested structures, the electric and magnetic field distributions and the resistance matching principle were given. Importantly, the design idea has the ability to be extended to other frequencies, such as terahertz, infrared, and optical frequencies.

Novel Quadruple-Band Microwave Metamaterial Absorber

The grain size effect of the Pb(Zr0.45Ti0.55)O3 thin films deposited on LaNiO3-coated silicon by modified sol–gel process

In this paper, a method of dose-modulated maskless lithography (DMML) with high efficiency for the fabrication of a special compound-eyes array with enlarged field-of-view is proposed. Before the fabrication process, practical measurements were primarily conducted to quantify the dose-modulated effect. Next, a digital gray pattern, generated according to the required exposure dose distribution of the design structure, was adopted as a virtual mask to modulate the exposure depth point-by-point. In this way, the whole exposure process requires only one-step. Besides, because the DMML uses sequential gray-levels to modulate the exposure depth, the fabricated structure has a more continuous profile surface. Combined with the thermal reflow process, and the pattern reversion process, the compound eyes array was transferred to the planar polydimethylsiloxane films with high quality. Subsequent tests reveal that the physical performance of fabricated compound eyes array, including the surface profile and the rotated orientation, has a good agreement with our design.

/pdf/dose-modulated-maskless-lithography-for-the-efficient-2i7avaoiwo.pdf

Dose-Modulated Maskless Lithography for the Efficient Fabrication of Compound Eyes With Enlarged Field-of-View

A maskless lithography method to realize the rapid and cost-effective fabrication of micro-optics elements with arbitrary surface profiles is reported. A digital micro-mirror device (DMD) is applied to flexibly modulate that the exposure dose according to the surface profile of the structure to be fabricated. Due to the fact that not only the relationship between the grayscale levels of the DMD and the exposure dose on the surface of the photoresist, but also the dependence of the exposure depth on the exposure dose, deviate from a linear relationship arising from the DMD and photoresist, respectively, and cannot be systemically eliminated, complicated fabrication art and large fabrication error will results. A method of compensating the two nonlinear effects is proposed that can be used to accurately design the digital grayscale mask and ensure a precise control of the surface profile of the structure to be fabricated. To testify to the reliability of this approach, several typical array elements with a spherical surface, aspherical surface, and conic surface have been fabricated and tested. The root-mean-square (RMS) between the test and design value of the surface height is about 0.1 μm. The proposed method of compensating the nonlinear effect in maskless lithography can be directly used to control the grayscale levels of the DMD for fabricating the structure with an arbitrary surface profile.

https://www.mdpi.com/2072-666X/8/10/314/pdf

Song Hu

Papers

Fourier-based analysis of moiré fringe patterns of superposed gratings in alignment of nanolithography.

Novel Quadruple-Band Microwave Metamaterial Absorber

The grain size effect of the Pb(Zr0.45Ti0.55)O3 thin films deposited on LaNiO3-coated silicon by modified sol–gel process

Dose-Modulated Maskless Lithography for the Efficient Fabrication of Compound Eyes With Enlarged Field-of-View

Fabrication of micro-optics elements with arbitrary surface profiles based on one-step maskless grayscale lithography