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- Åkerlind, Christina, 1974-
(författare)
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Optical Studies of Bio-inspired Materials for Camouflage
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the ongoing sensor-camouflage duel, new functionalities and sensing abilities are continuously incorporated in detector devices, requiring new capabilities on the camouflage side. The aim of this work is to contribute to improved camouflage including low polarization detectability in wavelength regions with both visible and invisible light. To find new surfaces that can be used as camouflage, we seek for materials that in a spectral design perspective meet the requests of military utility. We have represented this with a 'ladder model' which step by step connects the system and requirements aspects from a basic material level to a useful application.The focus in this study is mainly on the first rungs of the 'ladder' which are addressing aspects of spectral design and systems engineering as well as requirements of camouflage materials. We have stated six criteria for evaluating camouflage materials and their interactions with light. The criteria are related to reflection, gloss, degree of polarization, emissivity, broadband and dynamic properties.The included papers can be divided into two parts. The first part is related to aspects of the evaluation criteria for camouflage and the second part presents studies of bio-inspired materials and their performance related to the evaluation criteria.In connection with the presentation of the 'ladder model' for military utility and the six criteria for camouflage, several materials divided into the four categories: pigments, thin film coatings, multidimensional structures and metamaterials are surveyed. We also studied higher system design levels evaluating the visual and thermal contrast by inspecting images of an object's surface in a background. Important terms and parameters at this level were detectability and the lightness of a color. Furthermore a literature review of polarimetric environmental background properties was performed together with a reference materials study.Camouflage properties of several organic material surfaces have been studied. The biopolymeric materials range from beetle cuticle to cellulose based foams and protein fibres. In addition to white structures, we also investigated dynamic properties and initiated work using organic dyes to expand the use of the studied materials to camouflage applications. The main characterization techniques were reflection spectrometry, scatterometry and Mueller-matrix ellipsometry. These methods were used with an aim to mainly investigate the first three camouflage criteria (reflection, gloss, degree of polarization) but also touching on emissivity and dynamic coloring. Overall, the academic approach have been balanced with the requests and limits given by the military utility. The results will contribute to better camouflage by using advanced bio-inspired materials.
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- Åkerlind, Christina, et al.
(författare)
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Spectroscopic ellipsometry and vector network analysis for determination of the electromagnetic response in two wavelength regions
- 2008
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Ingår i: Physica Status Solidi. C: Current Topics in Solid State Physics. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1862-6351. ; 5:5, s. 1089-1092:5, s. 1089-1092
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Tidskriftsartikel (refereegranskat)abstract
- In this work, spectroscopic ellipsometry and vector network analysis are used to determine the electromagnetic response of three samples, an epoxy polymer, a sample with ferrit-based nanoparticles in a polymer matrix and silicon, in the wavelength ranges 0.4-30 μm and 0.75-7.59 cm. Both methods measure amplitude and phase changes due to interaction with a sample and can be used to measure the full complex-valued dielectric response to electromagnetic radiation. The data from the two methods show similar levels of the response at the two ends of the spectral gap between the ranges of the two methods.
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- Arwin, Hans, 1950-
(författare)
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Adsorption of proteins at solid surfaces
- 2018. - 2
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Ingår i: Ellipsometry of functional organic surfaces and films. - Cham : Springer. - 9783030093518 - 9783319758954 ; , s. 31-48
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Ellipsometry has a very high thin film sensitivity and can resolve sub-nm changes in the thickness of protein film on solid substrates. Being a technique based on photons in and photons out it can also be applied ad solid-liquid interfaces. Ellipsometry has therefore found many in situ applications on protein layer dynamics but studies of protein layer structure are also frequent. Numerous ex situ applications on detection and quantification of protein layers are found and several biosensing concepts have been proposed. In this chapter, the use of ellipsometry in the above mentioned areas is reviewed and experimental methodology including cell design is briefly discussed. The classical ellipsometric challenge to determine both thickness and refractive index of a thin film is addressed and an overview of strategies to determine surface mass density is given. Included is also a discussion about spectral representations of optical properties of a protein layer in terms of a model dielectric function concept and its use for analysis of protein layer structure.
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| 7. |
- Arwin, Hans, 1950-, et al.
(författare)
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Analysis of Mueller-matrix data from chiral structures in exoskeletons of scarab beetles
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Several species of scarab beetles exhibit extra-ordinary metallic-like structural colors. These color-generating structures also show complex polarization properties and unpolarized light can be reflected with near-circular polarization. Specimens of Cetonia aurata (Linnaeus, 1758) are here studied with a dual-rotating compensator ellipsometer using focusing probes. Mueller-matrix data are recorded with precision better than ±0.005 in the range 350 – 1000 nm for angles 20-60º. In a narrow spectral range in the green part of the spectrum, the Mueller-matrix elements m14 and m41 show large negative values and the reflected light is near-circular left-handed polarized. This effect originates from a chiral structure in the beetle exoskeleton. A twisted biaxial lamellae structure with a top dielectric layer is used in regression analysis to determine pitch of the helix and refractive indices of the chitin-based constituting materials. The applicability of this model to data from different scarab beetles is reviewed and it is found that the model show limitations for beetles with broad-band reflection, e.g. those with gold-like colors. For narrow-band optical features, the model provides an excellent fit for all 15 normalized Mueller-matrix elements over the full spectrum and angle of incidence range. Dispersion models like Cauchy, b-splines and oscillator-based models are employed for the biaxial layer and fit qualities for the tested models are compared.
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| 8. |
- Arwin, Hans, 1950-
(författare)
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Analysis of photonic structures in beetles using Mueller-matrix data
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Since one hundred years it is known that some scarab beetles reflect elliptically polarized light as demonstrated by Michelson (Phil. Mag. 21(1911)544) for the beetle Chrysina resplendens. The handedness of the polarization is in a majority of cases left-handed but also right-handed polarization has been found. The polarization and color effects are generated in the outer part of the exoskeleton, the so called cuticle. Our objective is here to demonstrate that structural parameters and materials optical functions of these photonic structures can be extracted by advanced modeling of spectral multi-angle Mueller-matrix data recorded from beetle cuticles.A dual rotating compensator ellipsometer (RC2, J. A. Woollam Co., Inc.) is used to record normalized Mueller-matrix elements mij (i,j=1..4) in the spectral range 300 – 900 nm at angles of incidence in the range 20-75º. All measurements are performed on the scutellum (a small triangular part on the dorsal side of the beetles) with focusing optics resulting in a spot size of the order of 0.05-0.1 mm. The software CompleteEASE (J. A. Woollam Co., Inc.) is used for regression analysis. Analysis of data measured on Cetonia aurata will be presented in detail and data from other beetles in the Cetoniinae and Rutelinae subfamilies will be briefly discussed.A contour plot of Mueller-matrix data measured on Cetonia aurata (insert) is shown below. This beetle has a metallic shine and if illuminated with unpolarized white light it reflects left-handed polarized green light as revealed by the non-zero Mueller-matrix elements m14 and m41 in the green spectral region for angles of incidence below about 45º. This is detailed in the graph to the right which shows a spectrum for Mueller-matrix element m41at 20º as well as fitted model data. The model used for the chiral nanostructure is based on a twisted lamella structure, also called Bouligand structure. Given the complexity of the nanostructure, an excellent model fit is achieved. The obtained model parameters are the spectral variation of the refractive index of the birefringent lamellas and the pitch. Limitations and development of the model will be discussed as well as its applicability to more complex beetle cuticle structures.Figure. Left: Mueller-matrix data versus wavelength and angle of incidence on Cetonia aurata. Each panel shows mij, where i and j correspond to the row and column, respectively. Right: Experimental and model-generated m41at an angle of incidence of 20º. In addition, Mueller-matrix spectra are very rich in information about reflection properties and allow parameterization of polarization parameters of the reflected light, e.g. in terms of azimuth and ellipticity of the polarization ellipse and the degree of polarization (see abstract by Järrendahl).
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| 14. |
- Arwin, Hans, 1950-, et al.
(författare)
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Comparison and analysis of Mueller-matrix spectra from exoskeletons of blue, green and red Cetonia aurata
- 2014
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 571, s. 739-743
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Tidskriftsartikel (refereegranskat)abstract
- The exoskeleton, also called the cuticle, of specimens of the scarab beetle Cetonia aurata is a narrow-band reflector which exhibits metallic shine. Most specimens of C. aurata have a reflectance maximum in the green part of the spectrum but variations from blue–green to red–green are also found. A few specimens are also more distinct blue or red. Furthermore, the reflected light is highly polarized and at near-normal incidence near-circular left-handed polarization is observed. The polarization and color phenomena are caused by a nanostructure in the cuticle. This nanostructure can be modeled as a multilayered twisted biaxial layer from which reflection properties can be calculated. Specifically we calculate the cuticle Mueller matrix which then is fitted to Mueller matrices determined by dual-rotating compensator ellipsometry in the spectral range 400–800 nm at multiple angles of incidence. This non-linear regression analysis provides structural parameters like pitch of the chiral structure as well as layer refractive index data for the different layers in the cuticle. The objective here is to compare spectra measured on C. aurata with different colors and develop a generic structural model. Generally the degree of polarization is large in the spectral region corresponding to the color of the cuticle which for the blue specimen is 400–600 nm whereas for the red specimen it is 530–730 nm. In these spectral ranges, the Mueller-matrix element m41 is non-zero and negative, in particular for small angles of incidence, implicating that the reflected light becomes near-circularly polarizedwith an ellipticity angle in the range 20°–45°.
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- Arwin, Hans, 1950-, et al.
(författare)
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Computer screen photo-assisted measurement of intensity or polarization change of light upon interaction with a sample
- 2006
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Patent (populärvet., debatt m.m.)abstract
- A method for measuring a property of a test sample utilizing one of the test methods ellipsometry, surface plasmon resonance and nephelometry, wherein the method includes the steps; providing a test sample being an object with which an optical interaction with light takes place, illuminating said test sample using a program controlled display as a light source, which program controlled display is composed of at least one activated pixel providing an illumination from an illuminating area of said program controlled display, arranging said program controlled display to illuminate said test sample with polarized light, detecting light emerging from said test sample utilizing a detector coupled to said program and evaluating said property from signals from said detector.
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| 19. |
- Arwin, Hans, 1950-
(författare)
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Ellipsometry-Based Sensor Systems
- 2006
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Ingår i: Encyclopedia of Sensors Vol. 3. - California, USA : American Scientific Publishers. ; , s. 329-358
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Encyclopedia of Sensors is the first encyclopedia ever published in the field of sensors. The multivolume encyclopedia will provide a complete coverage of most recent advances and emerging new sensor technologies in the fields of science, engineering and medicine. Although there are many books focused on sensors however no encyclopedic reference work has been published as of today. This encyclopedia will cover all aspects of sensor science and technology dealing with all types of sensor materials, their synthesis and spectroscopic characterization, sensor designs, fabrication and manufacturing techniques, sensor probes, features, physical, chemical and biosensors, their applications in electronics, photonic and optoelectronic industries, medicine, surface sensing, food industry, environmental engineering and nanotechnology. It is written for a wide range of audience from non-scientists to active scientists and engineers, professionals and experts working in the field of sensors.
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| 20. |
- Arwin, Hans, 1950-
(författare)
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Ellipsometry in Life Science
- 2005. - 1
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Ingår i: Handbook of Ellipsometry. - Norwich, NY : William Andrew Publishing/SpringerVerlag. - 0815514999 - 9783540222934 ; , s. 799-855
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Ever progressive miniaturization of integrated circuits and breakthroughs in knowledge of biological macromolecules deriving from DNA and protein surface research are propelling ellipsometry, a measurement technique based on phase and amplitude changes in polarized light, to greater popularity in a widening array of applications. Ellipsometry, without contact and non-damaging to samples, is an ideal measurement technique to determine optical and physical properties of materials at the nano scale. With the acceleration of new instruments and applications occurring today, this book provides a much needed foundation of the science and technology of ellipsometry for scientists and engineers in industry and academia at the forefront of nanotechnology developments in instrumentation, integrated circuits, fiber optics, biotechnology, and pharmaceuticals. Divided into four sections, this comprehensive handbook covers the theory of ellipsometry, instrumentation, applications, and emerging areas.
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- Arwin, Hans, 1950-, et al.
(författare)
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Enhancement in ellipsometric thin film sensitivity near surface plasmon resonance conditions
- 2008
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Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley-VCH Verlagsgesellschaft. - 1862-6300 .- 1862-6319. ; 205:4, s. 817-820
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Tidskriftsartikel (refereegranskat)abstract
- Ellipsometry used in internal reflection mode exhibits enhanced thin film sensitivity if operated close to surface plasmon resonance conditions. Compared to conventional ellipsometry, the changes in the ellipsometric parameter Δ are several orders of magnitude larger. Here, the origin of this large sensitivity is discussed by analysing thin film approximations of the complex reflectance ratio. It is found that the thickness sensitivity in Δ is proportional to the inverse of the difference between the intrinsic and the radiation-induced damping of the surface plasmons.
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| 22. |
- Arwin, Hans, 1950-, et al.
(författare)
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Exploring optics of beetle cuticles with Mueller-matrix ellipsometry
- 2014
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Ingår i: Materials Today: Proceedings. - : Elsevier. - 2214-7853.
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Konferensbidrag (refereegranskat)abstract
- Spectroscopic Mueller-matrix ellipsometry at variable angles of incidence is applied to beetle cuticles using a small (50 -100 μm) spot size. It is demonstrated how ellipticity and degree of polarization of the reflected light can be derived from a Mueller matrix providing a detailed insight into reflection properties. Results from Cetonia aurata, Chrysina argenteola and Cotinis mutabilis are presented. The use of Mueller matrices in regression analysis to extract structural and optical parameters of cuticles is briefly described and applied to cuticle data from Cetonia aurata whereby the pitch of the twisted layered structure in the cuticle is determined as well as the refractive indices of the epicuticle and the exocuticle.
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| 23. |
- Arwin, Hans, 1950-, et al.
(författare)
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Exploring polarization features in light reflection from beetles with structural colors
- 2015
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Ingår i: <em>Proc. SPIE </em>9429, Bioinspiration, Biomimetics, and Bioreplication 2015. - : SPIE - International Society for Optical Engineering. - 9781628415322 ; , s. 942909-1-942909-13
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Konferensbidrag (refereegranskat)abstract
- A Mueller matrix of a sample can be used to determine the polarization of reflected light for incident light with arbitrary polarization. The polarization can be quantified in terms of ellipticity, polarization azimuth and degree of polarization. We apply spectroscopic Mueller-matrix ellipsometry at multiple angles of incidence to study the cuticle of beetles and derive polarization features for incident unpolarized light. In particular we address chiral phenomena in scarab beetles, the origin of their structural colors and the observed high degree of circular polarization is discussed. Results from beetles in the Scarabaeidae subfamilies Cetoniinae and Rutelinae are presented including specimens with broad-band silver- or gold-like colors with metallic shine as well as specimens with narrow-band green or red reflectors. The variation of polarization with angle of incidence and occurrence of both left-handed and right-handed polarization from a single species are presented. We also use Mueller-matrix spectra in electromagnetic modeling and show how to determine structural parameters including cuticle layer thicknesses and optical properties. Interference oscillations in the observed spectra are due to allowed optical modes and we show how to develop a structural model of a cuticle based on this effect. Sum decomposition of Mueller matrices measured on a depolarizing cuticle of a beetle is briefly discussed.
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- Arwin, Hans, 1950-, et al.
(författare)
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Infrared ellipsometry studies of thermal stability of protein monolayers and multilayers
- 2008
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Ingår i: Physica Status Solidi. C: Current Topics in Solid State Physics. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1862-6351. ; 5:5, s. 1438-1441
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Tidskriftsartikel (refereegranskat)abstract
- Methodology for studies of effects of heating multilayers of human serum albumin (HSA) and anti-HSA is presented. Multilayers of anti-HSA were prepared on silicon substrates and studied with infrared spectroscopic ellipsometry equipped with a heat stage. The refractive index N = n + ik and the layer thickness are determined and the amide bands are analyzed. It is found that HSA/anti-HSA multilayers are stable for shorter times at temperatures above 100 °C, except for small thickness changes. Also pilot studies of effects of heating monolayers of proteins adsorbed on gold substrates is presented.
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