AR Optical Combiner Using Bandpass Polarization and Curved Reflection
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Solution Overview
Problem
Existing augmented reality (AR) devices face challenges in maximizing the utilization of image source energy while ensuring clear observation of the real-world scene and maintaining user privacy, with inefficiencies in light transmittance and interactivity.
Innovation Solution
An optical system incorporating a bandpass polarizing beam splitter and a curved bandpass semi-reflector, configured to allow polarization splitting and reflection/transmission of light within specific wavelength ranges, enhancing light permeability and privacy while maintaining energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional beam splitter is used to reflect image light, then image light can be directed to the user's eyes, but light transmittance is reduced and the real-world scene becomes less clear
Solution Approach 1:
The optical system segments the beam splitter function into two separate components: a polarizing beam splitter that directs image light to the user's eyes, and a separate semi-reflecting mirror that controls the reflection of image light. This segmentation allows each component to be optimized for its specific function, improving overall light transmittance while maintaining image brightness.
Solution Approach 2:
A wave plate is introduced as an intermediary element between the polarizing beam splitter and the semi-reflecting mirror. The wave plate converts linearly polarized light from the display into circularly polarized light, which then reflects off the semi-reflecting mirror and converts back to linear polarization. This intermediary transformation enables the system to achieve both high light transmittance and effective image light direction.
2Ease of operation
If a semi-reflecting mirror is used to allow user interaction with the real-world environment, then eye changes become visible, but image light leaks out and privacy is compromised
Solution Approach 1:
The system applies different optical properties to different wavelength ranges using bandpass filters. The semi-reflecting mirror is designed with specific reflective characteristics for certain wavelengths while being transparent to others. This local quality differentiation allows the system to reflect image light (in specific wavelength bands) to maintain privacy, while permitting other light to pass through for interactivity.
Solution Approach 2:
The optical system utilizes wavelength-specific parameter changes by employing bandpass polarizing beam splitters and bandpass semi-reflectors. These components are designed to operate with specific wavelength ranges (e.g., reflecting certain wavelengths while transmitting others), enabling the system to control light behavior differently across the spectrum to simultaneously achieve privacy and interactivity.
3Illumination intensity
If the beam splitter reflects more image light, then image brightness increases, but energy utilization efficiency decreases
Solution Approach 1:
The optical system ensures continuous useful action by minimizing light loss at each optical interface. The polarizing beam splitter is configured to efficiently direct image light without significant reflection losses, and the wave plate maintains polarization state transformation with minimal energy loss. This continuous efficient light transmission maintains image brightness while maximizing energy utilization.
Solution Approach 2:
The system employs wavelength-selective parameter changes through bandpass filters and polarizing components optimized for specific wavelength ranges. By concentrating the image light energy within these optimized wavelength bands and using components tuned to these parameters, the system achieves high brightness with minimal energy waste across the entire visible spectrum.
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 system improves light transmittance and clarity of the real-world scene, reduces energy waste, and enhances user interactivity without significantly reducing the efficiency of image source energy utilization.
Implementation Method 1
the bandpass polarizing beam splitter being configured to perform polarization splitting on light incident thereon in a given wavelength range and allow transmission of light out of the given wavelength range
Implementation Method 2
the bandpass polarizing beam splitter being configured to perform polarization splitting on light incident thereon in a given wavelength range
Implementation Method 3
a wave plate adjacent to the beam splitting side, and the beam splitter being configured to allow light emitted from the image source to be non-perpendicularly incident on the beam splitting side and be at least partially reflected towards the wave plate
Implementation Method 4
a curved bandpass semi-reflector located downstream of the wave plate in a path of reflected light and configured to allow reflection of light incident on the curved bandpass semi-reflector in the given wavelength range and allow transmission of light out of the given wavelength range
Implementation Method 5
configured to allow reflection of light incident on the curved bandpass semi-reflector in the given wavelength range
Data Source
Figure 1~2
Figure 3~5
Figure 6~8
AI summary
The present application discloses an augmented reality apparatus and an optical system thereof. The optical system includes an image source; a bandpass polarizing beam splitter, relative to the image source, defining a beam splitting side adjacent to the image source and a transmission side facing away from the image source, the bandpass polarizing beam splitter being configured to allow polarization splitting of light incident thereon in a given wavelength range and allow transmission of light out of the given wavelength range; a wave plate adjacent to the beam splitting side and configured in such a way that light emitted from the image source is able to be non-perpendicularly incident on the beam splitting side and be at least partially reflected towards the wave plate; and a curved bandpass semi-reflector located downstream of the wave plate in a path of the reflected light and configured to allow reflection of light incident on the curved bandpass semi-reflector in the given wavelength range and allow transmission of light out of the given wavelength range.