The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
Haojie Xia - One of the best experts on this subject based on the ideXlab platform.
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Sub-pixel Projector calibration method for fringe projection profilometry.
Optics express, 2017Co-Authors: Wei Zhang, Li Weishi, Luo Hui, Huining Zhao, Haojie XiaAbstract:Digital Projectors are used as standard parts at present in fringe projection profilometry systems to project structured-light patterns onto the object surface to be measured, and the distortion of the Projector Lens must be calibrated and compensated accurately to satisfy the accuracy requirement of industrial applications. A novel method is proposed to determine the Projector pixel coordinates of the marker points of a calibration target accurately in terms of projective transform. With the method, the Projector can be calibrated with accuracy of sub-pixel level. The method is applicable for the calibration target with a chessboard pattern or a circle pattern, and the calibration result is independent on the results of camera calibration. Experimental results are shown to demonstrate the effectiveness and validity of the proposed method.
Y C Fang - One of the best experts on this subject based on the ideXlab platform.
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2 × Zoom Ratio Telecentric Projector Lens Design for 1080 P High Definition Television with Minimum 8000 K Color Temperature
Optical Review, 2007Co-Authors: Y C Fang, W. T. Lin, Chen-mu Tsai, Yu-cheng LinAbstract:In today's digital age, digital Projectors and their application are gaining in significance, especially in the home theater area where the projected area is more than hundred inches. More attention has to be paid to the design of these than of ordinary data Projectors due to the enhancement of both definition and contrast for home theater Projectors. This complicates the optical design of the Projector, especially in 1080 P flat plane panel resolution requirements with strong offset of 130%, whose semi-image height (18.6 mm) is very close to that of 35 mm film (20 to 21 mm). In this paper the Lens design samples focus on the application of a Projector with a 1080 P digital micromirror device (DMD) system with 10.68 μm per pitch. Such Lenses have the telecentric design on the image side because of the total internal reflection (TIR) prism. The complicated design is the reason for this: firstly, there must be a very long back focal length due to the huge TIR prism and zoom mechanical system; secondly, there is an extremely relative luminance requirement (70% minimum) at semi-image height (18.6 mm); thirdly, there are difficulties in the elimination of lateral aberration due to the limited choice of glass and, fourthly, there is a 2 × zoom ratio with modulation transfer function requirement of 40% at 501p/mm at a semi-image height of 18.6 mm minimum and, most important, limited total overall length. The Lens design with 2 × zoom ratio for 1080 P resolution was presented with great success; the optimal calculation of lateral chromatic aberration via genetic algorithm (GA) was introduced in this research and then a local minimum of lateral color aberration was identified.
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Eliminating lateral color aberration of a high-resolution digital projection Lens using a novel genetic algorithm
Optical Engineering, 2007Co-Authors: Y C Fang, Tung-kuan LiuAbstract:Advances in digital image optics have increased the significance of lateral color aberration because it is easily seen in the projected area. The choice of optical glass plays a role in the elimination of lateral color aberration. Current optical software still has difficulty in finding the optimal combination of optical glasses for twelve or more elements in a projection Lens, the choice being among at least 300 optical glasses that have been developed. Even the modern damped least squares, a ray-tracing-based method, is limited, owing to its inability to identify an enhanced optical system configuration. As an alternative, this research proposes a new optimization process by using algorithms involving the theory of geometric optics in a Projector Lens, real encoding, multiple dynamic crossover, and random gene mutation techniques. Results and conclusions show that attempts to achieve negligible axial and lateral color aberration are successful.
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High definition DLP zoom Projector Lens design with TIR prism for high definition television (HDTV) - art. no. 63420Z
International Optical Design Conference 2006 Pts 1 and 2, 2006Co-Authors: Y C Fang, W. T. Lin, H.l. Tsai, Hsien Lin TsaiAbstract:In today's digital age, digital Projectors and their application are gaining in significance, especially in the home theater area. We have to pay more attention in our design than ordinary data Projectors designers do to the enhancement of both definition and contrast for home theater Projectors and this complicates the optical design of the Projector. In this paper the Lens design samples focused on the application of a Projector with a DMD (Digital Micro mirror Device) system. With the DMD device, there are three different optical engine designs at present: non-telecentric, telecentric with a TIR (Total Internal Reflection) prism and Field Lens types. The Lens design using a TIR prism will be discussed in this paper. Such Lenses have the telecentric design on the image side because of the TIR prism. The Lens design with 1.6X zoom ratio for 1080P resolution will be presented and its limitations regarding performance, F-number and zoom ratio will be discussed.
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High Definition DLP Zoom Projector Lens Design with TIR prism for HDTV
International Optical Design, 2006Co-Authors: Y C Fang, Wei Tang Lin, H.l. TsaiAbstract:In this paper the Lens design samples given were focused on the application of Projector with DMD system.There are three different optical design at this moment; non-telecentric, telecentric with TIR prism and Field Lens Type.
Wei Zhang - One of the best experts on this subject based on the ideXlab platform.
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Sub-pixel Projector calibration method for fringe projection profilometry.
Optics express, 2017Co-Authors: Wei Zhang, Li Weishi, Luo Hui, Huining Zhao, Haojie XiaAbstract:Digital Projectors are used as standard parts at present in fringe projection profilometry systems to project structured-light patterns onto the object surface to be measured, and the distortion of the Projector Lens must be calibrated and compensated accurately to satisfy the accuracy requirement of industrial applications. A novel method is proposed to determine the Projector pixel coordinates of the marker points of a calibration target accurately in terms of projective transform. With the method, the Projector can be calibrated with accuracy of sub-pixel level. The method is applicable for the calibration target with a chessboard pattern or a circle pattern, and the calibration result is independent on the results of camera calibration. Experimental results are shown to demonstrate the effectiveness and validity of the proposed method.
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Design of a free-form Lens system for short distance projection
Current Developments in Lens Design and Optical Engineering XII; and Advances in Thin Film Coatings VII, 2011Co-Authors: Bo Yang, Wei Zhang, Fujian DaiAbstract:A free-form Lens system design is proposed for short distance projection. Free-form surface shape and non-rotational symmetrical structure provide us more freedoms for optimization. The catadioptric structure is also used to reduce the overall length of the whole system. The designed Projector Lens system consists of two parts. The first part is a rotationally symmetrical Lens system which corrects the basic aberrations. The second part contains a free-form Lens and a reflector which correct the distortion and other aberrations. We achieve 55inch projected image size at a display screen which is 300mm away from the Lens system. The maximum distortion for all fields at all distances is less than 3%.
Yazhu Chen - One of the best experts on this subject based on the ideXlab platform.
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Flexible and accurate implementation of a binocular structured light system
Optics and Lasers in Engineering, 2008Co-Authors: Rongqian Yang, Sheng Cheng, Yazhu ChenAbstract:Abstract This paper presents a practical implementation of a binocular system for three-dimensional (3D) surface measurement. Manufacturing procedures are easy to implement because this system does not require that the optical axes of two cameras’ Lenses be coplanar and the structured light sheets be perpendicular to that plane. The method of structured light calibration is proposed to obtain the parameters of the structured light sheets. This calibration method can tolerate the surface condition of the calibration board. To eliminate the effect caused by the distortion of Projector Lens, each structured light sheet is fitted to a conicoid. Meanwhile, data acquired from two cameras are transformed into a unique coordinate system to avoid 3D data matching. Experiments are conducted to validate the flexibility, accuracy, and desirability of our system.
Mark C. Reuter - One of the best experts on this subject based on the ideXlab platform.
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Design of a new photo-emission/low-energy electron microscope for surface studies
Ultramicroscopy, 1991Co-Authors: R.m. Tromp, Mark C. ReuterAbstract:Abstract We have designed a new photo-emission/low-energy electron microscope (PEEM/LEEM) for surface studies in ultra-high vacuum (UHV). While following the general design concepts developed by Bauer and Telieps, significant innovations are made to enhance the resolution and capabilities of the instrument: a piezoelectrically driven sample stage, a magnetic cathode objective Lens, an in-vacuum deflection magnet, and a double-gap, in-vacuum Projector Lens. Particular attention was paid to integrating the electron-optical requirements and constraints with the stringent vacuum requirements. At the time of writing this paper, construction of the microscope is nearly completed.
