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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design and Fabrication of Gapless Triangular Micro-lens Arrays

Su, Ching-hua 29 June 2006 (has links)
This study presents a new process to fabricate gapless triangular micro-lens array (GTMA). The process includes optical simulation with tracepro, UV lithography, photoresist reflow process, Ni electroplating and hot embossing technique. After photoresist triangular column array is defined using UV lithography, reflow process is applied to melt photoresist triangular column array into the shape of triangular micro-lens array. With this reflowed triangular micro-lens array, Ni is deposited and covered uniformly on the triangular micro-lens array using electroplating. The growth rate of Ni is controlled at electroplating current density of 1 Ampere Square Decimeter (ASD; A/dm2). After this electroplating process is finished, a mold of GTMA is obtained, which is served as primary mold. Subsequently, with passivation technique applied on this mold¡¦s surface, electroplating process is applied again to obtain a secondary mold. Next, this secondary mold is served as master for the subsequent hot embossing process to replicate the GTMA pattern onto polymeric material PMMA and PET sheet. The mold with stiffness and hardness plays an important role in GTMA hot embossing process. In addition, this GTMA used as optical film can offer a 100 % fill factor and a simulation of optical coupling efficiency of 66.7% to improve luminance of backlight module (BLM). In addition, this study presents the fabricated molds of GTMA with different aspect-ratio about 0.109 and 0.133. The optical measurement of BLM shows that this optical film of GTMA pattern with aspect-ratio about 0.109 can increase 15.1% of luminance and with aspect-ratio about 0.133 can increase 22.1% of luminance.
2

Fabrication of Gapless Dual-Curvature Micro-lens Technique

Tzeng, Shiang-da 10 July 2007 (has links)
Light emitting diode (LED) will have development in liquid crystal display (LCD) backlight. Nevertheless, the point source of LED is not suitable for large size panel. Therefore, this research will change the package which is bullet type and design gapless dual-curvature micro lens (GDML). Using the optics software TracePro is simulation luminance to compare of hexagon, triangular and dual-curvature micro lens, and fabrication of the better size. We can get metal model using micro-electro-mechanical systems (MEMS) technology after electroforming and hot embossing. The micro lens is formed by UV cure in metal model. It has different curvature and fill factor 100%. The advantage of electroforming is can manufacture a lot of product fast with high performance. The shrinkage rate is less than 0.5%. The collocation package of micro lens and LED chip can improve intensity and uniformity.
3

Absolute depth using low-cost light field cameras

Rangappa, Shreedhar January 2018 (has links)
Digital cameras are increasingly used for measurement tasks within engineering scenarios, often being part of metrology platforms. Existing cameras are well equipped to provide 2D information about the fields of view (FOV) they observe, the objects within the FOV, and the accompanying environments. But for some applications these 2D results are not sufficient, specifically applications that require Z dimensional data (depth data) along with the X and Y dimensional data. New designs of camera systems have previously been developed by integrating multiple cameras to provide 3D data, ranging from 2 camera photogrammetry to multiple camera stereo systems. Many earlier attempts to record 3D data on 2D sensors have been completed, and likewise many research groups around the world are currently working on camera technology but from different perspectives; computer vision, algorithm development, metrology, etc. Plenoptic or Lightfield camera technology was defined as a technique over 100 years ago but has remained dormant as a potential metrology instrument. Lightfield cameras utilize an additional Micro Lens Array (MLA) in front of the imaging sensor, to create multiple viewpoints of the same scene and allow encoding of depth information. A small number of companies have explored the potential of lightfield cameras, but in the majority, these have been aimed at domestic consumer photography, only ever recording scenes as relative scale greyscale images. This research considers the potential for lightfield cameras to be used for world scene metrology applications, specifically to record absolute coordinate data. Specific interest has been paid to a range of low cost lightfield cameras to; understand the functional/behavioural characteristics of the optics, identify potential need for optical and/or algorithm development, define sensitivity, repeatability and accuracy characteristics and limiting thresholds of use, and allow quantified 3D absolute scale coordinate data to be extracted from the images. The novel output of this work is; an analysis of lightfield camera system sensitivity leading to the definition of Active Zones (linear data generation good data) and In-active Zones (non-linear data generation poor data), development of bespoke calibration algorithms that remove radial/tangential distortion from the data captured using any MLA based camera, and, a light field camera independent algorithm that allows the delivery of 3D coordinate data in absolute units within a well-defined measurable range from a given camera.
4

A Study of the Grinding Process for the Optical-Fiber Endface with Double-Variable Curvatures

Chen, Jun-Hong 02 September 2010 (has links)
Mechanical grinding process is the most popular way to fabricate the fiber micro lenses, although there are some other methods, such as chemical etching, laser machining and focused ion beam micro-cutting. Mechanical grinding has its uniqueness in grinding Conical-Wedge-Shaped Fiber Endface, fiber endface with polygon-cone-shape, and fiber endface with double-variable curvatures. The double-variable curvatures fiber endface polisher, designed and manufactured by Mechanism Design Lab of NSYSU, is employed in this study. The normal force of the fiber endface is derived firstly and then the experimental parameters and data are substituted into the material removal rate (M.R.R.) formula to obtain M.R.R. and the Preston¡¦s constant K. The process parameters of the feed rate and polishing time on the fabrication of the fiber endface are analyzed. The polisher is calibrated and adjusted to improve the precision of the optical-fiber endface. A fiber endface with double-variable curvature is successfully fabricated in a single grinding process by properly controlling the fiber rotation angle, inclining angle, and the distant between the endface and the grinding film simultaneously. The grinding process developed in this study can be applied for fabricating optical fiber lenses in fiber optics communication as well as different types of micro probes, and micro spectroscopefors in other applications.
5

Development of a novel gradient-force tapered fibre optical tweezers system for 3D optical trapping at near horizontal fibre insertion angles

Ross, Steven January 2015 (has links)
The use of optical fibre as a mechanism for the delivery of the trapping laser beam to the sample chamber significantly reduces both the size and the build costs of “Optical Tweezers”. Furthermore, the use of fibre facilitates the decoupling of the optical trapping beam from the microscope optics, which provides further scope for the development of a portable optical trapping system, and the potential for uncomplicated integration with other advanced microscopy systems such as an atomic force microscope (AFM) for example. For use with an AFM, the optical fibre must be inserted at an angle of 10° with respect to the sample chamber floor. However, previous literature suggests that 3D optical trapping with a single fibre inserted at an angle ≤20° is not feasible. This thesis presents the design, development, build and test of a single beam optical fibre based gradient force optical tweezers system and its associated software. An investigation is conducted to ascertain why optical trapping, using single fibre systems, cannot be achieved at sub 20° insertion angles, the result of which formed the basis of a hypothesis that explains this limitation. This finding led to the development of tapered optical fibre tips that are cable of 3D optical trapping at an insertion angle of ≤10°. The optimised optical fibre tapers are presented and their ability to trap both organic and inanimate material in 3D at an insertion angle of 10° is demonstrated. The near-horizontal insertion angle introduced a maximum trapping range (MTR). The MTR of the tips is determined empirically, evaluated against simulated data, and found to be tuneable through taper optimisation. Optical trap characterisation has been undertaken in terms of the optical trapping forces acting on the trapping subjects. Finally, the fibre tapering devices ability to reproduce identical tapers, or not, using the same device parameters, was investigated and the results in terms of geometric profile and optical performance are presented.
6

Development of dual view displays

Mather, Jonathan Francis January 2007 (has links)
This thesis is about ‘Dual View’ displays. These are displays that can show different images to different people. For example, the driver of a car could view a GPS map, whilst the passenger who looks at the display from a different angle, could watch a movie. This thesis describes some of the research that took the project from an idea to a refined product. Sharp’s first dual view display is prototyped, and problems such as crosstalk between the two views are seen. These problems are analysed and rectified to bring the device up to a high standard. In July 2005 Sharp used this technology to launch the world’s first dual view product. Since then a new design of dual view display has been investigated. This design is theoretically optimised and experimentally tested. The new design is shown to provide dual view with greater head freedom, greater efficiency, and lower crosstalk than the original parallax barrier design.
7

Design and Fabrication of Nonconventional Optical Components by Precision Glass Molding

He, Peng January 2014 (has links)
No description available.

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