This PDF file contains the front matter associated with SPIE Proceedings Volume 7618, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Compact and lightweight optical designs achieving visually acceptable image quality, field of view, eye clearance, eye box diameter and operating across the visible spectrum, are the key to the success of next generation head-worn displays. There have been several approaches in the design of head-worn displays including holographic optical elements and laser scanner systems. For example, Minolta has pursued a monochromatic display (green) with a 3 mm exit pupil realized by a 3.4 mm thick light guide with a holographic optical element to achieve an eyeglass form-factor head-worn display [1]. Our approach in this paper is to investigate the field of view, eyebox diameter, and the performance limit of a single element magnifier comprised of freeform surfaces. The surface shape is a major variable in such a constrained system with respect to the optimization degrees of freedom. Typical optical surfaces are functions mapping vectors in R² to real numbers representing the sag of the surface. A majority of optical designs to-date have relied on conic sections to which are added polynomials as the functions of choice. The choice of conic sections is easily justified, since conic sections are stigmatic surfaces under certain imaging geometries. The choice of polynomials from an image quality analysis point of view is understood since the wavefront aberration function is typically expanded in terms of polynomials. Therefore, a polynomial surface description may link a designer's understanding of the wavefront aberrations and the surface shape. However, from the point of view of shape optimization and representation, polynomial shape descriptions can be challenged. In Section 2, we briefly describe the radial basis function approach to represent freeform optical surfaces. In Section 3, we apply the RBF to design a single element see-through compatible head-worn display.

Head Mounted Displays (HMDs) have been utilized by the military for various applications since the 1980's. In the 1990's, this technology migrated to the consumer market. Most of these early systems suffered the major drawback that they were "look-at" versus "see through" systems, which prevented the user from seeing their environment. This reduced the utility of the devices and could potentially lead to safety issues. This presentation discusses the optical design of a novel see-through High Definition display device with a 40 degree field of view.

Employed in projection domes or in general, applications involving spherical surfaces, like professional flight simulators or automobile head-up displays, laser projectors offer great benefits over techniques involving liquid crystals or digital mirror devices. With the development of red and especially blue laser diodes with output powers in the range of several Watts, new prospects have been opened for compact and cheap laser projectors by direct modulation of the lasers with the pixel rate in scanning systems. In this paper, the requirements and challenges for the laser driver circuits are highlighted. For displaying high definition graphics and video resolutions with pixel rates above 100 MHz, the drivers need to provide very high bandwidth broadband modulation capability. Additionally high output currents in the Ampere region are required when driving high power laser diodes. Focusing on the parasitic effects of the laser diodes packages and the interconnection between drivers and lasers, restrictions and solutions for achieving the combination of these two requirements are shown. A 1.5 A, 100 MHz driver module which was developed under derived design rules is presented and test results are given for high power diodes in TO-Can and C-Mount packages.

Various techniques for three-dimensional/two-dimensional switchable liquid crystal displays are introduced. Key component of the three-dimensional/two-dimensional switchable displays is an active optical device with an on/off function. Liquid crystal has electrically controllable optical properties, making it ideal for the active optical devices. The applications of the liquid crystal to various three-dimensional/two-dimensional switchable displays including glassestype stereoscopic displays, autostereoscopic displays, and integral imaging displays are reviewed.

As three-dimensional (3D) techniques continue to evolve from their humble beginnings-nineteenth century stereo photographs and twentieth century movies and holographs, the urgency for advancement in 3D display is escalating, as the need for widespread application in medical imaging, baggage scanning, gaming, television and movie display, and military strategizing increases. The most recent 3D developments center upon volumetric display, which generate 3D images within actual 3D space. More specifically, CSpace volumetric display generates a truly natural 3D image consisting of perceived width, height, and depth within the confines of physical space. Wireframe graphics enable viewers a 360-degree display without the use of additional visual aids. In this paper, research detailing the selection and testing of several rare earth, single-doped, fluoride crystals, namely 1%Er: NYF₄, 2%Er: NYF₄, 3%Er: NYF₄ , 2%Er:KY₃F₁₀, and 2%Er:YLF, is introduced. These materials are the basis for CSpace display in a two-step twofrequency up-Conversion process. Significant determinants were tested and identified to aid in the selection of a suitable medium. Results show that 2%Er: NYF₄ demonstrates good optical emitted power. Its superior level of brightness makes it the most suitable candidate for CSpace display. Testing also proved 2%Er: KY₃F₁₀ crystal might be a viable medium.

The resolution of the reconstructed object from the Fourier hologram that is generated from multiple view images is analyzed in this paper. We found that the maximum view angle and the wavelength limit the maximum frequency of the reconstructed object. The relationship between the bandwidth of the object and the lens pitch of the lens array affects the aliasing of the reconstruction. All these four parameters determine the resolution of the reconstruction from the Fourier hologram. Based on these analyses, we propose a lens array shift method to enhance the resolution of the reconstructed object from the Fourier hologram. By shifting the lens array, multiple sets of element images are obtained, and high spatial density element image is combined from the multiple sets of element images. The resolution enhanced reconstruction of the object can be obtained from the Fourier hologram of the combined element images. The principles are verified by experiment.

The objective of this work is the suppression of speckles in an image illuminated by a remote laser. This is accomplished by a novel method in which the illuminating laser beam propagates through a multimode fiber dithered at an arbitrary section, then passes through a microlens array prior to illuminating the image generator. Thereby the speckle contrast is reduced to its minimum value for dithering frequencies of at least 25 Hz, attaining a magnitude speckle contrast of less than 12%, and illumination homogeneity across the illumination filed of less than 20%.

Artifact-metrics is an automated method of authenticating artifacts based on their measurable intrinsic characteristics such as microscopic random-patterns and the like which are emerging in their manufacturing process. They are very difficult to copy and control even for legal manufacturers. This paper describes the feasibility of an artifact-metric system using laser speckle patterns of the surface of security documents. Speckle patterns of the surface differ from each object depending on their microscopic geometry; they can be authenticated automatically by some matching algorithm that compares the input with the previously enrolled data. Our system consists of a laser diode and a CMOS camera which are attached firmly to a rigid metal frame and a matching algorithm by correlation coefficient method. To improve matching accuracy we investigate the influence of width and incident angle of the laser beam and aperture size and shooting angle for the camera on the matching accuracy through matching tests using 100 of ID cards. As a result, we found that aperture size of the camera and width of the laser are part of important factors for matching accuracy. Also, we achieved equal error rate of 0.1% using data size of 16 square pixels for speckle patterns.

A new electro-optic waveguide platform, which provides unprecedented voltage control over optical phase delays (> 2mm), with very low loss (< 0.5 dB/cm) and rapid response time (sub millisecond), will be presented. This technology, developed by Vescent Photonics, is based upon a unique liquid-crystal waveguide geometry, which exploits the tremendous electro-optic response of liquid crystals while circumventing their historic limitations. The waveguide geometry provides nematic relaxation speeds in the 10's of microseconds and LC scattering losses that are reduced by orders of magnitude from bulk transmissive LC optics. The exceedingly large optical phase delays accessible with this technology enable the design and construction of a new class of previously unrealizable photonic devices. Examples include: 2-D analog non-mechanical beamsteerers, chip-scale widely tunable lasers, chip-scale Fourier transform spectrometer (< 5 nm resolution demonstrated), widely tunable micro-ring resonators, tunable lenses, ultra-low power (< 5 microWatts) optical switches, true optical time delay devices for phased array antennas, and many more. All of these devices may benefit from established manufacturing technologies and ultimately may be as inexpensive as a calculator display. Furthermore, this new integrated photonic architecture has applications in a wide array of commercial and defense markets including: remote sensing, micro-LADAR, OCT, FSO, laser illumination, phased array radar, etc. Performance attributes of several example devices and application data will be presented. In particular, we will present a non-mechanical beamsteerer that steers light in both the horizontal and vertical dimensions.

In recent years the dispersion and directed assembly of nano-particles in liquid crystal media has proved an interesting field for investigation and one that may yield new hybrid materials for optical applications and fundamental research. In this paper, we investigate the dispersion of quantum dots in different liquid crystal phases, looking at aggregation and pattern formation. Quantum dot self-assembly in liquid crystals is dependent on particle surface properties and concentration in the liquid crystal medium. By varying these parameters we observe some fascinating structures and phase behavior using polarized optical microscopy and fluorescence microscopy.

The optical switching times of liquid-crystal cells using 5CB, 5OCB and PCH5 liquid crystal materials have been characterized as a function of applied voltage, V, and temperature, T. The transition time from 90 to 10 % transmission scales as V^-2 and is limited to 50 to 30 ns by the breakdown electric field, ~ 10⁶ V cm^-1 of the liquid crystal. The time from the initial voltage step to 90 % transmission, delay time, decreases with increasing voltage and approaches a constant value at higher electric fields, >10⁵ V cm^-1. Both the transition and delay times decrease with increasing temperature. The minimum transition times at temperatures a few degrees below the nematic-isotropic temperature are 32, 32, and 44 ns and delay times are 44, 25 and 8 ns for 5CB, 5OCB, and PCH5 respectively.

Carbon nanotubes (CNTs) can exist as clusters whenever doping amount in nematic liquid crystal (LC) mixture exceeds critical point. Based on experimental observation of electric field-dependent shape of the CNT cluster, it elongates along the field direction and its original morphology of the cluster is restored after the removal of the field. The elongation was fully reversible only below a certain breakdown field. Both clusters and elongated CNTs were observed under nonpolarized and polarized light. The cluster absorbs incident light completely while the elongated one absorbs light propagating along the long axis only. Utilizing the field-controlled cluster, light modulation for display application is possible.

Metaphase spindles are highly dynamic, nonequilibrium, steady-state structures. We study the internal fluctuations of spindles by computing spatio-temporal correlation functions of movies obtained from quantitative polarized light microscopy. These correlation functions are only physically meaningful if corrections are made for the net motion of the spindle. We describe our image registration algorithm in detail and we explore its robustness. Finally, we discuss the expression used for the estimation of the correlation function in terms of the nematic order of the microtubules which make up the spindle. Ultimately, studying the form of these correlation functions will provide a quantitative test of the validity of coarse-grained models of spindle structure inspired from liquid crystal physics.

A novel plastic substrate for flexible displays was developed. The substrate consisted of a polycarbonate (PC) base film coated with a gas barrier layer and a transparent conductive thin film. PC with ultra-low intrinsic birefringence and high temperature dimensional stability was developed for the base film. The retardation of the PC base film was less than 1 nm at a wavelength of 550 nm (film thickness, 120 μm). Even at 180 °C, the elastic modulus was 2 GPa, and thermal shrinkage was less than 0.01%. The surface roughness of the PC base film was less than 0.5 nm. A silicon oxide (SiO_x) gas barrier layer was deposited on the PC base film by a DC magnetron reactive sputtering method. In addition, a unique organic-inorganic hybrid material is coated on the SiOx to further improve the gas-barrier performance. The water vapor transmission rate of the film was less than 0.05 g/m²/day at 40 °C and 100% relative humidity (RH), and the permeation of oxygen was less than 0.05 cc/m2•day•atm at 40 °C and 90% RH. Indium Zinc Oxide optimized for the plastic substrate was deposited on the other side of the SiOx film by the DC magnetron sputtering method. The transmittance was 87% and the resistivity was 3.5×10^-4 ohm•cm.

In this paper we demonstrate the preparation of monodisperse particles from a liquid crystalline elastomer with a preferred director orientation. For this we use a microfluidic setup to create droplets from a liquid crystalline monomer which are polymerized in the liquid crystalline phase while flowing. When the obtained particles are heated above the transition temperature of the nematic phase, they show a reversible shape change from spherical to cigar-like. We show, that we can control the size as well as the polydispersity of these microactuators. If the particles are prepared in non-flowing conditions, no or an undefined shape change is observed. Particles polymerized in the isotropic phase show no shape deformation as well. Additionally we provide an experimental proof for the stability of these structures versus acidic and basic conditions.

A novel method for switching the viewing-angle of a liquid crystal display is proposed by using a polymernetworked liquid crystal cell in combination with a collimated backlight system. The bright state for a wide viewing-angle is obtained aligning liquid crystals randomly in polymer-networked structure, which diffuses a collimated backlight. The liquid crystals homogeneous-aligned by in-plane switching are operated as the bright state for a narrow viewing-angle since a collimated backlight passes through the liquid crystal layer intactly. It is demonstrated experimentally that the viewing-angle can be controlled omni-directionally without an additional panel or an additional backlight system.

We demonstrate a fast switching surface polymer-assisted vertically aligned (SPA-VA) liquid crystal (LC) cell. The deposition of the polymer nano spikes as a part of the alignment layer is achieved by polymerizing a small amount of a reactive monomer in vertically aligned liquid crystal in the absent of an applied voltage. The phase-separated polymer localized at the both substrate surfaces and formed nano-sized spikes. These polymer nano-spikes act as internal surface alignment layers and enhance the speed of field-induced reorientation of liquid crystal molecules.

In this paper we present the work performed by AlphaMicron in the area of Adaptive Window application using a guest-host liquid crystal configuration combined with liquid crystal based solar concentrator and high efficiency photovoltae. The system can be used for Zero-Energy Building applications by providing a dynamic solar heat gain coefficient. This allows the reduction of the energy loss through windows in mixed climate regions.

This investigation reports for the first time a novel phenomenon, called band-tunable color cone lasing emission (CCLE), based on a single-pitched one-dimensional photonic crystal-like dye-doped cholesteric liquid crystal (DDCLC) cell. The lasing wavelength in the CCLE pattern is distributed continuously at 676.7-595.6 nm as the oblique angle increases continuously from 0° to 50° relative to the helical axis. The variation of the lasing wavelength in the CCLE with the oblique angle is consistent with that of the wavelength at the long-wavelength edge (LWE) of the CLC reflection band (CLCRB) with the oblique angle. Simulation results obtained utilizing Berreman's 4×4 matrix method show that, at each oblique angle, the associated group velocity and density of photonic state (DOS) are near zero and large at the shortwavelength edge (SWE) and LWE of the CLCRB, respectively, and are in good agreement with experimental results. The particularly strong lasing ring emission at a cone angle of ~35° can be explained to be likely due to a special effect that, under the condition of overlap between the LWE of the CLCRB measured at 35° and the SWE of the CLCRB measured at 0°, the LWE and SWE fluorescence propagating along 35° and 0°, respectively, may indirectly enhance each other due to individual enhanced rate of spontaneous emission. Furthermore, the lasing band of the CCLE can be tuned from long-wavelength (deep red~orange) to short-wavelength (orange~green) regions by changing the concentration of the chiral or by the photo-irradiation on a DDCLC cell with a photoisoemerizable chiral dopant.

This work studies the biphotonic effect in samples that are cholesteric liquid crystals (CLCs) doped with azo-C5. The experimental results show that the photo-isomerization of azo-C5 not only changes the clearing point of the sample, but also shifts the reflection band that is associated with the planar texture. Additionally, azo dye-doped CLCs (DDCLCs) have bi-stable or tri-stable states, as determined by the ambient temperature. Photo-switching between these bi-stable/tristable states is systematically studied. The result indicates that photo-addressing one of these states (planar, focal conic, and isotropic states) using a low- or high-intensity Ar⁺ laser beam is feasible. The results thus obtained are used to fabricate a photo-rewritable DDCLC display.

A switchable surface using a liquid crystal and polymer composite film (LCPCF) based on phase separation between liquid crystals (LC) and polymers after photopolymerization is developed recently. The wettability of LCPCF is electrically tunable because of the orientation of liquid crystal directors anchored among the polymer grains under an in-planed electric field. A water droplet on the top of LCPCF can be manipulated under an inhomogeneous electric field on the LCPCF owning to the wettability gradient. The dynamics of a droplet of human sperms on the LCPCF is demonstrated as well. Three motions of sperm droplets are observed: the droplet collapse and the droplet stretch,. We found that the dynamics, concentrations, and activities of spermatozoa, affect the motions of a sperm droplet. The potential applications of LCPCF are polarizer-free displays, liquid lenses, and the microfluidic device in assisted reproductive technology (ART)

A use of liquid crystal panels (LCPs) as a random phase modulator in the optical encryption system based on the double random phase coding (DRPC) [Optics Letters, Vol.20, 767(1995)] is considered in the present paper. Required phase modulation property of LCPs as random phase modulators in the DRPC are investigated by computer simulations. It is found from simulation results that the required number of independent patches for phase modulations must be greater than 128 × 128 pixels for LCPs with the maximum phase modulation of 1.55π radians. It is also found that the required maximum phase modulation can be reduced to 1.25π radians by increasing the number of independent patches to 1024 × 1024 pixles. Experimental study using a commercially available LCP (EPSON, HTPS LCP, L3P14Y-55G00) verified partially these simulation results.

We report on the spectral transmittance and wavelength-dispersion properties of two-dimensional photonic lattices using holographic polymer dispersed liquid crystals (HPDLCs) and demonstrate their electrical control. A statistical thermodynamic model is employed to calculate spatial distributions of the formed polymer, liquid crystal molecules and the resultant anisotropic refractive index distribution under three-beam holographic exposure. The effect of multiple reflections inside an HPDLC film on the formed refractive index distribution is also taken into account in the theoretical analysis. Measured transmittance spectra and wavelength-dispersion angles are compared with the calculated results.

We describe wide temperature range bimesogenic chiral nematic liquid crystals with high flexoelectro-optic coefficients (e/K),of the order of 2.0 CN^-1 m^-1, high switching angles, > 160° and 50-100μs response times, which may be used to give gray scale devices in both the ULH texture, with an optimum optical in plane switch of 45° at fields of 2Vμm^-1 depending on helix pitch and suitable for LCoS devices, and in the USH or Grandjean texture with a unique optically isotropic "field off" black state and contrast ratios of > 5000:1, using "in plane" electric fields, with switching times of the order of 200μs. The new materials and devices give μs level to level switching and the real potential for colour filter free frame sequential colour switching. Highly reflective Blue Phase devices, stable over a 90°C temperature range, in which an electric field is used to switch the reflection from red to green, for example, will be described. Full RGB reflections may be obtained with switching times of a few milliseconds. New surface and volume activated reflecting N* Grandjean texture devices will also be described. Visible wavelength shifts of ~100nm are reported. These are activated by so called "command" surfaces or nanoscopic ferroelectric inclusions and conventional transverse electric fields. Finally we will briefly mention potential applications including high efficiency RGB liquid crystal laser sources.

LCOS for phase-only holography is ideally made to better optical tolerance than that for conventional amplitude modulating applications. Die-level assembly is suited to custom devices and pre-production prototypes because of its flexibility and efficiency in conserving the silicon backplane. Combined with automated assembly, it will allow high reproducibility and fast turnaround time, making a way for pre-production testing and customer sampling before mass production. Optical testing is the key element in the process. By taking into account the flatness of both the backplane and the front glass plate, we have assembled LCOS devices. We have reached our aim of less than one quarter wavelength phase distortion across the active area.

In this paper, a switchable window based on cholestreric liquid crystal (CLC) was demonstrated. Under different applied voltages, incoming light at visible and infrared wavelengths was modulated, respectively. A mixture of CLC with a nematic liquid crystal and a chiral dopant selectively reflected infrared light without bias, which effectively reduced the indoor temperature under sunlight illumination. At this time, transmission at visible range was kept at high and the windows looked transparent. With increasing the voltage to 15V, CLC changed to focal conic state and can be used as a reflective display, a privacy window, or a screen for projector. Under a high voltage (30V), homeotropic state was achieved. At this time, both infrared and visible light can transmit which acted as a normal window, which permitted infrared spectrum of winter sunlight to enter the room so as to reduce the heating requirement. Such a device can be used as a switchable window in smart buildings, green houses and windshields.

Green-emissive textured Zn₂SiO₄:Mn²⁺ phosphor film was fabricated by a thermal diffusion of ZnO:Mn on quartz glass. The characterization has been performed in terms of Mn2+ ions concentration (Mn/Zn=1~9 mol %). As an increase of Mn²⁺ ions concentration in the Zn₂SiO₄:Mn²⁺ phosphor film, the emission peak was red shifted from 519 nm to 526 nm, and the decay time to 10% of the maximum intensity was shorter from 20 ms to 0.5 ms. All annealed Zn₂SiO₄:Mn²⁺ phosphor films became textured along some hexagonal directions on the amorphous quartz glass. The brightest Zn₂SiO₄:Mn²⁺ film at optimal Mn²⁺ concentration of 5 % showed the photoluminescence brightness of 65 % and the shortened decay time of 4.4 ms in comparison with a commercially Zn₂SiO₄: Mn²⁺ powder phosphor screen. The excellencies can be attributed to a unique textured structure.

We propose and demonstrate a metal-dielectric thin film that delivers low reflection and high absorption over the entire visible spectrum. This thin black film consists of SiO₂/Cr/SiO₂/Al layers deposited on glass substrate. Measured reflectance and absorptance of the black film are 0.7% and 99.3%, respectively, when averaged over the range 380-780 nm. The total thickness of the black film is only about 220 nm. This thin black film can be used as a thin absorbing layer for displays that require both broadband anti-reflection and high contrast characteristics.

We report a method for the preparation of multi-domain liquid crystal (LC) alignment layers on polyimide (PI) surfaces using inkjet printed micro-bars. The substrates of PI alignment films with micro-bars are assembled in crossed fashion to form a two-dimensional lattice to enable a fringe-field-like structure and thus, the multi-domain LC alignment. A LC cell with twisted nematic (TN) and electrically-controlled birefringence (ECB) domains can be obtained when the cells are assembled according to the printing directions of the printed PI layers. Electro-optical properties of such cells are studied. The obtained multi-domain structures can be used to improve the viewing angle of TN displays.