Optical Assembly Standoffs for HMD Alignment Precision
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Solution Overview
Problem
Existing head-mounted displays (HMDs) face challenges in maintaining proper optical alignment between projectors and waveguides, leading to deviations in optical quality that can affect user experience in artificial reality applications.
Innovation Solution
The use of standoffs between the projector assembly and waveguide housing to align light projectors with input gratings of the waveguide, allowing for precise positioning and orientation, facilitated by cameras for alignment and potential machining of standoffs to achieve optimal alignment within predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional mounting methods are used without standoffs, then the device complexity is reduced, but the manufacturing precision and optical alignment quality deteriorate
Solution Approach 1:
Standoffs are introduced as intermediary components between the projector assembly and waveguide housing to achieve precise optical alignment. These standoffs act as mediators that provide fixed spacing and positioning, enabling the projector lens to be aligned with the waveguide input grating without requiring complex direct mounting mechanisms.
Solution Approach 2:
The standoffs are pre-configured with specific lengths and positioning features before assembly. By preparing the alignment structure in advance with predetermined geometry, the actual assembly process becomes simpler while maintaining high precision. The standoffs are designed with specific dimensions to automatically establish the correct optical path when positioned between the projector and waveguide.
2Manufacturing precision
If precise alignment is achieved through machining standoffs, then the optical quality improves, but the ease of manufacture decreases
Solution Approach 1:
The standoff dimensions, particularly length and positioning features, are carefully optimized to achieve the required optical alignment. By adjusting these parameters during the design phase, the standoffs can be manufactured using standard processes while still achieving precise alignment when assembled. The key parameters are calculated based on the optical requirements of the specific projector and waveguide combination.
3Reliability
If multiple standoffs are used for alignment, then the reliability of optical alignment improves, but the device complexity increases
Solution Approach 1:
Instead of using a single complex alignment mechanism, multiple standoffs are distributed at different locations around the projector assembly. Each standoff provides localized alignment support at its specific position, and collectively they ensure stable and reliable alignment. This distributed approach increases reliability by providing redundant alignment points while keeping each individual component simple.
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
Improves optical quality by ensuring accurate alignment of projectors with waveguides, enhancing the user's experience in augmented and virtual reality applications by minimizing deviations and maintaining optical precision.
Implementation Method 1
a waveguide configured for redirecting light from the at least one light projector to a position in front of a user's eyes
Implementation Method 2
the waveguide including at least one input grating corresponding to the at least one light projector
Data Source
AI summary
Optical assemblies may include a projector assembly, a waveguide, and at least two standoffs. The projector assembly may include at least one light projector and a housing. The waveguide may include at least one input grating corresponding to the at least one light projector. The standoffs may be between the housing and the waveguide, and may be configured for aligning the at least one light projector with the at least one input grating. Related head-mounted displays, systems, and methods are also disclosed.