Diffractive Optical Lens Structure to Reduce Scattering and Shadowing
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Solution Overview
Problem
Fresnel lenses suffer from light scattering and shadowing due to discontinuities between adjacent zones, which reduces their focusing efficiency.
Innovation Solution
Introduce continuous annular troughs or isolated holes in the intermediate zones of the lens, optimized using a computer algorithm to enhance optical efficiency by reducing scattering and shadowing, while maintaining the phase function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Fresnel lens with saw-tooth shaped concentric protrusions is used, then light gathering ability and compactness are improved, but light scattering and shadowing occur at zone boundaries reducing focusing efficiency
Solution Approach 1:
The lens is divided into a central region and multiple intermediate zones with different structural characteristics. The central region uses traditional refractive design while intermediate zones use diffractive structures, segmenting the optical path to optimize different functional requirements simultaneously.
Solution Approach 2:
Different regions of the lens are assigned different structural qualities: the central region has continuous refractive surfaces for high-quality focusing, while intermediate zones have diffractive protrusions optimized for light gathering. This local differentiation resolves the contradiction by allowing each region to optimize its specific function without compromising the other.
2Loss of energy
If diffractive optical lens with intermediate zones is used, then optical efficiency is improved by reducing scattering, but device complexity increases due to multi-region structure
Solution Approach 1:
The patent merges refractive and diffractive optical principles into a single hybrid lens structure. The central refractive region and intermediate diffractive zones work together as an integrated system, combining the advantages of both approaches while managing complexity through unified design parameters.
Solution Approach 2:
The lens utilizes curved surfaces and rotational symmetry in its design, with the intermediate zones featuring concentric circular protrusions. This curvature-based design simplifies manufacturing compared to asymmetric structures while maintaining the complex multi-functional optical performance.
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 proposed design significantly improves the optical efficiency of the lens by focusing a greater percentage of light onto the focal point, minimizing scattering and shadowing effects.
Implementation Method 1
A respective outer radius rh of each of the concentric zones in the intermediate region is rh=[(f+hλ0)2−f2]1/2, where λ0 is an operating wavelength of the diffractive optical lens, f is a focal length of the diffractive optical lens, and h is an integer
Implementation Method 2
The diffractive optical lens includes a central region shaped as a convex lens
Data Source
AI summary
The present disclosure describes an apparatus and system that includes a diffractive optical lens. The diffractive optical lens includes a central region shaped as a convex lens, an intermediate region laterally surrounding the central region and composed of multiple concentric zones, and an outer region laterally surrounding the intermediate region. A respective outer radius rh of each of the concentric zones in the intermediate region is (Eq. 1), where λ0 is an operating wavelength of the diffractive optical lens, f is a focal length of the diffractive optical lens, and h is an integer. At least one of the zones in the intermediate region includes at least one of (i) a continuous annular trough or (ii) a plurality of isolated holes that collectively encircle the central region.