Pleated Optical Surface Layout to Reduce Fresnel Lens Artifacts
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Solution Overview
Problem
Fresnel lenses suffer from low design freedom, poor processability, and light scattering due to discontinuous pleat structures when approximated by linear shapes, leading to artifacts and degraded optical characteristics.
Innovation Solution
An optical structure is divided into cells with aligned pleat structures that are shifted in parallel by a random amount within each cell to minimize approximation errors and scatter, maintaining optical continuity while reducing artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a curved surface structure is used to increase lens power, then the optical effect is improved, but the material cost and thickness increase proportionally
Solution Approach 1:
The lens is divided into multiple segments or zones with different optical powers. Instead of using a single thick curved surface, the lens comprises multiple thinner segments that collectively provide the desired optical effect, reducing overall material usage while maintaining lens power.
Solution Approach 2:
The invention transitions from a traditional two-dimensional curved surface to a three-dimensional micro-structured surface with varying heights and depths. This dimensional change allows light to be controlled through multiple reflections and refractions within the micro-structures, achieving high lens power with minimal material thickness.
2Length of stationary object
If a Fresnel lens with concentric circular structure is used to reduce thickness, then material cost is reduced, but design freedom and processability are limited
Solution Approach 1:
The invention replaces the traditional symmetric concentric circular structure of Fresnel lenses with an asymmetric micro-structured surface. The micro-structures have varying shapes, sizes, and orientations that are not radially symmetric, enabling greater design freedom for controlling light paths while maintaining thin profile and improved manufacturability through standard lithography processes.
3Adaptability or versatility
If a linear approximation structure is used to increase design freedom, then processability is improved, but approximation errors cause pleat discontinuities and light scattering
Solution Approach 1:
The invention applies different structural characteristics to different regions of the lens. Each local area contains micro-structures optimized for its specific function, with varying geometries and orientations. This local optimization ensures continuous light control across the entire lens surface while maintaining design freedom, eliminating the discontinuities that occur in uniform linear approximations.
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 method effectively reduces artifacts and maintains optical performance by approximating curved surfaces with linear pleat structures, enhancing design freedom and processability without increasing material costs.
Implementation Method 1
a first pleat structure and a second pleat structure which are different from each other are provided in one cell 14
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(c)
Figure 3~4
AI summary
An optical structure in which a plurality of cells having a pleat structure are regularly aligned in contact with each other on an embossed surface, the pleat structure has a plurality of inclined surfaces parallel to each other, the pleat structure has a linear ridge line formed of an inclined surface end, each ridge line is parallel to a straight line approximating a smooth curved line, depths of pleat structures of adjacent cells are uniform, an interval of ridge lines in a cell continuously varies between adjacent cells, an inclined surface group of each aligned cell displays a smooth curved surface appearance by reflected light of the inclined surfaces, and a distance of a ridge line, among ridge lines in each cell, closest to a predetermined reference point in the cell from the predetermined reference point has artificial fluctuation.