Light Ray Folding Structure for Wide-Aperture Long-Focal Imaging
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Solution Overview
Problem
Imaging systems in portable electronic devices face challenges in achieving a long focal length while maintaining small outer dimensions, as existing folding structures obstruct the entrance aperture, reducing modulation transfer function (MTF) and limiting performance.
Innovation Solution
A light ray path folding structure that allows a wider light ray path to enter the imaging system by folding it at least once within a reflection passage using reflective surfaces, maintaining a longer focal length and enabling a wider entrance aperture, thus improving performance and allowing a thin form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a Cassegrain double reflection-based system is used to fold the light ray path, then the focal length can be extended and the design becomes more compact, but the secondary mirror obscures a central portion of the entrance aperture, significantly reducing the MTF value and imaging performance
Solution Approach 1:
The patent removes the secondary mirror from the optical path, replacing it with a beam splitter positioned at an angle to the optical axis. This extraction of the obscuring element eliminates the aperture blockage that caused MTF degradation while maintaining the folded optical path for extended focal length.
Solution Approach 2:
The patent introduces a beam splitter as an intermediary element that redirects the light path without obstructing the entrance aperture. The beam splitter acts as a mediator that achieves the light path folding function previously performed by the secondary mirror, but without the harmful aperture obscuration.
2Reliability
If the entrance aperture is enlarged to improve MTF and reduce diffraction, then the light ray path width increases and performance improves, but the outer dimensions of the imaging system increase
Solution Approach 1:
The patent folds the optical path using a beam splitter positioned at an angle, effectively utilizing the depth dimension to extend the optical path length without increasing the aperture area. This dimensional transformation allows large aperture benefits without proportional increases in overall device footprint.
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 solution enables an imaging system with improved performance and a longer focal length without increasing the outer dimensions, facilitating a compact electronic device with enhanced resolution and contrast.
Implementation Method 1
a light ray path enters the folding structure at an angle such that the width of the light ray path when passing perpendicularly through the plane of the first end equals the width of the light ray path when entering the folding structure multiplied by the square root of the width, such that , the light ray path being folded at least once within the reflection passage by means of at least one reflective surface extending in parallel with the center axis
Data Source
Figure 1~2b
Figure 3~4
Figure 5~6
AI summary
A light ray path folding structure (1) comprising a reflection passage (2), a center axis (C) of the reflection passage (2) extending between a first end (3) and a second end (4). A light ray path (5) enters the folding structure (1) at an angle (β) such that the width (Y) of the light ray path (5) when passing perpendicularly through the plane of the first end (3) equals the width (X) of the light ray path (5) when entering the folding structure (1) multiplied by the square root of the width (X), such that Y=√2*X. The light ray path (5) is folded at least once within the reflection passage (2) by means of at least one reflective surface (6) extending in parallel with the center axis (C). A light ray path folding structure allows the electronic device, comprising the folding structure, to have a thin form factor while still having an imaging system with long focal length.