Rydberg atoms in room temperature vapor cells are promising candidates for realizing new kinds of quantum devices and sensors. However, the alkali vapor, which is most commonly used, introduces new technological challenges. We demonstrate the applicability of anodic bonding as a sealing method for vapor cells, which preserves vacuum levels down to 10-7 mbar for several years, while being compatible with thin-film electronics on glass. We furthermore prove, that the implementation of such thin-film electronics inside a highly reactive atmosphere of alkali vapor is possible. We also propose a new kind of gas sensor based on Rydberg excitations as a competitive and promising application of our Rydberg detection scheme.
An exact synthesis algorithm for dielectric thin film filters with uniform optical phase thickness was first presented
in 2004. This algorithm computes at least one thin film stack which realizes a given filter function. The feasibility
is guaranteed by a set of necessary and sufficient conditions the filter function has to fulfill. This set of conditions
only guarantees strictly positive refractive index values for all thin film layers. For a technological realization
strictly positive refractive index values are insufficient since only certain refractive index values can be realized
for a thin film layer.
In this paper an additional condition for the location of the zeros of the filter response function is derived.
Starting point is a boundary condition for the refractive index value for each of the N layers of the filter stack.
Each refractive index value can be selected arbitrarily from an interval which is bounded by a lower and an upper
refractive index boundary value. This additional zero location condition is necessary that at least one filter stack
exists which fulfills these boundary conditions to a given filter function.
Since the boundary conditions are determined by the used fabrication process for thin film filters the presented
additional condition for the location of the zeros has to be calculated only once when a new process is installed.
Large-area glass facades are widely spread in contemporary architecture. They meet demands for natural light illumination
of rooms and satisfy esthetic requirements of modern architecture. However, larger glass facades increase transfer of energy
into the building. Since this has to be compensated by the intense use of air conditioning, modulation of the energy passing
through the glazing is essential. The authors have been developing a corresponding system. It consists of a modified
twisted nematic (TN) liquid crystal (LC) cell which is embedded in a double glazing. Since a conventional outside film
polarizer is susceptible to heat, the authors substituted this component for an inside coatable polarizer. Long term outdoor
weathering tests demonstrated that the concept is viable. Part of the current research is the integration of the TN LC cell
into double-glazing. A further demand for such a system is a
cost-efficient manufacturing process. It has been investigated
to use the coatable polarizer at the same time as an alignment layer for the liquid crystal. Aluminum zinc oxide (AZO) is
to be used for the electrode material substituting conventionally used indium tin oxide (ITO) which is expensive. Currently
the authors are looking into the coating process for the inside polarizer.
A low temperature high quality gate dielectric process for bottom gate organic thin film transistors (OTFT) is introduced which is compatible to plastic substrates. The Al2O3 dielectric is grown from the aluminum gate electrode by anodic oxidation at room temperature and exhibits an exceptionally good electrical performance even for thin layers of 50nm. Finding an electrolyte which significantly reduces dielectric charges was instrumental for the desired OTFT application. The electrolyte and substrate dependent behaviour was characterized and compared to different dielectrics to point out the advantages of anodic oxidized aluminum. The characteristics of pentacene bottom contact OTFTs realized with anodized Al2O3 gate dielectric on glass and plastic substrates are presented.
An exact design method for multilayer dielectric thin film filters
of uniform optical thickness based on a frequency transformation and
classical lossless filter synthesis is introduced. The proposed method consists of finding the optimal realizable inverse transmittance function (power loss ratio) which fulfills additional constraints such as number of layers and the calculation of the refractive indices of the individual layers. The proposed algorithm can easily be implemented because it only requires determining the roots of a polynomial. In contrast to known methods the proposed
method is not limited to symmetrical multilayers or filters with geometric symmetry and allows for both reflective and transmissive characteristics of the optical filter. Several designs based on the new algorithm will be presented to demonstrate the usefulness of the exact synthesis procedure. The resulting filters can be transformed into filters with readily available indices using a known transform
Liquid crystal light modulators are versatile optical elements that modulate amplitude and phase of coherent or incoherent light waves in space and time, thus enabling implementation of innovative optical processing and measurement systems. A brief introduction of the most commonly used liquid crystal effects and devices highlights
the specific characteristics of "optical-grade" light modulators. These characteristics create unusual challenges for modulator designers requiring modifications of established manufacturing processes and development of new measurement concepts and systems for characterizing the liquid crystal light modulators. Specifically, a high precision measurement system for characterizing the voltage dependent complex transmissivity and a concept for
extracting liquid crystal cell parameters is presented.
Volumetric 3-D displays proposed and demonstrated in the past have been low in resolution and refresh rate, but not in cost. This paper describes the development of an electro-optic multiplanar volumetric 3-D display (without moving parts) based on unique liquid crystal (LC) switchable light diffusion panels. These LC switchable diffuser panels are produced by our proprietary holographic Light Shaping Diffuser fabrication process. Using a stack of closely spaced LC switchable diffusers, which have shown excellent switching speed, diffusion efficiency, and clarity, a multiplanar volumetric 3- D display was demonstrated, projecting full-color 2-D images from a high speed spatial light modulator.
Various 3-D display technologies have been proposed for future cockpit displays, all with limitations. This paper describes a 3-D display technology based on a unique multiplexed holographic projection screen developed at Physical Optics Corporation. Making use of multiplexed holographic projection of multiperspective images, this display allows 360 degree look-around viewing of volume-like 3-D images by many viewers without any eyewear. By means of a high-resolution, high-speed 2-D light modulator such as an LCD or Digital Micromirror Device, the display can produce real-time full-color, high resolution 3-D images.
This paper describes the development of a non-contact diagnosis system for analyzing the plasma density profile, temperature profile, and ionic species of a high energy laser-generated plasma. The system was developed by Physical Optics Corporation in cooperation with the U.S. Army Space and Missile Defense Command, High Energy Laser Systems Test Facility at White Sands Missile Range, New Mexico. The non- contact diagnostic system consists of three subsystems: an optical fiber-based interferometer, a plasma spectrometer, and a genetic algorithm-based fringe-image processor. In the interferometer subsystem, the transmitter and the receiver are each packaged as a compact module. A narrow notch filter rejects strong plasma light, passing only the laser probing beam, which carries the plasma density information. The plasma spectrum signal is collected by an optical fiber head, which is connected to a compact spectrometer. Real- time genetic algorithm-based data processing/display permits instantaneous analysis of the plasma characteristics. The research effort included design and fabrication of a vacuum chamber, and high-energy laser plasma generation. Compactness, real-time operation, and ease of use make the laser plasma diagnosis system well suited for dual use applications such as diagnosis of electric arc and other industrial plasmas.
Incoherent optical neural network implementations using only positive light intensities require a coding method to implement bipolar signals. The actual coding method significantly influences the manufacturability, performance, and reliability of the optical neural network. This paper describes new coding methods and compares them with currently used methods. Special attention is paid to the actual hardware implementation and the overall neural network performance under the influence of drift and manufacturing tolerances. New spatial light modulator architectures enable neural network implementations that have significantly reduced sensitivity to backlight non- uniformity, sensor array non-uniformity, and tolerances and drift of LC components. Simulations show that the new coding methods reduce the sensitivity of liquid crystal light modulator-based neural network nonlinearities by more than 50%, significantly simplifying practical implementation of large neural networks.
Image processing and recognition can benefit significantly from new iterative processing algorithms that require coherent detection of the output signal. A new compact and rugged Fourier optical signal processor architecture has been developed, in which a polarization-based common path interferometer performs coherent detection. Two orthogonal polarizations of the lightwave function as independent transmission channels for the object and the reference beam. The paper describes the basic parameters that govern the design of the polarization interferometry-based Fourier optical signal processor, and elaborates on implementation aspects such as special liquid crystal light modulators that modulate one polarization while passing the nonmodulated reference polarization without attentuation. This includes characterization results of actual components, development of an improved device layout, and experimental verification of the processor concept.
Head- and helmet-mounted displays can benefit greatly from new image generating technologies. This paper describes a liquid crystal digital scanner-based head-mounted display (DS-HMD) that has been developed at Physical Optics Corporation (POC). The HMD consists of low power light emitting diodes (LEDs), a liquid crystal digital scanner, and image projection optics produced by POC's proprietary holography technology. Modulating the individual LEDs while synchronously scanning perpendicularly generates a 2D image. The paper describes design, fabrication, and performance measurements for an actually implemented experimental liquid crystal digital scanner system, and design and fabrication of the holographic components.
A new Fourier optical architecture based on polarization multiplexing has been developed. In contrast to the customary scalar designs, the two orthogonal polarizations of the light wave are used to realize two independent transmission channels within the same volume. This result in a compact Fourier optical processor whose volume is reduced by 75 percent in comparison with the canonical 4-f system. Additionally the new architecture also for fully electronical switching between the two operation modes namely correlation and spectrum analysis. The paper describes the basic parameters which govern the design of miniaturized optical correlators and elaborates on an actual realization of a compact Fourier optical processor which employs polarization multiplexing.
A highly accurate measurement technique has been developed and applied for characterization of the complex transmittance of liquid crystal light valves (LC-LV). The measurement setup is based on a two-beam interference with partially coherent light. An arc lamp light source enables measurements over a large range of wavelengths. We propose a new Fourier transform interference pattern evaluation technique with a high signal-to-noise ratio. Calculations are sped up by FFT algorithms. Measurement results of the complex transmittance are shown for a twisted nematic and a Freederickzs liquid crystal light valve, built in our laboratory.
Optical signal processing systems frequently use Fourier transform techniques for correlation, filtering, etc. In practical applications the complex-valued filters placed in the frequency domain plane are often realized by a liquid crystal spatial light modulator (LCSLM). The requirements for such LCSLMs are very demanding, as they should offer a high resolution, high uniformity, low fluctuation in time and an increased number of grayscales or phase steps. We designed and manufactured an active matrix LCSLM (AMLCSLM) and the appropriate driving system meeting these requirements. The AMLCSLM consists of 480 by 480 pixels, each containing an amorphous silicon thin film transistor (aSi-TFT). Although the pixel size is only 50 by 50 micrometer squared, corresponding to a resolution of 508 dpi, an optical aperture of more than 40 percent is achieved. By the use of a transparent storage capacitor the pixel capacitance was greatly increased, resulting in a reduction of the fluctuation in time. The driving circuitry is capable of driving up to 256 grayscales at a frame rate of 100 Hz in dual scan driving mode. For the row scanning the commonly used rectangular impulse shape was substituted by a shortened trapezoidal impulse. As a result a very good uniformity over the area with an overall phase change error of less than 6 percent is obtained.