Folded Micro-Pyramid Optics for Lambertian-to-Batwing Conversion
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Solution Overview
Problem
Existing LED light sources emit light in a Lambertian distribution, which results in non-uniform illumination on flat surfaces due to varying path lengths, necessitating high light source density for uniformity, and bulk optical lenses are not feasible for compact applications like displays.
Innovation Solution
Microstructures fabricated on a light transmissive substrate transform Lambertian light distribution into a batwing distribution using pyramidal or frustums with specific roof angles and refractive indices, providing uniform illumination by maximizing intensity away from nadir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If bulk optical lenses are used to transform Lambertian distribution into batwing distribution, then uniform illumination over large area is achieved, but device size and structural complexity increase making it infeasible for compact applications
Solution Approach 1:
The patent segments the optical transformation function into multiple discrete microstructures (pyramids, prisms, or lenslets) arranged in an array on a planar substrate. Each microstructure independently transforms light in its local region, collectively achieving uniform batwing distribution across the entire output area without requiring a single complex bulk lens
Solution Approach 2:
The patent transitions from three-dimensional bulk optical lenses to two-dimensional microstructures fabricated on a planar substrate. This dimensional reduction enables compact integration while maintaining optical transformation functionality through carefully designed microstructure geometries and arrangements
2Productivity
If LED light sources are used to illuminate flat surfaces, then light generation is efficient, but non-uniform illumination occurs due to varying path lengths requiring high light source density
Solution Approach 1:
The patent introduces a light transmissive substrate with microstructures as an intermediary between the LED light source and the target surface. This intermediary transforms the inherently non-uniform Lambertian distribution from the LED into a uniform batwing distribution, eliminating the need for high light source density while maintaining LED efficiency
Solution Approach 2:
The patent changes the angular distribution parameters of light by designing microstructures with specific geometric parameters (pyramid angles, prism angles, lenslet curvatures) that redirect light rays to achieve the desired batwing intensity profile with peak intensity at ±45 degrees from the normal
3Illumination intensity
If light source density is increased to achieve uniform illumination, then illumination uniformity improves, but device complexity and power consumption increase
Solution Approach 1:
The patent uses a light transmissive substrate with microstructures as an intermediary that transforms the light distribution from a single or few LED sources into uniform illumination, eliminating the need to increase light source density while maintaining illumination uniformity
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 microstructures efficiently convert Lambertian light into batwing distribution, ensuring uniform illumination over large areas with reduced light source density, suitable for displays and large-area lighting.
Implementation Method 1
Microstructures fabricated on a light transmissive substrate transform Lambertian light distribution into a batwing distribution using pyramidal or frustums with specific roof angles and refractive indices
Data Source
AI summary
A light transmissive substrate that transforms light having a Lambertian distribution includes a substrate having a plurality of microstructures on a first surface, where each of the plurality of microstructures comprises an array of folded micro-pyramid microstructures, wherein each folded micro-pyramid microstructure comprises a base section with a roof angle and a recess being formed in a shape of a micro-pyramid and comprising a recess roof angle, wherein light having a Lambertian distribution that enters the first surface of the substrate is transformed into light having a distribution with a maximum intensity at an angle away from nadir and a minimum intensity at nadir that exits a second surface of the substrate.