14.2: A General Theory of Light Recycling with Light Pipes/Tunnels and Their Applications in LED Illuminators

Self Cite

As a follow‐up to our previous work we present in this paper a detailed study on LED light recycling with a recycling collar. for the PhlatLight™ LED devices that we use in our experimnets up to 75% brightness improvement has been achieved. Higher enhancement factors can be expected if we use LEDs with rougher emitting surfaces as the recycling efficiency of angular recycling configurations such as the recycling collar depends strongly on the scattering characteristics of the LED chip surface. More experimental work is expected to be carried out in the near future on multiple‐chip configurations.

Section: Fig 2 Brightness Enhancement Vs Collection Cone Anglescontrasting

confidence: 43%

P‐236: LED Light Recycling with Recycling Collars

Ouyang¹,

Li²

2008

Self Cite

“…The etendue reduction ratio is the ratio of the total area of the output aperture over that of the uncoated window. The principle of enhancing brightness through light recycling has been explained in our previous work 5,6 . For the specific DPR system described above (output etendue = 50 mm 2 *steradian) and with a 4:1 etendue reduction ratio (recycling light pipe etendue = 200 mm 2 *steradian), simulation has shown that 40% of total lumen gain has been achieved.…”

Section: Fig 6 Output Aperture Of the Recycling Light Pipementioning

confidence: 99%

25.2: Invited Paper: Dual Paraboloid Reflector Illumination System for Digital Cinema

Ouyang¹,

Li²

2011

Self Cite

It has long been demonstrated that, besides extending the life time of UHP lamps, the Wavien patented dual paraboloid reflector (DPR) can also enhance the lamp brightness in the low etendue regime. As a follow-up to our previous work we examine the possibility of extending the same DPR advantages to xenon arc lamps used in digital cinema. With ray tracing, we calculate the throughput efficiencies of a standard compound elliptical reflector used in the industry and a DPR reflector of similar size at various etendue values. The resultant efficiency/etendue curves are plotted and it is shown that, at a typical etendue value of 50 mm 2 *steradian for digital cinema up to 100% brightness improvement can be achieved. Another unique feature of the DPR system is that light recycling can be realized through etendue reduction by a recycling light pipe. Up to 40% recycling gain has been demonstrated with a 1:4 input/output etendue ratio. In addition, it is expected that the lifetime xenon lamps with the DPR can also be extended.

P‐169: LED Light Recycling: Some General Design Guidelines

Ouyang¹,

Zugby²,

Li³

2009

The concept of light recycling has been misunderstood by many who work in the industry as they believe it would violate the brightness principle. This paper first tries to dispel that myth by providing an intuitive interpretation of the brightness principle and hence showing that light recycling is not a violation of this principle. It then goes on to present some general design guidelines as to how and if light recycling can be used in a particular system to enhance its throughput. A highly efficient (with near 100% recycling efficiency) light recycling system and some experimental results are also presented at the end.