Fresnel Lens Prism Structure for Flare Reduction
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Solution Overview
Problem
Fresnel lenses in image observing devices suffer from flare due to light reflection off ineffective surfaces, which causes a spreading pattern of light around the light emission spot, affecting image clarity.
Innovation Solution
The Fresnel lens design incorporates prisms with noneffective surfaces that are inclined relative to the optical axis, featuring a first and second surface configuration to deflect light away from the observer's pupil, reducing flare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the noneffective surfaces are made parallel to the optical axis, then the manufacturing is simplified, but light reflection causes flare that deteriorates image clarity
Solution Approach 1:
The patent changes the orientation parameter of the noneffective surfaces from parallel to the optical axis to inclined relative to the optical axis. This parameter change redirects the reflected light away from the observer's pupil, thereby reducing flare while maintaining manufacturing feasibility through standardized molding techniques.
Solution Approach 2:
The patent converts the harmful reflection effect into a beneficial one by inclining the noneffective surfaces. Instead of reflecting light directly into the observer's eye (harmful), the inclined surfaces reflect light at angles that direct it away from the pupil (beneficial), thus transforming the harmful reflection into a useful light redirecting mechanism.
2Object-affected harmful factors
If the noneffective surfaces are inclined to reduce flare, then image clarity is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the noneffective surface into multiple surfaces (first noneffective surface and second noneffective surface) with different orientations. The first noneffective surface is inclined at a first angle and the second noneffective surface is inclined at a second angle, allowing precise control of light reflection paths while maintaining manufacturability through modular design.
3Device complexity
If a single inclined surface is used, then the structure is simplified, but light reflection control is insufficient
Solution Approach 1:
The patent applies different inclination angles to different portions of the noneffective surface. The first noneffective surface has a first inclination angle and the second noneffective surface has a second inclination angle, optimizing light reflection control at different locations to comprehensively prevent flare while maintaining overall structural simplicity.
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 inclined noneffective surfaces effectively redirect stray light, minimizing flare and enhancing image clarity by preventing unwanted light reflections.
Implementation Method 1
light of the image reaches not only the effective surfaces of the prisms but also the noneffective surfaces thereof. The light is reflected by the noneffective surfaces and may land at the eyes of the observer.
Data Source
AI summary
There is provided a Fresnel lens capable of restraining flare from occurring. Each of a plurality of prisms (11) of a Fresnel lens (10) has an effective surface (Es) and a noneffective surface (Ns). In each of the prisms (11), the noneffective surface (Ns) has a first noneffective surface (Ns1) and a second noneffective surface (Ns2) that is closer to a crest (11c) of the prism (11) than the first noneffective surface (Ns1). The first noneffective surface is inclined to an optical axis (Z1).