Diffractive Optical Element Profiles for Easier Replication
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Solution Overview
Problem
Existing diffractive optical elements (DOEs) with high frequency features are difficult to manufacture and replicate, especially when designed for wide field-of-view (FOV) or field-of-illumination (FOI), due to their complex and steep transitions.
Innovation Solution
Design DOEs with a maximum angle between adjacent levels or a smooth surface profile that satisfies θmax=arctan (3.5×RI), reducing the need for high frequency features, and using a replication tool with a multi-level or smooth surface structure that adheres to these criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DOEs are designed with high frequency features to achieve wide field-of-view or field-of-illumination, then optical performance is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent changes the geometric parameters of the DOE structure by limiting the maximum angle between adjacent levels to arctan(3.5×RI). This parameter constraint transforms the design approach from using high frequency features to using controlled angular transitions, thereby improving manufacturability while maintaining optical performance through optimized geometric parameters
Solution Approach 2:
The patent introduces smooth surface profiles with continuous curvature transitions instead of sharp high frequency features. By ensuring the surface profile has a maximum angle constraint and smooth transitions, the design achieves wide FOV/FOI performance without the manufacturing difficulties associated with steep, high frequency structural features
2Reliability
If DOEs are designed with steep transitions to achieve desired optical performance, then optical functionality is improved, but replication tool durability deteriorates
Solution Approach 1:
The patent applies parameter changes by constraining the maximum angle between adjacent levels to arctan(3.5×RI), which directly limits the steepness of transitions. This parameter control reduces stress concentrations and mechanical weaknesses in the replication tool structure, thereby extending tool durability while maintaining the necessary optical functionality through optimized angular parameters
Solution Approach 2:
The patent employs smooth surface profiles with continuous curvature instead of sharp transitions. This curvature approach eliminates stress concentration points that would otherwise compromise replication tool durability, while still achieving the desired optical performance through carefully controlled angular transitions that satisfy the arctan(3.5×RI) constraint
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
Enables easier manufacturing and replication of DOEs with improved optical performance, reducing defects and enhancing the durability of replication tools, while maintaining or exceeding the performance of DOEs with high frequency features.
Implementation Method 1
DOEs are optical components that are operable to modify an incident light's phase and/or amplitude to create a desired optical output pattern
Implementation Method 2
The depth of the pattern may be on the order of the wavelength of the light, specific to the application, and adjusted to the refractive index of the material of the DOE
Implementation Method 3
the surface topology of a master structure is duplicated into a thin film of a UV-curable replication material such as an UV-curable epoxy resin on top of a substrate
Data Source
AI summary
Design techniques are described for diffractive optical elements that, at least in some instances, can permit the design of diffractive optical elements without high frequency features, or with a significantly reduced number of such features. Diffractive optical elements designed in accordance with the described techniques can, in some instances, be easier to manufacture and/or replicate.