Structured Lens Angular Filter Light-Emitting Device Assembly
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Solution Overview
Problem
Existing light-emitting device assemblies face challenges in generating compact far-field illumination patterns with high light output efficiency due to the Lambertian intensity distribution of LEDs, which results in a significant fraction of optical power being wasted at angles far from the primary beam direction, making it difficult to achieve efficient far-field imaging in size-constrained applications.
Innovation Solution
A light-emitting device assembly comprising a concave optical collector, an emitter array, a structured lens with micro- or nano-structured elements, and an angular filter, where the structured lens has an effective focal length less than the distance between the lens and the emitter array, and the angular filter exhibits incidence-angle-dependent transmission to redirect light within a narrower angle, enhancing light collection and control over illumination patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional Lambertian LED emission is used, then the device structure is simple, but a significant fraction of optical power is wasted at angles far from the primary beam direction
Solution Approach 1:
The optical system is segmented into three distinct functional components: an optical collector to gather divergent light, a structured lens to focus and shape the beam, and an angular filter to eliminate unwanted angles. This segmentation allows each component to optimize its function, reducing overall energy waste while maintaining manageable system complexity
Solution Approach 2:
The structured lens acts as an intermediary between the Lambertian LED source and the far-field imaging plane. It mediates the transformation of divergent light into a controlled beam pattern, enabling efficient far-field imaging without requiring the LED itself to have a complex non-Lambertian emission pattern
2Adaptability or versatility
If far-field imaging optics are added to achieve selective illumination patterns, then illumination control is improved, but the device size increases significantly
Solution Approach 1:
The structured lens utilizes parameter changes in its micro- or nano-structure design to achieve a very short effective focal length. This allows the system to achieve far-field imaging capability in a compact form factor, enabling selective illumination pattern control without significantly increasing device volume
Solution Approach 2:
The invention transitions from conventional two-dimensional optical element design to three-dimensional micro- and nano-structured lens design. This dimensional transition enables advanced light manipulation capabilities in a compact footprint, achieving both illumination control and size constraints
3Measurement precision
If conventional lenses are used for far-field imaging, then imaging capability is achieved, but light collection efficiency is reduced due to the wide Lambertian distribution
Solution Approach 1:
The optical collector performs preliminary action by gathering divergent light from the LED before it reaches the structured lens. This pre-conditioning of the light reduces the angular spread, allowing the structured lens to more efficiently form the far-field image and improving overall light collection efficiency
Solution Approach 2:
The optical system employs a composite structure combining different optical elements with complementary functions: the optical collector for light gathering, the structured lens for focusing, and the angular filter for angular selection. This composite approach optimizes both imaging capability and light collection efficiency
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 solution enables efficient far-field imaging with selective activation of emitter array subsets, resulting in controlled illumination patterns and increased light output directionality, improving the fraction of light collected and projected into the desired pattern, thus addressing the inefficiencies of traditional systems.
Implementation Method 1
Those elements can be arranged so as to collectively impart on the output light a transverse-position-dependent phase delay that results in the effective focal length of the structured lens
Implementation Method 2
the angular filter exhibits incidence-angle-dependent optical transmission that decreases with increasing angle of incidence or that has a cutoff angle of incidence above which optical transmission is substantially prevented
Implementation Method 3
An array of emitters (e.g., an array of LEDs or pcLEDs) can be imaged into an image plane in the far field
Data Source
AI summary
A light-emitting device assembly includes a concave optical collector with a cavity, an emitter array of light-emitting elements, a transparent substrate across an open end of the collector, a structured lens, and an angular filter. The emitter array is positioned within the package cavity and emits from its emission surface output light that exits the cavity from the open its end through the substrate, and enables selective activation of and emission from individual elements of the array. The structured lens is formed on or in the substrate, and comprises micro- or nano-structured elements resulting in an effective focal length less than an effective distance between the structured lens and the emission surface. The angular filter is positioned on or in the substrate or on the emission surface and exhibits decreasing transmission or a cutoff angle with increasing angle of incidence.