Theoretical and experimental investigation of haze in transparent aerogels

A Passive High-Temperature High-Pressure Solar Steam Generator for Medical Sterilization

“…Unlike conventional translucent silica aerogel, [35][36][37][38][39] we have recently shown that it is possible to achieve ultra-high solar transmittance (z 95%) by optimizing the microstructure of the aerogel to reduce scattering. [40][41][42][43][44] The low scattering coefficient, i.e., longer photon mean free path, is especially beneficial when solar radiation is incident from oblique angles due to the diurnal movement of the sun and scattering by clouds and particulate matter in the atmosphere (see Note S2 for aerogel characterization details). To quantify the optical effect of adding the aerogel layer, we performed ray-tracing simulations ( Figure 3B), which showed that the additional aerogel layer had a minimal impact (z 5%) on the system's optical efficiency (see Note S3 for ray tracing details).…”

Engineering mesoporous silica for superior optical and thermal properties

“…In addition, it is well established that narrowing the pore size distribution and achieving small pores in silica aerogels will reduce volumetric optical scattering, resulting in increased visible transmittance and reduced haze, where the latter represents the percentage of light transmitted at high scattering angles. 26 Thus, microstructural properties such as pore size and fractality, defined as self-similarity over different length scales, can be used to purposefully design mesoporous materials to have both low thermal conductivity and high optical transparency. The above analysis provides a roadmap for achieving thermally insulating optical materials with the transparency of a standard window and the thermal insulation properties of an opaque aerogel.…”

Preparation of single- and double-layer antireflective coatings by sol-gel method

“…SiO2 and B-SiO2 coatings, respectively, consistent with the roughness values. In addition, if the thickness of coatings is increased, a maximum haze of 1.1% is observed, showing the high direct transmittance and low transmission haze of the coatings [24,28,35,36].…”

“…The optical results of this work are the results of total light transmittance (or reflectance) measurements obtained by the integrating sphere attachment. Transmission haze, the percentage ratio of the diffusely (scattered) transmitted light to the total transmitted light (Tdiffuse/Ttotal or (Ttotal-Tdirect)/Ttotal), can be estimated if the intensity of the directly transmitted light values are known [35]. By this approximation, transmission haze is found as 0.4% and 0.9% for A-…”

“…Effect of catalyst type on (a) transmittance and (b) reflectance spectra of singlelayer SiO2 coatings (WS=120 mm/min) Surface topography of the coatings must also be taken into consideration to prevent light scattering for attaining zero-reflectivity. A rough surface may lead to optical scattering loss in the transmitted light (transmission haze), especially if the magnitude of the surface roughness is close to the working wavelength of light[3,24,26,35]. Vincent et al[24] calculated the scattering loss in transmitted light (Tdiffuse/Ttotal ratio at  = 550 nm) caused by the surface roughness of their acid-(Rq = 0.3 nm) and base-catalyzed (Rq = 4.5-16.2 nm) silica films.…”