Broad-band heat reflector design using five-layer symmetrical periods from non-absorbing high- and low-refractive-index materials

Electron beam physical vapour deposited zirconia based ceramics for developments of solar surface coatings

“…Practical optical filter design assumes symmetrical periods, introducing the concept of an equivalent refractive index, known as Herpin index, for a given wavelength, and a wide spectral range is covered by stop bands of various periods combining stacks with overlapping reflectance bands at different design wavelengths. 24,25 One such design configuration comprised of 20(H/2 L H/2) 12 type periodic structure with 20 stacks, and each stack was designed at l 0i to reflect a specific band Dl i . Here, H/L stands for high/low index material with QWOT layer.…”

“…As already discussed in the section on 'Phase and microstructures', the thickness of 7YSZ was not uniform to provide repeatable QWOT layer in multilayer stacks, thereby not satisfying strictly the design requirements for optical thin film filters. [23][24][25][26][27] the TBC based system in fabricating broadband optical filters in multilayer configurations, incorporating thermally compatible ceramic materials that are envisaged to provide technological route for realisation of highly efficient and robust solar absorbing surface coatings with intended applications at ultrahigh temperature environments.…”

“…The model proposed by Turner and Baumeister23 was employed to design broadband reflector mirrors consisting of 7YSZ and Al 2 O 3 thin films having QWOT as layer thickness. Practical optical filter design assumes symmetrical periods, introducing the concept of an equivalent refractive index, known as Herpin index, for a given wavelength, and a wide spectral range is covered by stop bands of various periods combining stacks with overlapping reflectance bands at different design wavelengths 24 24,25 One such design configuration comprised of 20(H/2 L H/2)12 type periodic structure with 20 stacks, and each stack was designed at λ 0i to reflect a specific band Δ λ i .…”

Design of Wide-band Antireflection Coatings on GaAs Substrates for Long Wavelength IR Spectrum

“…The simplest AR coating is a single layer with optical thickness nd = λ/4, 3λ/4, 5λ/4 ... and refractive index n = n SUB 1/2 (n SUB is the substrate refractive index) which acts properly only at one wavelength [1]. Appropriate methods for multilayer coating design in wide spectral region are based on numerical optimization [1,3]. In any case the choice of initial coating structure is of great importance for the final results.…”

“…After optimization procedure they were converted into several multilayers with different structures. The final results are obtained by numerical optimization which algorithms are realized using programming language DELPHI [2,3]. The initial AR coatings are designed without taking into account dispersion of materials' refractive index.…”