Coded-Aperture Plate for Terminal-Imaging Seeker Weight Reduction

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Solution Overview

Problem

Terminal-imaging seekers in munitions face challenges due to the weight and size of traditional lens stacks, which hinder their ability to survive launch shocks and maintain effectiveness in smaller, higher-shock-tolerant designs.

Innovation Solution

The implementation of a coded-aperture plate system that replaces traditional lens stacks, using an optically-neutral lens with a coded-aperture plate and a focal plane array to form corrected images, reducing system volume and weight while maintaining image quality through reconstruction algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a traditional lens stack is used in the terminal-imaging seeker, then image quality can be maintained, but the system volume and weight increase

Engineering Contradiction:
Improveimage qualityVSAvoidsystem volume
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent replaces the traditional mechanical lens stack with a coded-aperture plate system combined with computational image reconstruction. The coded-aperture plate uses a pattern of transparent and opaque regions to modulate light, and the image processor reconstructs the final image from the captured data, eliminating the need for complex mechanical lens assemblies while maintaining imaging capability

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

Solution Approach 2:

The patent changes the optical parameters by using an optically-neutral lens with a convex front surface instead of a traditional lens stack. This single lens element with specific optical properties (optically-neutral) combined with the coded-aperture approach allows for reduced system volume while achieving the required image quality through computational processing

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If a traditional lens stack is used in the terminal-imaging seeker, then image quality can be maintained, but the weight increases

Engineering Contradiction:
Improveimage qualityVSAvoidseeker weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent replaces the traditional mechanical lens stack with a coded-aperture plate system combined with computational image reconstruction. The coded-aperture plate uses a pattern of transparent and opaque regions to modulate light, and the image processor reconstructs the final image from the captured data, eliminating the need for complex mechanical lens assemblies while maintaining imaging capability

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

Solution Approach 2:

The patent extracts and removes the heavy lens stack component from the terminal-imaging seeker system. By eliminating this substantial mechanical component and replacing it with lighter alternatives (single optically-neutral lens + coded-aperture plate + processor), the system achieves significant weight reduction while preserving image quality through computational methods

Inventive Principle:
Principle #2Taking out (Extraction)

3Weight of moving object

If the terminal-imaging seeker is made smaller to reduce weight, then weight and size are reduced, but the ability to survive launch shocks deteriorates

Engineering Contradiction:
Improveseeker weightVSAvoidshock tolerance
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The patent employs a composite design combining an optically-neutral lens with a convex front surface (aerodynamic shape) and a coded-aperture plate. This composite optical system achieves both reduced weight and improved shock tolerance, as the simpler structure with fewer moving parts and the aerodynamic convex surface better withstands launch shocks while maintaining imaging functionality

Inventive Principle:
Principle #40Composite materials

4Volume of moving object

If a coded-aperture plate system is used instead of a lens stack, then system volume and weight are reduced, but image reconstruction complexity increases

Engineering Contradiction:
Improvesystem volumeVSAvoidimage reconstruction complexity
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical complexity of a lens stack with computational complexity in the image processing domain. The coded-aperture plate captures light patterns that are then reconstructed into images using an image processor, trading mechanical/optical complexity for computational processing while achieving reduced system volume

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 solution enables the creation of high-quality images with reduced system volume and weight, enhancing the survivability and effectiveness of terminal-imaging seekers in munitions by using a flat camera design that is aerodynamically efficient and capable of reconstructing images from overlapping pinhole-like exposures.

Implementation Method 1

The optically-neutral lens is configured to receive light from a scene aligned along an optical axis and configured to transmit light from the scene received at the front convex surface to the back planar surface in an optically-neutral fashion

Methodology Applied
Scientific EffectOptical transmission: Light

Implementation Method 2

The coded-aperture plate is configured to transmit light through the plurality of pinhole-like transparent regions onto the imaging region of the focal plane array thereby forming a raw shadow image

Methodology Applied
Scientific EffectPinhole imaging: Light

Data Source

PatentEP3447545B1Terminal-imaging seeker with software defined optics
Publication Date: 2022.06.29 ROSEMOUNT AEROSPACE INC
  • EP3447545B1 patent drawingFigure 1A~1B
  • EP3447545B1 patent drawingFigure 2A~2C
  • EP3447545B1 patent drawingFigure 3

AI summary

Apparatus and associated methods relate to forming images for a terminal-imaging seeker using software defined optics. An optically-neutral lens with a ballistic-ogive-shaped front surface receives light from a scene aligned along an optical axis. The optically-neutral lens transmits the light received at the ballistic-ogive-shaped front surface to a planar rear surface, which is then transmitted to a coded-aperture plate aligned with the optical axis. The coded-aperture plate includes a plurality of pinhole-like apertures, each of which is configured to perform pinhole-like lensing of the scene. The plurality of pinhole-like apertures form a multiplex of overlapping images on a focal plane array aligned with the optical axis. An image processor reconstructs, based on a configuration of the plurality of pinhole-like apertures and the multiplex of overlapping images, a single image of the scene.