Near-Eye Projection Optics With Nested Paths for Compact Smart Glasses
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Solution Overview
Problem
Existing light-field projection systems for wearable devices, such as smart glasses, are bulky due to the need for multiple optical elements separated by a transparent medium, which compromises the device's form factor and image quality.
Innovation Solution
A near-eye image projection system utilizing a pin-light source, spatial light modulator (SLM), and optimized illumination and imaging optics to create a compact design suitable for wearable applications, with foveation capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple optical elements are separated by sufficient volume of transparent medium to achieve required characteristics, then the light-field image projection quality is improved, but the device form factor becomes bulky
Solution Approach 1:
The patent implements nested optical paths where the illumination optics and imaging optics are arranged in a compact configuration with the illumination optics in a third plane and imaging optics in a fourth plane, substantially perpendicular to the first plane. The optical paths are nested within each other, allowing sufficient separation distance for optical quality while maintaining a compact overall device volume suitable for wearable applications.
Solution Approach 2:
The patent transitions from a conventional planar arrangement to a three-dimensional configuration by placing the illumination optics in a third plane and imaging optics in a fourth plane, both substantially perpendicular to the first plane (SLM plane). This dimensional arrangement allows the optical paths to be compact in the first plane while maintaining sufficient separation distances in the third and fourth dimensions, resolving the contradiction between compactness and optical quality.
2Volume of moving object
If higher power optical elements with shorter focal length are used to shrink the optics, then the device form factor is reduced, but the illumination light structure quality deteriorates and optical artifacts increase
Solution Approach 1:
The patent changes the geometric parameters of the optical system by introducing perpendicular planes (third and fourth planes) relative to the SLM plane (first plane). This parameter change allows the use of optical elements with adequate focal lengths and power without increasing the footprint in the first plane, as the separation distances are achieved in the third and fourth dimensions. Consequently, high-quality illumination light structure is maintained while achieving a compact device form factor.
3Volume of moving object
If higher power optical elements are used to reduce device size, then the form factor is improved, but compensation requirements due to optical artifacts such as distortions and aberrations increase
Solution Approach 1:
By arranging the illumination optics in a third plane and imaging optics in a fourth plane, both perpendicular to the SLM plane, the patent achieves adequate optical separation distances without using higher power elements. This dimensional arrangement reduces optical artifacts such as distortions and aberrations, thereby minimizing the need for complex compensation mechanisms and keeping the device complexity low while maintaining a compact form factor.
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 system achieves a small form factor while maintaining high image quality, enabling applications in augmented and mixed reality devices like smart glasses.
Implementation Method 1
a pin-light source generating a plurality of incident light beams; a SLM configured to modulate said plurality of incident light beams
Implementation Method 2
illumination optics configured to deliver the incident light beams from the pin-light source to the SLM... The illumination optics defines a first optical path from the first plane to the second plane, and a second optical path from the third plane to the fourth plane
Implementation Method 3
imaging optics configured to deliver sequentially the modulated light beams from the SLM along a projection axis to an eye-box region in a second plane... The imaging optics defines a third optical path from the second plane to the first plane, and a fourth optical path from the first plane to the second plane
Data Source
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AI summary
Near-eye image projection system comprising a pin-light source generating incident light beams; a SLM generating modulated light beams forming pin-light images at a first plane; illumination optics, in a third plane, delivering the incident light beams from the pin-light source to the SLM; and imaging optics delivering the modulated light beams along a projection axis, in a fourth plane, to an eye-box region in a second plane parallel to the first plane. The third and fourth planes being substantially perpendicular to the first plane. The illumination optics defines a first optical path from the first plane to the second plane and a second optical path from the third plane to the fourth plane. The imaging optics defines a third optical path from the second plane to the first plane and a fourth optical path from the first plane to the second plane. A wearable device comprising the near-eye image projection system is also described.