第二高調波発生を用いた角度計測に関する研究

Tohoku University高偉課

MAXIPOL: Cosmic Microwave Background Polarimetry Using a Rotating Half-Wave Plate

We discuss MAXIPOL, a bolometric balloon-borne experiment designed to measure the E-mode polarization of the cosmic microwave background radiation (CMB). MAXIPOL is the first bolometric CMB experiment to observe the sky using rapid polarization modulation. To build MAXIPOL, the CMB temperature anisotropy experiment MAXIMA was retrofitted with a rotating half-wave plate and a stationary analyzer. We describe the instrument, the observations, the calibration and the reduction of data collected with twelve polarimeters operating at 140 GHz and with a FWHM beam size of 10 arcmin. We present maps of the Q and U Stokes parameters of an 8 deg^2 region of the sky near the star Beta Ursae Minoris. The power spectra computed from these maps give weak evidence for an EE signal. The maximum-likelihood amplitude of l(l+1)C^{EE}_{l}/(2 pi) is 55_{-45}^{+51} uK^2 (68%), and the likelihood function is asymmetric and skewed positive such that with a uniform prior the probability that the amplitude is positive is 96%. This result is consistent with the expected concordance LCDM amplitude of 14 uK^2. The maximum likelihood amplitudes for l(l+1)C^{BB}_{l}/(2 pi) and $\ell(\ell+1)C^{EB}_{\ell}/2\pi$ are -31_{-19}^{+31} and 18_{-34}^{+27} uK^2 (68%), respectively, which are consistent with zero. All of the results are for one bin in the range 151 < l < 693. Tests revealed no residual systematic errors in the time or map domain. A comprehensive discussion of the analysis of the data is presented in a companion paper.Comment: 19 pages, 11 figures, 2 tables, submitted to Ap

Fluidized bed hydrodynamics by means of electrical capacitance tomography

Fluidized bed reactors are utilized in a variety of applications from hydrocarbon cracking to drying of mineral ore to coating of pharmaceutical pills. A proper understanding of bed hydrodynamics is essential to properly design, operate and control the process. Intrusive and non-intrusive measurement techniques have been utilized to study various aspects of fluidized bed behaviour. Electrical Capacitance Tomography (ECT) has been utilized to determine the distribution of gas-solid mixture in the bed. The Digital Image Analysis Technique (DIAT) is used to determine the bubble behavior in two-dimensional beds. The bubble behavior has not been studied by ECT. The premise of this research is to test a new technique by combining ECT solid fraction maps with image processing techniques to determine the bubble characteristics in the bed. Electrical Capacitance Tomography (ECT) was used to map the relative fractions of sand-air mixture in a 14 cm ID acrylic vessel at two different static bed heights. The voids were defined as the areas of gas-solid mixture with value of less than 0.25. Afterwards simple image analysis techniques were applied to isolate bubbles from the rest of the bed. The resulting data were converted into binary images to extract hydrodynamic information. The two main parameters of interest were the bubble diameter and its rise velocity. The experimental average velocities and average diameters matched the results obtained from respective correlations in the literature. However, large spreads existed for both these parameters due to the simultaneous presence of bubbles and slugs. The experimental fluidized bed did not transition fully into the turbulent regime but has the character of a hybrid bubbling-slugging regime. This is illustrated by experimental diameters which indicate presence of bubbles and slugs simultaneously. The same information was illustrated by experimental velocity-diameter envelopes (minimum and maximum values) which overlapped for higher flow conditions. The radial solid fraction distribution illustrated the same point with an inverted “M” profile which has been associated previously with regime transition. The path of bubble rise was identified, mainly rising through the midway point between the bed’s center and its inner edge. Five different types of bubbles were identified using the two dimensional binary images of voids. However, this technique can only be used for regimes where voids/bubbles are the main source of gas transfer to the surface of the bed

Chromatic confocal gauging for high precision dimensional metrology

Interest in the chromatic confocal microscope in the high precision dimensional metrology industry is growing rapidly. In fact, the chromatic confocal microscope offers a “stylus like” distance measurement applicable to various surface types. In addition, the chromatic confocal microscope can potentially compete in resolution with contact measurement probes, while significantly increasing the sampling rate to several kHz. Therefore, such technology is key to the Taylor Hobson Ltd. strategy. The work embodied in this thesis focuses on the design, development, and evaluation of a low cost and high resolution version of the chromatic confocal microscope. Both product are currently in pre-production phase. The low cost version the chromatic confocal microscope is designed to be a compact and cost effective system while exhibiting “state of the art” performances. In fact, the raw material cost of the system is below £500, this being achieved while exhibiting an optical head outer diameter of 8 mm, a working distance of more than 27 mm, and a resolution better than 100 nm over a measurement range exceeding 7 mm. The high resolution version of the chromatic confocal microscope is dedicated to precision. The aim of the design is to exhibit the highest achievable resolution while maintaining a measurement working distance exceeding 12 mm. By tailoring the chromatic dispersion to be appropriately low, a resolution of better than 10 nm is achieved. Both designs have been tailored within a few design cycles; this has been achieved through the development of two novel models, the spectral irradiance model and the measurement standard deviation model. The spectral irradiance model enables the analytical estimation of the chromatic confocal peak from only the optical parameters of the optical heads. Based on a geometric approach; this is more than 5 times more precise than the previously used model based on wave optics. Furthermore, by applying a fully integrated system design approach incorporating design, production, and test of optical systems, the resulting chromatic confocal system surpasses comparable commercially available chromatic confocal gauges in terms of cost, resolution, numerical aperture, range of measurement, and working distance. Such performance is further enhanced by the use of staircase diffractive surfaces. Staircase diffractive surfaces are special hybrid aspheric diffractive surfaces exhibiting insignificant manufacturing losses allowing the design to be only limited by the scalar diffraction theory used by ray tracing packages. In addition, staircase diffractive lenses permit the passively athermalisation of the optical head of the chromatic confocal microscope. The work encapsulated in this thesis extends the current understanding of the measurement environment impact on chromatic confocal gauges. This study includes the impact of the surface reflectivity, roughness, and slope onto the linearity of the chromatic confocal microscope. Using the previously described findings, methods to mitigate the linearity error induced by the surface roughness, reflectivity, and slope are presented and applied.Engineering and Physical Sciences Research Council (EPSRC) scholarshi

Index to 1984 NASA Tech Briefs, volume 9, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1984 Tech B Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Focal position-controlled processing head for a laser pattern generator (LPG) for flexible micro-structuring

In micro-structuring processes a direct structuring of the substrate is, in most cases, not possible and therefore the profile is first obtained in photo resist and then, in a second step, transferred into the substrate. The resist structuring can be performed using the flexible characteristics of a laser pattern generator (LPG). In these processes, there is a beneficial relationship between the apparatus/equipment expense and the obtainable processing results. For a reproduceable processing result in all micro structuring tasks, good reproducibility of all process relevant parameters is required. In the application of a laser pattern generator, precise control of the focal position of the strongly focussed laser beam relative to the processing surface must be maintained. [Continues.

Modern lithographic techniques applied to stereographic imaging

The main aim of the research has been to produce and evaluate a high-quality diffusion screen to display projected film and television images. The screens have also been found to effectively de-pixelate LCD arrays viewed at a magnification of approximately 4x. The production process relies on the formation of localized refractive index gradients in a photopolymer. The photopolymer, specially formulated and supplied by Du Pont, is exposed to actinic light through a precision contact mask to initiate polymerization within the exposed areas. As polymerization proceeds, a monomer concentration gradient exists between the exposed and unexposed regions allowing the monomer molecules to diffuse. Since the longer polymer chains do not diffuse as readily, the molecular concentration of the material, which is related to its refractive index, is then no longer uniform. The generation of this refractive index profile can, to some extent, be controlled by careful exposure of the photopolymer through the correct mask so that the resulting diffusion screen can be tailored to suit specific viewing requirements. [Continues.

Development of a flexible and modular metrology system for measuring complex surfaces

The demand for customised optical devices is increasing tremendously. Such optical devices do not employ traditional designs like planar, spherical, or even aspherical shapes. Instead, modern lenses exhibit free-form surfaces with a large variety of gradients in all directions. Highly accurate and repeatable measurement of such lens surfaces represents a considerable challenge; therefore there is a pressing need to both improve the metrology systems used in the optical industry and to develop new generations of high-performance metrology systems that employ innovative measurement techniques.Workshops need fast measurement solutions for the rough surfaces produced in the early stages of a lens typical production chain. The last steps produce very smooth surfaces, usually ideally suited to interferometers. However, interferometers are physically not suited to the measurement of strong aspheres or free-form shaped objects. Therefore, research was undertaken to investigate a metrology solution applicable to all common surface types and roughness grades at any stage of the production chain.This PhD research presents a novel approach for applying the principle of a spherical coordinate measurement machine (SCMM) to lens metrology. SCMMs require the precise and repeatable alignment of all axes. Therefore, research was performed to investigate a novel method for generic axes alignment without the need for external tools. This method, with the enhanced SCMM approach, was then combined with research into suitable multi-sensor measurement modes, in order to adequately address the needs of all stages in the production chain. Coordinate measurement machines are subject to the influence of errors. Therefore, research was conducted to develop a novel user-interface and a patented device to analyse and compensate for errors of the applied rotational axes and the 3D-Scale. The mathematical models presented, enable a simple transfer to other types of SCMMs. Also, the researched processes, software tools and mechatronic devices may be generically adopted to other machines applying rotational axes. Therefore, in addition to providing advanced capabilities for high-accuracy measurement of lenses with complex morphologies; the results of this research and the new approaches developed may be employed with SCMMs more generally, in a wide range of industrial sectors