教師著作

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    Opto-mechanical analysis for confocal laser scanning microscopes
    (The International Society for Optical Engineering (SPIE), 2005-08-02) Chang, Gao-Wei; Twu, Ming-Jenq; Lin, Yu-Hsuan; Liao, Chia-Cheng; Kuo, Hung-Zen
    The confocal imaging has become one of the most widely applied microscopic techniques in various fields, such as biotechnology, automation engineering, optical engineering, solid-state physics, metallurgy, integrated circuit inspection, etc. Confocal laser scanning microscopy (CLSM) is primarily based on the use of apertures in the detection path to provide the acquired three-dimensional images with satisfactory contrast and resolution. The major objective of this paper is to analyze the imaging performance of the confocal microscopes with varying opto-mechanical conditions. In this paper, the working principles of the one- and two-dimensional scanning mechanisms in the microscopic systems are first reviewed and verified by opto-mechanical simulations. Then, for the imaging performance, the tolerance to the fabrication and assembly of the optical components in conventional confocal microscopes is also investigated by simulations. The simulation results indicate the importance of eliminating the effects of stray light in the microscopic systems.
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    Design and Implementation of Confocal Imaging Systems with a Generalized Theoretical Framework
    (Society of Photo-optical Instrumentation Engineers (SPIE), 2007-02-17) Chang, Gao-Wei; Liao, Chia-Cheng; Yeh, Zong-Mu
    Confocal imaging is primarily based on the use of apertures in the detection path to provide the acquired three-dimensional images with satisfactory contrast and resolution. For many years, it has become an important mode of imaging in microscopy. In biotechnology and related industries, this technique has powerful abilities of biomedical inspection and material detection with high spatial resolution, and furthermore it can combine with fluorescence microscopy to get more useful information. The objective of this paper is first to present a generalized theoretical framework for confocal imaging systems, and then efficiently to design and implement such systems with satisfactory imaging resolutions. In our approach, a theoretical review for confocal imaging is given to investigate this technique from theory to practice. Also, computer simulations are performed to analyze the imaging performance with varying optomechanical conditions. For instance, the effects of stray light on the microscopic systems are examined using the simulations. In this paper, a modified optomechanical structure for the imaging process is proposed to reduce the undesired effects. From the simulation results, it appears that the modified structure highly improves the system signal-to-noise ratio. Furthermore, the imaging resolution is improved through the investigation on the tolerance of fabrication and assembly of the optical components. In the experiments, it is found that the imaging resolution of the proposed system is less sensitive than that of common microscopes, to the position deviations arising from installations of the optical components, such as those from the pinhole and the objective lens.
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    Accurate and cost-effective MTF measurement system for lens modules of digital cameras
    (SPIE, 2007-01-30) Chang, Gao-Wei; Liao, Chia-Cheng; Yeh, Zong-Mu
    For many years, the widening use of digital imaging products, e.g., digital cameras, has given rise to much attention in the market of consumer electronics. However, it is important to measure and enhance the imaging performance of the digital ones, compared to that of conventional cameras (with photographic films). For example, the effect of diffraction arising from the miniaturization of the optical modules tends to decrease the image resolution. As a figure of merit, modulation transfer function (MTF) has been broadly employed to estimate the image quality. Therefore, the objective of this paper is to design and implement an accurate and cost-effective MTF measurement system for the digital camera. Once the MTF of the sensor array is provided, that of the optical module can be then obtained. In this approach, a spatial light modulator (SLM) is employed to modulate the spatial frequency of light emitted from the light-source. The modulated light going through the camera under test is consecutively detected by the sensors. The corresponding images formed from the camera are acquired by a computer and then, they are processed by an algorithm for computing the MTF. Finally, through the investigation on the measurement accuracy from various methods, such as from bar-target and spread-function methods, it appears that our approach gives quite satisfactory results.
  • Item
    Design and Implementation of Real-Time LED Spatial Radiance Measurement Systems
    (Society of Photo-optical Instrumentation Engineers (SPIE), 2007-02-13) Chang, Gao-Wei; Yeh, Zong-Mu; Liao, Chia-Cheng
    Light-emitting diodes (LEDs) have been recognized as a generation of new light sources because they possess the properties of energy-saving, environmental protection, long lifetime, and those lacking in conventional lighting. To satisfy the requirements for different applications (e.g., for large-scale displays), determining the spatial radiances of LEDs is important to identifying their viewing angle and utilizing their lighting efficiency. The objective of this paper is to build up a real-time spatial radiance measurement system for LEDs, on the basis of digital signal processing (DSP) techniques. In this paper, the system analysis is given to show the feasibility of this work. Two primary subsystems are devised to perform the real-time measurements. First, in the optoelectronic sensing and signal processing subsystem, a wide-bandwidth photodiode sensing circuit is employed to acquire optical signals at a high speed, and an automatic gain control (AGC) circuit is designed to increase the measurement range. To support high-speed data processing, a DSP-based platform is developed in the subsystem. Second, a light-source rotation scheme is used in the optomechanical subsystem. For performance evaluations, we adopt a standard calibrating light source to test and verify our system. Experimental results indicate that the proposed system gives satisfactory results.
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    A Progressive Design Approach to Enhance Project-based Learning in Applied Electronics through an Optoelectronic Sensing Project
    (Institute of Electrical and Electronics Engineers (IEEE), 2008-05-01) Chang, Gao-Wei; Yeh, Zong-Mu; Pan, Shih-Yao; Liao, Chia-Cheng; Chang, Hsiu-Ming
    In this paper, a progressive design learning approach is proposed in the course of ldquoapplied electronicsrdquo to help students to develop system design skills through an optoelectronic sensing project. This project offers a progressive guideline to lead student teams to design, build, and troubleshoot their optoelectronic systems. Such a system contains a light-source current stabilizer, a photodiode amplifier, a microcontroller system (including input and output), and optomechanical devices. In this approach, students are motivated to learn the required knowledge and skills in a future professional capacity. Those skills include designing specification, realizing teamwork and communication, and developing a variety of optoelectronic sensing techniques. Through this project, an optoelectronic sensing system is established called a spatial radiance distribution measurement system for various light sources. In particular, this kind of system is useful and important for LED industries. The course evaluations have been obtained from classmates and instructors and these results indicate that the objectives of this course are achieved.