Antireflective surfaces

Antireflective coatings are those appUed on different devices to reduce light reflection. These coatings are used in a wide range of areas, from sophisticated telescopes and solar panels to surgical tools. There are different ways to obtain surfaces with antireflective 

Another methodology to obtain antireflective coatings is the superposition of films with different refraction index according to the so called bottom antireflective coating technique. In these cases, the coating design is made in such a way that the refraction index gradually decreases from the layer closest to the substrate towards the outer layer. 

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Abstract In solar applications microstructured polymer surfaces can be used as optically functional devices. Examples are antireflective surfaces, dayUghting, sun protection systems, concentrator photovoltaic modules and light trapping structures in organic solar cells. The examples and the principles of function of the respective microstmctures are described in detail. The suitability of different manufacturing methods is discussed. Two of them, ultraprecision machining and interference lithography are described. For the latter experimental results are shown. Finally, the opportunities and the risks of the shown approaches are discussed. 

Such subwavelength gratings can be used for antireflective surfaces or for polarization-sensitive devices. 

Some of the most remarkable developments in nanoscience and technology have come from adapting new understandings of how things work in nature (biomimetics). These also provide rich examples of classical colloidal and interfacial phenomena taken to a smaller scale and in new ways. Examples include some of the advances in reflective and antireflective surfaces, adhesive surfaces, wetting and slip on surfaces and nanomechanics. 

Rahman, A., Liu, M., Black, C.T., 2014. Block copolymer self assembly for design and vapor-phase synthesis of nanostmctured antireflective surfaces. J. Vac. Sci. Technol. B 32 (6), 06FE02. 

Di Mundo, R., De Benedictis, V., Palumbo, R, d Agostino, R., 2009. Fluorocarbon plasmas for nanotexturing of polymers a route to water-repellent antireflective surfaces. Appl. Surf. Sci. 255, 5461-5465. 

This effect can, in principle, be very useful in the development of new antireflective surfaces for solar cells. 

This article addresses key aspects of diffractive optics. Common analytical models are described and their main results summarized. Exact numerical methods are applied when precise characterization of the periodic component is required, whereas approximate models provide analytical results that are valuable for preliminary design and improved physical insight. Numerous examples of the applications of diffractive optical components are presented. These are optical interconnects, diffractive lenses, and subwavelength elements including antireflection surfaces, polarization devices, distributed-index components, and resonant filters. Finally, recording of gratings by laser interference is presented and an example fabrication process summarized. 

FIGURE 13 Applications of subwavelength gratings (a) antireflection surface, (b) retardation plate, (c) polarizing beam splitter, (d) diffractive lens, (e) blazed grating, and (f) wavelength-selective reflector (filter). 

Superhydrophobic surfaces have a number of potential applications such as dust-free and self-cleaning surfaces for solar cells and satellite dishes, corrosion-resistant surfaces for heat transfer devices, transparent and antireflective surfaces, anti-freezing and anti-snow surfaces [1], The fact that Uquid in contact with such surface slides with low friction su ests applications such as the fabrication of microfluidics and medical devices. The non-wettable character has been claimed in biomedical applications ranging from blood vessel replacement to wound management [6], Other unexpected applications will emerge as the technology of making non-wettable surfaces matures. 

Glytsis EN, Gaylord TK. (1988) Antireflection surface struemre dielectric layerfs) over a high spatial-frequency surface-relief grating on a lossy substrate. Appl Opt2L7 QSS) 4288— 4304. 

Glytsis EN, Gaylord TK. (1992) High-spatial-frequency binary and multilevel stairstep gratings Polarization-selective mirrors and broadband antireflection surfaces. Appl Opt 31(22) 4459 470. 

Motamedi ME, Southwell WH, Gunning WJ. (1992) Antireflection surfaces in silicon using binary optics technology. Appl Opt 31(22) 4371 376. 

DeNatale JF, et oL (1992) Fabrication and characterization of diamond moth eye antireflective surfaces on Ge. J Appl Phys 71 1388—1393. 

Gombert A, et al. (1999) Subwavelength-stmcmred antireflective surfaces on glass. Thin Solid Films 351 73. 

Wilson SJ, Hudey MC. (1982) The optical properties of moth eye antireflection surfaces. OpticaActa29. 993—1009-... 

The book b ins with a chapter that describes certain functions of the skin which contributes to the new area of bio-inspired design. The next four chapter have more specific subjects with its technological applications. Chapter 2 analyzes the shark skin effect or the commonly known antifriction surfaces. Chapter 3 discusses the Lotus effect or the usually known self-cleaning surfaces. Chapter 4 analyzes the Moth-eye effect or the commonly known antireflection surfaces and Chap. 5 describes the Gecko effect or the usually known dry adhesive surfaces. 

Gombert et al. have reported subwavelength structured antireflective surfaces prepared on glass by embossing a nickel master shim on acrylic siloxane layer with UV irradiation (Gombert et al., 1999). Hemispherical reflectance values of <1% are achieved for nonabsorbing planar sheet. 

Gombert A., Glaubitt W., Rose K., Dreibholz J., Blasi B., Heinzel A., Spom D., Doll W., Wittwer V. Subwavelength-stmctured antireflective surfaces on glass. Thin Solid Films 1999 351 73-78... 

The question which kind of antireflection surface relief is the most efiicient, regular or random, is still open to debate [188]. Some of the most eflicient detectors in the solar cells field actually have random surface profiles— stochastically distributed pyramids made in transparent conductive oxide (zinc oxide) using chemical vapor deposition [197]. However, ordered and random profiles both effectively behave as gradient refractive index profile starting Irom the effective value nearly equal to that of the environment index and ending with that of the substrate. In this manner, the question reduces to the determination of an optimal gradient-index profile. 

J.R. Wendt, G.A. Vawter, R.E. Smith, M.E. Warren, Fabrication of subwavelength, binary, antireflection surface-relief stractures in the near infrared. J. Vac. Sci. Technol. B Microelectron. Nanometer Stract. 14(6), 4096 099 (1996)... 

A.B. Marker, J.F. DeNatale, Diamond gradient index moth-eye antireflection surfaces for... 

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