Cemented Three-Lens Optical System for HMD Chromatic Aberration
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Solution Overview
Problem
Existing optical systems for head mount displays face challenges in achieving a compact size with a wide field of view and high optical performance while minimizing chromatic aberration, as reducing the number of lenses compromises optical performance and increasing the number of lenses complicates size reduction.
Innovation Solution
The optical system consists of a first lens with a transmissive reflective surface on the pupil side, a second lens cemented with either the first or third lens, and a third lens with a transmissive reflective surface on the display side, optimizing the optical path length and Abbe number difference to correct chromatic aberration and maintain high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the number of lenses is reduced to two for miniaturization, then the size is reduced, but chromatic aberration correction becomes difficult and optical performance deteriorates
Solution Approach 1:
The patent combines multiple functions into the three-lens structure: each lens serves both as a focusing element and a chromatic aberration correction element. The first lens (negative meniscus) corrects chromatic aberration from the display element, the second lens (positive meniscus) provides additional chromatic correction and focusing, and the third lens (negative meniscus) completes the correction while enabling compact form factor. This merging of functions allows achieving chromatic aberration correction with only three lenses rather than requiring more lenses.
Solution Approach 2:
The patent employs specific parameter ranges for each lens to optimize both size and chromatic aberration correction. The first lens has a negative meniscus shape with specific curvature radii (R1, R2) and focal length f1, the second lens has a positive meniscus shape with curvatures (R3, R4) and focal length f2, and the third lens has a negative meniscus shape with curvatures (R5, R6) and focal length f3. These parameter optimizations enable the three-lens system to achieve adequate chromatic aberration correction while maintaining a compact form factor suitable for HMDs.
2Reliability
If the reflective polarizer is disposed between the lens surfaces, then the optical performance is improved, but the size reduction becomes difficult
Solution Approach 1:
The patent merges the reflective polarizer function with the lens surfaces by forming transmissive reflective surfaces directly on the first and third lenses. This integration eliminates the need for separate reflective polarizer components that would increase size, while still achieving the desired optical performance for polarized light reflection and transmission. The transmissive reflective surfaces are formed on the outer surfaces of the first and third lenses, combining the optical functions within the existing lens structure.
3Reliability
If three lenses are used with a reflective polarizer, then the optical performance is improved, but the device complexity increases
Solution Approach 1:
The patent reduces device complexity by merging the reflective polarizer function into the lens structures themselves. The first lens includes a first transmissive reflective surface, and the third lens includes a second transmissive reflective surface. This integration eliminates separate reflective polarizer components, reducing the total component count while maintaining optical performance. The second lens is cemented to either the first or third lens, further reducing the number of air-glass interfaces and simplifying the overall structure.
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 a compact, high-performance optical system with sufficient chromatic aberration correction, maintaining a wide field of view and high resolution, thus enhancing user immersion without increasing the size of the display apparatus.
Implementation Method 1
a first lens (101) having a first transmissive reflective surface (R1) on a surface on the observation surface side; a third lens (103) having a second transmissive reflective surface (R2) on a surface on the display element side
Implementation Method 2
The light beam from the display surface transmits through the second transmissive reflective surface, transmits through the third lens, the second lens, and the first lens in this order
Data Source
AI summary
An optical system includes, in order from a pupil surface side to a display surface side, a first lens having a first transmissive reflective surface on the pupil surface side, a second lens, and a third lens having a second transmissive reflective surface on the display surface side. The second lens is cemented with the first or third lens. The light beam from the display surface transmits through the second transmissive reflective surface, transmits through the third, second, and first lenses in this order, is reflected by the first transmissive reflective surface, transmits through the first, second, and third lenses in this order, is reflected by the second transmissive reflective surface, transmits through the third, second, and first lenses in this order, transmits through the first transmissive reflective surface, and enters the pupil surface.