Automatic design of a one-to-many optical-interconnects lens system using aspherics

Use of an aspherical surface in the design of a lens system for one-to-many optical-interconnects (OTM-OI), composed of a doublet lens and a gradient-index (GRIN) lens array has been investigated. Applying the procedure of ALSIE (Automatic Lens design by Solving InEqualities), the off-axis lens systems, which feature the optical performance of the OTM-OI lens system, are optimized at 0.1 numerical aperture with a total field of view of 2°. Three aspherical designs with the aspherical surface for different surfaces are presented. The aspherical designs show preferable modulation transfer function (MTF) for high frequency as compared with the spherical design.     

A Novel Spread Function for Observation of Random Surface

When a random rough surface is viewed obliquely by an imaging system, the position of a viewed point fluctuates with surface displacements. This fluctuation introduces an additional blur to the images that are mapped on the average surface. A new class of spread function, which represents the resolution associated with the randomness of an imaging object, is introduced to treat this problem and an analytical expression of the function is obtained for a Gaussian random surface under the presence of shadowing effects. This spread function is useful in understanding the loss in resolution of images of a random surface such as the thermal imagery of an ocean surface in the near horizon.     

Fabrication of Optical Components and Modules Using Photo-fabrication Technique

We describe optical components and optical modules using a photofabrication technique to demonstrate applicability of the technique for optical purposes. A thick plate and a prism were fabricated to study fabric characteristics. Examples of optical modules implemented by the photofabrication technique are a beam expander and an interferometer baseplate.     

Efficiency of Blazed Diffractive Optics Produced by Diamond Turning

In blazed diffractive optics produced by the diamond turning process, the finite size of the tool causes a decrease in diffraction efficiency. To analyze the influence of the tool, we evaluate first-order diffraction efficiency of periodic gratings based on the electromagnetic theory. The design indices of the diffractive optics for higher efficiency are shown. Even with the same power of diffractive optics, the efficiency differs with the front or back side of the surface. The efficiency of a diffractive-refractive hybrid lens depends on the curvature of the refractive surface.     

Analysis of photodecomposition of gaseous chlorobenzene by KrF excimer laser.

Gaseous monochlorobenzene was irradiated with KrF excimer laser (248 nm) under reduced pressure. The photodecomposition was an apparent first order reaction. When the system contained no additive gas, the photolysis was found to give benzene (conversion yield: 49%) in the gas phase and many unidentified products in the solid phase. On the other hand, in the presence of oxygen, carbon dioxide (10%), carbon monoxide (16%), hydrogen chloride (52%) and acetylene (2%) are produced and the peaks shown on the gas chromatogram of the solid phase were effectively suppressed.     

Novel Phenomena of Crystallization and Emulsification of Hydrophobic Solute in Aqueous Solution

Emulsification of lauric acid in an aqueous ethanol solution including lauric acid solute has been observed during cooling before crystallization of lauric acid occurs. The nature of two different solubility curves was explained for the system of lauric acid and aqueous ethanol solution. The mutual solubility of the two liquid phases controls emulsification; the solid solubility of lauric acid controls crystallization. The mutual solubility curve appears at relatively high temperature, and the solid solubility curve at relatively low temperature. Crystallization essentially generates a solid metastable zone under the solid solubility curve. A supersaturated solution can be obtained in the metastable zone. However, no nucleation occurs in the metastable zone. The metastable zone, therefore, still caused emulsification at low temperature before crystallization of lauric acid occurred. The hypothetical mutual solubility curve for the aqueous solution including hydrophobic solutes appeared invariably even at low temperature in the metastable zone under the solid solubility. Copyright 2001 Academic Press.     

Development of a novel electrochemical cell for slab optical waveguide spectroscopy for in situ observation of methylene blue and anions on an electrode/electrolyte interface

A new spectroelectrochemical cell for slab optical waveguide (SOWG) spectroscopy was developed in order to observe in situ an electrode/electrolyte interface for bulk electrolysis. The new SOWG spectroelectrochemical cell has been evaluated by simultaneous electrochemical-absorption experiments of methylene blue (MB) using cyclic voltammetry (CV) and SOWG spectrometry. CV was performed in the SOWG spectroelectrochemical cell using indium tin oxide (ITO) coated glass as the working electrode, platinum wire as the counter electrode and a silver/silver chloride electrode (Ag/AgCl) as the reference electrode. Based on the CV and SOWG spectrometric data, it was found that the SOWG spectra showed the MB spectra on the electrode surface selectively and that SOWG with the cell would be useful as a tool for in situ study of an electrode/electrolyte interface. Using this cell, the effects of the supporting electrolytes, NaNO₃, KNO₃, CH₃COONa, and CH₃COOK on the absorbance of MB were examined at the potential of +0.8 V versus Ag/AgCl. The decrease in MB absorbance by nitrate ions was greater than that of acetate ions. Therefore the competitive adsorption of nitrate ions was stronger than that of acetate ions. Thus, the decrease in absorbance of MB in the presence of anions demonstrates the competitive adsorption of anions. These results show that the extent of specific adsorption of electrolytes was observed by measuring the SOWG absorbance intensity of MB.     

Isopropoxyaluminum 1,1′-biphenyl-2-oxy-2′-perfluorooctanesulfonamide as a catalyst for Tishchenko reaction

Isopropoxyaluminum 1,1′-biphenyl-2-oxy-2′-perfluorooctanesulfonamide (3) has been evaluated as an aluminum-based catalyst for the Tishchenko reaction. Compound 3 was found to exert high catalytic activity in the reaction with aliphatic aldehydes and also enabled smooth dimerization of enolizable aldehydes. This advantage was highlighted by the quantitative formation of ethyl acetate from acetaldehyde by the present system.     

Asymmetric transfer hydrogenation of aryl ketones catalyzed by salt-free two samarium centers supported by a chiral multidentate alkoxy ligand

[reaction: see text] We synthesized a chiral multidentate ligand, (R,R,R,R)-N,N,N',N'-tetra(2-hydroxy-2-phenylethyl)-1,3-xylylene diamine [(R)-2], which can support two metals at adjacent positions. Asymmetric transfer hydrogenation of acetophenone and its derivatives was conducted by using salt-free bimetallic lanthanoid complexes of (R)-2, and the combination of two samarium atoms and (R)-2 was found to be the best catalyst system for asymmetric transfer hydrogenation of aryl ketones in high enantioselectivity (up to >99% ee).     

Colouring mechanism of dyed KDP crystal by quantum chemistry

Dye adsorption mechanism, in particular, colouring mechanism of KDP (KH₂PO₄) crystal was investigated by quantum chemistry in this study. Phenomena, such as different preferentially coloured faces of KDP when co-crystallised with different dyes, are explained by the minimum and maximum values of electrostatic potential (ESP). Furthermore, it is found that the ESP distribution of a dye molecule may not necessarily be the single mechanism affecting the dye adsorption in a crystal structure; and that the degree of protonation, crystal surface condition, steric exclusion of dye and the orientation of dye molecules situating on the crystal surface may as well be important factors for the dye adsorption.