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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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| 16. |
- 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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| 21. |
- 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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| 25. |
- 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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| 33. |
- Arwin, Hans, 1950-, et al.
(författare)
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Polarization effects in reflection from the cuticle of scarab beetles studied by spectroscopic Mueller-matrix ellipsometry
- 2012
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Ingår i: AES 2012, Advanced Electromagnetics Symposium.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Polarization effects in reflection from the cuticle of scarab beetles studied by spectroscopic Mueller-matrix ellipsometry H. Arwin*, T. Berlind, J. Birch, L. Fernandez Del Rio, J. Gustafson, J. Landin,R. Magnusson, C. Åkerlind, and K. JärrendahlDepartment of Physics, Chemistry and Biology, Linköping University, Sweden*corresponding author: han@ifm.liu.se Abstract- Many scarab beetles exhibit structural colors and complex polarization phenomena in reflection. These effects are characterized with spectroscopic Mueller-matrix ellipsometry in our work. The polarization ellipse of reflected light as well as the degree of polarization is presented including variations with angle of incidence and wavelength. Emphasis is on beetles showing chiral effects and structural modeling of cuticle nanostructure is discussed. Background Since one hundred years it is known that some scarab beetles reflect elliptically polarized light as demonstrated by Michelson for the beetle Chrysina resplendens [1]. The handedness of the polarization is in a majority of the cases left-handed but also right-handed polarization has been found [2,3]. The ellipticity varies with wavelength and viewing angle but can be close to +1 or -1 (right or left circular polarization, respectively) and in addition these beetles may exhibit beautiful structural colors. The polarization and color effects are generated in the outer part of the exoskeleton, the cuticle. These natural photonic structures are often multifunctional and play important roles for survival of beetles, e.g. for hiding from or scaring predators, for intraspecies communication, etc. [4]. However, such structures may find use in many commercial applications and a major motivation for detailed studies of natural photonic structures is that they inspire to biomimetic applications [5,6].Approach Our objective is to use spectral Mueller-matrix data on scarab beetles to parameterize reflection properties in terms of polarization parameters and degree of polarization. The studied beetles all are phytophagous and include species from the Cetoniinae subfamily (e.g. Cetonia aurata and Coptomia laevis,), the Rutelinae subfamily (e.g. Chrysina argenteola and Chrysina resplendens) and the Melolonthinae subfamily (Cyphochilus insulanus). Furthermore, structural modeling is presented on Cetonia aurata and a few more beetles to demonstrate that structural parameters can be extracted by advanced modeling of Mueller-matrix data.Experimental A dual rotating compensator ellipsometer (RC2, J. A. Woollam Co., Inc.) is used to record all 16 Mueller-matrix elements mij (i,j=1..4) in the spectral range 300 – 900 nm at angles of incidence in the range 20-70º. The elements are normalized to m11 and thus have values between -1 and +1. 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 50-100 mm. The software CompleteEASE (J. A. Woollam Co., Inc.) is used for analysis.Results and discussion As an example, Fig. 1 shows contour plots of Mueller-matrix data measured on Cetonia aurata. 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 clearly seen in the graph to the right in Fig. 1 which shows a spectrum for Mueller-matrix element m41at 20º as well as fitted model data. A model based on a twisted lamella structure, also called Bouligand structure, is used to model the chiral nanostructure [4]. 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. The model also includes a dielectric surface layer. Fig.1. Left: Mueller-matrix data on Cetonia aurata. Each contour plot shows mij, where i and j correspond to the row and column, respectively. m11 =1 and is not shown but is replaced with a photo of the beetle. Right: Experimental and model-generated Mueller-matrix element m41at an angle of incidence of 20º. From the Mueller-matrix data one can also determine so called derived parameters including azimuth and ellipticity of the polarization ellipse and the degree of polarization. The variations of these parameters with angle of incidence are presented for a selection of scarab beetles. Examples of both left-handed and right-handed polarization effects are shown and the importance of degree of polarization will be discussed.Concluding remarks Mueller-matrix spectra at oblique incidence are very rich in information about reflection properties and allows parameterization of polarization parameters of the reflected light. Both left-handed and right-handed reflected light is found in scarab beetles. Mueller-matrix data can also be used for a detailed modeling of the nanostructure of the cuticle of beetles.AcknowledgementsFinancial support was obtained from the Knut and Alice Wallenberg foundation and the Swedish Research Council. The Museum of Natural History in Stockholm, the National Museum of Natural Science in Madrid, the Berlin Museum of Natural History and the Natural History Museum in London are acknowledged for loan of beetles. REFERENCESMichelson, A. A. “On Metallic Colouring in Birds and Insects,” Phil. Mag., 21, 554-567, 1911.Goldstein, D. H. “Polarization properties of Scarabaeidae,” Appl. Opt., 45, 7944-7950, 2006.Hodgkinson, I., Lowrey, S., Bourke, L., Parker, A. and McCall, M. W. “Mueller-matrix characterization of beetle cuticle polarized and unpolarized reflections from representative architectures,” Appl. Opt., 49, 4558-4567, 2010.Vukusic, P. and Sambles, J. R. “Photonic structures in biology,” Nature, 424, 852-855, 2003.Lenau, T. and Barfoed, M. “Colours and Metallic Sheen in Beetle Shells - A Biomimetic Search for Material Structuring Principles Causing Light Interference,” Adv. Eng. Mat., 10, 299-314. 2008.Parker, A. R. and Townley, H. E “Biomimetics of photonic nanostructures,” Nature Nanotech., 2, 347-351, 2007.
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| 34. |
- Arwin, Hans, 1950-
(författare)
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Polarized reflection and nanostructure in scarab beetles studied by spectroscopic Mueller-matrix ellipsometry
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Michelson showed one hundred years ago that the scarab beetle Chrysina resplendens reflects near-circular polarized light [1]. More recent Mueller-matrix methodology has been employed to detail polarization phenomena in the exoskeleton of beetles [2,3]. The polarization is in a majority of cases left-handed but also right-handed polarization has been found. In addition these beetles may exhibit beautiful structural colors. Such structures may find use in many applications and a major motivation for detailed studies of natural photonic structures is that they inspire to biomimetic applications. Here we apply spectroscopic Mueller-matrix ellipsometry on scarab beetles with objective to model natural photonic nanostructures and to describe reflection properties in terms of polarization parameters and degree of polarization.The studied beetles are from the following subfamilies: Cetoniinae (Cetonia aurata and Coptomia laevis); Rutelinae (Chrysina argenteola and Chrysina resplendens); and Melolonthinae (Cyphochilus insulanus). A dual rotating compensator ellipsometer (RC2, J. A. Woollam Co., Inc.) is used to record normalized Mueller-matrix spectra in the spectral range 300 – 900 nm at angles of incidence in the range 20-70º.From Mueller-matrix data one can determine so called derived parameters of the reflected light including azimuth and ellipticity of its polarization ellipse and the degree of polarization. The variation of these parameters with wavelength and angle of incidence are presented for a selection of the scarab beetles above. Examples of both left-handed and right-handed polarization are shown for narrow-band and wide-band reflecting beetles and the importance of degree of polarization will be discussed.Structural modeling is presented on Cetonia aurata to demonstrate that structural parameters can be extracted by advanced modeling of Mueller-matrix data. Cetonia aurata has a metallic shine and if illuminated with unpolarized white light it reflects left-handed polarized green light as revealed by a non-zero Mueller-matrix elements m14 and m41 in the green spectral region. At near-normal incidence the polarization can be almost circular. A model based on a twisted lamella structure, also called Bouligand structure, is used to model this chiral nanostructure. The obtained model parameters are the spectral variation of the refractive index of the birefringent lamellas and the pitch. The model also includes a dielectric surface layer.Keywords: Mueller-matrix ellipsometry; scarab beetles; natural nanostructures; circular polarization References:Michelson, A. A. “On Metallic Colouring in Birds and Insects,” Phil. Mag. 21 (1911) 554-567Arwin, H., Magnusson, R., Landin, J., Järrendahl, K., “Chirality-induced polarization effects in the cuticule of scarab beetles: 100 year after Michelson”, Phil. Mag. 92 (2012) 1583-1599Hodgkinson, I., Lowrey, S., Bourke, L., Parker, A., McCall, M. W., “Mueller-matrix characterization of beetle cuticle polarized and unpolarized reflections from representative architectures”, Appl. Opt. 49 (2010) 4558-4567
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| 38. |
- Arwin, Hans, 1950-
(författare)
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Structural and optical properties of chiral natural photonic structures determined from spectroscopic Mueller-matrix data
- 2012
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Ingår i: E-MRS 2012 Fall Meeting.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Resume : In nature one can find advanced photonic structures which often are multifunctional. High-precision analysis of such structures is a prerequisite for a biomimetic approach to synthesize analogous structures for technical applications. Here we employ spectroscopic Mueller-matrix ellipsometry to address chiral photonic structures in scarab beetles. Such structures exhibit structural colors with metallic shine but also complex polarization properties. At the same time they are hard and lightweight components in the exoskeleton of beetles. With a dual rotating compensator ellipsometer we measure Mueller-matrix data on beetles with precision better than ±0.005 in the range 350 – 1000 nm at angles of incidence 20-75º. These Mueller matrices directly provide phenomenological descriptions of polarization properties of exoskeletons and both left-handed and right-handed near-circularly reflected light can be found. By using non-linear regression analysis with Mueller-matrix data and an appropriate structural model, one can extract structural and optical details including pitch of the helical structure, as well as thicknesses and the refractive indices of the various layers in the birefringent chitin-based materials constituting the exoskeleton. The applications of Mueller-matrix analysis will be demonstrated on a selection of photonic structures in scarab beetles including wide band non-chiral, narrow-band chiral and wide-band chiral structures.
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| 39. |
- Arwin, Hans, 1950-, et al.
(författare)
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Sum decomposition of Mueller matrices from beetle cuticles
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Spectral Mueller matrices are very rich in information about physical properties of a sample. We have recently shown that polarizing properties like ellipticity and degree of polarization can be extracted from a Mueller matrix measured on a beetle cuticle (exoskeleton). Mueller matrices can also be used in regression analysis to model nanostructures in cuticles. Here we present the use of sum decomposition of Mueller matrices from these depolarizing biological reflectors to explore the fundamental character of these reflectors. The objective is to decompose a Mueller matrix into well- defined ideal non-depolarizing matrices corresponding to mirrors, circular polarizers, halfwave retarders etc.Generally it is possible to decompose a measured depolarizing Mueller matrix M into four (or fewer) non-depolarizing matrices according to M=λ1M1+λ2M2+λ3M3+λ4M4, where λ1, λ2, λ3 and λ4 are eigenvalues of the covariance matrix of M. Two strategies for decomposition will be discussed. A Cloude decomposition will provide the eigenvalues and also the Mi’s although the latter will contain severe noise in some spectral regions. However, a major advantage with the Cloude decomposition is that the number of nonzero eigenvalues is directly obtained, i.e. the number of contributing Mi matrices. In an alternative decomposition, the Mi’s are assumed and the eigenvalues are found by regression analysis based on M. In the case with two non-zero eigenvalues we define a model Mueller matrix MD=αRM1+βRM2 with αR+βR=1. With αR as adjustable parameter, the Frobenius norm ||M-MD|| is minimized for each wavelength in the spectral range of M. For more complex structures, the regression can be extended by adding more matrices up to a total of four. Advantages with a regression approach are its simplicity and stability compared to a Cloude decomposition.Mueller-matrix spectra of beetle cuticles are recorded with a dual rotating compensator ellipsometer in the spectral range 400 – 900 nm at angles of incidence in the range 20 - 75°. The application of decomposition on biological reflectors is demonstrated on M measured on the beetle Cetonia aurata, which represents a narrow-band chiral Bragg reflector with two non-zero eigenvalues. A decomposition in an ideal mirror and a circular polarizer is feasible. In another example, the broad-band and gold-colored beetle Chrysina argenteola, we show that more than two eigenvalues can be nonzero, especially at oblique incidence, and additional matrices are involved.
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| 40. |
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| 41. |
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| 42. |
- Arwin, Hans, 1950-
(författare)
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TIRE and SPR-enhanced SE for adsorption processes
- 2018
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Ingår i: Ellipsometry of functional organic surfaces and films. - Cham : Springer. - 9783030093518 - 9783319758954 ; , s. 419-435
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Ellipsometry configurations in internal reflection mode facilitate studies of adsorption processes without the light beam passing through the medium from which adsorption accurs. Monitoring of adsorption processes on surfaces in opaque media is thus possible. If the surface in addition has a thin semitransparent metal film in which surface plasmon polaritons can be excited, one can achieve very high sensitivity to small changes in surface mass density of an adsorbed biolayer. Thickness changes as small as on pm can be resolved. In this chapter the theory for Total Internal Reflection Ellipsometry (TIRE), also called surface plasmon resonance enhanced ellipsometry, will be described and instrumentation will be briefly discussed. TIRE applied in spectroscopic as well as in angle of incidence interrogation modes will be considered. Finally applications in the areas of bioadsorption processes, biosensing, gas adsorption and biolayer imaging will be reviewed.
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| 43. |
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| 44. |
- Arwin, Hans, 1950-, et al.
(författare)
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Total Internal Reflection Ellipsometry : monitoring of proteins on thin metal films
- 2006
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Ingår i: Proteins on surfaces. - Berlin, Heidelberg : Springer Verlag. - 9185457167 - 9783540326588 - 9783540326571 ; , s. 105-118
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- A measurement technique based on ellipsometry performed under conditions of total internal reflection is presented here. This technique is called total internal reflection ellipsometry (TIRE). When extended with the surface plasmon resonance effect, TIRE becomes a powerful tool for monitoring protein adsorption on thin metal films. A brief description of TIRE is presented here together with some examples of measurement system setups. Two examples of applications are included, followed by a short presentation of possible future applications of TIRE.
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| 45. |
- Arwin, Hans, 1950-, et al.
(författare)
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Total internal reflection ellipsometry : principles and applications
- 2004
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Ingår i: Applied Optics. - 0003-6935 .- 1539-4522. ; 43:15, s. 3028-3036
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Tidskriftsartikel (refereegranskat)abstract
- A concept for a measurement technique based on ellipsometry in conditions of total internal reflection is presented. When combined with surface plasmon resonance (SPR) effects, this technique becomes powerful for monitoring and analyzing adsorption and desorption on thin semitransparent metal films as well as for analyzing the semitransparent films themselves. We call this technique total internal reflection ellipsometry (TIRE). The theory of ellipsometry under total internal reflection combined with SPR is discussed for some simple cases. For more advanced cases and to prove the concept, simulations are performed with the Fresnel formalism. The use of TIRE is exemplified by applications in protein adsorption, corrosion monitoring, and adsorption from opaque liquids on metal surfaces. Simulations and experiments show greatly enhanced thin-film sensitivity compared with ordinary ellipsometry.
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| 46. |
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| 47. |
- Bakker, Jimmy W.P., et al.
(författare)
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Immunodetection using computer screen photo-assisted ellipsometry
- 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. 1431-1433
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Tidskriftsartikel (refereegranskat)abstract
- Detection of antibody-antigen reactions is demonstrated by measuring changes in reflectance of light polarized parallel to the plane of incidence, using a computer screen as light source and a web camera as detector, giving results similar to traditional off-null ellipsometry and in accordance with a simplified theoretical model.
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| 48. |
- Baroni, M. P. M. A., et al.
(författare)
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Optical and morphological properties of porous diamond-like-carbon films deposited by magnetron sputtering
- 2006
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 352:32-35, s. 3734-3738
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Tidskriftsartikel (refereegranskat)abstract
- Porous diamond-like-carbon (PDLC) thin films obtained on silicon substrate by DC low energy magnetron sputtering have been investigated by photoluminescence, transmission and reflection spectroscopy, photoacoustic and spectroscopic ellipsometry. The absorption features observed for these films show similarities with those of porous silicon (PS) as well as in the performed gradient structural pattern classification of the SFM porosity, by means of the computational GPA-flyby environment on PS and PDLC samples. The dielectric function is also calculated for the bulk diamond-like carbon using the full-potential linearized augmented plane wave method within the framework of local density approximation to density functional theory. From the measurement a low real dielectric constant of about 4.5 at 0.8 eV was found whereas the calculated e(1)(0) for the bulk diamond has a value of 5.5.
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| 49. |
- Bergqvist, Jonas, et al.
(författare)
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Determination of optical constants and phase transition temperatures in polymer fullerene thin films for polymer solar cells
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Plastic photovoltaics combining semiconducting polymers with fullerene derivatives have the potentialto become the first cost efficient solar cells able to compete with fossil fuels. The maximum powerconversion efficiency is already 8.3%[1] , and new polymers arrive frequently in the search for efficienciesof 10%. As a first step in the screening of candidate materials, the optical constants of the purepolymer as well as the polymer blend with fullerenes are determined from Variable Angle SpectroscopicEllipsometry (VASE), using Tauc-Lorentz oscillator models, throughout the solar spectrum. Thesemodels are then used to predict the upper limits to photocurrent generation in devices, in transfermatrix simulations of the multilayer thin film photovoltaic devices. This forms an essential step in thechoice of materials for optimization in devices.Materials optics measurements are also used to deduce the phase diagram of polymer and polymerblend films. The glass transition temperature is very important for plastic solar cells and mustbe higher than the 80C a device can reach to avoid degradation during operation. Temperaturedependent ellipsometric measurements has proven to be a feasible way to determine phase transitionsin polymer thin films[2] . These transitions are displayed as a sudden change of the volumetricexpansion coefficient, and are manifested by an abrupt increase of thickness at the phase transitiontemperature. For thickness determination a Cauchy model is applied to the transparent infrared partof the spectra.References1. Z. He, C. Zhong, X. Huang, W-Y. Wong, H. Wu, L. Chen, S. Su, Y Cao, Advanced Materials 23, 4636(2011)2. M. Campoy-Quiles, P.G. Etchegoin, D.D.C. Bradley, Synthetic Metals 155, 279(2005)
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| 50. |
- Bergqvist, Jonas, et al.
(författare)
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In situ reflectance imaging of organic thin film formation from solution
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The rapid progress of organic photovoltaic devices during the last decade, with power conversion efficiencies now exceeding 8%, has brought the technology close to an industrial breakthrough. For polymer solar cells, roll to roll printing is desired to gain the production advantage. The formation of the photoactive material from solutions needs to be controlled and optimized. Therefore a suitable method to monitor the deposition process is needed as deviations of drying times1 and drying rates2 during the coating process have proven to generate morphology variations causing variations in photocurrent generation.Here we demonstrate how reflectance imaging can be used to monitor the drying process, both for spin coating and blade coating deposition. A blue LED is used as light source to generate specular reflections imaged by a CMOS camera. The thinning of the wet film can then be observed by thin film interference, and can be recorded for each pixel. This enables an estimation of the evaporation rate for each pixel mapped over the substrate. For spin coating the evaporation rate is shown to increase with the distance from the rotation center, whereas the air flow is the determining parameter during blade coating. By mapping the times when interference ceases, lateral variations in drying time are visualized. Furthermore the quenching of polymer photoluminescence during the drying process can be visualized, thus creating a possibility to estimate morphological variations. Moreover lateral thickness variations of the dry film can be visualized by scanning ellipsometry. After depositing a top electrode photocurrent images can be generated by a laser scanning method. This allows for a direct comparison of drying conditions and photocurrent generation. The possibility to monitor the thin film formation as well as lateral variations in thickness in-situ by a non-invasive method, is an important step for future large scale applications where stable high performing generating morphologies have to be formed over large areas.1Schmidt-Hansberg, B.; Sanyal, M.; Klein, M.F.G.; Pfaff, M.; Schnabel, N.; Jaiser, S.; Vorobiev, A.; Müller, E.; Colsmann, A.; Scharfer, P.; Gerthsen, D.; Lemmer, U.; Barrena, E.; and Schabel, W., ACS Nano 5 , 2011, 8579-85902 Hou, L.; Wang, E.; Bergqvist, J.; Andersson, V.B.; Wang, Z.; Müller, C.; Campoy-Quiles, M.; Andersson, M.R.; Zhang, F.; Inganäs, O.,Adv. Func. Mat. 21 , 2011, 3169–3175
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