Aligning Diffractive Optical Elements in Wearable Heads-Up Displays
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Solution Overview
Problem
Wearable heads-up displays face challenges in aligning diffractive optical elements precisely, leading to misalignment issues that affect the visibility of projected images, particularly in multi-laser projectors, due to sensitivity to angle and position, and the need for careful alignment to maintain the eyebox and prevent obstruction of the field of view.
Innovation Solution
A method and system for aligning a diffractive optical element within a wearable heads-up display by determining and matching the inner and outer pupillary distances, using a support structure with a transparent combiner and projector, and compensating for curvature deviations in eyeglass lenses, involving fiducial marks and precise edging techniques to ensure accurate positioning and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a diffractive optical element is used in a wearable heads-up display, then the field of view is maintained and aesthetic appeal is improved, but precise alignment becomes difficult due to sensitivity to angle and position
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-positioning fiducial marks on the diffractive optical element and support structure before assembly. These fiducial marks serve as predetermined reference points that guide the alignment process, ensuring the DOE is positioned correctly relative to the projector and lens without requiring complex real-time adjustment during final assembly.
Solution Approach 2:
The patent uses fiducial marks as intermediary reference elements that mediate between the diffractive optical element and the support structure. These marks provide a stable, measurable reference that simplifies the alignment process by transforming the complex task of precise DOE positioning into a simpler fiducial mark alignment task, which can be achieved through standard manufacturing tolerances.
2Reliability
If the diffractive optical element is positioned to maintain eyebox, then image visibility is improved, but obstruction of field of view may occur
Solution Approach 1:
The patent applies local quality by positioning the diffractive optical element and its associated components (projector, lens) at specific localized regions of the support structure. The fiducial marks are placed at predetermined locations that optimize the optical path while minimizing obstruction. This localized positioning ensures the eyebox is maintained for image visibility while the overall component arrangement prevents field of view obstruction.
3Ease of manufacture
If curvature deviations in eyeglass lenses are not compensated, then manufacturing is simpler, but alignment precision deteriorates
Solution Approach 1:
The patent implements feedback by measuring the actual curvature of the eyeglass lens and using this information to adjust the positioning of the diffractive optical element and support structure. The fiducial marks serve as reference points that allow for measurement and correction of curvature deviations, enabling precise alignment even when lens curvature varies from ideal specifications.
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 approach enables precise alignment of the diffractive optical element, ensuring that projector light is directed correctly into the user's eye, maintaining a wide field of view and aesthetic appeal while preventing obstruction, thus improving the visual quality and usability of wearable heads-up displays.
Implementation Method 1
a diffractive optical element positioned within the lens to align the DOE with the eye of the user
Data Source
AI summary
Systems, devices, and methods for aligning a diffractive element in a wearable heads-up display (“WHUD”) are described. A WHUD that includes a projector, a transparent combiner, a WHUD frame, and a diffractive optical element (DOE) embedded in the transparent combiner, requires alignment between the DOE and the eye of the user and/or the projector. A WHUD includes a DOE aligned with an eye of a user when the WHUD is worn on the head of the user. A method of aligning a DOE in a WHUD with an eye of a user when the WHUD is worn on a head of a user includes aligning a first part of the WHUD frame with a first part of the face of the user, and aligning the DOE with a second part of the WHUD frame.