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By anodically etching a (100)-oriented Al foil with an etching mask in hydrochloric acid solution, an ideally ordered array of Al holes was obtained. The Al hole array structure showed wavelength selective thermal radiation property. Wavelength band of the thermal radiation could be tuned by controlling the aperture size of the hole. The aperture size of the Al hole was controlled by optimizing geometrical structures of the etching mask and anode etching conditions.

The fabrication of a three-dimensional (3D) ordered array of metal and/or metal oxide nanoparticles in an anodic porous alumina matrix and the application of a 3D array of Au nanoparticles as a substrate for the measurement of surfaceenhanced Raman scattering (SERS) are discussed. The 3D structure is prepared by a repeated process composed of the formation of nanoholes by the anodization of Al and the subsequent electrochemical deposition of a metal into the holes. The dependence of the SERS intensity on the number of layers of the Au nanoparticle array was examined. In addition, the effect of the gap size between Au nanoparticles was also investigated. The present process allows the fabrication of 3D functional optical devices based on the enhancement of the electric field of incident light.

The fabrication of highly ordered anodic porous alumina and its application to the fabrication of several types of functional optical devices are described. Highly ordered hole array structures of anodic porous alumina, which were formed under appropriate anodizing conditions, were applied as a starting structure in several processes for the fabrication of ordered structures used for the functional optical devices. On the basis of these processes, twodimensional photonic crystals and localized surface plasmonic devices were prepared.

Three-dimensional (3D) structuring of polymers by tightly focused femtosecond laser pulses and interference is demonstrated. Photo-structuring by the tightly focused sub-1 ps laser pulses realizes a direct laser writing inside dielectric materials without self-focusing. Photo-polymerization of 3D photonic crystal templates with photonic stop bands in IR-spectral region has been achieved. Holographic photo-polymerization of photonic crystal templates with counter-propagating beams was numerically modeled. Three-dimensional structures with an axial period smaller than the lateral can be recorded using the counter-propagating beam alignment. Photo-polymerization of large-area polymeric structures with a high surface-to-volume ratio is demonstrated.

The physical principles underlying the three-dimensional (3D) laser microstructuring technique are outlined, its applications for the fabrication of 3D photonic crystals are described. Structures recorded by direct laser writing and holographic recording techniques in SU-8 photoresist are presented along with their structural and optical characterization.

We report on three-dimensional (3D) holographic recording in As2S3 glass using 800 nm wavelength, 150 fs duration pulses. Diffractive beam splitter was used to generate 2 - 5 beams which were then focused for recording by objective lens of numerical aperture NA = 0.75. The recorded 3D hologram was read out by diffraction of 632 nm HeNe laser beam confirming the expected pattern of holograms. The mechanism of photo-darkening and optical damaging of As2S3 glass and dielectrics in general is discussed. Two-photon absorption cross-section, σ2 = 74.6 x 10-50 cm4/s, was determined by transmission for pulses of 150 fs and 800 nm wavelength. Also, it is demonstrated that the optical damage threshold scales as the bandgap energy for the fluorides. Nano-/micro-structuring of As2S3 glass by ablation in air will be also demonstrated. High fluence (> 5 J/cm2) irradiation of the 800 nm wavelength, 150 fs duration pulses was used to ablate As2S3 glass. Self-organized growth of the fibers, rods, and microsphere-type structures was observed. Composition of the nano-/micro-structured material was close to that of the source As2S3 glass (with up to 20% surplus of sulphur in nano-rods). Straight rods as thin as 20 nm in diameter and over 1 μm-long were obtained. Application potential of nano-/micro-structured As2S3 glass is discussed.© (2004) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We demonstrate fabrication of two-dimensional (2D) photonic crystal (PhC) structure inside the volume of SU-8 resist film by four beams interference. This structure, actually, is a 3D structure fabricated inside the film without sample scanning or laser beam steering. The mechanism of recording in transparent dielectrics is discussed in terms of third harmonic generation, white light continuum, and thermal emission by "hot" electrons.

Fabrication and characteristics of two-dimensional (2D) and three-dimensional (3D) periodic structures, recorded in the bulk of SU8 photoresist film by multiple-beam interference is described. Multiple beams (up to nine) were generated by a diffractive beam splitter. Recording was performed by ultrashort laser pulses with temporal width of 140 fs (FVWM) and central wavelength of 800 nm, derived from a Ti:sapphire laser. Intensity-dependent photomodification of the photoresist was due to single-photon as well as multi-photon (two and three) absorption. After the development, the exposed resist films contained free-standing 2D and 3D periodic dielectric structures with unexposed exposed regions removed by the development. Detailed examination of the samples has revealed close resemblance between their structure and the light intensity distributions in the multiple-beam interference fields, expected from the numerical calculations. Quality of the samples recorded by a single-photon absorption was lower than that of other samples, in particular due to poor development quality. The microfabrication method used in this work appears to be a suitable for obtaining photonic crystal templates.

This paper presents a technique for determining a tooth's pose given a dental plaster cast and a set of generic tooth models. The ultimate goal of pose estimation is to obtain information about the sizes and positions of the roots, which lie hidden within the gums, without the use of X-rays, CT or MRI. In our approach, the tooth of interest is first extracted from the 3D dental cast image through segmentation. 2D views are then generated from the extracted tooth and are matched against a target view generated from the generic model with known pose. Additional views are generated in the vicinity of the best view and the entire process is repeated until convergence. Upon convergence, the generic tooth is superimposed onto the dental cast to show the position of the root. The results of applying the technique to canines demonstrate the excellent potential of the algorithm for generic tooth fitting.

We describe a novel microfabrication method based on interference of several coherent laser pulses in photosensitive media. The method allows to transform the periodic multidimensional interference patterns into periodic modulation of dielectric properties of the material, and is therefore potentially suitable for the photonic crystal fabrication in materials like photoresists, photosensitive glasses, and others. We have fabricated one, two, an three-dimensional photonic crystals with different lattices and sub-micrometer periods. The fabricated structures have high structural quality, as evidenced by confocal and scanning electron microscopes. Furthermore, using numerical simulations we explore the possibilities to obtain body-centered-cubic and diamond photonic crystal lattices by varying optical phases of the interfering beams. Numerical simulations are also used to reveal photonic bandgap properties of some 2D photonic crystals, fabricated using this technique.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Space analysis is an important procedure by orthodontists to determine the amount of space available and required for teeth alignment during treatment planning. Traditional manual methods of space analysis are tedious and often inaccurate. Computer-based space analysis methods that work on 2D images have been reported. However, as the space problems in the dental arch exist in all three planes of space, a full 3D analysis of the problems is necessary. This paper describes a visualization and measurement system that analyses 3D images of dental plaster models. Algorithms were developed to determine dental arches. The system is able to record the depths of the Curve of Spee, and quantify space liabilities arising from a non-planar Curve of Spee, malalignment and overjet. Furthermore, the difference between total arch space available and the space required to arrange the teeth in ideal occlusion can be accurately computed. The system for 3D space analysis of the dental arch is an accurate, comprehensive, rapid and repeatable method of space analysis to facilitate proper orthodontic diagnosis and treatment planning.