Nested Axisymmetric Mirrors for Compact Neutron Imaging

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Solution Overview

Problem

Current neutron imaging technologies face limitations due to low neutron flux from compact sources, requiring high-flux research reactors and struggling with refractive optics' chromatic aberrations, which restrict spatial resolution and accessibility.

Innovation Solution

The use of nested, axisymmetric mirrors with grazing-incidence reflection, capable of redirecting neutrons through multiple reflections to enhance flux and reduce distortions, allowing for achromatic operation and increased angular collection, effectively utilizing compact neutron sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a small aperture is used to achieve high L/D ratio for high-resolution imaging, then spatial resolution is improved, but neutron flux illuminating the object is severely restricted

Engineering Contradiction:

Improvespatial resolutionVSAvoidneutron flux

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent employs nested mirrors where multiple mirror layers are positioned concentrically around the neutron beam path. Each mirror layer reflects neutrons that pass through the previous layers, effectively nesting the optical components to maximize flux collection while maintaining imaging resolution

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention transitions from traditional single-plane collimation to three-dimensional flux collection using mirrors positioned at multiple angles and distances. The mirrors are arranged in nested layers at different radial distances from the beam axis, collecting neutrons from multiple spatial dimensions simultaneously

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If refractive optics are used to focus neutrons, then flux concentration is improved, but chromatic aberrations occur due to refractive index dependence on neutron wavelength

Engineering Contradiction:

Improveneutron flux concentrationVSAvoidspatial resolution

Core Design Contradiction:

Quantity of substanceVSMeasurement precision

Solution Approach 1:

The patent replaces refractive optics with reflective optics. Instead of using lenses that refract neutrons based on wavelength-dependent indices of refraction, the invention uses mirrors that reflect neutrons based on grazing incidence angles, eliminating chromatic aberrations while maintaining flux concentration capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the fundamental optical parameter from refractive index to grazing incidence angle. By controlling the angle of incidence on mirror surfaces rather than relying on wavelength-dependent refraction, the system achieves wavelength-independent focusing that eliminates chromatic effects

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If elliptical KB mirrors are used for neutron focusing, then flux collection is improved for small sources, but imaging distortions occur due to magnification dependence on incident angle for large sources

Engineering Contradiction:

Improveneutron flux collectionVSAvoidimaging geometry

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent divides the single elliptical mirror into multiple nested mirror layers, each optimized for specific angular ranges. This segmentation allows different mirror layers to handle different portions of the neutron beam, reducing geometric distortions while maintaining overall flux collection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The nested mirror configuration serves multiple functions simultaneously: flux collection, collimation, and distortion correction. The system can handle both small and large source sizes effectively, providing universal applicability across different source geometries that single mirrors cannot achieve

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 significantly increases neutron flux and spatial resolution, enabling high-quality imaging with compact sources and reducing the need for large research reactors, while minimizing optical aberrations and chromatic issues.

Implementation Method 1

nested, axisymmetric mirrors with grazing-incidence reflection, capable of redirecting neutrons through multiple reflections

Methodology Applied

Scientific EffectGrazing-incidence reflection: Reflection

Data Source

PatentUS8735844B1Compact neutron imaging system using axisymmetric mirrors

Publication Date: 2014.05.27 UNIVERSITY OF ALABAMA

AI summary

A dispersed release of neutrons is generated from a source. A portion of this dispersed neutron release is reflected by surfaces of a plurality of nested, axisymmetric mirrors in at least an inner mirror layer and an outer mirror layer, wherein the neutrons reflected by the inner mirror layer are incident on at least one mirror surface of the inner mirror layer N times, wherein N is an integer, and wherein neutrons reflected by the outer mirror are incident on a plurality of mirror surfaces of the outer layer N+i times, where i is a positive integer, to redirect the neutrons toward a target. The mirrors can be formed by a periodically reversed pulsed-plating process.