VCSEL Array Light Source for Fabry-Perot Acoustic Probe

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Solution Overview

Problem

Variation in film thickness of the polymer film between mirrors in a Fabry-Perot probe leads to inconsistent cavity length, causing sensitivity changes in acoustic wave detection, resulting in inaccurate sound pressure distribution measurements when using single-wavelength measurement light.

Innovation Solution

An acoustic wave acquiring apparatus with a controller to adjust the wavelength of measurement light for each element of a Fabry-Perot interferometer, using a VCSEL array light source to ensure optimal sensitivity across the probe surface by matching the wavelength to the cavity length at each position, and an optical sensor to measure changes in reflected light for accurate acoustic wave intensity acquisition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single-wavelength measurement light is used with a Fabry-Perot probe that has variation in cavity length, then the device complexity is reduced, but the measurement precision deteriorates due to sensitivity changes at different positions

Engineering Contradiction:
Improvelight source configurationVSAvoidsound pressure distribution measurement
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by making each element of the array light source emit light at a wavelength optimized for its specific position on the Fabry-Perot probe. The controller adjusts the wavelength of measurement light according to the cavity length at each position, ensuring that each local region operates at its optimal resonance condition. This resolves the contradiction by maintaining measurement precision across the entire probe surface without requiring a complex multi-wavelength system, as each element operates independently at its locally optimized wavelength.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If the measurement light wavelength is optimized for each position on the probe, then the measurement precision is improved, but the device complexity increases due to need for wavelength control per element

Engineering Contradiction:
Improvedetection sensitivityVSAvoidwavelength control system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies dynamics by implementing a controller that dynamically adjusts the wavelength of measurement light for each element based on the cavity length characteristics of the Fabry-Perot probe at corresponding positions. This dynamic wavelength adjustment allows the system to adapt to variations in cavity length across the probe surface, maintaining optimal detection sensitivity without requiring manual calibration or complex hardware modifications. The controller automatically optimizes the wavelength for each position, resolving the contradiction between measurement precision and device complexity.

Inventive Principle:
Principle #15Dynamics

3Device complexity

If a single-element probe is used, then the device complexity is reduced, but the productivity deteriorates due to lengthy scanning time for wide measurement regions

Engineering Contradiction:
Improveprobe structureVSAvoiddata acquisition speed
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent applies segmentation by dividing the light source into an array of multiple independent elements, each corresponding to a specific position on the Fabry-Perot probe. This segmentation allows simultaneous measurement across multiple positions rather than sequential scanning with a single element. Each element can be independently controlled to emit light at the optimal wavelength for its corresponding probe position, enabling parallel data acquisition and significantly improving productivity while maintaining manageable device complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

4Measurement precision

If the reception region is reduced to improve resolution, then the measurement precision is improved, but the productivity deteriorates due to increased scanning requirements

Engineering Contradiction:
Improveimaging resolutionVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies dimensionality change by transitioning from a single-element probe requiring one-dimensional scanning to an array light source with multiple elements operating in parallel across two dimensions. Each element in the array corresponds to a specific reception region on the probe, allowing simultaneous measurement across the entire field of view. This dimensional transition enables high-resolution imaging without the need for time-consuming sequential scanning, as all spatial positions are measured concurrently, thus improving productivity while maintaining measurement precision.

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

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 comprehensive and accurate measurement of sound pressure distribution in a batch mode, correcting sensitivity variations and enhancing imaging resolution and speed.

Implementation Method 1

A transducer using a piezoelectric effect and a transducer using capacity variations have been used as acoustic wave detectors in photoacoustic imaging

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

A structure in which light is resonated between two parallel reflective plates is called a Fabry-Perot interferometer

Methodology Applied
Scientific EffectFabry-Perot interferometer: Fabry-Perot Interferometer

Implementation Method 3

A detector using optical resonance has recently been developed

Methodology Applied
Scientific EffectOptical resonance: Resonance

Implementation Method 4

A semiconductor laser called a vertical-cavity surface-emitting laser (VCSEL) is explained below

Methodology Applied
Scientific EffectLight emission from VCSEL: Laser

Implementation Method 5

an optical sensor configured to measure a light quantity of reflected light

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentUS10180347B2Acoustic wave acquiring apparatus and control method therefor
Publication Date: 2019.01.15 CANON KK
  • US10180347B2 patent drawing
  • US10180347B2 patent drawing
  • US10180347B2 patent drawing

AI summary

An acoustic wave acquiring apparatus is used that includes: an array light source including a plurality of elements emitting measurement light; a controller controlling the wavelength of the measurement light, for each of or the plurality of elements; a Fabry-Perot interferometer including a first mirror upon which the measurement light is incident and a second mirror upon which an acoustic wave from a subject is incident; an optical sensor measuring a light quantity of reflected light by the first and the second mirror; and a processor acquiring an intensity of the acoustic wave on the basis of a change of the light quantity of the reflected light, which is a distance between the first mirror and the second mirror, occurring due to the incidence of the acoustic wave.