A Guiding Light In Innovation

1. An Investigation Into LED Multiplexingand HomogenisationPresenter : Kevin RogersAuthors: Kevin Rogers, Nigel Copner, Paul Driscoll, Ron Yandle, Peter Excell, Kang Li A Guiding Light In Innovation

2. Contents • Introduce multiplexing methodology • Introduce Cymtec’s Neolight LED Multiplexer • Building an optical model of the Neolight LED multiplexer • Analysis of the model • Optimisation of the model • Analysis of optimised model A Guiding Light In Innovation

3. Why Multiplex? • LEDs are a very efficient light source with long lifetimes • Narrow emission spectrum of LEDs only allows discrete colours • General lighting and illumination requires white light • Combining multiple wavelengths can produce white light which allows LEDs to penetrate several markets A Guiding Light In Innovation

4. Producing White Light with LEDs A Guiding Light In Innovation

5. Neolight LED Multiplexor • Integrates collimation, colour mixing and homogenisation into a single compact package • High Luminous flux • High efficiency • Preserves etendue • Dynamic colour variation A Guiding Light In Innovation

6. Neolight LED Multiplexor Light Pipe Homogeniser Long Pass Dichroic Filters Short Pass Dichroic Filters Tapered Collimators A Guiding Light In Innovation

7. Neolight LED Multiplexor – Building an Optical Model - Sources • LEDs used are Luminus PT-120 • Top-down modelling approach using Zemax source radial component • Source dimensions, normalised far field angular distribution, total luminous flux, and normalised spectral data inputted into non-sequential component editor from datasheet A Guiding Light In Innovation

8. Neolight LED Multiplexor – Building an Optical Model – Mechanical Design • Imported CAD model • Glass defined from Zemax glass catalogue • Relatively simple shapes so little discrepancy between imported CAD and Zemax generated objects A Guiding Light In Innovation

9. Neolight LED Multiplexor – Building an Optical Model – Optical Coatings • Several optical coatings utilised including high-reflection, anti-reflection, long pass filters, short pass filters • Zemax has several methods of defining coatings including ideal coatings, actual coating recipe, and coefficients of reflection and transmission A Guiding Light In Innovation

10. Neolight LED Multiplexor – Running an Optical Model A Guiding Light In Innovation

11. Neolight LED Multiplexor – Optimisation • Using LED XY chromaticity coordinates an illustration of achievable colour gamut is possible • By varying the drive currents of the LEDs and therefore the Luminous flux, nearly all CCTs and a range of colours available A Guiding Light In Innovation

12. Neolight LED Multiplexor – Optimisation • Using Zemax optimisation algorithms it is possible to target specific XY chromaticity coordinates and hence specific CCTs • A commonly used CCT is 6504K of the CIE D65 standard illuminant which is X = 0.31271 and Y = 0.32902 • These can be set as targets in the merit function editor, the luminous flux for each LED set as variables and optimisation carried out A Guiding Light In Innovation

13. Neolight LED Multiplexor – Optimisation • LED Luminous flux required from each LED to reach 6504K, produced from optimisation: • Gives rise to following ratio: Red 0.2801: Green 0.683 : Blue 0.036 • Within confines of LED operation: A Guiding Light In Innovation

14. Neolight LED Multiplexor – Evaluation A Guiding Light In Innovation

15. Closing Remarks and References • Demonstrated using an optical model a method of producing a colour changeable small area source with an excess of 2000lm • This unlocks many new applications with etendue restrictive systems, and pushes the boundaries of systems already utilising LED technologies • Experimental results to be published at Photonics West 2011 A Guiding Light In Innovation