Diffractive Optical Element Fabrication via 3D Printed Mold and Index Matching
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Solution Overview
Problem
Conventional methods for fabricating diffractive optical elements have limited flexibility in designing the 3D profile and are costly, requiring specialized facilities, with challenges in achieving nanoscale precision and inducing chromatic aberration or dispersion.
Innovation Solution
The method involves fabricating a three-dimensional mold with a relief pattern complementary to the desired diffractive pattern using three-dimensional printing, followed by contacting the mold with a solidifiable transmissive material and a substance with a refractive index difference less than 0.002, allowing for larger feature sizes and reduced manufacturing costs while maintaining optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to fabricate diffractive optical elements with nanoscale precision, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the critical parameter from nanoscale dimensions to microscale dimensions (features of several micrometers instead of nanometers). This parameter change allows the use of conventional 3D printing technology instead of specialized nanofabrication facilities, thereby reducing device complexity while maintaining adequate manufacturing precision for the intended application
Solution Approach 2:
The patent applies a substance with refractive index closely matched to the transmissive substrate (difference less than 0.002) to specific regions interfacing with the diffractive pattern. This local application of index-matched material enables the micrometric features to achieve the necessary optical path differences without requiring nanoscale precision throughout the entire structure
2Reliability
If conventional methods are used to fabricate diffractive optical elements, then optical quality is improved, but manufacturing cost increases
Solution Approach 1:
The patent scales up the feature dimensions from nanometers to micrometers, which enables the use of inexpensive 3D printing technology instead of costly cleanroom nanofabrication processes. The optical quality is maintained through the combination of micrometric features with index-matched substances that provide the necessary phase modulation
Solution Approach 2:
The patent employs inexpensive materials including 3D printed transmissive substrates and common index-matched substances (such as oils or liquids) instead of expensive specialized optical materials and coatings. This substitution of cheap materials achieves adequate optical performance at significantly reduced manufacturing cost
3Reliability
If traditional diffractive optical elements are designed with nanoscale features, then diffraction efficiency is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent changes the critical dimension parameter from nanoscale to micrometric scale (several micrometers). This parameter change makes the structure manufacturable with conventional 3D printing technology while maintaining diffraction efficiency through the use of index-matched substances that compensate for the larger feature sizes
Solution Approach 2:
The patent creates a composite optical system consisting of a 3D printed transmissive substrate with micrometric diffractive features combined with index-matched substances. This composite approach allows the relatively low-precision 3D printed features to achieve high diffraction efficiency when combined with the optical properties of the index-matched material
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
This approach simplifies the production of high-quality diffractive optical elements with feature sizes orders of magnitude larger than traditional nanoscale, reducing manufacturing costs and increasing design flexibility, while effectively inducing or maintaining chromatic aberration or dispersion.
Implementation Method 1
printing by the three-dimensional printing system a transmissive substrate having a pattern (e.g., a diffractive pattern) corresponding to the computer object data
Implementation Method 2
Relying on light diffraction, the DOEs alter the wavefront to obtain a desired intensity distribution in a specific plane, downstream the optical path
Implementation Method 3
contacting the transmissive substrate with one or more substances wherein a difference in refractive indices between the substance(s) and the transmissive substrate is less than about 0.1
Data Source
AI summary
A method of fabricating an optical element, comprises fabricating a three-dimensional mold having a relief pattern complementary to a pattern of the optical element to be fabricated, contacting the relief pattern with a solidifiable transmissive material, and solidifying the material thereby forming a transmissive substrate having the pattern thereupon. The method also comprises contacting the transmissive substrate with one or more substances wherein a difference in refractive indices between the substance(s) and the transmissive substrate is less than about 0.1.