Far-field distance for surface light source with different luminous area

Liu, Xianming; Cai, Wentao; Li, Xiaohua; Du, Xiaoqing; Chen, Weimin

doi:10.1364/ao.52.001629

Cited by 11 publications

(8 citation statements)

References 10 publications

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“…The calculations for the illumination of a workplane due to transmission of light by the TC panels was executed in the far field where the crossing of rays (caustics) is negligible and the illumination distribution has the form of the intensity distribution. The optical fiber has a circular end and hence, the far field is defined as the region outside an imaginary hemisphere with a radius bigger than at least five times the diameter [12]. The RADI-ANCE software can model customized luminaires and define the luminous intensity distribution, using the function ies2rad, for calculating illuminance at different points inside the modeled room.…”

Section: Illumination Calculations Over a Workplanementioning

confidence: 99%

Evaluating energy consumption saving from translucent concrete building envelope

Ahuja

Mosalam

2017

Energy and Buildings

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The translucent concrete (TC) as a building envelope can offset some lighting energy that is consumed within a room in an office. It is constructed from concrete panels which are functionalized by embedding optical fibers during the manufacturing phase to transmit sunlight. From preliminary results, a volumetric fiber ratio of 6% used in the TC panel leads to savings in lighting energy by around 50%. The utility of panels is enhanced if it reduces the heating and cooling requirements of the office room. The sunlight channeled by optical fibers can contribute in heating of room during winter but in summer months, it leads to spike in cooling loads. Also, daylight reduces heat dissipation from lighting installations and positively impacts cooling loads. The conduction through walls allows heat to be removed from the room during morning but transmits heat from ambient environment into the room later in the afternoon and evening. The presented research combines thermal and lighting analyses to search for an optimal fiber volumetric ratio for TC panels that would result in energy savings. The TC panels can cut down energy expenditure by 18% for a fiber volumetric ratio of 5.6% which renders the fabrication process to be practical.

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Section: Illumination Calculations Over a Workplanementioning

confidence: 99%

Evaluating energy consumption saving from translucent concrete building envelope

Ahuja

Mosalam

2017

Energy and Buildings

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“…The relative measurement distance, which is defined by the ratio of measurement distance d to the largest dimension of the source D, is set as abscissa. For the rectangular-shaped LED array, the length-width ratio of the rectangle has little effects on the error if the diagonal is taken as the longest segment [16]. Therefore, the results shown in Fig.…”

Section: Measurement Error Definition and Analysismentioning

confidence: 99%

“…Schematic diagram of LED array with angular tilt misalignment. tan A cos C × tan γ; (16) and sin α sin C × sin γ:…”

Section: B Rotational Misalignmentmentioning

confidence: 99%

Analysis of misalignment-induced measurement error for goniophotometry of light-emitting diode arrays

Cai

Liu

et al. 2013

Appl. Opt.

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The luminous distribution characteristics of light sources can be measured by goniophotometry. In this work, the misalignment of luminary-induced measurement errors as the main factor affecting the measurement accuracy is analyzed. A calculation method for measurement error is proposed. Then, the translational and angular misalignment-induced measurement errors are calculated and analyzed. Results show that the measurement errors induced by misalignments may be great in some cases even if the far-field condition is satisfied. For luminaries with different radiation patterns, the acceptable misalignment tolerances corresponding to measurement error of less than 1% are given.

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“…Figure 4 illustrates the light intensity distributions at different distances from the three light sources. On the basis of the far-field distance calculation proposed in [16,17], the Type 1 pc-WLED sample light-emitting surface (structured as a phosphor dome) was approximately 3 mm in diameter, and the far field was 10 times the diameter of the surface, namely, 30 mm. In relation to the light intensity distributions at the 100-mm distance, the Type 1 pc-WLED had an NCC of higher than 0.999, indicating that its light source was 30 mm away from the far field.…”

Section: Experimental Measurementmentioning

confidence: 99%

Combining near-field hyperspectral imaging and far-field spectral-angular distribution to develop mid-field white LED optical models with spatial color deviation

Lee

Chen

2016

Opt. Express

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The integration of spatial distribution of light intensity and color in the midfield is instrumental for LED optical design. On the basis of this rationale, we proposed an accurate and convenient method for developing white LED optical models. Near-field hyperspectral images and far-field spectral-angular distributions were integrated to illustrate changes in spatial light intensity and color distribution in the mid-field, to the exclusion of the absorption, conversion, and scattering of phosphors. The corresponding optical models were developed for three LED samples under different packaging conditions. Their normalized cross-correlation values for spatial light intensity and correlated-color-temperature distribution between simulation and measurement averaged as high as 0.995 and 0.99 respectively, which validated the accuracy and feasibility of the proposed method.

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Far-field distance for surface light source with different luminous area

Cited by 11 publications

References 10 publications

Evaluating energy consumption saving from translucent concrete building envelope

Evaluating energy consumption saving from translucent concrete building envelope

Analysis of misalignment-induced measurement error for goniophotometry of light-emitting diode arrays

Combining near-field hyperspectral imaging and far-field spectral-angular distribution to develop mid-field white LED optical models with spatial color deviation

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