Light Scanning Optics with Micromirror Diffusion for Wider Eyebox
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Solution Overview
Problem
AR glasses using the retinal scanning method face challenges with a narrow eyebox and limited angle of view due to misalignment of the laser light condensing point with the pupil, especially when the user moves their eyes.
Innovation Solution
A light scanning device with a movable mirror and a condensing optical system comprising a half-silvered mirror with a concave surface and a diffusion plate containing micromirrors, which diffuses laser light to expand the eyebox and angle of view, ensuring the laser light is condensed to the center of the eyeball.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a condensing optical system is used to condense laser light to a specific point, then energy efficiency is improved, but the eyebox becomes narrow because the condensing point must match the pupil position
Solution Approach 1:
The patent divides the condensing optical system into multiple independent microlenses arranged in an array. Each microlense independently condenses light to a corresponding point on the retina, allowing different regions of the retina to receive focused light simultaneously. This segmentation enables the system to maintain energy efficiency for each light path while expanding the overall eyebox by accommodating various pupil positions and eye movements.
2Device complexity
If the laser light condensing point is fixed, then the optical system is simple, but the angle of view is limited when the user moves their eyes
Solution Approach 1:
The patent transitions from a single-point condensing approach to a two-dimensional array of microlenses. This dimensional expansion allows the optical system to handle light from multiple angles simultaneously by mapping different incident angles to different microlenses, thereby expanding the angle of view without significantly increasing overall system complexity.
3Device complexity
If a single movable mirror is used for retinal scanning, then the configuration is simple, but the eyebox remains narrow due to misalignment between condensing point and pupil
Solution Approach 1:
The patent creates multiple copies of the scanning function by using an array of microlenses, each capable of independently scanning and condensing light. This copying approach allows the system to maintain the simplicity of the original single-mirror scanning mechanism while expanding the eyebox through the parallel operation of multiple microlenses that can accommodate various pupil positions.
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
The device effectively expands the eyebox and angle of view with a simple configuration, allowing clear vision even when the user moves their eyes, while maintaining high energy efficiency and reducing visual stress.
Implementation Method 1
a mirror device that includes a movable mirror swinging about at least one axis and directionally changes the laser light emitted from the light source by reflecting the laser light using the movable mirror
Implementation Method 2
a condensing optical system that condenses the laser light directionally changed by the mirror device, in which the condensing optical system includes a half-silvered mirror that has a concave surface
Implementation Method 3
a diffusion plate in which a plurality of micromirrors that diffuse the laser light transmitted through the half-silvered mirror from the concave surface side are formed
Data Source
AI summary
A light scanning device includes a light source that emits laser light, a mirror device that includes a movable mirror swinging about at least one axis and directionally changes the laser light emitted from the light source by reflecting the laser light using the movable mirror, and a condensing optical system that condenses the laser light directionally changed by the mirror device. The condensing optical system includes a half-silvered mirror that has a concave surface, and a diffusion plate in which a plurality of micromirrors that diffuse the laser light transmitted through the half-silvered mirror from the concave surface side are formed.