Numerical Aperture Of Optical Fiber Research Articles

Daylighting and energy performance of the combination of optical fiber based translucent concrete walls and windows

Optical fiber based translucent concrete (OFTC) is a kind of innovative building envelope for building energy efficiency. Prior studies indicated that both optical fibers and OFTC have angular transmittance that strongly depends on the angle of incidence, but most research on OFTC at the building level did not take this feature into account. This study focused on the annual daylighting and energy performance of the combination of OFTC walls with windows. The analysis was based on a cellular office room with an external OFTC wall and a window in Beijing, considering the influence of window-to-wall ratios, fiber volumetric ratios, optical fiber numerical aperture, and glazing types on building daylighting and energy performance. The results indicate that the combination of OFTC walls and windows can achieve the least net electricity use, which is about 32.07% and 5.36% lower than the optimal case with only OFTC walls, and that with the combination of conventional concrete walls and windows, respectively. The use of high numerical aperture optical fibers in OFTC can further contribute to building energy efficiency, but might increase the risk of daylight glare. However, the effects of OFTC walls on daylight glare are insignificant especially when the window-to-wall ratio is high.

Daylighting performance simulation and analysis of translucent concrete building envelopes

A novel optical fiber (OF) embedded building envelope, namely translucent concrete (TC), was proposed and popularized for its light transmission property and unique artistic features, but there is still a lack of in-depth research on its daylighting performance analysis. To reveal the impacts of multi-factors on TC daylighting performance, an optical model of TC was established based on a ray-tracing method. In the model validation, both the simulated transmittance of OFs and illuminance of translucent concrete were in a good agreement with the experimental results. The simulation results showed when the numerical aperture (NA) of the OFs increased from 0.51 to 0.70, the annual average luminous flux of TC under seven cities conditions could be enhanced by up to 40.62%. In terms of effective illuminance, the optimum fiber volume ratio of the seven cities was determined, respectively. Besides, it was found that the core-cladding interface losses could lead to a relative deviation over 5% when the length of 1-mm OFs with 0.51 NA exceeded 259 mm, and the deviation could be larger with the decrease in diameter of OFs and the increase both in length and NA of OFs.

Research of the measuring technique of numerical aperture of optical fiber using near infrared light

AbstractIn this paper, we demonstrate a new technology in which we use the near infrared (NIR) electro‐optical device and projection method to measure the numerical aperture (NA) of NIR fiber. Using the optical coupler to let the NIR light enter into an optical fiber, the projection pattern is then measured at the distance of L, where the length L and the diameter W of the projection pattern area on screen is recorded. The NA of NIR fiber is computed from the recorded data. This is a fast method for testing NA and can measure the NA deviation to an accuracy of 0.01. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 582–584, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23161