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Christina Åkerlind

Other affiliations: Linköping University
Bio: Christina Åkerlind is an academic researcher from Swedish Defence Research Agency. The author has contributed to research in topics: Emissivity & Radiative cooling. The author has an hindex of 7, co-authored 15 publications receiving 105 citations. Previous affiliations of Christina Åkerlind include Linköping University.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a metamaterial composite paper based on cellulose nanofibrils (CNF) and silicon dioxide (SiO2) microparticles with infrared (IR) Frohlich phonon resonances is presented.
Abstract: Materials that provide independent control of infrared thermal radiation and haze in the visible could benefit many areas and applications, including clothing, packaging and photovoltaics. Here, we study this possibility for a metamaterial composite paper based on cellulose nanofibrils (CNF) and silicon dioxide (SiO2) microparticles with infrared (IR) Frohlich phonon resonances. This CNF–SiO2 composite shows outstanding transparency in the visible wavelength range, with the option of controlling light diffusion and haze from almost zero to 90% by varying the SiO2 microparticle concentration. We further show that the transparent metamaterial paper could maintain high thermal emissivity in the atmospheric IR window, as attributed to strong IR absorption of both the nanocellulose and the resonant SiO2 microparticles. The high IR emissivity and low visible absorption make the paper suitable for passive radiative cooling and we demonstrate cooling of the paper to around 3 °C below ambient air temperature by exposing it to the sky.

41 citations

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TL;DR: In this paper, a reflective radiative cooler and a transparent radiative cooling based on cellulose derivatives manufactured via electrospinning and casting, respectively, were demonstrated for use as coatings on silicon samples exposed to sun light at daytime.
Abstract: Radiative cooling passively removes heat from objects via emission of thermal radiation to cold space. Suitable radiative cooling materials absorb infrared light while they avoid solar heating by either reflecting or transmitting solar radiation, depending on the application. Here, we demonstrate a reflective radiative cooler and a transparent radiative cooler solely based on cellulose derivatives manufactured via electrospinning and casting, respectively. By modifying the microstructure of cellulose materials, we control the solar light interaction from highly reflective (> 90%, porous structure) to highly transparent (≈ 90%, homogenous structure). Both cellulose materials show high thermal emissivity and minimal solar absorption, making them suitable for daytime radiative cooling. Used as coatings on silicon samples exposed to sun light at daytime, the reflective and transparent cellulose coolers could passively reduce sample temperatures by up to 15 °C and 5 °C, respectively.

26 citations

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TL;DR: The design of combat aircraft with high military effectiveness, affordability and military suitability requires balancing the efforts of many engineering disciplines during all phases of the developmen ...

20 citations

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TL;DR: Optical properties in terms of the complex-valued dielectric function were determined for spin-coated films of a Rose Bengal derivative using variable angle of incidence spectroscopic ellipsometry as mentioned in this paper.

20 citations

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TL;DR: reflectance, scattering, and polarization properties of the cuticle of the scarab beetle Cyphochilus insulanus are studied with spectral directional hemispherical reflectance, bidirectional reflection distribution function (BRDF), and Mueller-matrix spectroscopic ellipsometry (MMSE).
Abstract: Optical properties of natural photonic structures can inspire material developments in diversified areas, such as the spectral design of surfaces for camouflage. Here, reflectance, scattering, and ...

19 citations


Cited by
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Proceedings Article
01 Jan 1999
TL;DR: In this paper, the authors describe photonic crystals as the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures, and the interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.
Abstract: The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

2,722 citations

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TL;DR: This paper reviews the current status of instruments for measuring the full 4×1 Stokes vector S, which describes the state of polarization of totally or partially polarized light, and the 4×4 Mueller matrix M, which determines how the SOP is transformed as light interacts with a material sample or an optical element or system.
Abstract: This paper reviews the current status of instruments for measuring the full 4×1 Stokes vector S, which describes the state of polarization (SOP) of totally or partially polarized light, and the 4×4 Mueller matrix M, which determines how the SOP is transformed as light interacts with a material sample or an optical element or system. The principle of operation of each instrument is briefly explained by using the Stokes-Mueller calculus. The development of fast, automated, imaging, and spectroscopic instruments over the last 50 years has greatly expanded the range of applications of optical polarimetry and ellipsometry in almost every branch of science and technology. Current challenges and future directions of this important branch of optics are also discussed.

138 citations

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TL;DR: The role thatmicrostructures play in enhancing optical performance or creating new optical properties in nature is summarized, with a focus on the regulation mechanisms of the solar and infrared spectra emanating from the microstructures and their role in the field of thermal radiation.
Abstract: Precise optical and thermal regulatory systems are found in nature, specifically in the microstructures on organisms' surfaces. In fact, the interaction between light and matter through these microstructures is of great significance to the evolution and survival of organisms. Furthermore, the optical regulation by these biological microstructures is engineered owing to natural selection. Herein, the role that microstructures play in enhancing optical performance or creating new optical properties in nature is summarized, with a focus on the regulation mechanisms of the solar and infrared spectra emanating from the microstructures and their role in the field of thermal radiation. The causes of the unique optical phenomena are discussed, focusing on prevailing characteristics such as high absorption, high transmission, adjustable reflection, adjustable absorption, and dynamic infrared radiative design. On this basis, the comprehensive control performance of light and heat integrated by this bioinspired microstructure is introduced in detail and a solution strategy for the development of low-energy, environmentally friendly, intelligent thermal control instruments is discussed. In order to develop such an instrument, a microstructural design foundation is provided.

63 citations

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TL;DR: In this article, the authors report a circular polarisation study of the macroscopic reflections of the wing scales of Callophrys rubi and Teinopalpus imperialis that reveals no significant difference in the reflectance values for left and right-circularly polarized light.

56 citations

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TL;DR: Stretchable copolymer membranes are used for the fabrication of mechanically and electrically actuated camouflage devices that function over an unprecedented spectral window and may afford new scientific and technological opportunities not only for adaptive optics and photonics but also for any platform that can benefit from simultaneously controlling visible light and heat.
Abstract: Soft, mechanically deformable materials and systems that can, on demand, manipulate light propagation within both the visible and infrared (IR) regions of the electromagnetic spectrum are desirable for applications that include sensing, optoelectronics, robotics, energy conservation, and thermal management. However, the development of such technologies remains exceptionally difficult, with relatively few examples reported to date. Herein, this challenge is addressed by engineering cephalopod-inspired adaptive camouflage platforms with multispectral functionality. First, stretchable copolymer membranes that feature outstanding unstrained protonic conductivities of up to ≈90 mS cm-1 , demonstrate increases of ≈80% in their conductivities at strains of 200%, and exhibit no loss in electrical performance even under extreme elongations of 500% are described. Next, the membranes are used for the fabrication of mechanically and electrically actuated camouflage devices that function over an unprecedented spectral window; can simultaneously modulate their visible and IR specular-to-diffuse transmittance ratios by >3000-fold and >4-fold, respectively; feature rapid response times of ≈0.6 s; and exhibit good performance after repeated actuation. These findings may afford new scientific and technological opportunities not only for adaptive optics and photonics but also for any platform that can benefit from simultaneously controlling visible light and heat.

55 citations