2006.12
About Instruments Today No. 155
The Era of LED Lighting Has Come [ 下載 PDF ]
Bin-Juine Huang
LED is a cold light source with heat dissipation rate several times higher than traditional light sources. The requirement of operating junction temperature limit at < 90 °C makes the heat dissipation become very difficult. However, the directness of LED lighting leads to a higher lighting efficiency to the target. The high-power LED lighting efficiency has been shown as the first time to be able to exceed the traditional lighting technology such as mercury or sodium lamps. The latest research results by New Energy Center of National Taiwan University has shown that a single LED fixture can illuminate 8,836 lumen at 150 W power input, with fixture efficacy 63 lm/W which may be the world record for high-power LED lighting. The fixture weighs 8.5 kg. At 10 m lamp height, the average luminous flux on road surface is 18.5 lx with max value 47 lx and uniformity 3.2, which meets the IESNA standard for roadway lighting.
Quantum-Cutting Phosphors and Their Application in Green Lighting [ 下載 PDF ]
Teng-Ming Chen, Te-Ju Lee
The principle of quantum cutting (QC), QC phosphors, and experimental instrumentations are introduced and reviewed in the article. Recently, intensive research activity has been focused on QC by down conversion mechanism in rare-earth-doped phosphors in the vacuum ultraviolet (VUV) spectral region, mainly because VUV-excited phosphors are indispensable for applications of plasma display panels (PDP) and mercury-free lighting. With proper design by integrating rare earth ions into appropriate host matrix materials, the quantum efficiency of QC phosphors can reach in principle up to 195% (i.e., LiGdF4:Eu) and 194% (i.e., BaF2:Gd, Eu), respectively. Furthermore, the research on QC phosphors generally requires light source such as synchrotron radiation. The QC phosphor K2GdF5:Tb3+ is used herein as an example to illustrate the investigation of VUV spectroscopy, mechanism of QC, and the quantum efficiency as a function of Tb3+ dopant content.
Application of LED for Projector Illumination [ 下載 PDF ]
Cheng-Huan Chen
The function of illumination optics for projection displays is to direct light source onto a small area of microdisplay within a limited incident solid angle, and therefore the collection efficiency is especially important compared to other illumination applications, which is also the main technical issue for LED application to projection displays. This paper starts from the introduction of projector illumination optics and then illustrates the merit and drawback of exploiting LED as the light source for projection displays by comparing LED with traditional projector lamps. Finally a review on the LED illumination optics for projectors and development of LED dedicated for projectors will be given.
The Application of Automatic Optical Inspection on Backlight Unit Inspector [ 下載 PDF ]
Ruei-Hung Tsai, Tzu-Hsuan Wei, Jen-Yu Wen, Jui-Pi Chen
LCD manufacturing is one of the core industries in Taiwan's 'Two Trillion & Twin Star Industries Development Plan', and it is now still growing. To display image, LCD needs a light source, and the most common way is to use backlight units (BLU), where CCFL and LED dominate the market at present moment. Between these two light sources, LED has more advantages beyond CCFL, and as a result, the market share is changing. ITRC, based on many-years experience in remote sensing instrument development, has achieved the first in-line BLU inspector to supplement the growing industry in Taiwan. This article describes the development status of BLU and corresponding inspection instruments.
Diffusion MR White Matter Tractography [ 下載 PDF ]
Wen-Yih Isaac Tseng, Kuo-Chiang Chu
MRI can be used to probe internal structure and function of a living body by magnetically labeling the proton spins with the physical property of interest. The theory and experiment of measuring diffusion coefficients in terms of MR signal attenuation has been established for decades, but recent advance of diffusion tractography has enabled us, for the first time, to visualize and analyze the axonal fiber tracts in the living brain non-invasively. To date, significant progress in technical development has been made to resolve complicated geometry of fiber tracts. This unique capability opens up a door to the study of cytoarchitectural changes of cerebral white matter in neurological or psychiatric diseases. The purpose of this article, therefore, is to introduce the basic principles of MR diffusion tractography, state-of-the-art techniques and its applications to neuroimaging.
Introduction to Solid-State NMR Spectroscopy [ 下載 PDF ]
Jerry Chun Chung Chan
Nuclear magnetic resonance (NMR) spectroscopy has a large variety of applications. To date, six scholars have been granted the Nobel prizes because of their NMR based research. There are three sub-disciplines in NMR spectroscopy, viz. the solution-state NMR, solid-state NMR and magnetic resonance imaging. In this short review article, we will briefly discuss some of the common techniques of solid-state NMR and their related applications, including the determination of backbone torsion angle of polypeptides, the structural elucidation of glass systems, and the study of biomineralization.
Resonant Soft X-Ray Scattering [ 下載 PDF ]
Di-Jing Huang, Hong-Ji Lin, Chien-Te Chen
The charge, orbital, or spin ordering of valence electrons in advanced materials can be incommensurate with the periodic structure of lattice. To detect such an ordering with conventional X-ray diffraction is difficult. Resonant soft X-ray scattering is a newly developed technique and sensitive to the charge, orbital, or spin ordering of valence electrons in transition-metal compounds. We present the basic principle, an experimental setup, and two examples of resonant soft X-ray scattering measurements.
The Circuit and System Design of Economical Linear CCD [ 下載 PDF ]
Yu-Chieh Chen, Feng-Chang Hsu, Tai-Shan Liao
The electric circuit of the high-resolution linear CCD image system often contains various kinds of noise because of the high pixel rate; therefore, reducing the noise to achieve good image sensing has become an important issue. Because of the increasing need for precision measurement, Automatic Optical Inspection (AOI) is now considered the main technology for quality control and precision measurement. However, most AOI systems in Taiwan are not only imported from other countries but also costly, and it is difficult to integrate AOI into manufacturing machines. This paper discusses noise reduction in the design of linear CCD systems and the employment of the high-resolution linear CCD module to include AOI in manufacturing equipment so that measurement and quality control can be integrated in a single machine to reduce the cost.
Introduction to Ion Beam Processing Technology (II) [ 下載 PDF ]
Han-Chang Pan, Chien-Ying Su, Chien-Nan Hsiao
A review of various ion beam assisted deposition (IAD) techniques of functional thin film is presented. The different kind of IAD techniques such as, sputtering and evaporation, chemical vapor deposition, reactive etching, and polymer surface modification are discussed. This is followed by a discussion of physical and chemical properties in use to explain ion-to-film interaction in the ion beam assisted process.
Improvement in Characteristics of Optical Fiber Amplifiers by Using the Residual Pump Sources [ 下載 PDF ]
Shien-Kuei Liaw, Cheng-Kai Huang, Yuan-Lung Hsiao, Tzu-Yu Chien
The paper investigates on improvement in two kinds of optical amplifiers characteristics using the residual pumping sources. The first part is to design a C+L band erbium doped fiber amplifier (EDFA) in a parallel-pumping loop-back scheme. For the C-band EDFA, the pumping laser is forward pumping; For the L-band EDFA, the optimal configuration is based on the utilization of two-stage pumping laser diodes. After reuse the residual pumping power, the improvement in gain and noise figure (NF) are realized. The second part is focused on high-efficiency Raman fiber amplifier (RFA). By setting up reflection route on the structure end, pumping efficiency is improved by the double-pass gain medium scheme for both signal and pump source. The efficiency of pump laser used in the structure is 69% higher than that of the conventional configuration. A higher gain and lower NF is achieved.
3-D Moiré Automatic Monitoring System Applied in the Pulse Measurement [ 下載 PDF ]
Rong-Seng Chang, Kai-Sheng Chen, Yu Wei Liou
The main purpose of this paper is to present an optical measurement system to monitor and measure the height and micro-movement of the surface. By the way of the optical characteristic, our system provides lots of advantages such as non-contact, non-invasive, fast running, and easy to setup. Using the shadow moiré combing with the computer program, the movement of the surface can be calculated by the change of the moiré fringe, and monitored with the time graphically and rapidly. Then, taking advantage of the regional measurement of the moiré, we enhance the analysis from a point to an area. By this system, we can catch the information of the surface entirely and more efficiently. And further, we design a pulse measurement system by the moire measurement system given above. According to the steps of pulse diagnosis of traditional Chinese medicine, we can catch pulse waveform, amplitude, and frequency easily. And the waveform is calculated from the vibration of our skin at the position on our wrist called the Guan point. These results are verified and showed that our system is feasible to measure the arterial pulsation of our body.
