Conical Imaging Apparatus with Deformable Mirror for Rotating Blades

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Solution Overview

Problem

Existing methods for imaging rotating components, such as fan blades in turbofan engines, face challenges with high-speed rotation and synchronization issues, particularly during accelerations, and are sensitive to out-of-balance conditions.

Innovation Solution

A conical imaging apparatus with a deformable mirror and a light field camera, where the mirror has a variable focal length and is axisymmetric, allowing for wide-field imaging of rotating components, and the camera can produce both still images and video, with data transmission and storage capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple cameras are mounted on and rotate with the helicopter rotor, then imaging of rotating components is achieved, but the system becomes highly sensitive to out-of-balance conditions and unsuitable for high-speed rotation

Engineering Contradiction:
Improveimaging stabilityVSAvoidsystem sensitivity to imbalance
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A stationary mirror is introduced as an intermediary element to reflect light from the rotating fan blades to the stationary camera. This mediator allows the imaging function to be achieved without directly mounting cameras on the rotating component, thereby eliminating sensitivity to rotational imbalance while maintaining imaging capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The mirror creates an optical copy or reflection of the rotating fan blades, allowing the stationary camera to capture images of the rotating component without physically rotating with it. This copying approach enables imaging of high-speed rotation without the complications of mounting sensors on the rotating part.

Inventive Principle:
Principle #26Copying

2Device complexity

If strobe cameras remain static with respect to the rotating component, then out-of-balance sensitivity is reduced, but synchronization with rotation rate becomes difficult during accelerations

Engineering Contradiction:
Improvebalance sensitivityVSAvoidsynchronization capability
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The stationary mirror continuously reflects light from all positions of the rotating fan blades to the stationary camera throughout the rotation cycle. This continuous optical path eliminates the need for strobe synchronization, as the mirror constantly captures and redirects light regardless of the rotation speed or acceleration state, providing uninterrupted imaging.

Inventive Principle:
Principle #20Continuity of useful action

3Area of stationary object

If a conical imaging apparatus with a deformable mirror is used, then wide-field imaging with maintained focus is achieved, but device complexity increases

Engineering Contradiction:
Improvefield of viewVSAvoidmirror deformation mechanism
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The mirror is made deformable with variable focal length, allowing it to dynamically adjust its optical properties. This dynamic capability enables the mirror to maintain focus across a wide field of view by changing its curvature to compensate for the conical geometry and varying distances to different parts of the fan, achieving wide-area imaging with consistent image quality.

Inventive Principle:
Principle #15Dynamics

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

Enables effective imaging of rotating components by maintaining focus and balance, allowing for analysis of vibrations, icing, and bird-strike resistance, while providing continuous monitoring during normal operation.

Implementation Method 1

The mirror is located at an apex end with the reflective surface being directed toward a base end

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3239685B1Imaging a rotating component
Publication Date: 2019.06.12 ROLLS ROYCE PLC
  • EP3239685B1 patent drawingFigure 1
  • EP3239685B1 patent drawingFigure 2
  • EP3239685B1 patent drawingFigure 3

AI summary

An imaging apparatus (202) for imaging a rotating component is shown. The imaging apparatus has a proximal end (301) configured to be attached to the rotating component, along with a distal end (302). The imaging apparatus has located within it a convex mirror (306) at the distal end, which has a reflective surface (309) which is directed toward the proximal end and having a field of view (FM) wider than the imaging apparatus. The imaging apparatus also has located within it a camera (307) at the proximal end, the camera being directed towards to distal end and having a field of view (FC) which includes the mirror.