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Liquid Crystal Optical Device

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ISBN: 9783039280568 / 9783039280575 Year: Pages: 98 DOI: 10.3390/books978-3-03928-057-5 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Physics (General) --- Science (General)
Added to DOAB on : 2020-01-30 16:39:46
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The Special Issue “Liquid Crystal Optical Devices” discusses recent developments in the rapidly advancing subject of liquid crystals (LCs).

Liquid Crystal on Silicon Devices: Modeling and Advanced Spatial Light Modulation Applications

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ISBN: 9783039218288 / 9783039218295 Year: Pages: 172 DOI: 10.3390/books978-3-03921-829-5 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2019-12-09 11:49:16
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Liquid Crystal on Silicon (LCoS) has become one of the most widespread technologies for spatial light modulation in optics and photonics applications. These reflective microdisplays are composed of a high-performance silicon complementary metal oxide semiconductor (CMOS) backplane, which controls the light-modulating properties of the liquid crystal layer. State-of-the-art LCoS microdisplays may exhibit a very small pixel pitch (below 4 ?m), a very large number of pixels (resolutions larger than 4K), and high fill factors (larger than 90%). They modulate illumination sources covering the UV, visible, and far IR. LCoS are used not only as displays but also as polarization, amplitude, and phase-only spatial light modulators, where they achieve full phase modulation. Due to their excellent modulating properties and high degree of flexibility, they are found in all sorts of spatial light modulation applications, such as in LCOS-based display systems for augmented and virtual reality, true holographic displays, digital holography, diffractive optical elements, superresolution optical systems, beam-steering devices, holographic optical traps, and quantum optical computing. In order to fulfil the requirements in this extensive range of applications, specific models and characterization techniques are proposed. These devices may exhibit a number of degradation effects such as interpixel cross-talk and fringing field, and time flicker, which may also depend on the analog or digital backplane of the corresponding LCoS device. The use of appropriate characterization and compensation techniques is then necessary.

Nanomaterials in Liquid Crystals

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ISBN: 9783038971153 9783038971160 Year: Pages: 160 DOI: 10.3390/books978-3-03897-116-0 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Physics (General) --- Chemistry (General)
Added to DOAB on : 2018-09-25 11:14:33
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The dispersion of nanomaterials in liquid crystals, both of the thermotropic and the lyotropic kind, has attracted much interest over recent years. This is in part related to the success of liquid crystals in several applications, in particular flat screen displays, besides others. The dispersion of nanoparticles allows the fine-tuning of liquid crystalline properties and the addition of functionalities associated with the properties of the nanoparticles. These include the addition of ferroelectricity, magnetic properties, optic and plasmonic properties, for example through quantum dots and gold nanoparticles, but also directed conductivity, by exploiting the respective conductivity anisotropy of nanotubes. In addition, such behaviors can be achieved through transfer and templating of the self-organization of the liquid crystalline order onto dispersed anisotropic nanoparticles, allowing the formation of ordered nanostructures. Furthermore, the formation of partially ordered fluids can be induced by dispersing shape anisotropic nanoparticles in an isotropic solvent. Such lyotropic systems have recently experienced a revived interest. This genuinely multidisciplinary field of research has led to a wealth of novel systems in soft condensed matter and promises new applications in the areas of displays, optical elements, meta-materials, sensors, drug delivery, and many more. Various examples are presented in this publication.

Microlenses

ISBN: 9783038420507 9783038420507 Year: Pages: 160 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2015-10-22 08:40:45
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The study and application of microscale lenses and lens arrays enjoys a long history. Advances in microfabrication technologies in the past few decades have enabled the design and fabrication of microlenses and microlens arrays through many different approaches. In recent years, there has been notably a host of exciting developments in the microlenses and microlens arrays, including tunable-focus ones, those fabricated on non-planar substrates and surfaces, and microlens arrays mimicking natural compound eyes, to name just a few. The developments in microlenses and microlens arrays have found profound applications in many engineering and biomedical fields, including but not limited to optical coherence tomography (OCT), endoscopy, photolithography, 3-dimensional imaging, optical communications, and lab on chips. This Special Issue aims to highlight the state of the art in the development of microlenses and microlens arrays; examples being fabrication technologies and optical characterizations. It also focuses on their applications when implemented in microoptical systems.

Ionic Liquid Crystals

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ISBN: 9783039210862 / 9783039210879 Year: Pages: 108 DOI: 10.3390/books978-3-03921-087-9 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- Chemical Engineering
Added to DOAB on : 2019-06-26 08:44:06
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In this book we have collected a series of state-of-the art papers written by specialists in the field of ionic liquid crystals (ILCs) to address key questions concerning the synthesis, properties, and applications of ILCs. New compounds exhibiting ionic liquid crystalline phases are presented, both of calamitic as well as discotic type. Their dynamic and structural properties have been investigated with a series of experimental techniques including differential scanning calorimetry, polarized optical spectroscopy, X-ray scattering, and nuclear magnetic resonance, impedance spectroscopy to mention but a few. Moreover, computer simulations using both fully atomistic and highly coarse-grained force fields have been presented, offering an invaluable microscopic view of the structure and dynamics of these fascinating materials.

Optical MEMS

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ISBN: 9783039213030 / 9783039213047 Year: Pages: 172 DOI: 10.3390/books978-3-03921-304-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2019-12-09 11:49:15
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Optical microelectromechanical systems (MEMS), microoptoelectromechanical systems (MOEMS), or optical microsystems are devices or systems that interact with light through actuation or sensing at a micro- or millimeter scale. Optical MEMS have had enormous commercial success in projectors, displays, and fiberoptic communications. The best-known example is Texas Instruments’ digital micromirror devices (DMDs). The development of optical MEMS was impeded seriously by the Telecom Bubble in 2000. Fortunately, DMDs grew their market size even in that economy downturn. Meanwhile, in the last one and half decade, the optical MEMS market has been slowly but steadily recovering. During this time, the major technological change was the shift of thin-film polysilicon microstructures to single-crystal–silicon microsructures. Especially in the last few years, cloud data centers are demanding large-port optical cross connects (OXCs) and autonomous driving looks for miniature LiDAR, and virtual reality/augmented reality (VR/AR) demands tiny optical scanners. This is a new wave of opportunities for optical MEMS. Furthermore, several research institutes around the world have been developing MOEMS devices for extreme applications (very fine tailoring of light beam in terms of phase, intensity, or wavelength) and/or extreme environments (vacuum, cryogenic temperatures) for many years. Accordingly, this Special Issue seeks to showcase research papers, short communications, and review articles that focus on (1) novel design, fabrication, control, and modeling of optical MEMS devices based on all kinds of actuation/sensing mechanisms; and (2) new developments of applying optical MEMS devices of any kind in consumer electronics, optical communications, industry, biology, medicine, agriculture, physics, astronomy, space, or defense.

Keywords

scanning micromirror --- electromagnetic actuator --- angle sensor --- flame retardant 4 (FR4) --- variable optical attenuator (VOA) --- wavelength dependent loss (WDL) --- polarization dependent loss (PDL) --- micro-electro-mechanical systems (MEMS) --- tunable fiber laser --- echelle grating --- DMD chip --- MEMS scanning micromirror --- fringe projection --- laser stripe scanning --- quality map --- large reflection variations --- 3D measurement --- laser stripe width --- vibration noise --- MLSSP --- MEMS scanning mirror --- wavefront sensing --- digital micromirror device --- ocular aberrations --- dual-mode liquid-crystal (LC) device --- infrared Fabry–Perot (FP) filtering --- LC micro-lenses controlled electrically --- spectrometer --- infrared --- digital micromirror device (DMD) --- signal-to-noise ratio (SNR) --- stray light --- programmable spectral filter --- digital micromirror device --- optical switch --- microscanner --- input shaping --- open-loop control --- quasistatic actuation --- residual oscillation --- usable scan range --- higher-order modes --- resonant MEMS scanner --- electrostatic --- parametric resonance --- NIR fluorescence --- intraoperative microscope --- 2D Lissajous --- fluorescence confocal --- metasurface --- metalens --- field of view (FOV) --- achromatic --- Huygens’ metalens --- bio-optical imaging --- optical coherence tomography --- confocal --- two-photon --- spectrometer --- MEMS mirror --- electrothermal bimorph --- Cu/W bimorph --- electrothermal actuation --- reliability --- n/a

The Future of Hyperspectral Imaging

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ISBN: 9783039218226 / 9783039218233 Year: Pages: 220 DOI: 10.3390/books978-3-03921-823-3 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Chemistry (General)
Added to DOAB on : 2019-12-09 16:39:37
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hyperspectral imaging --- Raman --- fluorescence --- sorting --- quality control --- black polymers --- PZT --- classification --- machine learning --- alternating direction method of multipliers --- Cramer–Rao lower bound --- forward observation model --- linear mixture model --- maximum likelihood --- multiband image fusion --- total variation --- fingerprints --- blood detection --- age determination --- hyperspectral imaging --- lossless compression --- multitemporal hyperspectral images --- information theoretic analysis --- predictive coding --- hyperspectral imaging --- plant phenotyping --- disease detection --- spectral tracking --- time series --- hyperspectral imaging --- principal component analysis --- oxygen saturation --- wound healing --- diabetic foot ulcer --- Raman spectroscopy --- chemical imaging --- compressive detection --- spatial light modulators (SLM) --- digital micromirror device (DMD) --- digital light processor (DLP) --- optimal binary filters --- Chemometrics --- multivariate data analysis --- compressive sensing --- hyperspectral imaging --- multiplexing system --- liquid crystal --- three-dimensional imaging --- integral imaging --- remote sensing --- point target detection --- CS-MUSI --- hyperspectral --- video --- imaging --- coastal dynamics --- moving vehicle imaging --- bi-directional reflectance distribution function (BRDF) --- hemispherical conical reflectance factor (HCRF) --- stereo imaging --- digital elevation model --- Virginia Coast Reserve Long Term Ecological Research (VCR LTER) --- Hyperspectral imaging --- painting samples --- retouching pigments --- watercolours --- multivariate analysis --- potatoes --- sprouting --- primordial leaf count --- hyperspectral imaging --- spectroscopy --- fusion --- wavelength selection --- PLSR --- interval partial least squares --- deep learning --- hyperspectral imaging --- neural networks --- machine learning --- image processing --- hyperspectral imaging --- medical imaging by HSI --- HSI for biology --- remote sensing --- hyperspectral microscopy --- fluorescence hyperspectral imaging --- Raman hyperspectral imaging --- infrared hyperspectral imaging --- statistical methods for HSI --- hyperspectral data mining and compression --- statistical methods for HSI --- hyperspectral data mining and compression

Neural Microelectrodes: Design and Applications

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ISBN: 9783039213191 / 9783039213207 Year: Pages: 378 DOI: 10.3390/books978-3-03921-320-7 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Technology (General) --- General and Civil Engineering
Added to DOAB on : 2019-12-09 11:49:15
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Neural electrodes enable the recording and stimulation of bioelectrical activity in the nervous system. This technology provides neuroscientists with the means to probe the functionality of neural circuitry in both health and disease. In addition, neural electrodes can deliver therapeutic stimulation for the relief of debilitating symptoms associated with neurological disorders such as Parkinson’s disease and may serve as the basis for the restoration of sensory perception through peripheral nerve and brain regions after disease or injury. Lastly, microscale neural electrodes recording signals associated with volitional movement in paralyzed individuals can be decoded for controlling external devices and prosthetic limbs or driving the stimulation of paralyzed muscles for functional movements. In spite of the promise of neural electrodes for a range of applications, chronic performance remains a goal for long-term basic science studies, as well as clinical applications. New perspectives and opportunities from fields including tissue biomechanics, materials science, and biological mechanisms of inflammation and neurodegeneration are critical to advances in neural electrode technology. This Special Issue will address the state-of-the-art knowledge and emerging opportunities for the development and demonstration of advanced neural electrodes.

Keywords

neural interface --- silicon carbide --- robust microelectrode --- microelectrode array --- liquid crystal elastomer --- neuronal recordings --- neural interfacing --- micro-electromechanical systems (MEMS) technologies --- microelectromechanical systems --- neuroscientific research --- magnetic coupling --- freely-behaving --- microelectrodes --- in vivo electrophysiology --- neural interfaces --- enteric nervous system --- conscious recording --- electrode implantation --- intracranial electrodes --- foreign body reaction --- electrode degradation --- glial encapsulation --- electrode array --- microelectrodes --- neural recording --- silicon probe --- three-dimensional --- electroless plating --- intracortical implant --- microelectrodes --- stiffness --- immunohistochemistry --- immune response --- neural interface response --- neural interface --- micromachine --- neuroscience --- biocompatibility --- training --- education --- diversity --- bias --- BRAIN Initiative --- multi-disciplinary --- micro-electromechanical systems (MEMS) --- n/a --- silicon neural probes --- LED chip --- thermoresistance --- temperature monitoring --- optogenetics --- microfluidic device --- chronic implantation --- gene modification --- neural recording --- neural amplifier --- microelectrode array --- intracortical --- sensor interface --- windowed integration sampling --- mixed-signal feedback --- multiplexing --- amorphous silicon carbide --- neural stimulation and recording --- insertion force --- microelectrodes --- neural interfaces --- intracortical --- microelectrodes --- shape-memory-polymer --- electrophysiology --- electrode --- artifact --- electrophysiology --- electrochemistry --- fast-scan cyclic voltammetry (FSCV) --- neurotechnology --- neural interface --- neuromodulation --- neuroprosthetics --- brain-machine interfaces --- intracortical implant --- microelectrodes --- softening --- immunohistochemistry --- immune response --- neural interface --- shape memory polymer --- deep brain stimulation --- fast scan cyclic voltammetry --- dopamine --- glassy carbon electrode --- magnetic resonance imaging --- system-on-chip --- neuromodulation --- bidirectional --- closed-loop --- sciatic nerve --- vagus nerve --- precision medicine --- neural probe --- intracortical --- microelectrodes --- bio-inspired --- polymer nanocomposite --- cellulose nanocrystals --- photolithography --- Parylene C --- impedance --- Utah electrode arrays --- electrode–tissue interface --- peripheral nerves --- wireless --- implantable --- microstimulators --- neuromodulation --- peripheral nerve stimulation --- neural prostheses --- microelectrode --- neural interfaces --- dextran --- neural probe --- microfabrication --- foreign body reaction --- immunohistochemistry --- polymer --- chronic --- electrocorticography --- ECoG --- micro-electrocorticography --- µECoG --- neural electrode array --- neural interfaces --- electrophysiology --- brain–computer interface --- in vivo imaging --- tissue response --- graphene --- n/a

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