Molded Dichroic Mirror for Seeker Signal Separation

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Solution Overview

Problem

The high cost and labor-intensive grinding process of dichroic mirrors used in seekers makes them expensive to produce, and existing materials like fused silica are unsuitable for molding due to high softening temperatures and dielectric constant issues.

Innovation Solution

Molding dichroic mirrors from materials like polysiloxane and lithia potash borosilicate, which have low dielectric constants and softening temperatures suitable for current molding equipment, allowing for cost-effective production while maintaining mechanical robustness and optical performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If dichroic mirrors are ground from fused silica, then manufacturing precision and optical performance are improved, but manufacturing cost and labor intensity increase significantly

Engineering Contradiction:
Improvemirror precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical grinding process with an injection molding process to manufacture dichroic mirrors. The molded mirrors are made from polysiloxane material that can be directly formed into precise optical shapes through molding, eliminating the need for expensive and labor-intensive grinding operations while maintaining manufacturing precision

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

Solution Approach 2:

The patent changes the material parameter from fused silica to polysiloxane, which has a lower softening temperature and can be processed through molding. This parameter change enables a fundamentally different manufacturing approach (molding vs. grinding) that reduces cost while achieving comparable precision

Inventive Principle:
Principle #35Parameter changes

2Reliability

If fused silica is used for dichroic mirrors, then optical performance is maintained, but molding is not feasible due to high softening temperature

Engineering Contradiction:
Improveoptical performanceVSAvoidsoftening temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent changes the material parameter from fused silica to polysiloxane, which has a significantly lower softening temperature that allows it to be processed through injection molding. The polysiloxane material is specifically selected to have thermal properties enabling molding while maintaining the optical performance required for dichroic mirror functionality

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If traditional grinding processes are used, then precision dichroic mirrors are produced, but production time and labor intensity increase

Engineering Contradiction:
Improvemirror precisionVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces the sequential mechanical grinding process with a parallel injection molding process that can produce multiple mirrors simultaneously. The molding process allows for high-volume production with consistent precision, dramatically improving productivity compared to individual grinding operations

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

Solution Approach 2:

The patent incorporates the mirror shape and optical properties directly into the molding process through preliminary action - the mold cavity is designed to produce the final precise mirror shape in one step, eliminating the need for subsequent grinding and polishing operations that would reduce productivity

Inventive Principle:
Principle #10Preliminary action

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 use of polysiloxane and lithia potash borosilicate materials reduces manufacturing costs significantly while achieving precision and performance comparable to ground and polished mirrors, with reduced boresight error and lower signal absorption.

Implementation Method 1

a dichroic mirror configured to reflect the infrared signal to the first receiver and to transmit the radio frequency signal to the second receiver

Methodology Applied
Scientific EffectDichroic reflection: Reflection

Implementation Method 2

The material is preferably selected to be able to reflect certain frequencies while allowing other frequencies to pass, or be transmitted

Methodology Applied
Scientific EffectFrequency selective transmission: Filter (optical)

Data Source

PatentEP3751320B1Seeker with a molded dichroic mirror
Publication Date: 2024.03.27 RAYTHEON CO
  • EP3751320B1 patent drawingFigure 1
  • EP3751320B1 patent drawingFigure 2

AI summary

A molded dichroic mirror and a seeker comprising a molded dichroic mirror are provided. The dichroic mirror may be molded from polysiloxane or lithia potash borosilicate and may be coated to reflect an infrared signal and configured to transmit a radio frequency signal between 33 GHz and 37 GHz.