Switchable Liquid Crystal Contact Lens With Low-Scatter Diffractive Cell
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Solution Overview
Problem
Existing electrically-switchable contact lenses with diffractive optical elements face challenges in achieving acceptable optical performance without light scatter and are difficult to manufacture.
Innovation Solution
A liquid crystal cell with a diffractive optical element that switches between unmatched and matched states, featuring diffraction blazes with rounded corners and non-vertical edges, reduces light scatter and improves alignment, while maintaining sufficient diffractive efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If diffractive optical elements are introduced to provide switchable optical powers, then the contact lens becomes electrically-switchable between different focal powers, but light scatter arises from the diffractive optical elements degrading optical performance
Solution Approach 1:
The patent applies curvature to the diffraction blaze profiles by replacing sharp corners with rounded transitions. Specifically, the diffraction blazes have curved surfaces instead of angular geometry, which smooths the light transmission and reduces scattering while maintaining the diffractive optical power switching capability
Solution Approach 2:
The patent changes the geometric parameters of the diffraction blazes by introducing curvature radius as a new parameter. The blaze profiles are defined with specific curvature radii at peaks and troughs, transforming the traditional angular blaze geometry into a curved geometry that reduces light scatter while preserving diffractive efficiency
2Adaptability or versatility
If conventional diffractive optical elements are used, then switchable optical powers are achieved, but manufacturing difficulty increases
Solution Approach 1:
The patent modifies the manufacturing parameters of the diffractive optical element by specifying curvature radii for the blaze profiles. This parameter change enables the use of standard optical fabrication techniques while achieving the desired curved blaze geometry, thereby improving manufacturability compared to conventional angular blaze designs
3Power
If sharp-edged diffraction blazes are used, then maximum diffractive efficiency is achieved, but light scatter increases due to the sharp corners
Solution Approach 1:
The patent replaces sharp corners with curved surfaces in the diffraction blaze profiles. The curved geometry maintains the diffractive optical power while smoothing light transmission, thereby reducing scatter without significant loss of diffractive efficiency
Solution Approach 2:
The patent employs a composite approach by combining curved surface geometry with appropriate materials for the diffractive optical element. The curved blaze profiles are formed using suitable optical materials that maintain both high diffractive efficiency and low scatter characteristics
Data Source
AI summary
An electrically-switchable liquid crystal cell (10) is provided, along with a lens (50) comprising the cell, and methods of manufacturing the cell. The liquid crystal cell (10) includes a diffractive optical element (12) and liquid crystal material (14) switchable between an unmatched state and a matched state. In the unmatched state, the effective refractive index of the liquid crystal material (14) is different from the refractive index of the base material (18) of the diffractive optical element (12). In the matched state, the effective refractive index of the liquid crystal material (14) matches the refractive index of the base material (18). In the matched state the diffractive optical element does not contribute a focal power for the lens. The diffractive optical element (12) has a number of peaks (20) and troughs (30) having rounded corners.