High‐pixel‐rate grating‐light‐valve laser projector

Abstract— A high‐pixel‐rate, high‐contrast (30,000:1) wide‐color‐gamut grating‐light‐valve laser projector is reported. A new optical engine enabling high‐frame‐rate (240 Hz) scan projection is employed. Panoramic wide‐angle‐scan projection with a 64:9 aspect ratio was also developed. Speckle noise is eliminated using a simple but highly efficient technique. The optical throughput efficiency of the grating‐light‐valve laser projector is reviewed.     

Preparation and non-linear optical properties of CdS quantum dots in Na2O-B2O3-SiO2 glasses by the sol-gel technique

Non-linear optical properties of CdS quantum dots embedded in the sol-gel derived Na₂O-B₂O₃-SiO₂x³ glass matrix have been studied using nanosecond degenerate four-wave mixing (DFWM), pump-probe experiments, and time-resolved subpicosecond DFWM measurements. The concentration of CdS microcrystallites was varied from 1.4 to 10.2 wt% while the particle size was controlled to be in the range of 3–6 nm in diameter so that the confinement effects can be realized. The third-order susceptibility, ³, was determined to be of the order of 10^–7-10^–6 e.s.u. near the resonant wavelength between 450 and 470 nm by the nanosecond DFWM and pump-probe experiments, and of the order of 10^–11-10^–10 e.s.u. at the off-resonant wavelength, 580 nm, by a time-resolved DFWM measurement with 400 fs laser pulse. The decay time changed from 0.5 to 50 picoseconds as a function of the size, size distribution and number density of CdS microcrystallites in the glasses. Photodarkening reduced the optical non-linearity of the melt-quenched samples by a factor of 20, while it had no appreciable effect on that of the sol-gel derived samples.[/p]     

Experimental measurement on tangential momentum accommodation coefficient in a single microtube

The tangential momentum accommodation coefficient (TMAC) was investigated experimentally from the mass flow rate through a single microtube under the slip flow and the early part of the transition regime. The measurements were carried out by the constant-volume method under the mean Knudsen number smaller than 0.3, which is based on the mean pressure of the inlet and the outlet of the microtube, to apply the second-order slip boundary condition. To measure TMACs on various materials, quite large microtube was employed, which require the reduction in leakage. TMAC was obtained from the slip coefficient determined by the relation of the mass flow rate to the mean Knudsen number. The obtained mass flow rate was well explained by the theoretical equation. TMACs of deactivated-fused silica with argon, nitrogen, and oxygen were measured, showing the tangential momentum was not accommodated completely to the surface, and the values showed good agreement with previous studies. From the comparison between microtubes with different inner diameter, it is showed that TMAC is determined mainly by gas species and surface material.     

Effect of temperature on humido-sensitive conducting polymer actuators

Temperature dependence of water vapor sorption and electro-active polymer actuating behavior of free-standing films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) was investigated by means of sorption isotherm and electromechanical analyses. The non-porous PEDOT/PSS film, having a specific surface area of 0.13 m² g^?1, sorbed water vapor of 1080 cm³(STP) g^?1, corresponding to 87 wt%, at relative water vapor pressure of 0.95. A temperature rise from 25 °C to 40 °C lowered sorption degree, indicative of an exothermic process, where isosteric heat of sorption decreased with increasing water vapor sorption and the value reached 43.9 kJ mol^?1, being consistent with the heat of water condensation (44 kJ mol^?1). Upon application of 10 V, the film underwent contraction of 2.46% at 5 °C caused by desorption of water vapor due to Joule heating, which slightly decreased to 2.10% at 45 °C. The speed of contraction was one order of magnitude faster than that of expansion and less dependent on the temperature since water vapor sorbed in the film were forced to desorb by Joule heating. In contrast, the higher the temperature the faster the film expansion because diffusion coefficient increased as the temperature became higher.     

Negation-Limited Complexity of Parity and Inverters

In negation-limited complexity, one considers circuits with a limited number of NOT gates, being motivated by the gap in our understanding of monotone versus general circuit complexity, and hoping to better understand the power of NOT gates. We give improved lower bounds for the size (the number of AND/OR/NOT) of negation-limited circuits computing Parity and for the size of negation-limited inverters. An inverter is a circuit with inputs x ₁,…,x _n and outputs ¬ x ₁,…,¬ x _n . We show that: (a) for n=2 ^r ?1, circuits computing Parity with r?1 NOT gates have size at least 6n?log?₂(n+1)?O(1), and (b) for n=2 ^r ?1, inverters with r NOT gates have size at least 8n?log?₂(n+1)?O(1). We derive our bounds above by considering the minimum size of a circuit with at most r NOT gates that computes Parity for sorted inputs x ₁≥???≥x _n . For an arbitrary r, we completely determine the minimum size. It is 2n?r?2 for odd n and 2n?r?1 for even n for ?log?₂(n+1)??1≤r≤n/2, and it is ?3n/2??1 for r≥n/2. We also determine the minimum size of an inverter for sorted inputs with at most r NOT gates. It is 4n?3r for ?log?₂(n+1)?≤r≤n. In particular, the negation-limited inverter for sorted inputs due to Fischer, which is a core component in all the known constructions of negation-limited inverters, is shown to have the minimum possible size. Our fairly simple lower bound proofs use gate elimination arguments in a somewhat novel way.     

Limiting negations in non-deterministic circuits

The minimum number of NOT gates in a Boolean circuit computing a Boolean function f is called the inversion complexity of f. In 1958, Markov determined the inversion complexity of every Boolean function and, in particular, proved that log₂(n+1) NOT gates are sufficient to compute any Boolean function on n variables. In this paper, we consider circuits computing non-deterministically and determine the inversion complexity of every Boolean function. In particular, we prove that one NOT gate is sufficient to compute any Boolean function in non-deterministic circuits if we can use an arbitrary number of guess inputs.     

Technique for anisotropic extension of organic crystals: application to temperature dependence of electrical resistance

We have developed a technique for the anisotropic extension of fragile molecular crystals. The pressure medium and the instrument, which extends the pressure medium, are both made from epoxy resin. Since the thermal contraction of our instrument is identical to that of the pressure medium, the strain applied to the pressure medium has no temperature dependence down to 2 K. Therefore, the degree of extension applied to the single crystal at low temperatures is uniquely determined from the degree of extension in the pressure medium and thermal contractions of the epoxy resin and the single crystal at ambient pressure. Using this novel instrument, we have measured the temperature dependence of the electrical resistance of metallic, superconducting, and insulating materials. The experimental results are discussed from the viewpoint of the extension (compression) of the lattice constants along the parallel (perpendicular) direction.     

Formation of Zirconia Solid Solutions Containing Alumina Prepared by New Preparation Method

In the system ZrO₂–Al₂O₃, a new method for preparing ZrO₂ solid solutions from ZrCl₄ and AlCl₃ using hydrazine monohydrate is investigated. c -ZrO₂ solid solutions containing up to ∼40 mol% Al₂O₃ crystallize at low temperatures from amorphous materials. The formation mechanism is discussed from IR spectral data. The values of the lattice parameter α increase linearly from 0.5072 to 0.5105 nm with increasing Al₂O₃ content. At higher temperatures, transformation of the solid solutions proceeds as follows: c ( SS ) → t ( ss ) → t ( ss ) +α-Al₂O₃→ m +α-Al₂O₃. m -ZrO₂–α-Al₂O₃ composite ceramics are fabricated by hot isostatic pressing for 2 h at 1250°C and 196 MPa. Microstructures and mechanical properties are examined, in connection with increasing Al₂O₃ content.     

Demonstration of 13.56-MHz class-E amplifier using a high-Voltage GaN power-HEMT

A 13.56-MHz class-E amplifier with a high-voltage GaN HEMT as the main switching device is demonstrated to show the possibility of using GaN HEMTs in high-frequency switching power applications such as RF power-supply applications. The 380-V/1.9-A GaN power HEMT was designed and fabricated for high-voltage power-electronics applications. The demonstrated circuit achieved the output power of 13.4 W and the power efficiency of 91% under a drain-peak voltage as high as 330 V. This result shows that high-voltage GaN devices are suitable for high-frequency switching applications under high dc input voltages of over 100 V.