LED Metasurface Collimation Without External Optics
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) require external lenses or reflectors to collimate light, increasing their thickness and size, which is a limitation in applications like smartphones where miniaturization is essential, especially for infrared LEDs used in iris scanning.
Innovation Solution
Integration of subwavelength scattering antennas within the LED substrate or on its surface to alter the phase and amplitude of emitted light, allowing for collimated light output without external optics, thereby reducing the package thickness and eliminating the need for external lenses or reflectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If external lenses or reflectors are used to collimate light from LEDs, then light collimation is achieved, but the package thickness increases
Solution Approach 1:
The patent merges the collimation function with the LED package structure by integrating subwavelength scattering antennas directly into the LED substrate or package housing. This eliminates the need for separate external lenses or reflectors, achieving light collimation while maintaining a thin profile. The scattering antennas are positioned within the LED package at a distance of approximately one-quarter wavelength from the LED chip, combining multiple functions (light emission and collimation) into a single integrated structure.
Solution Approach 2:
The patent transitions from conventional macro-scale optical elements (lenses and reflectors) to subwavelength-scale scattering antennas. By operating at the subwavelength dimension, the system achieves collimation functionality with structures that are significantly thinner than traditional optical components. The subwavelength scattering antennas create constructive interference patterns that collimate light without requiring the thickness of conventional lenses.
2Illumination intensity
If external lenses are used to collimate light, then collimated light output is achieved, but the device complexity increases
Solution Approach 1:
The patent combines the light emission and collimation functions into a single integrated structure. The subwavelength scattering antennas are embedded within the LED package, eliminating the need for separate external optical components. This integration reduces the number of parts, simplifies assembly, and decreases overall device complexity while maintaining effective light collimation.
3Illumination intensity
If external optical assemblies are used, then light collimation is improved, but the ratio of package thickness to LED die thickness increases
Solution Approach 1:
The patent employs subwavelength scattering antennas that operate at dimensions much smaller than the wavelength of emitted light. This allows the package thickness to be reduced to approximately one-quarter wavelength, achieving a package-to-die thickness ratio of about 10:1 or less. The subwavelength dimension enables collimation functionality without the bulk required by conventional optical components.
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
This approach enables the production of thinner, more compact LEDs with improved light collimation and efficiency in coupling light to external optics, enhancing the performance of LEDs in miniaturized devices like smartphones.
Implementation Method 1
an array of subwavelength scattering antennas positioned within the emitted light path, the array of subwavelength scattering antennas configured to alter the phase and amplitude of scatter of the LED emitted light
Data Source
AI summary
A system, method and device for collimating the output of a light emitting diode (LED) are disclosed. The system, method and device include an LED substrate including a top surface from which the light is emitted, and an array of sub wavelength scattering antennas positioned within the emitted light path, the array of sub wavelength scattering antennas configured to select directions of scatter of the LED emitted light to provide collimated light output from the device. The array may be aligned perpendicular to the plane of propagation of the light emitted from the LED and may be positioned adjacent to the top surface. The array may be at least partially, or completely, positioned within the LED substrate. The array may be spaced a distance from the top surface and the spacing may be achieved using a dielectric spacer adjacent to the top surface. The array may be positioned within the dielectric spacer.