Optical Pulse Train Shape Measurement

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Solution Overview

Problem

Existing shape measurement methods face challenges in achieving nanometer-order measurement resolution and meter-order measurement range simultaneously, as well as femtosecond-order time resolution, due to limitations in current technologies.

Innovation Solution

The method involves irradiating a measurement object with an optical pulse train having predetermined frequency distributions, where the optical pulses are controlled using an optical comb to establish a correspondent relation between pulse numbers and frequency distributions, enabling precise measurement of optical shapes through interference signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional shape measurement methods are used, then measurement can be performed, but nanometer-order measurement resolution and meter-order measurement range cannot be achieved simultaneously

Engineering Contradiction:
Improvemeasurement resolutionVSAvoidmeasurement range
Core Design Contradiction:
Measurement precisionVSLength of stationary object

Solution Approach 1:

The measurement system segments the optical pulse train into multiple discrete pulses, each with specific frequency distributions. By analyzing the correspondent relations between pulse numbers and frequency distributions across multiple pulses, the system achieves both high resolution (through frequency analysis) and large range (through pulse sequence numbering)

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces a temporal dimension by using optical pulse trains where pulses are disposed chronologically in numerical order. The measurement extracts information from the correspondent relations between pulse numbers (temporal sequence) and frequency distributions, adding a time-based dimension to the measurement that enables simultaneous achievement of high resolution and large range

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If conventional shape measurement methods are used, then measurement can be performed, but femtosecond-order time resolution cannot be realized

Engineering Contradiction:
Improvetime resolutionVSAvoidmeasurement system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention replaces mechanical timing systems with optical frequency-based timing. By using the correspondent relation between pulse numbers and frequency distributions, the system achieves femtosecond-order time resolution through optical frequency measurements rather than mechanical timing mechanisms, thereby reducing device complexity while improving time resolution

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

3Length of stationary object

If measurement range is increased to meter-order, then larger objects can be measured, but measurement resolution deteriorates from nanometer-order

Engineering Contradiction:
Improvemeasurement rangeVSAvoidmeasurement resolution
Core Design Contradiction:
Length of stationary objectVSMeasurement precision

Solution Approach 1:

The optical pulse train is segmented into multiple discrete pulses with identifiable pulse numbers. Each pulse carries frequency distribution information that encodes position data. By segmenting the measurement into discrete pulse events, the system maintains nanometer-order resolution through frequency analysis while achieving meter-order range through pulse sequence identification

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system changes the parameter being measured from continuous spatial position to discrete pulse number combined with frequency distribution. This parameter transformation allows the system to measure large distances (meter-order) by counting pulses while maintaining high precision (nanometer-order) through frequency distribution analysis

Inventive Principle:
Principle #35Parameter changes

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

This approach allows for a wide measurement range with nanometer-order resolution and femtosecond-order time resolution, eliminating the trade-off between resolution and range, and enabling non-contact, non-destructive measurement of complex shapes.

Implementation Method 1

an interference signal generated when the detection target optical pulse train interferes in a propagation space with a predetermined optical path length

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP3425326B1Shape measurement methods and shape measurement devices
Publication Date: 2021.11.10 UNIVERSITY OF ELECTRO-COMMUNICATIONS
  • EP3425326B1 patent drawingFigure 1
  • EP3425326B1 patent drawingFigure 2
  • EP3425326B1 patent drawingFigure 3

AI summary

A shape measurement method of the present invention includes: a step of irradiating a measurement object with an optical pulse train in which a plurality of optical pulses that have predetermined frequency distributions on a time axis are disposed chronologically in numerical order; and a step of measuring an optical shape of the measurement object in accordance with a correspondent relation between numbers of the optical pulses of a plurality of detection target optical pulse trains after the emitted optical pulses act on the measurement object and a correspondent relation between the frequency distributions in the optical pulses.