FASID Focal-Plane Mapping for Manufacturable GRIN Lens Imaging

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Solution Overview

Problem

Current fabrication processes for graded-index (GRIN) optics are limited by refractive index difference and spatial resolution, particularly in the short wavelength range, hindering their use in applications like wide-angle imaging and LIDAR systems.

Innovation Solution

A detector system and method that utilizes geometric optics transformation and spatial-angular information at the focal plane of a GRIN lens to optimize the refractive index distribution, minimizing overlap of input angles and enhancing separation resolution through diagonalization of a linear system matrix.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If transformation optics is used to project a sky hemi-sphere onto a plane using a GRIN lens, then the imaging capability is improved, but the fabrication precision deteriorates due to large variations in refractive index across the structure volume

Engineering Contradiction:
Improveimaging capabilityVSAvoidfabrication precision
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent transforms the optical problem from physical space to angular space, changing the design parameters from refractive index distribution to angular mapping functions. This allows achieving the same imaging effect without requiring extreme refractive index variations that are difficult to fabricate.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a new dimension of angular space to describe and control light propagation. By mapping rays based on their angular coordinates rather than relying solely on physical position and refractive index, the system achieves complex imaging functions with manufacturable GRIN profiles.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If present day fabrication processes are used for GRIN optics, then the manufacturing ease is improved, but the measurement precision deteriorates due to limitations in refractive index difference and spatial resolution

Engineering Contradiction:
Improvemanufacturing easeVSAvoidseparation resolution
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical/fabrication-based approach to achieving optical performance with a computational/algorithmic approach. By using angular space transformations and optimization algorithms, the system achieves high separation resolution without requiring ultra-precise fabrication of refractive index profiles.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If a GRIN lens with large variations in refractive index is designed to project sky hemi-sphere onto a plane, then the imaging performance is improved, but the device complexity increases due to fabrication limitations in short wavelength range

Engineering Contradiction:
Improveimaging performanceVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the design parameters from physical refractive index distribution to angular mapping relationships. This transformation simplifies the design process and reduces device complexity while maintaining imaging performance, as angular mappings can be achieved with standard GRIN fabrication capabilities.

Inventive Principle:
Principle #35Parameter changes

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

Improves the performance of GRIN lenses by reducing fabrication limitations, enabling better separation and imaging capabilities, particularly for astronomical and LIDAR applications.

Implementation Method 1

graded index (GRIN) optical element... refractive index distribution... optical rays emanated by two different point sources... are mapped uniquely onto the same location on the focal plane

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3729148B1System and method for focal-plane angular-spatial illuminator/detector (FASID) design for improved graded index lenses
Publication Date: 2026.02.04 LAWRENCE LIVERMORE NAT SECURITY LLC
  • EP3729148B1 patent drawingFigure 1a~1b
  • EP3729148B1 patent drawingFigure 1c
  • EP3729148B1 patent drawingFigure 2

AI summary

The present disclosure relates to a method for imaging an optical signal received by a graded index (GRIN) optical element to account for known variations in a graded index distribution of the GRIN optical element. The method may involve using a plurality of optical detector elements to receive optical rays received by the GRIN optical element at a plane, where the plane forms a part of the GRIN optical element or is downstream of the GRIN optical element relative to a direction of propagation of the optical rays. The optical rays are then traced to a plurality of additional specific locations on the plane based on the known variations in the graded index distribution of the GRIN optical element. A processor may be used to determine information on both an intensity and an angle of the received optical rays at each one of the plurality of specific locations on the plane of the GRIN optical element.