AR Optical Device Using Polarizing Element for Luminous Efficiency
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Solution Overview
Problem
Existing augmented reality optical devices face challenges in maintaining high luminous efficiency for both real object image light and virtual image light, with issues such as reduced luminous efficiency for real object image light due to reflective units and decreased efficiency for virtual image light when using half mirrors.
Innovation Solution
The use of a polarizing optical element, such as a reflective polarizing plate, is introduced to transfer virtual image light by reflection and real object image light by transmission, maintaining luminous efficiency for virtual image light while enhancing it for real object image light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective unit is used to project virtual image onto retina, then virtual image luminous efficiency is improved, but real object image light transmission is blocked
Solution Approach 1:
The invention changes the optical parameter of the reflective unit by introducing polarization characteristics. The reflective unit is configured to reflect only s-polarized light while transmitting p-polarized light, thereby separating the handling of virtual image light and real object image light based on their polarization states. This allows the reflective unit to simultaneously achieve high virtual image luminous efficiency through selective reflection and maintain real object image light transmission through selective transmission.
Solution Approach 2:
The invention applies different optical properties to different polarization components of light. The reflective unit exhibits directionally selective reflection characteristics, reflecting s-polarized light (used for virtual images) while transmitting p-polarized light (used for real object images). This local differentiation of optical properties based on polarization direction resolves the contradiction between reflecting virtual image light and transmitting real object image light.
2Adaptability or versatility
If half mirror is used to combine virtual and real images, then both images can be observed simultaneously, but transmittance of virtual images is low
Solution Approach 1:
The invention transforms the half mirror from a non-polarizing beam splitter to a polarizing beam splitter. By introducing polarization selectivity, the beam combining element can differentiate between virtual image light (s-polarized) and real object image light (p-polarized). This allows near-100% reflection of virtual image light while transmitting real object image light, dramatically improving virtual image transmittance compared to conventional non-polarizing half mirrors.
Solution Approach 2:
The polarizing beam combining element exhibits different transmission and reflection properties for different polarization directions. It reflects s-polarized light with high efficiency while transmitting p-polarized light, creating directional selectivity that resolves the contradiction between simultaneous image observation and virtual image brightness.
3Reliability
If prism or variable focus lens is used to adjust focal length, then virtual image focus can be maintained, but device complexity increases
Solution Approach 1:
The invention replaces the mechanical/optical focusing system (prism or variable focus lens) with a polarization-based optical path separation system. By using polarizing beam combining elements and controlling polarization states, the system achieves focus maintenance through optical design rather than mechanical adjustment, eliminating the need for additional focusing hardware and control software.
Solution Approach 2:
The polarizing beam combining element serves multiple functions simultaneously: it combines virtual and real images, maintains focus through its optical design, and enables luminous efficiency improvement. This multi-functionality eliminates the need for separate focusing mechanisms, reducing overall device complexity while maintaining virtual image focus.
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 solution effectively increases the luminous efficiency for real object image light while maintaining the luminous efficiency for virtual image light, addressing the limitations of previous technologies.
Implementation Method 1
the image output unit outputs virtual image light polarized in a first direction; and wherein the polarizing optical element transfers the virtual image light polarized in the first direction, output from the image output unit, to the pupil of the eye of a user by reflecting it, and transfers light polarized in a second direction perpendicular to the first direction, out of the real object image light incident onto the polarizing optical element, to the pupil of the eye of the user by transmitting it therethrough
Implementation Method 2
the polarizing optical element transfers the virtual image light polarized in the first direction, output from the image output unit, to the pupil of the eye of a user by reflecting it, and transfers light polarized in a second direction perpendicular to the first direction, out of the real object image light incident onto the polarizing optical element, to the pupil of the eye of the user by transmitting it therethrough
Data Source
AI summary
The present invention provides an optical device for augmented reality using a polarizing optical element, the optical device including: an image output unit configured to output virtual image light, which is image light corresponding to a virtual image; a polarizing optical element configured to transfer the virtual image light, output from the image output unit, to a pupil of an eye of a user; and an optical means configured such that the polarizing optical element is disposed therein, and configured to transfer real object image light, output from a real object, to the pupil of the eye of the user by transmitting it therethrough; wherein the image output unit outputs virtual image light polarized in a first direction; and wherein the polarizing optical element transfers the virtual image light polarized in the first direction to the pupil of the eye of the user by reflecting it.