Spatial Filter Cylindrical Surface High Power Laser Thermal Damage

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Solution Overview

Problem

High-power laser beams cause damage to spatial filters by melting or evaporating the material, leading to enlarged apertures and potential damage to nearby optical or electronic components due to melted or evaporated material and scattered laser beams.

Innovation Solution

Spatial filters with non-planar surfaces, such as cylindrical or prismatic structures with gaps, are used to transmit electromagnetic radiation, reducing thermal loading by allowing incident beams to hit the surface at a glancing angle and scattering radiation away from the main beam plane, thereby enhancing thermal tolerance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spatial filter with a planar surface is used to restrict high-power laser beams, then the beam quality is improved, but the material of the spatial filter is damaged by melting or evaporation

Engineering Contradiction:

Improvespatial filter durabilityVSAvoidthermal damage to spatial filter

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies curvature by replacing the planar surface with a cylindrical surface. The spatial filter element has a curved surface that causes incident laser beams to strike at glancing angles rather than perpendicular angles. This curvature distributes the thermal load over a larger surface area and prevents concentrated heating that leads to melting and evaporation, thereby resolving the contradiction between maintaining spatial filtering function and preventing thermal damage.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent transitions from a two-dimensional planar surface to a three-dimensional curved surface. By adding the dimensional aspect of curvature, the spatial filter can deflect beams in multiple directions and distribute thermal energy across a larger volume and surface area. This dimensional change allows the filter to maintain its beam-restricting function while significantly improving thermal tolerance.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If high-power laser beams are transmitted through a spatial filter, then the spatial restriction function is achieved, but the aperture is enlarged due to material evaporation

Engineering Contradiction:

Improveaperture stabilityVSAvoidspatial filter material evaporation

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The cylindrical curved surface prevents concentrated thermal loading at any single point that would cause localized evaporation and aperture enlargement. The curvature distributes the beam energy across the curved surface, preventing the material loss that would otherwise enlarge the aperture and compromise spatial filtering precision.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If a spatial filter is exposed to high-power laser beams, then the beam filtering is effective, but nearby optical or electronic components are damaged by scattered beams and melted material

Engineering Contradiction:

Improvecomponent safetyVSAvoidscattered radiation and melted material

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The curved surface of the cylindrical spatial filter deflects scattered radiation in multiple directions away from the main beam path and away from nearby components. This curvature prevents scattered beams from concentrating on adjacent optics or electronics, and also directs melted or evaporated material away from sensitive components, thereby protecting them from damage.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent converts the potentially harmful scattered radiation and melted material into beneficial effects by using the curved surface to redirect them away from sensitive components. The scattering that would normally be harmful is now used to distribute energy away from the beam path, and the melted material is directed away from components rather than onto them.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 non-planar surface design significantly improves the thermal tolerance of spatial filters, reducing damage from high-power laser beams and minimizing the risk of damage to other components by spreading the radiation over a larger surface area and scattering stray light effectively.

Implementation Method 1

scattering radiation away from the main beam plane

Methodology Applied

Scientific EffectScattering: Scattering

Implementation Method 2

allowing incident beams to hit the surface at a glancing angle

Methodology Applied

Scientific EffectGlancing angle incidence: Reflection

Data Source

PatentUS10394042B1Spatial filters with high power handling capabilities

Publication Date: 2019.08.27 LOCKHEED MARTIN COHERENT TECHNOLOGIES INC

AI summary

An apparatus includes a source configured to generate a beam of electromagnetic radiation propagating in a first direction and a spatial filter. The spatial filter is configured to restrict the beam of electromagnetic radiation in one or more dimensions and includes at least one set of rods including a first rod and a second rod. The first rod is a first cylindrical structure with a first axis in a first plane and the second rod is a second cylindrical structure with a second axis in a second plane parallel to the first plane. The first axis and the second axis are longitudinal axes, and the first and the second rods have shaped surfaces in portions of their respective surfaces facing one another.