Multilayer Gyroscope Mirror Coating for UV Loss Blocking

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Solution Overview

Problem

High energy components in the plasma of a ring laser gyroscope can activate loss centers in mirror materials, reducing laser power due to ultraviolet (UV) absorption, leading to instability and increased failure rates.

Innovation Solution

A multilayer mirror design incorporating a UV filter section with alternating layers of high and low refractive index materials, including specific filter layers to block UV energy and prevent its impact on high refractive index materials, thereby minimizing loss centers and enhancing stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a multilayer mirror uses high refractive index optical materials in the reflector section, then the reflectivity and optical performance are improved, but UV energy activates loss centers that absorb laser light, reducing power and stability

Engineering Contradiction:
Improvelaser powerVSAvoidstability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

A UV filter section is introduced as an intermediary layer between the UV plasma environment and the high refractive index reflector section. This filter section blocks UV energy from reaching the reflector, preventing UV-induced loss center activation while allowing the high refractive index materials to maintain their optical performance in the visible laser wavelength range

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If UV filter layers are added to protect the reflector section, then stability and reliability are improved, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
ImprovestabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The UV filter section is designed to serve multiple functions: it blocks UV radiation, maintains optical performance in the visible range, and integrates with the existing multilayer mirror structure. By combining UV protection with the optical filter design, the patent avoids adding excessive complexity while achieving reliability improvement

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If UV filter layers are added to protect the reflector section, then stability and reliability are improved, but manufacturing precision requirements increase

Engineering Contradiction:
ImprovestabilityVSAvoidlayer thickness precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The UV filter section is designed and positioned in advance, before the reflector section is fully assembled or before the mirror is deployed into the plasma environment. This preliminary placement allows for controlled deposition and thickness optimization without the need for post-assembly adjustments, reducing the overall manufacturing precision burden

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 UV filter component reduces loss increase in multilayer mirrors, increasing the stability and life of ring laser gyroscopes, and minimizing manufacturing and field failures.

Implementation Method 1

an ultraviolet (UV) component in the plasma can activate loss centers that absorb the laser light

Methodology Applied
Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Implementation Method 2

The filter section substantially blocks ultraviolet (UV) energy, thereby preventing UV energy from substantially impinging on the high refractive index optical material of the reflector section

Methodology Applied
Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

a reflector section that includes a plurality of alternating layers of a high refractive index optical material and a low refractive index optical material

Methodology Applied
Scientific EffectOptical interference: Interference

Implementation Method 4

a reflector section that includes a plurality of alternating layers of a high refractive index optical material and a low refractive index optical material

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4006594B1Ultraviolet filter for ring laser gyroscope mirrors
Publication Date: 2025.10.08 HONEYWELL INTERNATIONAL INC
  • EP4006594B1 patent drawingFigure 1
  • EP4006594B1 patent drawingFigure 2
  • EP4006594B1 patent drawingFigure 3

AI summary

A multilayer mirror comprises a reflector section including a plurality of alternating layers of a high index material and a low index material, and a filter section over the reflector section. The filter section comprises a first filter layer including a low index material on a layer of high index material of the reflector section; a second filter layer on the first filter layer, the second filter layer comprising a high index material that is different than the high index material in the reflector section; and a third filter layer on the second filter layer, the third filter layer comprising a low index material. Each filter layer has an optical thickness greater than or equal to the optical thickness of each layer of the alternating layers. The filter section substantially blocks ultraviolet (UV) energy, thereby preventing UV energy from substantially impinging on the high index material of the reflector section.