The Yellow-Ring Measurement of White LED by the Reflective Lightspot Method (RLM)

2013 ◽  
Vol 284-287 ◽  
pp. 2805-2811
Author(s):  
Ching Ching Yang ◽  
Hsin Yi Tsai ◽  
Wen Tse Hsiao ◽  
Kuo Cheng Huang
Keyword(s):  
Beam Splitter ◽  
Optical Axis ◽  
Ccd Camera ◽  
White Led ◽  
Automatic Inspection ◽  
Phosphor Layer ◽  
The Real ◽  
Acrylic Plate ◽  
Working Distance ◽  
Plm System

The yellow-ring (YR) is a chromatism phenomenon which is caused by the inhomogeneous phosphor layer of the white-light LED (WLED). The characterized lightspot with YR is that the yellow light appears in the periphery of white lightspot zone. The lightspot image of WLED can be acquired from two approaches; projective lightspot method (PLM) and transmissive lightspot method (TLM). By the PLM system, the lightspot could be projected on the spot screen (wall or others) and its image is acquired by a CCD camera. However, the working distance between camera and sample WLED must be larger (~ 2 m) to obtain the lightspot image without tilt aberration. For the convenience of automatic inspection, the working distance in the TLM system can be modified to 0.3 m. Since the light travels through the spot screen, such as copier paper or acrylic plate, etc., the camera cannot obtain the real lightspot image in the TLM system. In practice, the material of spot screen will absorb and scatter the WLED light, and in the image color would be a bit different between the real lightspot and the acquired lightspot. In order to improve the above disadvantages, the study presents the reflective lightspot method (RLM) that the camera acquires the reflective lightspot image from the 50/50 beam splitter at the same optical axis. The RLM system is not only able to capture the tilt-less lightspot image, but also obtain readily the non-saturated image. The experiment results show the RLM system has the better evaluation of YR index (YRI), and is more suitable for the automatic inspection of WLEDs.

Designing high-resolution slow scan CCD-based TEM camera systems

1992 ◽  
Vol 50 (2) ◽  
pp. 946-947
Author(s):  
James F. Mancuso ◽  
William B. Maxwell ◽  
Russell E. Camp ◽  
Mark H. Ellisman
Keyword(s):  
Fiber Optics ◽  
Ccd Camera ◽  
High Energy ◽  
Phosphor Layer ◽  
X Ray ◽  
Light Production ◽  
Camera Systems ◽  
X Ray Imaging ◽  
Electron Image ◽  
Scintillating Fiber

The imaging requirements for 1000 line CCD camera systems include resolution, sensitivity, and field of view. In electronic camera systems these characteristics are determined primarily by the performance of the electro-optic interface. This component converts the electron image into a light image which is ultimately received by a camera sensor.Light production in the interface occurs when high energy electrons strike a phosphor or scintillator. Resolution is limited by electron scattering and absorption. For a constant resolution, more energy deposition occurs in denser phosphors (Figure 1). In this respect, high density x-ray phosphors such as Gd2O2S are better than ZnS based cathode ray tube phosphors. Scintillating fiber optics can be used instead of a discrete phosphor layer. The resolution of scintillating fiber optics that are used in x-ray imaging exceed 20 1p/mm and can be made very large. An example of a digital TEM image using a scintillating fiber optic plate is shown in Figure 2.

Study of reflection-beam shape using beam splitter and CCD camera

2015 ◽  
Author(s):  
Binh X. Cao ◽  
Munju Bae ◽  
Park Jiyeon ◽  
Hyonkee Sohn ◽  
Jiwhan Noh
Keyword(s):  
Beam Splitter ◽  
Ccd Camera ◽  
Beam Shape

Research on Screw Thread Form Based on Non-Contact Measurement

2011 ◽  
Vol 101-102 ◽  
pp. 593-596
Author(s):  
Shao Feng Shen ◽  
Xian Cheng Wang ◽  
Jun Hua Chen
Keyword(s):  
Measurement Accuracy ◽  
Optical Axis ◽  
Optical Field ◽  
New Method ◽  
Detection Accuracy ◽  
Screw Thread ◽  
Characteristic Parameters ◽  
The Real ◽  
Contact Measurement ◽  
High Skill

There is a problem with non-contact measurement and detection, which reduces its measurement accuracy. Methods developed for measuring and inspecting screw thread characteristic parameters usually using a camera, which is controlled to scan the projection of thread in the parallel optical field to obtain thread images. However, with the block of screw line on the projection of the real thread form, it is impossible to acquire the real thread form from images. The traditional way is adjusting the optical axis to a suitable angle with the thread axis to acquire the real thread form projection, which has some problems, such as time consuming, high skill of operator, high-precision equipment for adjustment, inaccuracy, and so on. Hence, a new method through digital image calibration is presented. The results of relevant simulation indicated the feasibility of this new method, which improves thread measurement and detection accuracy.

Failure Mechanism of Phosphor Layer for High-Power GaN-Based White-LED

2012 ◽  
Vol 49 (10) ◽  
pp. 102302
Author(s):  
吴艳艳 Wu Yanyan ◽  
冯士维 Feng Shiwei ◽  
周舟 Zhou Zhou ◽  
魏光华 Wei Guanghua
Keyword(s):  
Failure Mechanism ◽  
High Power ◽  
White Led ◽  
Phosphor Layer

Development of Inspection Machine that Detect Small Particles Added on Surface with Precise Pattern by Capturing Backwards Scattered Polarized Light

2012 ◽  
Vol 6 (6) ◽  
pp. 781-791 ◽  
Author(s):  
Tsuyoshi Nomura ◽  
◽  
Tatsuo Nagasaki ◽  
Masami Ito
Keyword(s):  
Optical System ◽  
Small Particle ◽  
Laser Light ◽  
Polarized Light ◽  
Ccd Camera ◽  
Horizontal Line ◽  
Small Particles ◽  
The Real ◽  
Inspection Machine

The paper discusses the development of inspectionmachine to detect small particle by capturing backwards scattered polarized light. The proposed optical system consists of very low angle (2°) horizontal line laser light withSpolarized characteristics and angle 150° backwards line CCD Camera to capturePpolarized light from particles on wafer or glass and so on. This system is confirmed to apply the real production of wafer or glass.

Study on Inspection Methods for High-Speed Progressive-Die Punched Strips

2014 ◽  
Vol 940 ◽  
pp. 69-73
Author(s):  
Zheng Ping Hai ◽  
Zhi Hong Yang ◽  
Jian Hua Ning
Keyword(s):  
Real Time ◽  
High Speed ◽  
Automatic Inspection ◽  
Charge Coupled Device ◽  
Progressive Die ◽  
The Real ◽  
Online Inspection

The inspection of sheet strips post high-speed punching mainly relies on the manual off-line inspection with basic inspection equipment or CCD equipment. Such inspections cannot reflect the real-time conformity of strip machining, and in severe cases, lead to rejects in batches, causing a tremendous waste in production. Now that the application of charge-coupled device (CCD) technology in product inspection is relatively mature, it would be a very good thought to adopt the CCD technology to realize real-time online inspection of conformity of the high-speed punched strips. KeyWords: CCD technology; strip; online automatic inspection; progressive die

Faulty Scarfing Slab Detection Using Machine Vision

2012 ◽  
Vol 462 ◽  
pp. 185-190 ◽  
Author(s):  
Doo Chul Choi ◽  
Yong Ju Jeon ◽  
Sang Woo Kim
Keyword(s):  
Machine Vision ◽  
False Alarm ◽  
Imaginary Part ◽  
Gabor Filter ◽  
Detection Algorithm ◽  
Inspection System ◽  
Automatic Inspection ◽  
Finished Steel ◽  
The Real

In this study, we developed a detection algorithm using machine vision for faulty scarfing on slabs. Scarfing is a process for burning out defective areas on the surface of semi-finished steel products so that the product is suitable for subsequent rolling or forging. In the case of rolling, a poorly scarfed slab can cause serious defects. Therefore, an automatic inspection system for scarfed slabs should be developed. In the image of faultily scarfed slab, discontinuous bright bands and borderlines are observed. To detect the bright bands, we examined the real part of a Gabor filter. However, because the size of the bright bands is not fixed, the parameters of the real part of the Gabor filter were determined adaptively using the imaginary part of the Gabor filter. The performance of the proposed algorithm was tested with 2292 images of scarfed slabs of which 49 of the images were of faulty scarfed slabs. The proposed algorithm was able to detect defects with 95.9% accurate and the false alarm was 1.6%.

scholarly journals The Effects of TiO2 Diffuser-Loaded Encapsulation on Corrected Color Temperature Uniformity of Remote Phosphor White LEDs

2019 ◽  
Vol 9 (4) ◽  
pp. 675 ◽  
Author(s):  
Yung-Fang Chou ◽  
Chi-Feng Chen ◽  
Shang-Ping Ying ◽  
Yun-Ying Yeh
Keyword(s):  
Energy Efficient ◽  
High Efficiency ◽  
Luminous Flux ◽  
Color Temperature ◽  
White Led ◽  
Phosphor Layer ◽  
White Leds ◽  
Color Uniformity ◽  
Remote Phosphor ◽  
The Mean

With the development of high-efficiency and high-power LEDs, they have become the most energy-efficient and environmentally friendly artificial light source. Phosphor-converted white LEDs are currently mainstream in the market. The remote phosphor is an effective way to enhance the conversion efficiency and lifetime of phosphor-converted LEDs. For applications of high-quality lighting and LCD backlights, the uniformity of angular correlated color temperature (CCT) is very important. This report explored a remote phosphor white LED with low angular CCT variance and high luminous efficiency by using TiO2 diffuser-loaded encapsulation. Experimental results revealed that for the TiO2 diffuser-loaded encapsulation remote phosphor white LED, the angular color uniformity could be improved by 31.82% and the luminous flux by 8.65%. Moreover, the mean CCTs of the TiO2 diffuser-loaded encapsulation and non-diffuser remote phosphor white LEDs were similar at a driving current of 350 mA. Finally, we showed that incorporating the TiO2 diffuser into the phosphor layer of the remote phosphor white LEDs, does not influence the reliability of the LED.

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