Search

This paper is to propose a systematic evaluation for paint messages among C++/CLI controls, e.g., form, button, and picture box. Specifically, the occurrences of such messages and priorities of their processing are investigated to enhance the design of programming models for graphical user interface (GUI). To demonstrate the effectiveness of this approach, those models are progressively integrated with processing paint messages from various controls, in a graphically-demanding C++/CLI project.

With a series of C++/CLI programming models, this paper is to propose an object-oriented framework to establish and explore the consistency of the migration design from hand-made to wizard readable codes in an integrated development environment (IDE), e.g., Microsoft Visual Studio (VS). To demonstrate the effectiveness of the migration approach, a sufficient-as-possible hand-made project is devised, where the controls include menu-strip, dialog box, and picture box, to achieve the command-driven graphics functionalities with numeric data.

The objective of this paper is to investigate the effect of message flows on Windows objects that are dynamically allocated in memory. In our approach, the tasks of retaining message flow and those of creating message loops are designed thru the use of modal and modeless forms (dialog boxes) from VC++ assemblies. Our experiments show that circulating message in a single thread can connect allocated objects and make them perform multithreading-like behavior.

The goal of this paper is to propose a programming model for supporting the technique of multithreading that performs real-time allocation of VC++ controls. In our approach, the design of task-interfacing class (TIC) plays an essential role in meeting the requirement of real-time, spatially distributed processing. Thru constructing the class, its object integrates multiple tasks as the class members, in preparation for the work of multithreading, where each task performs with an individual thread. Our experiments exhibit that the TIC model performs satisfactory results for the Windows programming.

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.

In response to the growing demand of photonic systems engineers in industries, this paper proposes a term project that help students gain insight into photonics instrumentation via a grating-based spectrometer. The students are guided through simulations and experiments for the spectral filtering system and then implement the spectrometer using some technical notes and testing kits. They perform experiments and tests to verify and refine their works. A contest is held at the end of the course where the measurement accuracy and repeatability of the proposed systems are evaluated. This project has been used for two semesters, and both the instructors' and the students' feedback are discussed.

This paper proposes a remote education system, Virtual Photonics Experiments Network (V-PEN), for teaching photonics experiments. In this approach, teaching and learning photonics become easier by the V-PEN. A design procedure for transforming real experiments to online experiments is also proposed, and a Michelson interference system as an example is employed to describe the procedures of the online experiments. This photonics experiment platform has been used for a semester. The survey of learners' feedback is also presented.

The spectral responsivities of a color video camera are very important electro-optical characteristics for image formation. An automatic testing and measurement system for camera spectral responsivities is proposed. This technique primarily involves a spectral characterization process. This process is to excite a camera by a collection of colored incident light, called color stimuli, so that the spectral features of camera imaging can be truly extracted from observations. In our experiments, the satisfactory results show that the normalized mean squares estimation errors for color channels are all less than 0.03. It appears that our approach considerably simplifies the hardware complexity of conventional approaches for spectral measurements.

We report a periodically poled lithium niobate (PPLN) crystal for both temperature-insensitive laser Q-switching and temperature-tuned wavelength conversion. The PPLN crystal consists of two sections, a 20.3-mum period section functioning as an electro-optic Bragg grating for Qswitching a diode-pumped Nd:YVO4 laser at 1064 nm and a 31-mum-period section functioning as an optical parametric generator for down converting the generated 1064-nm laser. When driving the PPLN Bragg grating with 170-V voltage pulses, we measured 181 muJ pulse energy at 1064 nm from the Nd:YVO4 laser pumped by 20.4 W diode power. The 181-muJ pulsed laser was further converted into mid-infrared radiation in the monolithic PPLN crystal with 35% parametric efficiency. The wavelengths were broadly tunable in the range of 1.75-1.88 mum (signal) and 2.7-2.44 mum (idler) via temperature without affecting the performance of the PPLN Bragg Qswitch.

We demonstrate the PPLN crystal as a laser Q-switch by using electro-optic Bragg modulator effect and generate 200-muJ/pulse with 10 kHz switching rate at 19-W diode pump power.

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.

For years, the technology of TFT-LCDs (thin-film-transistor liquid crystal displays) has grown very rapidly, especially in the market share and technical development of FPD industries. To effectively promote the industry's capacity for the mass production and quality control, it is urgent to design and develop LC cell optical parameter measurement systems. The goal of this paper is to develop a multiple-functional and cost-effective measurement system to lower the manufacturing cost for the industry. The optical parameters includes the pretilt angle, liquid crystal (LC) cell gap (or phase retardation), and twist angle, which highly influence the display quality. In this paper, we first study the past approaches and analyze their measurement performance. Then, a simple and cost-effective method is proposed to achieve the multiple functions. That is, in addition to the precise measurement of the three important optical parameters, the proposed system can measure the voltage-transmittance (V-T) curve. In our approach, the theoretical study, simulation, and experiment are performed to show the feasibility of the system implementation. Finally, the proposed system is developed to automatically measure the LC cell parameters. Experimental results indicate that the proposed measurement system gives a satisfactory result.

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.

With the rapid growth of optoelectronics technologies, photodiodes (PDs) has been widely used in optical measurement systems, color measurement and analysis systems, etc. To meet most of the measurement requirements, the determination of PD spectral responses is very important. The goal of this paper is to develop a high-accuracy and cost-effective spectral response measurement system for PDs. In this paper, the proposed system contains a grating-based spectral filtering module, an amplifier module, and a digital-signal-processing (DSP) based platform. In the spectral filtering module, a single-grating monochromator based on a Czerny-Turner configuration is first analyzed and simulated, and then the experiments are conducted to check if the measurement accuracy is satisfactory. In the measurement system, optoelectronic signals from the PD under test are acquired from the amplifier module and the DSP-based platform is developed to communicate and manipulate the measured data. Through comparison with the measurement data from a commercially available system, it is found that our approach gives quite satisfactory results.

In imaging systems, color plays an essential role in conveying and recording visual information from the real world. To faithfully represent colors acquired from digital cameras, a spectral responsivity measurement system is proposed for those devices in this paper. For estimating spectral responsiv ities of digital color cameras, a filter-based optical system is designed with proper filter selections. Since the spectral filters primarily prescribe the optical characteristics of the system, the filter consideration is important to the optical design of the system with the presence of noise. A theoretical basis is presented to confirm that sophis ticated filter selections can make this sy stem as insensitive to noise as possible. Also, we propose a filter selection method based on the or thogonal-triangular (QR) decomposition with column pivoting (QRCP). To investigate the noise effects, we assess the estimation errors between the actual and estimated spectral responsivities, with the different signal-to-noise ratio (SNR) levels of an eight-bit/channel camera. To demonstrate the effectiveness of this approach, the experimental results from the filter-based optical system with the spectral filters selected from the QRCP-based method is much less sensitive to noise than those with other filters from different selections. It is found that the measuremen t accuracy is fairly satisfactory. Key words : Filter-based optical systems, orthogonal-trian gular (QR) decomposition with column pivoting.

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.

It is well known that white light interferometry (WLI) is important to nano-scale 3-D profile measurement technology. To archive cost-effective and accurate measurements, the researches for WLI are widely spreading. Our objective is to build up a 3-D micro-structure profile measurement system based on WLI, for micro-mechatronic, micro-optical, and semi-conductor devices. This paper briefly reviews related WLI theory and then the principle of spectral coherence is employed to improve the system design. Specifically, proper spectral filters can be used to extend the coherence length of the light source to the order of several ten micrometers. That is, the coherence length of the filtered light source is longer than that of the original source. In this paper, Michelson interference experiments are conducted with filtered and unfiltered white light sources, to show the feasibility of the concept of spectral coherence. The Michelson interferometer is adopted due to its convenience of optical installation and its acceptable tolerance to noise. The experiment results indicate that our approach is feasible and thus it can improve the WLI measurement performance.

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.

With the increasing demand on miniaturization of optical modules, it is important to measure their image quality for consumer electronic devices, such as video cameras, mobile phones, etc. This is because the effect of diffraction arises from the miniaturized optical modules and as a result, it degrades the resolution of the imaging processes. Modulation transfer function (MTF) has been widely recognized as a useful and important tool for assessing the image quality. Therefore, the objective of this paper is to develop a MTF measurement system for the optical modules, on the basis of digital signal processing. In our approach, a spatial light modulator (SLM) is employed to spatially modulate the light, which is emitted from a white-light LED, with the bar patterns of variable frequencies, the modulated light then goes through the module under test, and it is eventually detected by a charge-couple-device (CCD). Obviously, the mapping from the collection of the modulated light to the output images is treated as a computation kernel of the MTF measurement. The corresponding images formed by the optical module are acquired by a digital signal processor (DSP) based system and they are processed by an algorithm for computing the MTF, which is implemented in the system. Finally, it is found that our experiments give quite satisfactory results.

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.

Liquid crystal displays (LCDs) or thin-film transistor (TFT) LCDs have been regarded as a promising technology in flat panel displays (FPDs). To meet the demands of the mass production and quality control, the development of automatic electro-optical characteristics measurement systems for LCDs is very important. To achieve this, we propose a generalized spectroscopic ellipsometry (GSE) based technique to measure the characteristics of LCDs. Our approach involves two primary steps. First, we review a theoretical basis for generalized spectroscopic ellipsometries for the LCD measurement. Those are mainly categorized into two classes of ellipsometries: the transmission variable angle spectroscopic ellipsometry (VASE) and the spectroscopic ellipsometry (SE) using a photoelastic modulator (PEM), called PEM SE. Second, on the basis of the VASE and PEM SE, we present a GSE-based system to measure the electro-optical characteristics for twisted nematic liquid crystals (TNLCs) and super twisted nematic liquid crystals (STNLCs). In this paper, the simulation results indicate the feasibility of this technique. Finally, the automatic GSE-based system is presented for measuring the LCD electro-optical characteristics.

For estimating spectral responsivities of digital video cameras, a filter-based optical system is designed with sophisticated filter selections, in this paper. The filter consideration in the presence of noise is central to the optical systems design, since the spectral filters primarily prescribe the structure of the perturbed system. A theoretical basis is presented to confirm that sophisticated filter selections can make this system as insensitive to noise as possible. Also, we propose a filter selection method based on the orthogonal-triangular (QR) decomposition with column pivoting (QRCP). To investigate the noise effects, we assess the estimation errors between the actual and estimated spectral responsivities, with the different signal-to-noise ratio (SNR) levels of an eight-bit/channel camera. Simulation results indicate that the proposed method yields satisfactory estimation accuracy. That is, the filter-based optical system with the spectral filters selected from the QRCP-based method is much less sensitive to noise than those with other filters from different selections.

The determination of spectral responsivities plays a significant role in analyzing and predicting the performance of digital imaging systems for remote sensing. For example, given the spectral response functions, we can readily obtain the colorimetric data from a camera corresponding to the remote illuminated objects. In this paper, we develop a filter-based optical system to estimate these functions. The design objective of this system is to effectively select a limited amount of spectral (or broadband) filters to characterize the spectral features of color imaging processes, which are contaminated with noise, so that the spectral response functions can be estimated with satisfactory accuracy. In our approach, a theoretical study is first presented to pave the way for this work, and then we propose a filter selection method based on the technique of orthogonal-triangular (QR) decomposition with column pivoting, called QRCP method. This method involves QR computations and a column permutation process, which determines a permutation matrix to conduct the subset (or filter) selection. Experimental results reveal that the proposed technique is truly consistent with the theoretical study on filter selections. As expected, the optical system with the filters selected from the QRCP method is much less sensitive to noise than those with other spectral filters from different selections. It turns out that our approach is an effective way to implement the optical system for estimating spectral responsivities of digital imaging systems.

For many years, fiber-optics communication has become an essential part of the development of our modern society. For example, its significance comes from the increasing demands on real-time image transmission, multimedia communication, distance learning, video-conferencing, video telephone, and cable TV, etc. This paper is to develop an automatic transmittance measurement system for a DWDM (dense wavelength division multiplexing) filter. In this system, a grating-based monochromators is devised to generate a collection of monochromatic light with various wavelengths, instead of using an expensive tunable laser. From this approach, the cost of the proposed system will be much lower than that of those having the same functions, by one order. In addition, we simulate the spectral filtering to investigate the resolving power of the system. It appears that our simulations give quite satisfactory results.

The process of eliminating the color errors from the gamut mismatch, resolution conversion, quantization and nonlinearity between scanner and printer is usually recognized as an essential issue of color reproduction. A new formulation based on the inverse plant control for the color error reduction process is presented. In this formulation, the printer input and scanner output correspond to the input and output of a system plant respectively. If the printer input equals the scanner output, there are no color errors involved in the entire system, i.e., the plant becomes an identity system. To achieve this goal, a plant inverse should be identified and added to the original system. Since the system of a combination of both scanner and printer is highly nonlinear, multilayer backpropagation neural networks, which have the capability to learn arbitrary nonlinearity, are applied to identify the plant inverse. A number of test samples are conducted to verify the effectiveness of the proposed method. >

This paper presents the design and implementation of a CMAC neural network chip used in color image reproduction systems for color correction. An effective address mapping procedure is proposed to implement the hardware architecture of CMAC model, which has the advantages of high processing speed and low chip area overhead. VHDL-based high-level synthesis approach is employed for the synthesis of logic circuit of CMAC chip. >

Summary form only given.Wireless communication and microwave technology need a microwave signal with high spectral purity and stability. We obtained a signal of this quality from an optoelectronic oscillator (OEO). In order to improve the quality of the OEO further, we successfully built a self-pulse injection locked OEO. The self-pulse-injection locked oscillator is described. The bandwidth of the modulator and the PIN photodetector are both 6 GHz.

Reproducing colors with rich saturation, from illuminating objects, is usually recognized as an essential issue for CCD camera imaging. In this paper, we propose a colorimetric calibration scheme regarding self-luminous images for CCD cameras. And, an efficient algorithm to generate highly saturated color stimuli is devised for investigating the CCD camera performance of image reproduction. In this scheme, a set of color samples containing highly saturated colors is generated, from an advanced CRT, as color stimuli for colorimetric characterization. To demonstrate the effectiveness of this algorithm, a realization of color samples, uniformly distributed in CIE LAB, are presented for illustration.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The spectral sensitivity of a CCD camera is a prominent electro-optical characteristic for color image formation. In this paper, spectral estimation of color CCD cameras generally involves the assessment of overall spectral sensitivities, which are composed of those of optics, filters, and CCD sensors. To this end, we develop an automatic testing/measurement system with an optical platform. And, the spectral characterization of a CCD camera imaging process is presented in the approach of vector representation for the estimation problem. This technique examines the modulated incident colored lights, which are regarded as a set of color stimuli candidates, to be the effective color stimuli, such that they can be successfully applied to generic estimation algorithms. To show the feasibility of this work, a realization of a basic set of color stimuli candidates is generated in the numerical and graphical forms. In our approach the use of a spectrophotometer is needed only for the system calibration. It would be pleasing that this technique will practically simplify the complexity of the spectral estimation problem of CCD cameras.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We report an electro-optic Bragg modulator using a periodically poled lithium niobate (PPLN) crystal. We measured a half-wave voltage of 160 V when transmitting a 1064 nm laser through a 14.2 mm long, 780 microm thick, 20.13 microm period PPLN crystal at the Bragg angle. We also demonstrated a Q-switched Nd:YVO(4) laser using such a PPLN Bragg modulator as its Q-switch, producing 7.8 ns, 201 microJ pulses at a 10 kHz repetition rate when pumped by a 19.35 W diode laser at 808 nm.

A colorimetric modeling technique is proposed to give a computational model associated with colorimetry so that the repre- sentation of color acquired from camera imaging is accurate and meaningful. First of all, the camera spectral responses are esti- mated and the colorimetric quality is evaluated to reveal the feasi- bility of this work. In the modeling process, we present a spectral matching method and an approach of determining a reference-white luminance. As a result, the acquired color and the true (or mea- sured) color can be well coordinated, with the strength of a global illumination or display white, in a perceptually uniform color space, e.g., in CIE 1976 L*a*b* space (abbreviated as CIELAB). Then, lower-degree polynomial regression is employed to eliminate color errors due to the mismatch between spectral response functions. Experimental results indicate that the root-mean-square DEab value (i.e., color error) from the degree-3 polynomial regression is less than a just-noticeable difference (about 2.3) in CIELAB. It appears that the proposed technique can establish an accurate colorimetric model for vision systems. © 2000 SPIE and IS&T. (S1017-9909(00)01604-4)