Three-dimensional complex image coding using a circular Dammann grating

Recently, optical image coding using a circular Dammann grating (CDG) has been proposed and investigated. However, the proposed technique is intensity based and could not be used for three-dimensional (3D) image coding. In this paper, we investigate an optical image coding technique that is complex-amplitude based. The system can be used for 3D image coding. The complex-amplitude coding is provided by a circular Dammann grating through the use of a digital holographic recording technique called optical scanning holography. To decode the image, along the depth we record a series of pinhole holograms coded by the CDG. The decoded reconstruction of each depth location is extracted by the measured pinhole hologram matched to the desired depth. Computer simulations as well as experimental results are provided.     

Rendering of specular surfaces in polygon-based computer-generated holograms

A technique is presented for realistic rendering in polygon-based computer-generated holograms (CGHs). In this technique, the spatial spectrum of the reflected light is modified to imitate specular reflection. The spectral envelopes of the reflected light are fitted to a spectral shape based on the Phong reflection model used in computer graphics. The technique features fast computation of the field of objects, composed of many specular polygons, and is applicable to creating high-definition CGHs with several billions of pixels. An actual high-definition CGH is created using the proposed technique and is demonstrated for verification of the optical reconstruction of specular surfaces.     

Linear and Nonlinear Optical Properties of TeO2 Glass

A thin plate of TeO₂ glass of 5.0 × 4.0 × 0.25 mm³ size, which was large enough for various optical measurements, was obtained by a rapid quenching method. The linear refractive index was measured as a function of wavelength from 486.1 to 1000 nm. The refractive index at 486.1 nm was as high as 2.239. The optical energy band gap was estimated as 3.37 eV from the optical absorption spectrum. The third-order nonlinear optical susceptibility, χ⁽³⁾, was determined by the third-harmonic generation (THG) method. The χ⁽³⁾ value was as high as 1.4 × 10⁻¹² esu, about 50 times as large as that of SiO₂ glass. The results are discussed based on Lines' model in which an influence of cationic empty d -orbitals on the nonlinear properties was taken into account.     

Analysis of phase-controlled resonant DC-AC inverters with class Eamplifier and frequency multipliers

This paper presents a minute analysis and experimental results of phase-controlled resonant DC-AC inverters with class E amplifiers and frequency multipliers. The circuit is composed of two identical class E amplifiers or frequency multipliers, which are used as DC-AC inverters and connected in parallel. The two inverters are driven at the same switching frequency, and the overall output power of the circuit can be controlled by varying the phase shift between the drive voltages of the two inverters. The circuit can regulate the output voltage at a constant switching frequency. The measured efficiency was over 93% at an output power of 0.98 W and a switching frequency of 0.5 MHz for both of the inverters with amplifier and frequency doubler     

DEVELOPMENT OF PLASMA SPRAYED LUBRICANT FREE SLIDE PLATES WITH CERAMIC COAT FOR RAILWAY USE

Ceramic coated slide plates were developed in order to ensure smooth sliding of the tongue rail and tight contact with stock rail. The 0·5 mm thickness thin metallic bonded layer was synthesized by spraying ceramic powders using conventional plasma spraying technique. Coated materials were mostly Al₂O₃ ceramic including metallic materials. It is concluded field tests that coated plates satisfied endurance specifications, corrosion, wear and load specifications without any maintenance of ceramic coated plates. Since field tests have been successfully performed, more than 10,000 slide plates are being used in Japan by Shin-kansen Rail Way and private railway companies.     

Neutron Diffraction Study on the Structure of Na-Si-O-N Oxynitride Glasses

The local structure of a Na₂O─SiO₂ oxide glass and a Na₂O─iO₂─Si₃N₄ oxynitride glass has been investigated by the pulsed neutron diffraction method. In the oxide glass, the first peak of radial distribution function (RDF) curves appeared at 0.1627 nm corresponding to Si─O boxh length. In the oxynitride glass, the first peak of the RDF curve was shifted to longer distances at 0.1650 nm due to the coexistence of Si─O and Si─N boxhs. The first peak in the RDF curve of the oxynitride glass was deconvoluted into two peaks whose positions are located at 0.1626 and 0.1709 nm. The one at 0.1626 nm is ascribed to Si─O boxhs and the other at 0.1709 nm to Si─N boxhs. The number of silicon atoms around a nitrogen was found to be 2.42, suggesting that not all of the nitrogen atoms are boxhed to three silicon atoms, but 58% twofold (─N─) and 42% threefold (>N─) nitrogens coexist in the present Na-Si-O-N oxynitride glass. The formation of twofold nitrogens may arise from the reaction between ≡Si─O⁻ and ≡Si₃N groups. This model is compatible with the experimental observation that the density and Vickers hardness of oxynitride glasses increase with the nitrogen content.     

Immunoglobulin-secreting cells in healthy peripheral blood mononuclear cells

Immunoglobulin-secreting cells were measured in healthy uncultured peripheral blood mononuclear cells (PBMCs) in vitro. The percentage of IgM-, IgG- and IgA-secreting cells in adult PBMCs was 0.053, 0.099 and 0.065%, respectively. The percentage of IgM-, IgG- and IgA-secreting cells was 0.73, 5.2 and 3.8% of surface IgM-, IgG- and IgA-bearing cells, respectively. The numbers of IgM-, IgG- and IgA-secreting cells increased with age in childhood. However, the numbers of all three classes were slightly decreased in adults compared with children aged 9-15 years. These results may explain the difference in immunity in vivo.