Faceted Optics for LED Arrays with Discontinuous Surfaces
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Solution Overview
Problem
Conventional optics for illumination devices with multiple LED dies face challenges in minimizing beam spread while obscuring the LED dies, often resulting in non-uniform beams and artifacts due to the arrangement of light sources and the optic's design, which conflicts with achieving high brightness and narrow beam divergence.
Innovation Solution
The use of faceted optics with a discontinuous reflective or refractive surface, approximating a curved surface, such as a paraboloid, to create a solid structure of transparent material that minimizes the visibility of discrete light sources and artifacts, achieving a substantially uniform beam with low divergence and high central brightness by optimizing the number, size, and arrangement of facets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple LED dies are arranged in an array to increase light output, then the total light output increases, but the light source becomes an extended source rather than a point source, making collimation difficult and causing beam divergence
Solution Approach 1:
The optic surface is divided into multiple discrete facets instead of being continuous. Each facet independently redirects light from specific LED dies, allowing the extended light source to be treated as multiple point sources. This segmentation enables collimation of light from each die while maintaining high total light output from the array.
2Quantity of substance
If conventional optics are used with multiple LED dies, then the light output increases, but dark borders between individual dies appear in the beam profile, disrupting uniformity
Solution Approach 1:
Different regions of the optic surface are assigned different facet orientations and properties tailored to the local LED die arrangement. Each facet is designed to redirect light from its corresponding LED die, ensuring uniform light distribution across the entire beam profile while eliminating dark borders between dies.
3Manufacturing precision
If features are placed at the exit surface of the optic to disperse the beam, then individual dies are obscured, but the overall light beam becomes undesirably broadened
Solution Approach 1:
Light is redirected and uniformized at the entrance surface of the optic before the light travels through the optic body to the exit. The faceted surface at the light source end pre-distributes light from multiple dies uniformly, eliminating the need for exit-surface dispersion features that would broaden the beam. The beam exits already uniformized without requiring additional broadening features.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The faceted optics produce a beam that is substantially free of images and artifacts, with local brightness variations less than 5%, and a beam divergence angle exceeding the baseline by less than 10%, ensuring a uniform and efficient light distribution suitable for various illumination applications.
Implementation Method 1
the surface of the optic is faceted, i.e., approximated by multiple (typically planar) surface segments
Implementation Method 2
a solid structure formed of a substantially transparent material
Implementation Method 3
whereas a point source placed at the focus of a parabolic reflector produces a collimated beam
Data Source
AI summary
Faceted optics for use in conjunction with (typically planar) arrangements of discrete light sources (e.g., an array of multiple LED dies) improve or optimize the trade-off between beam divergence and beam non-uniformity, and between non-uniformities resulting from the imaging of the extended light source and artifacts introduced by the optic itself.