Engineered Diffuser for SAL Seeker Uniformity

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Solution Overview

Problem

Semi-active laser (SAL) seekers face challenges in achieving a wide field of regard and uniform laser spot distribution due to atmospheric scintillation and non-uniform energy distribution, which are exacerbated by the absence of a gimbal system, leading to reduced performance and increased costs in existing strap down and velocity pursuit seekers.

Innovation Solution

The implementation of an engineered diffuser, a computer-generated optical element, at the entrance aperture of the SAL seeker to distribute incoming laser energy uniformly and mitigate scintillation effects, maintaining compatibility with fast optics and compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a gimbal system is used to provide a wide field of regard, then the field of regard is improved, but the device complexity and cost increase

Engineering Contradiction:

Improvefield of regardVSAvoidgimbal system complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent removes the gimbal system from the seeker architecture, extracting the problematic component that caused complexity and cost issues. The field of regard requirement is met through alternative means (optimized optical design and engineered diffuser) rather than mechanical gimbaling, thus resolving the contradiction between wide FOR and simple/cheap design

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The engineered diffuser serves multiple functions: it corrects atmospheric scintillation effects, improves spot uniformity, and enables the strap-down configuration to achieve adequate field of regard without gimbals. This multi-functional element replaces what would traditionally require separate subsystems

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If atmospheric scintillation correction is implemented using fiber optic faceplates, then scintillation is reduced, but the cost increases significantly

Engineering Contradiction:

Improvescintillation correctionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive fiber optic faceplates with a much cheaper engineered diffuser that can be manufactured using standard optical fabrication techniques. The diffuser achieves comparable or superior scintillation correction at a fraction of the cost, making the system economically viable

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The engineered diffuser modifies the optical parameters of the incoming laser signal by introducing controlled wavefront distortions that compensate for atmospheric scintillation effects. This parameter-based approach achieves correction without requiring expensive materials

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional optics are used without an engineered diffuser, then the design is simpler, but the spot uniformity deteriorates

Engineering Contradiction:

Improveoptical design simplicityVSAvoidspot uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The engineered diffuser introduces localized optical modifications at specific positions in the optical path to correct spot uniformity issues. By applying targeted corrections only where needed rather than redesigning the entire optical system, the patent maintains relative simplicity while achieving superior spot uniformity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The engineered diffuser acts as an intermediary optical element between the conventional optics and the detector. It mediates the interaction by conditioning the light field to produce uniform spots, allowing the use of simpler conventional optics while achieving high precision spot uniformity

Inventive Principle:

Principle #24Intermediary (Mediator)

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 engineered diffuser provides a uniform energy distribution over a large field of view, effectively addressing scintillation and spot uniformity issues while reducing costs by eliminating the need for expensive fiber optic faceplates and improving the overall performance of the SAL seeker.

Implementation Method 1

an engineered diffuser, a computer-generated optical element, at the entrance aperture of the SAL seeker to distribute incoming laser energy uniformly

Methodology Applied

Scientific EffectDiffraction: Diffraction

Implementation Method 2

atmospheric scintillation and uniformity problems further aggravate the performance of SAL seekers. Air turbulence near the ground is a primary source of atmospheric scintillation, and the air turbulence makes it appear to the SAL seeker that the laser spot is jumping or moving randomly

Methodology Applied

Scientific EffectScintillation: Scintillation

Data Source

PatentUS7575191B2Binary optics SAL seeker (BOSS)

Publication Date: 2009.08.18 LOCKHEED MARTIN CORP

AI summary

The present invention relates to a strap down SAL seeker that includes an optical system having an engineered diffuser for transforming a laser spot into a uniform distribution of optical energy with a predetermined shape. The predetermined shape is preferably a square “top hat” or uniform scatter pattern. The SAL seeker further includes a silicon quad detector, having a focal plane defined by at least two axes. The detector is operatively associated with the engineered diffuser, and it generates signals indicative of the position of the optical energy with respect to the focal plane of the detector.