Faraday Rotator Optical Assembly for Compact HMD
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Solution Overview
Problem
Conventional head-mounted display devices have bulky and heavy optical systems that lead to user discomfort, inefficient image transmission, and shorter battery life due to high power consumption.
Innovation Solution
The use of a compact optical assembly comprising a first polarization-sensitive reflector, a second polarization-sensitive reflector, and a Faraday rotator, which creates a folded optical path to efficiently project image light to the user's eyes, reducing physical size and power consumption while maintaining a wide field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional optical assemblies are used in head-mounted display devices, then the optical system can direct light toward the user's eyes, but the device becomes bulky and heavy causing user discomfort
Solution Approach 1:
The patent employs a folded optical path design where light travels through multiple reflections at polarization-sensitive surfaces, transforming a linear optical path into a three-dimensional folded structure. This allows the optical system to achieve the required light directionality within a compact volume, reducing both the physical size and weight of the head-mounted display device while maintaining effective light delivery to the user's eyes
2Ease of operation
If conventional optical assemblies are used in head-mounted display devices, then the optical system can direct light toward the user's eyes, but the device becomes bulky and heavy
Solution Approach 1:
The folded optical path configuration allows the optical system to achieve the required light directionality within a compact volume by utilizing three-dimensional space efficiently. The light path is folded multiple times through polarization-sensitive reflectors, enabling the optical assembly to be significantly smaller than conventional linear designs while maintaining full functionality
3Use of energy by moving object
If conventional optical assemblies are used in head-mounted display devices, then the optical system can direct light toward the user's eyes, but light transmission efficiency is poor leading to higher power consumption
Solution Approach 1:
The patent utilizes polarization-sensitive reflectors that are specifically designed to transmit light with particular polarization states while reflecting orthogonal polarizations. By controlling the polarization state of light at each reflection interface, the system achieves high light transmission efficiency through the folded path, minimizing energy loss and reducing the power consumption of the display device
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 results in a lightweight, efficient, and comfortable head-mounted display device with extended battery life by optimizing the optical path and reducing the physical dimensions of the display device.
Implementation Method 1
The Faraday rotator is disposed between the first polarization-sensitive reflector and the second polarization-sensitive reflector so that the Faraday rotator converts: (i) light having the first polarization into light having the third polarization, (ii) light having the third polarization into light having the second polarization, and (iii) light having the second polarization into light having the fourth polarization
Implementation Method 2
The first polarization-sensitive reflector is positioned to transmit light having a first polarization and reflect light having a second polarization orthogonal to the first polarization
Implementation Method 3
The second polarization-sensitive reflector is positioned to reflect light having a third polarization and transmit light having a fourth polarization orthogonal to the third polarization
Data Source
AI summary
An optical assembly includes a first polarization-sensitive reflector, a second polarization-sensitive reflector, and a Faraday rotator. The first polarization-sensitive reflector is positioned to transmit light having a first polarization, and reflect light having a second polarization that is orthogonal to the first polarization. The second polarization-sensitive reflector is positioned to reflect light having a third polarization that is different from the first polarization and the second polarization, and transmit light having a fourth polarization that is orthogonal to the third polarization. The Faraday rotator is disposed between the first polarization-sensitive reflector and the second polarization-sensitive reflector so that the Faraday rotator converts: (i) the light having the first polarization into the light having the third polarization, (ii) the light having the third polarization into the light having the second polarization, and (iii) the light having the second polarization into the light having the fourth polarization.