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Mechanics and Evaluation of Integrating of Remote Phosphors into the Secondary Optics of Luminaires Based on High Brightness LEDs

Makkaoui, Ahmad

[Thesis]. Manchester, UK: The University of Manchester; 2017.

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Abstract

A typical “white” LED comprises a blue source and one or more phosphors, which down-convert the high energy blue light to longer wavelengths. The resultant “mixture” of wavelengths (predominantly residual blue light from the source and yellow and red from the phosphors) produces white light. Typically, phosphors are coated directly (proximally) onto the blue source. This work differs from the conventional approach by incorporating phosphors in a secondary optic, which is remote from the source. This has the advantages of being able to recover the source LED and to change the output wavelength by stacking optics that contain different levels of different phosphors, or by mixing different phosphors into a single optic. The work has created a range of secondary optics that contain one or more phosphors at relatively low levels of addition (1%-4% by weight) in thermoplastic and thermosetting matrices including polystyrene, poly(methylmethacrylate) and silicone. The phosphors are based on a range of YAGs and nitrides. The secondary optics were manufactured by injection moulding (thermoplastics) or casting (thermosets) and were used singly or in stacked layers to down-convert light from a royal blue (450 nm) LED source to produce a range of “white” light sources. Both injection moulding and casting are relatively inexpensive and commonly encountered processes.The optical performance of these optics was measured by Spectral Power Distribution (SPD), chromaticity, Colour Temperature (CCT) and Colour Rendering Index (CRI). CCT and CRI values ranged from 3000K to 6500K and (80-95) depending on the phosphor composition.Measurements were also carried out on the long-term performance of the secondary optics and these showed little or no change after 24 months continuous and intermittent exposure. Two peer-reviewed publications were produced as a result of the research that took place at the university. These were:• Methven, J. M., Pickering, P. J., Makkaoui, A. & Owens, H. (2013). Luminaires based on Innovative Injection Moulded Secondary Optics which incorporate Remote Phosphors. International Conference on Innovative Technologies IN-TECH 2013, Budapest• Methven, J. M., Pickering, P. J., Makkaoui, A. & Saluja, A. (2014). Luminaires based on Innovative Injection Moulded Secondary Optics which incorporate Remote Phosphors. International Conference on Innovative Technologies IN-TECH 2014, Budapest

Keyword(s)

LED; Remote Phosphor

Bibliographic metadata

Type of resource:
Content type:
Form of thesis:
Type of submission:
Degree type:
Doctor of Philosophy
Degree programme:
PhD Mechanical Engineering
Publication date:
Location:
Manchester, UK
Total pages:
357
Abstract:
A typical “white” LED comprises a blue source and one or more phosphors, which down-convert the high energy blue light to longer wavelengths. The resultant “mixture” of wavelengths (predominantly residual blue light from the source and yellow and red from the phosphors) produces white light. Typically, phosphors are coated directly (proximally) onto the blue source. This work differs from the conventional approach by incorporating phosphors in a secondary optic, which is remote from the source. This has the advantages of being able to recover the source LED and to change the output wavelength by stacking optics that contain different levels of different phosphors, or by mixing different phosphors into a single optic. The work has created a range of secondary optics that contain one or more phosphors at relatively low levels of addition (1%-4% by weight) in thermoplastic and thermosetting matrices including polystyrene, poly(methylmethacrylate) and silicone. The phosphors are based on a range of YAGs and nitrides. The secondary optics were manufactured by injection moulding (thermoplastics) or casting (thermosets) and were used singly or in stacked layers to down-convert light from a royal blue (450 nm) LED source to produce a range of “white” light sources. Both injection moulding and casting are relatively inexpensive and commonly encountered processes.The optical performance of these optics was measured by Spectral Power Distribution (SPD), chromaticity, Colour Temperature (CCT) and Colour Rendering Index (CRI). CCT and CRI values ranged from 3000K to 6500K and (80-95) depending on the phosphor composition.Measurements were also carried out on the long-term performance of the secondary optics and these showed little or no change after 24 months continuous and intermittent exposure. Two peer-reviewed publications were produced as a result of the research that took place at the university. These were:• Methven, J. M., Pickering, P. J., Makkaoui, A. & Owens, H. (2013). Luminaires based on Innovative Injection Moulded Secondary Optics which incorporate Remote Phosphors. International Conference on Innovative Technologies IN-TECH 2013, Budapest• Methven, J. M., Pickering, P. J., Makkaoui, A. & Saluja, A. (2014). Luminaires based on Innovative Injection Moulded Secondary Optics which incorporate Remote Phosphors. International Conference on Innovative Technologies IN-TECH 2014, Budapest
Keyword(s):
Thesis main supervisor(s):
Thesis co-supervisor(s):
Language:
en

Institutional metadata

University researcher(s):

Record metadata

Manchester eScholar ID:
uk-ac-man-scw:309384
Created by:
Makkaoui, Ahmad
Created:
1st June, 2017, 11:02:16
Last modified by:
Makkaoui, Ahmad
Last modified:
3rd November, 2017, 11:19:10

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