Far-field condition for light-emitting diode arrays

Moreno, Iván; Sun, Ching Cherng; Ivanov, R.

doi:10.1364/ao.48.001190

Cited by 50 publications

(36 citation statements)

References 9 publications

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“…Therefore, the far-field condition can be assumed for this application. The reader can be assumed to be located in the far field of LEDs [15]. The zenith angle is represented by θ as shown in Figure 1.…”

Section: Signal and System Modelsmentioning

confidence: 99%

A MISO UCA Beamforming Dimmable LED System for Indoor Positioning

Taparugssanagorn

Siwamogsatham

Pomalaza‐Ráez

2014

Sensors

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The use of a multiple input single output (MISO) transmit beamforming system using dimmable light emitting arrays (LEAs) in the form of a uniform circular array (UCA) of transmitters is proposed in this paper. With this technique, visible light communications between a transmitter and a receiver (LED reader) can be achieved with excellent performance and the receiver's position can be estimated. A hexagonal lattice alignment of LED transmitters is deployed to reduce the coverage holes and the areas of overlapping radiation. As a result, the accuracy of the position estimation is better than when using a typical rectangular grid alignment. The dimming control is done with pulse width modulation (PWM) to obtain an optimal closed loop beamforming and minimum energy consumption with acceptable lighting.

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Section: Signal and System Modelsmentioning

confidence: 99%

A MISO UCA Beamforming Dimmable LED System for Indoor Positioning

Taparugssanagorn

Siwamogsatham

Pomalaza‐Ráez

2014

Sensors

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“…The main aim of our work, i.e., a uniform light distribu− tion at a given distance, can be achieved by proper light sources spacing in a planar or non−planar surface [1][2][3][4]. However, the mentioned optical set−ups require many inde− pendent light sources, usually more than eight.…”

Section: Motivationmentioning

confidence: 99%

Uniform illumination by diffractive shaping of independent light beams

Sobczyk

Sypek

Makowski

et al. 2011

Opto-Electronics Review

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This article presents a new optical set-up for illumination of a common area with a few independent light sources. The main aim is to create a uniform light distribution of a constant shape even if one of the light sources will stop working. In such a case, the shape of the light distribution should remain unchanged, however, the total light intensity will be lower. The novelty of the proposed solution is based on the usage of a small number of the independent light sources in opposite to a well known LED arrays approach. The beam shaping is made using Dammann gratings and specially designed blazed phase diffractive gratings. The article contains the theoretical analysis and the computer simulation verified by the experiment.

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“…More recently, far-field conditions for LEDs 6 and arrays 7 have been calculated, which show that far-field conditions are often only met at far larger distances than conventional guidelines suggest, but experimental validation is currently lacking. Within the lighting community, measurement distances as far as 15 times the maximum dimension of the light emitting area of the luminaire are not exceptional.…”

Section: Introductionmentioning

confidence: 99%

Near-field and far-field goniophotometry of narrow-beam LED arrays

Jacobs

Forment

Rombauts

et al. 2014

Lighting Research & Technology

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In lighting calculations and simulations, the emission of a light source is conventionally modeled using the far-field luminous intensity distribution. However, the advent of luminaires including large arrays of LEDs with focusing optics creating narrow beams has made the traditional limiting photometric distance to reach far-field conditions less easy to determine. Furthermore, even correct far-field data can lead to erroneous predictions when illuminances are determined on a task surface which is positioned within the near-field region. A near-field representation could overcome these problems, but experimental validation for such LED arrays is lacking. This paper reports on near-field and farfield laboratory experiments using an array of two and five narrow-beam LEDs. A near-field approach makes discussions to determine the far-field photometric distance superfluous and leads to correct illuminances at any location with respect to the array, irrespective of the dimensions of the array and the beam angle of the individual components. Introducing the near-field representation of light sources in lighting design offers more accurate predictions when luminaires based on LED arrays with focusing optics are involved.

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Far-field condition for light-emitting diode arrays

Cited by 50 publications

References 9 publications

A MISO UCA Beamforming Dimmable LED System for Indoor Positioning

A MISO UCA Beamforming Dimmable LED System for Indoor Positioning

Uniform illumination by diffractive shaping of independent light beams

Near-field and far-field goniophotometry of narrow-beam LED arrays

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