Miniature Diffraction Grating Fabrication via Nanoimprint Lithography

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Solution Overview

Problem

Existing methods for fabricating miniature spectrally encoded endoscopy (SEE) probes face challenges in creating sub-mm transmission gratings with high diffraction efficiency and precisely assembling optical components, particularly due to difficulties with elastomeric stamps in high aspect ratio grating patterns.

Innovation Solution

The use of nanoimprint lithography to fabricate miniature diffraction gratings on SEE imaging optics, involving a rigid grating master with a reverse pattern, functionalization of the surface, and replication using UV curing epoxy or low-cost polymers, eliminating the need for an intermediate elastomeric mold and enabling high groove-density gratings with high aspect ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If soft lithography with elastomeric stamps is used to fabricate gratings, then the fabrication process is simple, but the method fails when the aspect ratio of the grating pattern is very high due to insufficient stiffness

Engineering Contradiction:

Improvefabrication process simplicityVSAvoidgrating pattern replication accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the material parameter from soft elastomeric material to rigid material for the stamp, enabling it to maintain structural integrity and replicate high aspect ratio grating patterns accurately without deformation, thus resolving the contradiction between ease of manufacture and manufacturing precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical friction-based removal process with a chemical release mechanism by functionalizing the master grating surface, allowing the rigid stamp to be easily removed without friction, thus maintaining both ease of manufacture and manufacturing precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If hard material is used for the elastomeric stamp to provide stiffness for high aspect ratio gratings, then the grating pattern can be replicated accurately, but the stamp cannot be easily removed from the master grating due to friction

Engineering Contradiction:

Improvegrating pattern replication accuracyVSAvoidstamp removal difficulty

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical friction-based attachment with a chemical bonding mechanism that can be easily reversed, allowing the rigid stamp to be firmly attached during replication but easily removed afterward, thus resolving the contradiction between manufacturing precision and ease of manufacture

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the surface property parameter of the master grating through functionalization, creating a release layer that reduces friction and enables easy removal of the rigid stamp, thus maintaining both manufacturing precision and ease of manufacture

Inventive Principle:

Principle #35Parameter changes

3Productivity

If intermediate elastomeric molds are used in the fabrication process, then the replication process is established, but the method cannot accommodate high groove-density master gratings with high groove aspect ratio

Engineering Contradiction:

Improvereplication process efficiencyVSAvoidcompatibility with high aspect ratio gratings

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent changes the material parameter from soft to rigid, enabling the stamp to accommodate high aspect ratio gratings while maintaining replication efficiency, thus resolving the contradiction between productivity and adaptability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the soft-lithography mechanical system with a rigid-lithography system using chemical release, expanding the method's adaptability to high aspect ratio gratings while maintaining productivity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method allows for the production of ultraminiature SEE probes with improved diffraction efficiency and reduced manufacturing costs, enabling smaller probe sizes and facilitating minimally-invasive imaging in previously inaccessible areas, while avoiding the limitations of soft-lithography methods.

Implementation Method 1

replication using UV curing epoxy or low-cost polymers

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Data Source

PatentUS10261223B2System and method for fabrication of miniature endoscope using nanoimprint lithography

Publication Date: 2019.04.16 CANON USA INC

AI summary

Exemplary method and system for providing a diffractive configuration in an optical arrangement are provided. For example, a material can be provided with at least one patterned surface having a very high aspect ratio. The material can be connected with at least one portion of a waveguide arrangement using a pre-polymer adhesive composition. Further, the pre-polymer adhesive composition can be caused to polymerize so as to form the diffractive configuration which at least approximately replicates a structure or at least one feature of the patterned surface.