Folded Optical Module Layout for Compact VR Imaging
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Solution Overview
Problem
Current VR devices suffer from large size and weight due to reduced imaging quality when minimizing the optical module length by decreasing the number of lenses or optical films.
Innovation Solution
A folded optical path design with a specific ratio of optical path length between folded optical paths to the overall optical path length, utilizing a first lens, a second lens, a beam splitting element, a first phase retarder, and a polarizing reflective element, maintaining superior imaging quality while reducing the overall length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the number of optical lenses or optical films is decreased to reduce the overall length of the optical module, then the overall length is reduced, but the imaging quality is compromised
Solution Approach 1:
The patent introduces a folded optical path design that changes the spatial arrangement of optical elements from a linear configuration to a folded configuration. By using beam splitting elements and polarizing reflective elements, the optical path is folded back on itself, effectively reducing the overall length of the optical module in the direction of light propagation while maintaining the necessary optical path length for high-quality imaging.
Solution Approach 2:
The optical module is segmented into multiple functional sections with specific optical path length ratios. The patent divides the optical path into segments with different length ratios (first optical path length ratio and second optical path length ratio), allowing each segment to be optimized for specific functions while collectively achieving both compact size and high imaging quality.
2Manufacturing precision
If traditional aspheric and Fresnel VR optical structures are used, then imaging quality can be maintained, but the overall length of the optical module increases
Solution Approach 1:
The patent employs a folded optical path design that transforms the traditional linear optical structure into a compact folded configuration. This dimensional change allows the optical module to achieve short overall length while maintaining adequate optical path length for high-quality imaging, overcoming the limitation of traditional aspheric and Fresnel structures.
Solution Approach 2:
The patent optimizes specific parameters including the first and second optical path length ratios, curvatures of optical surfaces, and refractive indices to achieve both compact size and high imaging quality. By carefully controlling these parameters within specific ranges, the patent resolves the contradiction between short overall length and high imaging quality.
3Length of stationary object
If the optical path length ratio is optimized within specific ranges, then the overall length is minimized, but the design complexity increases
Solution Approach 1:
The patent manages design complexity by establishing specific parameter ranges for the first and second optical path length ratios. By constraining these ratios within defined ranges (first ratio between 0.2-0.5, second ratio between 0.5-0.8), the patent achieves systematic optimization that balances compact size with manageable design 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 design effectively minimizes the optical module's size and weight, enhancing user experience by maintaining high imaging quality and reducing assembly complexity and costs.
Implementation Method 1
a beam splitting element, a first phase retarder, and a polarizing reflective element
Implementation Method 2
a first phase retarder, and a polarizing reflective element, wherein the first phase retarder is located between the beam splitting element and the polarizing reflective element
Implementation Method 3
a beam splitting element, a first phase retarder, and a polarizing reflective element
Implementation Method 4
an optical module, which includes a first lens and a second lens
Data Source
AI summary
The disclosure provides an optical module and a head mounted display. The optical module includes a first lens and a second lens, a beam splitting element, a first phase retarder, and a polarizing reflective element, wherein the first phase retarder is located between the beam splitting element and the polarizing reflective element; the beam splitting element is located on one side of the second lens, and the first phase retarder and the polarizing reflective element are located on either side of the first lens; wherein a ratio of an optical path length between folded optical paths of the optical module to a total optical path length of the optical module is 0.2 to 0.3.