Aperture Segmentation for Scintillation Mitigation in Fixed Guidance Sensors

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Solution Overview

Problem

Atmospheric scintillation causes guidance errors in missiles and guided ordnance by introducing non-uniform irradiance, leading to performance degradation, especially in fixed sensors, which are not gimbaled and thus more costly and complex.

Innovation Solution

A guidance system comprising a detector and an optical system with a spreader and condenser, where the spreader subdivides the input aperture into subregions and the condenser converges the energy onto the detector, reducing the effects of scintillation by spatially homogenizing and focusing the energy, allowing for accurate targeting without the need for gimbal mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a gimbaled configuration with movable optical elements is used to correct guidance errors, then guidance accuracy is improved, but device complexity and cost increase substantially

Engineering Contradiction:
Improveguidance accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The aperture is divided into multiple segments or zones, each with its own fixed optical element (lens or mirror) having different optical powers. This segmentation allows the system to correct for atmospheric turbulence effects across different field of view regions without requiring complex gimbal mechanisms, thereby maintaining guidance accuracy while reducing system complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the aperture are equipped with optical elements having locally optimized properties (different focal lengths, curvatures, or optical powers) tailored to correct turbulence effects in specific regions. This local optimization enables accurate compensation for spatially varying atmospheric conditions without requiring a complex movable platform

Inventive Principle:
Principle #3Local quality

2Measurement precision

If a gimbaled configuration with movable optical elements is used to correct guidance errors, then guidance accuracy is improved, but manufacturing cost increases substantially

Engineering Contradiction:
Improveguidance accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The aperture is divided into multiple segments or zones, each with its own fixed optical element (lens or mirror) having different optical powers. This segmentation allows the system to correct for atmospheric turbulence effects across different field of view regions without requiring complex gimbal mechanisms, thereby maintaining guidance accuracy while reducing system complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of moving the entire optical platform or large optical elements to track targets (conventional approach), the invention inverts the approach by using multiple fixed optical elements with different optical powers to achieve the same tracking and correction functionality through optical diversity rather than mechanical motion, significantly reducing manufacturing cost

Inventive Principle:
Principle #13The other way round (Inversion)

3Measurement precision

If a gimbaled configuration with movable optical elements is used to correct guidance errors, then guidance accuracy is improved, but reliability decreases due to increased failure susceptibility

Engineering Contradiction:
Improveguidance accuracyVSAvoidsystem reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The aperture is divided into multiple segments or zones, each with its own fixed optical element (lens or mirror) having different optical powers. This segmentation allows the system to correct for atmospheric turbulence effects across different field of view regions without requiring complex gimbal mechanisms, thereby maintaining guidance accuracy while reducing system complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of moving the entire optical platform or large optical elements to track targets (conventional approach), the invention inverts the approach by using multiple fixed optical elements with different optical powers to achieve the same tracking and correction functionality through optical diversity rather than mechanical motion, significantly reducing manufacturing cost

Inventive Principle:
Principle #13The other way round (Inversion)

4Device complexity

If a fixed sensor configuration is used, then device complexity is reduced, but guidance accuracy deteriorates due to atmospheric scintillation effects

Engineering Contradiction:
Improvesystem complexityVSAvoidguidance accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The aperture is divided into multiple segments or zones, each with its own fixed optical element (lens or mirror) having different optical powers. This segmentation allows the system to correct for atmospheric turbulence effects across different field of view regions without requiring complex gimbal mechanisms, thereby maintaining guidance accuracy while reducing system complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system employs multiple fixed optical elements with different optical parameters (focal lengths, curvatures, optical powers) to capture and process light from different angular regions. By combining information from these elements with different parameters, the system compensates for atmospheric scintillation effects and maintains high guidance accuracy without mechanical complexity

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

The system effectively minimizes the impact of atmospheric scintillation, enabling precise targeting and reducing system complexity and cost by using a fixed seeker configuration, while maintaining accurate trajectory control.

Implementation Method 1

Atmospherically induced scintillation may cause substantial aberrations in perceived energy received from a distance

Methodology Applied
Scientific EffectScintillation: Scintillation

Implementation Method 2

the condenser converges the spread energy onto the detector

Methodology Applied
Scientific EffectOptical focusing: Focusing

Data Source

PatentEP1946034B1Methods and apparatus for guidance systems
Publication Date: 2017.11.22 RAYTHEON CO
  • EP1946034B1 patent drawingFigure 1
  • EP1946034B1 patent drawingFigure 2
  • EP1946034B1 patent drawingFigure 3

AI summary

The optical system comprises a condenser (420) and a spreader (415) The spreader (415) subdivides an input aperture of the optical system into subregions The condenser (420) condenses the energy transmitted by the spreader (415) onto a detector Subdividing the aperture tends to minimize the effects of fluctuations larger than the size of the subregions on the transfer function.