Papers by Keyword: Light Source

Abstract: The Ce doped Strontium Magnesium silicate phosphor Sr₂MgSi₂O₇:Ce is compounded by using high temperature roasting process, and the plane sample of prepared phosphor is obtained by tablet press method. A modified MCJ-01A friction tester with the friction pair of glass bar against on the plane phosphor sample is used to determine the triboluminescence property of Ce doped Strontium Magnesium silicate phosphor in the linear contact sliding friction. Examination on the triboluminescence of Ce doped Strontium Magnesium silicate phosphor indicates that a quality triboluminescent phosphor with 448nm± blue spectrum emission can be obtained only in the 1200°C calcining temperature, and only 0.010 molar Ce doping concentration in the Sr₂MgSi₂O₇:Cex can promote the prepared phosphor to generate a higher triboluminecent emission and a smaller full width at half maximum (FWHM). The suitable level of applied load is beneficial to hold a balance between wear increment and spectrum intensity. Finally a triboluminescent unit with squirrel cage structure is constructed to realize the triboluminescence of multiple glass bars against on the cylindrical phosphor in the manner of sliding friction. This can satisfy the light emitting of 360o azimuth, and generate more tribological luminous flux.

Abstract: In order to investigate the influence of the light source with different illuminance and color temperature on the observers’ visual performance, five kinds of light sources were selected, named LED1, LED2, LED3, LED4 and Fluorescent, which have different illuminance or color temperature. 3 series of visual experiments, such as the ‘find out’ experiment, compared experiment, dose experiment were designed.13 observers were organized to carry out the experiment in the given time in turn. The reading rate, accuracy , index of mental capacity (IMC) and visual comfortable level score were analyzed, the results indicated that the light source with the lower color temperature and medium illuminance has the best visual performance and comfortable visual feel.

Abstract: Crack detection and monitoring has become one of a focus center for the health monitoring of engineering structures under the influence of mechanical deformation.This paper discusses the detecting, tracking and monitoring mechanisms for the crack, by initiating a sensing system by using a standard notched specimen. Crack features such as magnitude of crack travel versus crack opening are displacement indicators that can vary due to the applied load on the normal line to the direction of the crack travel. More ever, the rate of the crack opening is considered to be proportional to the rate of the crack travel.Lines of three optical fibers of 125 nm are embedded and fixed at two ends and pass across the direction of the crack travel at an approximation of 2mm apart. The light of 2V from the source is passed through the optical fiber, across the crack tip. The crack opening forces the optical fiber to extend under tension, and hence the interruption of its diameter. This causes the decrease in the light intensity traveling through the fiber till the total failure of the fiber, to declare presence of crack. The embedded fiber optics on the specimen links the instrumentation optical system which permits the light beam throughput. Finally the converted light beam into voltage domain allowed us to closely analyze the crack tendency, and eventually be able to establish a model and sensor equation which governs the trend of the crack growth.

Abstract: Accurately achieve the luminance of light sources at night images is significantly important to vision-based night visibility estimation. In this paper, we propose a practical night visibility algorithm. This algorithm contains two main parts, light sources recognition and edge extraction. Firstly, we give the model of vision-based visibility estimation, and propose the framework of algorithm. Secondly, we give the method to extract light sources from multiple potential targets by the prior knowledge of space information. Then, we analysis the features of light source image, and explain the expanded temple to cut sub-image of light source, and induce in PS level set to segment the edge. Experiments show that, the light source average recognition precision is approach to 0.95 at the condition of moderate breeze, and compared with the manual segment, the precision of light source segment is approach to 0.99 at the condition of real visibility larger than 500m.

Abstract: In order to study the influence by non-uniformity of illumination on testing performance of optical measurement system, the causes of non-uniformity were analyzed. We constructed the relationship model between interval distance of LED light source and illumination. The distribution of illumination with different intervals of LED were simulated. Then relationship model between viewing-field angle at object plane of optical system and illumination was established. Influence of viewing-field angle at object plane on distribution of illumination was studied. The experimental results indicate that non-uniform light source and wide viewing-field angle are two main causes for non-uniformity in optical imaging system. Larger interval distance of LED or viewing-field angle will result in non-uniformity of illumination.

Abstract: With the rapid development of the construction industry, people pay more and more attention to the huge energy consumption of buildings. To promote energy-saving design is the only way to improve the present situation. The electric lighting accounts for 15% ~25% of the total consumption of buildings, which directly affect the effect of energy saving. Therefore, to promote energy-saving design of the electric lighting, such as using natural light, using efficient energy-saving light source, using reasonable lighting system, using efficient lighting control system decreasing the invalid energy consumption of the electric lighting system itself and so on is really the key to decrease the energy consumption level of buildings.

Abstract: A new display technology is being developed that uses quantum dot materials, the luminescence with different color different dot sizes from CdSe quantum dot made by us is presented. The fabrication methods, the luminescence behaviors for the materials are also reviewed. A bright future of the applications of the quantum dots luminescence materials and its applications in display devices is described.

Abstract: Compare the different appearance of jadeite-jade with three standard light sources, daylight D65,incandescent light A and fluorescent light F2(CWF),whose colors are purple to bluish violet with low chroma and low lightness in. The analysis of color index in the CIE 1976L* a* b uniform color space shows that the hue of lavender is influence by the light of standard light sources, followed by chroma, simultaneously value is seldom influenced obviously. And the color saturation of purple jade samples with CWF is usually higher, showing more vivid purple. However, D65 is benefit to the lightness of the purple jade, in which the average of color differences is known as the largest while the variance is the smallest. As D65 can be used to distinguish the purple color of jade samples most greatly, it is intended to be the best light source for appreciation of jadeite-jade. In consideration of the better quality of the purple color displayed with the CWF, it can be used during business transaction process.

Abstract: A novel reflective metal anode with different groove structures and a set of parallel long narrow stripe Carbon nanotube (CNT) cathodes to fabricate a 7 inches field emission backlight unit (CNT-FEBLU) has been carried out in this paper. In comparison with a simple diode structure, which has the same stripe cathode unit with screen printing phosphor layer on ITO glass surface as the anode, the reflective metal anode has some advantages such as sustaining high field emission current, no unexpected arcing, and high illumination and uniformity without phosphor degradation. The results show that a reflective metal anode not only conducts the residual charges and heat from the phosphor surface effectively, but also reflects the light to one side of the panel through the cathode end and exhibits high illumination without obvious obstacle by the narrow stripe cathodes. The luminance of the reflective metal groove anode we proposed is 11530 cd/m², with the emission current density of 1.52 mA/cm² under the electric field about 1.07 V/μm.

Abstract: Retroreflective film are used widely in traffic and municipal field as information carrier, the retroreflection index is considered the most important parameter, test methods of this parameter including absolute and relative method, traditional instruments are consisted of light source, photometric detector, angle adjust device, etc. The complex structure of instrument add the uncertainty component, so reflectance spectrum is used to calculated the film retroreflection index, this method would improve the testament accuracy and provide more light sources choices without structure adjustment.