Curved Phase Retarder Optical System for HMD Aberration Correction
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Solution Overview
Problem
Optical systems for head-mounted displays face challenges in achieving a wide field of view with high contrast and low distortion while maintaining a compact design, particularly in utilizing reflective polarizers and partial reflectors spaced apart.
Innovation Solution
The optical system incorporates an integral third optical assembly with a curved phase retarder disposed between the first and second optical assemblies, which includes a reflective polarizer and a partial reflector, allowing for additional aberration correction and maintaining a compact design even with a relatively low optical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a reflective polarizer and partial reflector are spaced apart in optical systems, then the field of view and contrast are improved, but the system size and complexity increase
Solution Approach 1:
The patent combines the reflective polarizer and partial reflector into a single integrated optical element with a specific layered structure. The reflective polarizer layer and partial reflector layer are positioned in close proximity within the same optical assembly, eliminating the need for separate spaced-apart components while maintaining the desired optical performance for wide field of view and high contrast
Solution Approach 2:
The integrated optical element serves multiple functions simultaneously: it acts as both a reflective polarizer and a partial reflector, while also functioning as an optical lens. This multi-functionality reduces the number of separate components needed in the system, thereby reducing overall system complexity while achieving the desired optical effects
2Manufacturing precision
If additional optical assemblies are added for aberration correction, then image quality and contrast are improved, but the system becomes more complex and less compact
Solution Approach 1:
The patent integrates aberration correction functionality into the existing optical assemblies by incorporating specific lens elements with defined focal lengths and curvatures. The third optical assembly with focal length greater than the first two assemblies provides aberration correction without requiring additional separate correction components, thereby maintaining image quality while limiting system complexity
Solution Approach 2:
The patent achieves aberration correction by carefully selecting and adjusting optical parameters such as focal lengths, radii of curvature, and spacing between optical elements. By optimizing these parameters, the system corrects optical aberrations and maintains high image quality without adding excessive complexity or size
3Volume of moving object
If the optical power is reduced for compact design, then the system size is reduced, but the field of view and imaging performance deteriorate
Solution Approach 1:
The patent utilizes optical assemblies with specifically designed curvatures, where each assembly has a defined radius of curvature at its apex. The third optical assembly has a larger radius of curvature than the first two, which allows for compact sizing while maintaining adequate field of view and imaging performance through optimized curved surface geometry
Solution Approach 2:
The patent optimizes the balance between compact size and performance by carefully selecting focal lengths and curvature parameters. The third optical assembly has a focal length greater than the first two assemblies, which compensates for the reduced optical power and maintains adequate field of view while keeping the overall system compact
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 provides a wide field of view with high contrast and low distortion in a compact system, enhancing the performance of head-mounted displays.
Implementation Method 1
a reflective polarizer substantially transmitting light having a first polarization state and substantially reflecting light having an orthogonal second polarization state
Implementation Method 2
a curved first phase retarder for changing a polarization state of light passing therethrough
Implementation Method 3
a partial reflector having an average optical reflectance of at least 30% for a desired plurality of wavelengths
Data Source
AI summary
An optical system for displaying an object to a viewer is described. The optical system includes an integral first optical assembly, an integral second optical assembly, and an integral third optical assembly disposed between the integral first and second optical assemblies. The integral first optical assembly has a first focal length and includes one or more first optical lenses, and a reflective polarizer. The integral second optical assembly has a second focal length and includes one or more second optical lenses, and a partial reflector having an average optical reflectance of at least 30% for a desired plurality of wavelengths. The integral third optical assembly has a third focal length and includes a curved first phase retarder. The third focal length is greater than a smaller of the first and second focal lengths.