Optical Probe With Index-Matching Liquid for Micro-Optical Testing

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Solution Overview

Problem

Existing optical probes face challenges in efficiently testing micro-optical components with high port count, small pitch, and low mode-field size variation, while maintaining high reproducibility and throughput, especially in the near ultraviolet, visual, and infrared ranges, and are limited by working distances and pitch accuracy.

Innovation Solution

An optical probe with a movable probe head and micro-optical elements, operated in an index matching liquid, featuring a compact design for insertion into trenches, capable of high port count, low pitch accuracy, and small mode-field size, with adjustable mode-field diameter and pitch, and calibrated for robust probing across various wavelengths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an optical probe is designed with a compact probe head for insertion into narrow trenches (250 μm or less), then the probing capability for high port count and small pitch components is improved, but the mechanical contact stability and alignment precision deteriorate

Engineering Contradiction:
Improvetesting throughputVSAvoidpitch accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces an index-matching liquid as an intermediary medium between the optical probe and the micro-optical component. This liquid filling the gap eliminates air gaps and refraction issues, enabling stable optical coupling even with compact probe design, thus resolving the contradiction between compact size and alignment precision

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the optical parameter by using an index-matching liquid with refractive index matched to the micro-optical component. This parameter change allows the compact probe head to maintain optical coupling stability despite reduced mechanical contact stability, achieving both high productivity and acceptable precision

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the optical probe operates at high working distances (at least 10 μm), then the ease of operation and accessibility are improved, but the coupling efficiency and signal strength deteriorate

Engineering Contradiction:
Improveprobing accessibilityVSAvoidcoupling efficiency
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The index-matching liquid acts as a mediator that maintains effective optical coupling even at increased working distances. By eliminating air gaps and reducing refraction losses, the liquid enables the probe to operate at greater distances while maintaining coupling efficiency, thus resolving the contradiction between accessibility and reliability

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If the optical probe is designed for high port count (at least 24 channels), then the testing capability for multi-channel components is improved, but the device complexity and calibration difficulty increase

Engineering Contradiction:
Improvemulti-channel testing capabilityVSAvoidprobe structure complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent designs the optical probe with multi-functional capability to handle high port count testing. The probe head incorporates multiple optical fibers and micro-optical elements that can simultaneously test multiple channels, reducing the need for repeated measurements and simplifying the overall testing process despite increased device complexity

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

4Manufacturing precision

If the mode-field size is reduced (10 μm or less), then the pitch accuracy and resolution are improved, but the coupling loss and sensitivity to misalignment increase

Engineering Contradiction:
Improvemode-field precisionVSAvoidcoupling stability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The index-matching liquid serves as a mediator that compensates for the increased sensitivity of small mode-fields. By eliminating air gaps and providing a stable optical interface, the liquid reduces coupling losses and mitigates the impact of misalignment, enabling the use of small mode-fields for high precision testing while maintaining coupling stability

Inventive Principle:
Principle #24Intermediary (Mediator)

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 efficient optical testing of micro-optical components with high reproducibility and throughput, achieving low coupling variations and improved coupling efficiency across multiple channels without realignment, suitable for diverse environmental conditions.

Implementation Method 1

US 6925238 B2 discloses using an index matching material in a probing procedure in order to reduce reflection

Methodology Applied
Scientific EffectIndex matching: Refraction

Data Source

PatentEP4621457A1An optical probe and related methods
Publication Date: 2025.09.24 KEYSTONE PHOTONICS GMBH
  • EP4621457A1 patent drawingFigure 1~2
  • EP4621457A1 patent drawingFigure 3a~3f
  • EP4621457A1 patent drawingFigure 3g~5

AI summary

The present invention relates to optical coupling between optical components and, more particular, to an optical probe (1) configured for optical testing of at least one micro-optical component (50), to a method for producing an optical probe (1), and to a method for optical testing of at least one micro-optical component (50). The optical probe (1) is comprising: - a probe head (10), wherein the probe head (10) comprises a test component (2); - at least one micro-optical element (20), wherein the micro-optical element (20) is a separate element with regard to the test component (2) and in mechanical contact with the test component (2), wherein the micro-optical element (20) is configured to optically couple light (3) between the test component (2) and the micro-optical component (50), thereby being configured to determine an optical performance of the micro-optical component (50), and wherein the micro-optical element (20) is configured to be operated in an index matching liquid (17).