AR Optical Layout Using Polarization to Block Projector Light Leakage
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Solution Overview
Problem
Conventional head-mounted augmented reality (AR) apparatuses suffer from issues such as direct visibility of the image projection source, light emission affecting image quality and user comfort, and privacy concerns due to light exiting the apparatus, which interferes with interactions and can be exacerbated by additional lenses.
Innovation Solution
An optical system incorporating a polarizing beam splitter, polarizer, and wave plates to control light polarization, ensuring that light emitted from the image projection source is managed to prevent direct visibility and exit from the apparatus, enhancing user comfort, privacy, and interaction quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional head-mounted AR apparatus is designed without additional light control components, then the device complexity is reduced, but the user comfort deteriorates due to direct visibility of the image projection source and light emission affecting image quality
Solution Approach 1:
A polarizer is introduced as an intermediary component between the image projection source and the user's eye. This polarizer selectively transmits polarized light while blocking direct light from the projection source, thereby improving user comfort without requiring complex structural modifications to the AR apparatus
Solution Approach 2:
The patent changes the polarization state of light as a key parameter to control light transmission. By using a polarizer that only transmits polarized light, the system effectively blocks direct light from the projection source while allowing reflected image light to pass through, resolving the contradiction between device simplicity and user comfort
2Ease of manufacture
If a conventional head-mounted AR apparatus is designed without additional light control components, then the manufacturing cost is reduced, but privacy deteriorates due to light exiting the apparatus being visible to others
Solution Approach 1:
The polarizer serves as a privacy-protection intermediary by selectively transmitting only polarized light. This prevents direct light from the projection source from exiting the apparatus in directions other than toward the user's eye, thereby maintaining user privacy without adding complex optical systems
Solution Approach 2:
By controlling the polarization parameter of light, the system ensures that only properly polarized light (from the reflected image path) can exit the apparatus. Direct light from the projection source, which lacks the correct polarization state, is blocked, thus protecting user privacy while keeping the manufacturing process simple
3Object-affected harmful factors
If a polarizer is added to the optical system to block direct light, then user comfort is improved, but device complexity increases
Solution Approach 1:
The polarizer is designed to perform multiple functions simultaneously: it blocks direct light from the projection source to improve user comfort, transmits reflected image light to maintain image quality, and prevents light leakage to protect user privacy. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity
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 effectively reduces the visibility of the image projection source and light emission from the apparatus, improving user comfort and privacy while enhancing image quality and reducing power consumption.
Implementation Method 1
a polarizing beam splitter having a beam splitting side adjacent to the image projection source and a transmission side facing away from the image projection source, the polarizing beam splitter being arranged such that light emitted from the image projection source is able to be non-perpendicularly incident on and be at least partially reflected by the beam splitting side, and the polarizing beam splitter being configured such that when light is incident on the beam splitting side, a polarized light component, whose polarization is in a first direction, passes through the polarizing beam splitter and is transmitted through the transmission side thereof, and a polarized light component, whose polarization is in a second direction perpendicular to the first direction, is reflected from the beam splitting side
Implementation Method 2
the optical system also comprises a polarizer disposed between the image projection source and the beam splitting side of the polarizing beam splitter, and the polarizer is configured to allow polarized light, whose polarization is in the second direction, to be transmitted therethrough and polarized light, whose polarization is in the first direction to be absorbed
Implementation Method 3
a wave plate adjacent to the beam splitting side, the light emitted from the image projection source being able to be at least partially reflected by the beam splitting side towards the wave plate
Data Source
AI summary
The disclosure relates to an optical system for an augmented reality apparatus, comprising: an image projection source; and a polarizing beam splitter. The polarizing beam splitter is arranged such that light emitted from the image projection source is able to be non-perpendicularly incident on the beam splitting side and be at least partially reflected. The polarizing beam splitter is configured such that a polarized light component passes through the polarizing beam splitter and is transmitted through the transmission side thereof, and a polarized light component is reflected from the beam splitting side. The optical system also comprises a polarizer disposed between the image projection source and the polarizing beam splitter, and the polarizer is configured to allow polarized light, whose polarization is in the second direction, to be transmitted therethrough and polarized light, whose polarization is in the first direction to be absorbed.