Rotatable Pancake Lens Astigmatism Correction
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Solution Overview
Problem
Existing pancake lenses in head-mounted displays face challenges in providing adjustable accommodation and tunable astigmatism correction without adding thickness, weight, or design complexity.
Innovation Solution
The optical module incorporates a pancake lens with a primary and secondary optical element, each having a cylindrical surface profile with approximately 2.5 D of cylindrical power, which are rotatable to provide astigmatism correction. These elements can be independently aligned to adjust the cylindrical power and orientation, allowing for prescription correction without additional optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional prescription correction elements are added to pancake lenses, then astigmatism correction capability is improved, but device thickness and weight increase
Solution Approach 1:
The patent combines astigmatism correction functionality directly into the existing pancake lens structure by integrating cylindrical surface profiles onto the primary and secondary optical elements. This merging approach eliminates the need for separate prescription correction elements, thereby providing astigmatism correction capability while avoiding additional weight and thickness.
Solution Approach 2:
The primary and secondary optical elements are designed to serve multiple functions: they perform the core pancake lens function of achieving compact optical path folding while simultaneously providing astigmatism correction through their cylindrical surface profiles. This multi-functionality resolves the contradiction by making the existing components do double duty rather than adding dedicated correction elements.
2Reliability
If additional optical elements are added for prescription correction, then optical performance is improved, but device complexity increases
Solution Approach 1:
The patent merges astigmatism correction functionality into the existing primary and secondary optical elements of the pancake lens. By integrating cylindrical surface profiles onto these elements, the design avoids adding separate correction components, thereby maintaining optical performance while minimizing device complexity.
Solution Approach 2:
The patent makes the cylindrical surface profiles rotatable about the optical axis, allowing dynamic adjustment of the astigmatism correction orientation. This dynamic capability enables the system to adapt to different prescription requirements without adding multiple fixed correction elements, thus improving optical performance while keeping the structure relatively simple.
3Reliability
If cylindrical surface profiles are added to optical elements, then astigmatism correction is improved, but manufacturing complexity increases
Solution Approach 1:
The patent combines the cylindrical surface profiles with the existing spherical or aspherical surfaces of the primary and secondary optical elements. This merging allows astigmatism correction to be achieved through the lens shaping process itself, utilizing standard optical manufacturing techniques rather than requiring additional assembly steps or separate components.
Solution Approach 2:
The patent modifies the surface geometry parameters of the existing optical elements by adding cylindrical components to their surface profiles. This parameter change approach allows astigmatism correction to be achieved through conventional lens manufacturing processes, maintaining ease of manufacture while improving optical functionality.
4Adaptability or versatility
If rotatable elements are added for adjustable correction, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent introduces rotatability to the primary and secondary optical elements, allowing users to adjust the orientation of the cylindrical surface profiles to match different astigmatism axis orientations. This dynamic adjustment capability provides adaptability for various prescriptions while maintaining a relatively simple structure by using the existing lens elements themselves rather than adding separate adjustment mechanisms.
Solution Approach 2:
The rotatable primary and secondary optical elements serve dual purposes: they maintain the core pancake lens function of compact optical path folding while simultaneously providing adjustable astigmatism correction. This multi-functionality achieves adaptability without proportionally increasing device complexity, as the same components perform both functions.
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 configuration enables compact, lightweight, and adjustable optical correction for astigmatism, enhancing the optical performance of head-mounted displays while maintaining a minimal form factor and reducing design complexity.
Implementation Method 1
a primary optical element having a cylindrical surface profile defining a primary cylinder axis rotatably alignable with a first direction; and a secondary optical element having a cylindrical surface profile defining a secondary cylinder axis rotatably alignable with a second direction
Data Source
Figure 1A~1B
Figure 1C~2
Figure 3~4
AI summary
An optical module includes an electronic display configured to project image light along an optical axis and a lens assembly aligned with the optical axis, the lens assembly including (i) a primary optical element having a cylindrical surface profile defining a primary cylinder axis rotatably alignable with a first direction, and (ii) a secondary optical element having a cylindrical surface profile defining a secondary cylinder axis rotatably alignable with a second direction. Astigmatism correction for the optical module may be achieved through independent rotation and alignment of the primary and secondary optical elements with respective correction settings.