Prof. Gao-Wei Chang Profile

Prof. Gao-Wei Chang

Associate Professor at National Taiwan Normal Univ

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Author

Publications (18)

Proceedings Article | 14 May 2010 Paper

A generalized approach to modeling radiation pattern measurement methods for high-power LEDs

Gao-Wei Chang, Chia-Cheng Liao, Yung-Chang Chen

Proceedings Volume 7717, 77171F (2010) https://doi.org/10.1117/12.854194

KEYWORDS: Light emitting diodes, Sensors, Calibration, 3D metrology, Reflectors, Optical scanning, Distance measurement, 3D modeling, Optical scanning systems, Radiation effects

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Proceedings Article | 17 February 2007 Paper

Design and implementation of confocal imaging systems with a generalized theoretical framework

Gao-Wei Chang, Chia-Cheng Liao, Zong-Mu Yeh

Proceedings Volume 6503, 65030L (2007) https://doi.org/10.1117/12.702769

KEYWORDS: Confocal microscopy, Imaging systems, Sensors, Objectives, Microscopes, Image resolution, Point spread functions, Tolerancing, Optical components, Optical simulations

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Proceedings Article | 13 February 2007 Paper

Design and implementation of real-time LED spatial radiance measurement systems

Gao-Wei Chang, Zong-Mu Yeh, Chia-Cheng Liao

Proceedings Volume 6486, 64860K (2007) https://doi.org/10.1117/12.701665

KEYWORDS: Light emitting diodes, Amplifiers, Digital signal processing, Light sources, Sensors, Optoelectronics, Resistance, Calibration, Sensing systems, LED lighting

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Proceedings Article | 12 February 2007 Paper

Multiple-functional and cost-effective liquid-crystal cell parameter measurement system

Gao-Wei Chang, Yu-Hsuan Lin, Zong-Mu Yeh

Proceedings Volume 6487, 64870Z (2007) https://doi.org/10.1117/12.700071

KEYWORDS: Liquid crystals, Polarizers, LCDs, Polarimetry, Molecules, Control systems, Optics manufacturing, Optical alignment, Crystals, Electro optical systems

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Proceedings Article | 9 February 2007 Paper

High-accuracy and cost-effective photodiode spectral response measurement system

Gao-Wei Chang, Chia-Cheng Liao, Zong-Mu Yeh

Proceedings Volume 6471, 647117 (2007) https://doi.org/10.1117/12.701656

KEYWORDS: Diffraction gratings, Optical filters, Diffraction, Photodiodes, Optical amplifiers, Calibration, Spectral resolution, Lamps, Optoelectronics, Monochromators

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Proceedings Article | 29 January 2007 Paper

Accurate spectral response measurement system for digital color cameras

Gao-Wei Chang, Zong-Mu Yeh

Proceedings Volume 6493, 649311 (2007) https://doi.org/10.1117/12.702943

KEYWORDS: Optical filters, Cameras, Signal to noise ratio, Optical design, Imaging systems, Error analysis, Interference (communication), Reconstruction algorithms, Light sources, RGB color model

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Proceedings Article | 29 January 2007 Paper

Accurate and cost-effective MTF measurement system for lens modules of digital cameras

Gao-Wei Chang, Chia-Cheng Liao, Zong-Mu Yeh

Proceedings Volume 6494, 64940S (2007) https://doi.org/10.1117/12.702678

KEYWORDS: Modulation transfer functions, Cameras, Spatial frequencies, Imaging systems, Spatial light modulators, Contrast transfer function, Digital cameras, Modulation, Diffraction, Optical filters

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Proceedings Article | 19 January 2007 Paper

White light interferometric profile measurement system using spectral coherence

Gao-Wei Chang, Yu-Hsuan Lin, Zong-Mu Yeh

Proceedings Volume 6463, 64630I (2007) https://doi.org/10.1117/12.700003

KEYWORDS: Optical filters, Light sources, Spectral coherence, Michelson interferometers, Light, 3D metrology, Charge-coupled devices, Digital signal processing, Interferometry, Filtering (signal processing)

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Proceedings Article | 12 September 2005 Paper

DSP-based MTF measurement system for optical imaging modules

Gao-Wei Chang, Shih-Yao Pan

Proceedings Volume 5881, 58810T (2005) https://doi.org/10.1117/12.616294

KEYWORDS: Modulation transfer functions, Digital signal processing, Spatial light modulators, Imaging systems, Image processing, Modulation, Signal processing, Spatial frequencies, Light emitting diodes, Charge-coupled devices

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Proceedings Article | 1 September 2005 Paper

Automatic LCD electro-optical characteristics measurement system based on generalized spectroscopic ellipsometry

Gao-Wei Chang, Yu-Hsuan Lin

Proceedings Volume 5875, 58750W (2005) https://doi.org/10.1117/12.616875

KEYWORDS: Liquid crystals, LCDs, Electro optics, Spectroscopic ellipsometry, Electro optical systems, Ellipsometry, Refractive index, Light sources, Thin films, Interfaces

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Proceedings Article | 24 August 2005 Paper

Design and implementation of high-performance and cost-effective white-light interferometric profile measurement systems

Gao-Wei Chang, Yu-Hsuan Lin, Chi-Cheng Kuan

Proceedings Volume 5878, 58781C (2005) https://doi.org/10.1117/12.616765

KEYWORDS: Optical filters, Light sources, Interferometry, Light, 3D metrology, Charge-coupled devices, Spectral coherence, Superposition, 3D image processing, Ferroelectric materials

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White light interferometry (WLI) has played an important role in nano- and micro-scale profile measurement technology. To meet the demand of high-accuracy, high-repeatability, and cost-effective measurement, the research activities on WLI and its applications are rapidly in progress. WLI is based on the superposition of waves with different but very close wavelengths to produce beat phenomena (or to generate detectable envelopes in the interferogram) and then to identify the locations of the zero-order interference fringes (or those of the maximum intensities of interference fringes without the optical path difference). The locations reflect the information of three dimensional (3D) surface profiles from the consecutively acquired images in a WLI system. The objective of this paper is to develop a high-accuracy and cost-effective WLI measurement system, especially for the surfaces of micro-mechatronic devices, micro-optical components, semiconductor devices, etc. In our approach, the feasibility of the use of spectral coherence properties to meet the system design requirement is first investigated. Specifically, proper spectral filters are employed to enhance the coherence length of the light source (i.e., that of the filtered light source) to an order of ten micrometers. Then, a Young's double-slit interference experiment with filtered and unfiltered white light sources is conducted to demonstrate the effectiveness of this technique. Also, we adopt a Michelson interferometric configuration as the optical module of the proposed WLI system, for the sake of its simplicity. Experimental results indicate that several inexpensive spectral filters, a lower-grade charge-couple-device (CCD) image sensor, and a PZT (piezoelectric transducer) with a lower movement resolution are merely needed to develop the WLI system, instead of the use of higher-grade optical and optomechanical components. It turns out that the proposed system with high-accuracy measurement performance is more cost-effective than others.

Proceedings Article | 24 August 2005 Paper

Optomechanical analysis for confocal laser scanning microscopes

Gao-Wei Chang, Ming-Jenq Twu, Yu-Hsuan Lin, Chia-Cheng Liao, Hung-Zen Kuo

Proceedings Volume 5877, 587710 (2005) https://doi.org/10.1117/12.616640

KEYWORDS: Confocal microscopy, Microscopes, Sensors, Objectives, Point spread functions, Image processing, Laser scanners, Optical simulations, Tolerancing, Light sources

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Proceedings Article | 19 February 2004 Paper

Design and analysis of filter-based optical systems for spectral responsivity estimation of digital video cameras

Gao-Wei Chang, Hong-Da Jian, Zong-Mu Yeh, Chin-Pao Cheng

Proceedings Volume 5251, (2004) https://doi.org/10.1117/12.513500

KEYWORDS: Optical filters, Cameras, Signal to noise ratio, Optical design, Interference (communication), Error analysis, Filtering (signal processing), Video, Signal processing, Quantization

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Proceedings Article | 5 February 2004 Paper

Spectral responsivity estimation and noise effect analysis for digital imaging systems

Gao-Wei Chang, Hung-Zen Kuo, Chung-Fan Tu

Proceedings Volume 5238, (2004) https://doi.org/10.1117/12.511529

KEYWORDS: Optical filters, Filtering (signal processing), Cameras, Condition numbers, Imaging systems, Digital imaging, Error analysis, RGB color model, Image filtering, Image processing

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Proceedings Article | 14 August 2003 Paper

Automatic spectral transmittance measurement system for DWDM filters

Gao-Wei Chang, Ming-Yu Heish

Proceedings Volume 5246, (2003) https://doi.org/10.1117/12.511086

KEYWORDS: Optical filters, Dense wavelength division multiplexing, Transmittance, Monochromators, Spectral resolution, Light sources, Filtering (signal processing), Optical design, Telecommunications, Tunable lasers

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SPIE Journal Paper | 1 October 2000

Colorimetric modeling for vision systems

Gao-Wei Chang, Yung-Chang Chen

JEI, Vol. 9, Issue 04, (October 2000) https://doi.org/10.1117/12.10.1117/1.1289355

KEYWORDS: Cameras, Systems modeling, Visual process modeling, Imaging systems, RGB color model, Optical filters, Process modeling, Mathematical modeling, Color imaging, Imaging devices

Proceedings Article | 18 June 1998 Paper

Colorimetric calibration of CCD cameras for self-luminous images

Gao-Wei Chang, Yung-Chang Chen

Proceedings Volume 3422, (1998) https://doi.org/10.1117/12.311094

KEYWORDS: CCD cameras, Calibration, CRTs, Light emitting diodes, RGB color model, Color and brightness control algorithms, Detection and tracking algorithms, Light sources, Image processing, Modulation

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Proceedings Article | 18 June 1998 Paper

Spectral estimation of color CCD cameras

Gao-Wei Chang, Yung-Chang Chen

Proceedings Volume 3422, (1998) https://doi.org/10.1117/12.311073

KEYWORDS: CCD cameras, Modulation, Imaging systems, CRTs, Light sources, Optical filters, Image processing, Spectral resolution, Silicon, Light

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Showing 5 of 18 publications

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