Polarized LED Packaging for AR Eye Tracking
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Solution Overview
Problem
Conventional LED packaging is agnostic to light polarization, resulting in the emission of all mixed polarization states, which can limit the effectiveness of applications such as iris recognition and eye tracking in head-mounted displays, particularly in virtual and augmented reality systems.
Innovation Solution
The integration of polarizing or wavefront-altering optical components, such as polarization filters and quarter wave plates, into the LED packaging process to modify the polarization state of emitted photons, along with sidewall masking to enhance optical efficiency and control the emission spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED packaging is used without polarization filters, then the manufacturing process is simple and cost-effective, but the emitted light contains all mixed polarization states which reduces the effectiveness of eye-tracking and iris recognition applications
Solution Approach 1:
The patent applies polarization filters and wavefront-altering optical components during the LED packaging process itself, before the LED is deployed in the final application. This preliminary modification of the emitted light's polarization state during manufacturing ensures that the LED package inherently provides polarized light output, eliminating the need for additional polarization components in the application system and maintaining manufacturing simplicity while improving application effectiveness
Solution Approach 2:
The patent integrates optical components (polarization filters, quarter wave plates) within the LED package structure during encapsulation. These optical components are nested inside or attached to the LED package, allowing the compact LED module to emit polarized light directly, thereby resolving the contradiction between manufacturing simplicity and application effectiveness
2Reliability
If polarization filters and optical components are integrated into the LED packaging process, then polarized light emission is achieved for improved eye-tracking and iris recognition, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines multiple functions (light emission, polarization filtering, wavefront alteration) into a single integrated LED package unit. By merging the LED die, encapsulant, and optical components into one packaged assembly during the manufacturing process, the system achieves polarized light emission without requiring separate components in the application, thus managing complexity at the manufacturing stage while simplifying the overall system architecture
Solution Approach 2:
The LED package is designed to serve multiple functions: light emission, polarization control, and wavefront modification. This multi-functional packaging approach allows a single component to replace what would otherwise require multiple separate elements, reducing the overall device complexity in the application while maintaining the improved application effectiveness
3Adaptability or versatility
If multiple layers of optical filtering material are added to the LED package, then greater selectivity of the emitted spectrum is achieved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the optical filtering function into multiple discrete layers (polarization filters, quarter wave plates, high-pass filters, low-pass filters, bandgap filters) that can be independently selected and applied during packaging. This segmentation allows the manufacturer to choose only the specific layers needed for a given application, achieving spectral selectivity without necessarily implementing all possible filtering layers, thus managing complexity while maintaining adaptability
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 polarized LEDs that improve eye-related functions like iris recognition and eye tracking by reducing reflections and enhancing contrast, thereby improving the performance of these applications in head-mounted displays.
Implementation Method 1
a polarization filter applied as a film on top of the encapsulant to filter or modify the polarization of the emitted photons
Implementation Method 2
polarizing or wavefront-altering optical components (e.g., a polarization filter applied as a film on top of the encapsulant)
Implementation Method 3
The high reflectivity of the sidewall material encourages unpolarized photons that would not have been emitted though the top surface of the LED package to be reflected back though the optical filtering film
Data Source
AI summary
Methods and apparatus for fabricating light-emitting diodes (LEDs) that include polarizing or wavefront-altering optical components are described in which additional optical components are added to the LED package to filter or modify the polarization of the emitted photons. Packaged LEDs that include polarizing or wavefront-altering optical components are also described. The packaged LEDs may emit infrared light that is polarized or otherwise altered by the optical components added during the fabrication process.