Optical Deflection Measurement for Cantilever Stress Analysis

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Solution Overview

Problem

Measuring the differential responses of multi-layered materials, such as stress induced by coating processes, is challenging due to extraneous forces introduced during the measurement process, which can overwhelm the small responses of interest.

Innovation Solution

A non-contact method using collimated light to measure the deflection of a cantilevered material strip before and after processing, calculating the induced stress by analyzing the change in reflected light position, allowing for repeated measurements over time to plot stress changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If physical contact measurement methods are used to measure deflection of multi-layered materials, then measurement can be performed with simple equipment, but extraneous forces from the measuring process overwhelm the small differential responses being measured

Engineering Contradiction:

Improvemeasurement precisionVSAvoidextraneous forces

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical contact-based deflection measurement with optical measurement. A laser beam reflects off the cantilever surface, and position-sensitive detectors track the reflected light position to calculate deflection. This optical system eliminates mechanical contact, thereby removing extraneous forces that would contaminate the measurement of small differential responses in multi-layered materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces light as an intermediary between the measurement system and the cantilever. Instead of direct mechanical contact, the laser beam serves as a mediator that interacts with the cantilever surface through reflection. This intermediary approach allows measurement of deflection without applying physical forces that could disturb the delicate multi-layered structure being measured.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If non-contact optical measurement is used to avoid extraneous forces, then measurement precision improves, but device complexity increases due to laser equipment and position-sensitive detectors

Engineering Contradiction:

Improvemeasurement precisionVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent describes a measurement system that can determine multiple characteristics of the cantilever (deflection, stress, material properties) using a single integrated optical setup. The laser and position-sensitive detectors serve multiple functions: measuring deflection at different positions, tracking deflection over time, and enabling calculation of various material characteristics from the same data set, thereby justifying the device complexity through multi-functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of information

If repeated measurements are taken over time to plot stress changes, then comprehensive material characterization is achieved, but measurement time increases

Engineering Contradiction:

Improvematerial characterization completenessVSAvoidmeasurement time

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

The patent enables continuous or repeated deflection measurements over time using the optical system. The laser continuously tracks the cantilever deflection as it evolves during processes like coating curing or stress relaxation. This continuous measurement capability provides complete material characterization data without significant time loss, as the optical system requires no setup adjustment between measurements and can rapidly capture deflection changes.

Inventive Principle:

Principle #20Continuity of useful 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

Accurately determines stress and other material characteristics without physically touching the material, effectively isolating the measurement from extraneous forces and providing precise data on material responses.

Implementation Method 1

A collimated light shines on the material under test, is reflected off it, and is then captured by a device that records the position where the reflected light is captured

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS11754505B2Measuring deflection to determine a characteristic of a cantilever

Publication Date: 2023.09.12 UNITED STATES OF AMERICA THE AS REPRESENTED BY THE SEC OF THE ARMY

AI summary

Disclosed are methods that, by not physically touching a material being measured, can measure the material's differential response quite accurately. A collimated light shines on the material under test, is reflected off it, and is then captured by a device that records the position where the reflected light is captured. This process is done both before and after the material is processed in some way (e.g., by applying a coat of paint). The change in position where the reflected light is captured is used in calculating the deflection of the material as induced by the process. This measured induced deflection is then used to accurately determinate the stress introduced into the material by the process. Other characteristics of the material under test, such as aspects of the material composition of a bi-metallic strip, for example, may also be determined from a deflection measurement.