Browsing by Author "Lu, Mao-Hong"

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Analysis of the through-focus images with boundary-element method in high resolution optical metrology
(2006-10-01)
Shyu, Deh-Ming
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Lu, Mao-Hong
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光電工程學系
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Department of Photonics
For through-focus focus metric we build a measurement system, in which a single diffraction-limited micro lens is used for imaging and a grating with a few pitches is used as a target. In this system, the optical field is calculated by the boundary-element method, in which a new algorithm is developed to reduce the dimension of a matrix. As a result, the memory capacity required in this calculation is much reduced up to 83% in our simulation case. An optimization of the grating structure is made to obtain the highest sensitivity for the critical dimension metrology. With the optimized grating structure the simulation shows a sensitivity of less than 1 nm in the through-focus focus metric. (c) 2006 American Institute of Physics.
Color separation system with angularly positioned light source module for pixelized backlighting
(2010-01-18)
Chen, Po-Chou
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Lin, Hui-Hsiung
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Chen, Cheng-Huan
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Lee, Chi-Hung
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Lu, Mao-Hong
A color-separation system that angularly positions color LEDs to produce color separation and a lens array to focus this light onto the pixels is proposed. The LED rays from different incident angles are mapped into corresponding sub-pixel positions to efficiently display color image, which can be used to replace the absorbing color filter in the conventional liquid crystal layer. In this paper, the prototype backlight has been designed, fabricated and characterized. The measurement results of this module showed that a gain factor of transmission efficiency three times more than that of conventional color filters efficiency improvement and a larger color gamut are expected. (C)2010 Optical Society of America
Design of hybrid grating for color filter application in liquid crystal display
(2007-08-01)
Lin, Hui-Hsiung
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Lu, Mao-Hong
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光電工程學系
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Department of Photonics
Conventional color liquid crystal displays obtain red, green, and blue (RGB) lights by three color filters which absorb other spectra and allow a specific color to transmit. Consequently, the efficiency of conventional color filter in the liquid crystal display is no more than 1/3. The hybrid grating substituted for the color filter use a cold cathode fluorescent lamp or RGB light-emitting diode backlight module in the liquid crystal display to improve the efficiency is proposed. It consists of a set of dual-grating and dual-lenticular lens array. The simulation results of hybrid grating exhibit a gain factor of 1.78 in efficiency, compared with conventional color filters.
Dual-wavelength membrane-based diffractive optical element with extended depth-of-focus for optical pickup head
(2007-08-01)
Lin, Hui-Hsiung
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Lu, Mao-Hong
;
光電工程學系
;
Department of Photonics
An improved structure and optimization method for a high-numerical-aperture application for optical pickup heads that uses a low-stress silicon-nitride-membrane-based diffractive optical element to generate dual-wavelength pseudo-Bessel beams is described in this paper. The dual-wavelength membrane-type diffractive optical element with an extended focal depth for next-generation optical pickup applications has been demonstrated. The theoretical simulation and fabrication results detailing the resolution, longer depth-of-focus and diffractive efficiency are presented for the newly designed membrane diffractive optical element (DOE). This implies that the problems of disc vibration as well as the assembly and optical alignment of the many elements are solved.
Dye-less color filter fabricated by roll-to-roll imprinting for liquid crystal display applications
(2009-07-20)
Lin, Hui-Hsiung
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Lee, Chi-Hung
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Lu, Mao-Hong
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光電工程學系
;
Department of Photonics
A diffractive grating is promising for color separation to effectively replace conventional absorptive dye color filter in liquid crystal displays. In this paper, we demonstrated a color separation module consisting of an aspheric-lenticular lens array and a blazed grating to substitute for the dye color filter. Each component was designed to match the recent fabrication ability of our roll-to-roll imprinting. The measurement results of a prototype module showed a gain factor of transmission efficiency three times more than that of conventional color filters. (C) 2009 Optical Society of America
High-resolution through-focus metric with two-pitch grating target
(2007-08-01)
Shyu, Deh-Ming
;
Lu, Mao-Hong
;
Ko, Chun-Hung
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光電工程學系
;
Department of Photonics
Through-focus focus-metric is a method that is used to analyze images on a fixed plane with the help of focus-metric values when the target moves through the focus. In this study, an optical microscope having a magnification of 250x is constructed. A two-pitch grating target is imaged on a CCD detector and through-focus image data are measured. In addition, the optical field on the CCD detector is simulated using the boundary element method and physical optics propagation. By comparing the measured focus-metric signatures with the simulated signatures, information regarding the linewidth is obtained. The results show that the through-focus focus-metric method is a very sensitive method that can be used for measuring parameters such as the linewidth. Thus, a nanoscale resolution can be achieved. (C) 2007 Elsevier B.V. All rights reserved.
Light pipe array as coupling adaptor between fiber array and free-space wavelength division demultiplexer
(2007-08-01)
Sze, Jyb-Rou
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Lu, Mao-Hong
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Lee, Keh-Yi
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光電工程學系
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Department of Photonics
A light pipe array (LPA) is proposed as a coupling adaptor between a commercial fiber array and a free-space dense wavelength division demultiplexer (free-space DWDDM). The LPA has been fabricated on a silicon-on-insulator wafer using the semiconductor fabrication technology and coated with a thermal oxidation layer on its input and Output surfaces as an antireflection film. In the experiment, the free-space DWDDM system with the LPA has been demonstrated with an insertion loss of 2.4 dB and an adjacent cross-talk of - 17 dB.
Synthesis of arbitrarily discrete, diffractionless beams using dual-wavelength diffractive objective lens for optical pickup head
(2010-02-01)
Lin, Hui-Hsiung
;
Lu, Mao-Hong
;
光電工程學系
;
Department of Photonics
Sensitivity to disk vibration and large component number, which complicates assembly and optical alignment, are the drawbacks of traditional optical pickup systems. Here, a numerical method of designing a dual-wavelength diffractive objective lens with high numerical aperture for generating arbitrarily discrete, diffractionless beams with extended depth of focus is presented. Simulation and experimental results show that the optimized design provides better resolution, longer depth of focus and higher diffractive efficiency. The proposed design is promising for next-generation optical pickup systems that are more robust to disk vibration and easier to assemble. (C) 2010 Optical Society of America