Retinal Projection Optics for Replicated Exit Pupil Detection
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Solution Overview
Problem
Existing optical systems for virtual retinal scan displays struggle to accurately determine the positions of replicated exit pupils relative to the pupil center, leading to potential confusion and ambiguities in image processing.
Innovation Solution
An optical system comprising a projector unit with controllable deflection devices for multiple light beams, an optical segmentation element, and a computing unit to differentiate and ascertain the positions of first and second exit pupils relative to the pupil center using sensors and infrared wavelengths, ensuring precise projection onto the retina.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an optical replication component is used to direct light beams in a replicated manner toward the user's eye, then multiple spatially-offset exit pupils are produced, but it becomes difficult to accurately determine the positions of replicated exit pupils relative to the pupil center
Solution Approach 1:
The patent segments the detection process by using separate sensors for different wavelength ranges. First sensors detect backscattered light in the first wavelength range to determine positions of first exit pupils, while second sensors detect backscattered light in the second wavelength range to determine positions of second (replicated) exit pupils. This segmentation allows accurate position determination for each group of exit pupils independently.
Solution Approach 2:
The patent introduces wavelength-specific backscattered light detection as an intermediary measurement method. By detecting backscattered light at different wavelengths from the user's eye, the system obtains indirect information about exit pupil positions without directly measuring the exit pupils themselves, enabling precise position determination for both original and replicated exit pupils.
2Adaptability or versatility
If multiple exit pupils are produced simultaneously as pairs, then the system achieves multi-eyebox functionality, but confusion and ambiguities occur in subsequent image processing
Solution Approach 1:
The patent uses wavelength differentiation (analogous to color changes) to distinguish between first and second exit pupils. First exit pupils are associated with light beams in a first wavelength range, while second exit pupils are associated with light beams in a second wavelength range. This wavelength encoding allows the image processing device to clearly differentiate between pupils from different eyeboxes, eliminating confusion in image processing.
Solution Approach 2:
The patent performs preliminary differentiation of exit pupil positions based on wavelength-specific detection before image processing. The computing unit determines positions of first exit pupils and second exit pupils separately using backscattered light at different wavelengths, and this pre-differentiated position information is then used by the image processing device to correctly process images for each eyebox, preventing subsequent confusion.
3Ease of operation
If backscattered light detection is used to determine exit pupil positions, then non-invasive measurement is achieved, but detection accuracy is reduced when exit pupils are replicated and positioned closely
Solution Approach 1:
The patent segments the detection system into wavelength-specific detection channels. First sensors detect backscattered light in the first wavelength range to determine first exit pupil positions, while second sensors detect backscattered light in the second wavelength range to determine second exit pupil positions. This segmentation maintains non-invasive detection while improving precision by preventing signal overlap between replicated exit pupils.
Solution Approach 2:
The patent changes the detection parameter from generic light detection to wavelength-specific backscattered light detection. By utilizing different wavelength ranges for detecting different groups of exit pupils, the system maintains the non-invasive nature of backscattered light detection while significantly improving measurement precision for closely positioned replicated exit pupils.
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
Prevents double images by accurately distinguishing between first and second exit pupils, enhancing image clarity and processing precision in virtual retinal scan displays.
Implementation Method 1
a first sensor designed to detect second light beams backscattered by an outer eye surface, in particular the iris or sclera, of the user
Implementation Method 2
an optical segmentation element, which is arranged between the projector unit and the redirection unit and with the aid of which the image content and the second light beams are projectable via different imaging paths
Implementation Method 3
The deflection device is in particular a micromirror mounted rotatably about a first and/or second axis of rotation. The controllable deflection device is designed in this context to deflect the at least one first light beam for scanning projection
Data Source
AI summary
An optical system for a virtual retinal scan display. A plurality of first exit pupils and replicated, second exit pupils are produced. A computing unit is designed, depending on second light beams, backscattered by an outer eye surface and detected using a first sensor, in a first infrared wavelength range or the modulation of the power of a second light source, and/or depending on third light beams, backscattered by the outer eye surface, in a second infrared wavelength range or a modulation of a power of a third light source and/or depending on backscattered third light beams detected using a second sensor, or the modulation of the power of the third light source, to ascertain the positions of the first exit pupils relative to a pupil center and the positions of the second exit pupils relative to the pupil center.