Multichannel Confocal Sensor Using Integrated Optics Circuits

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Solution Overview

Problem

Existing multichannel confocal sensors face challenges in achieving high density, small pitch, high lateral and depth resolution, and reduced manufacturing constraints, particularly with fiber optics which are difficult to manufacture and align, and introduce wavelength-dependent biases.

Innovation Solution

A multichannel confocal sensor utilizing integrated optics circuits with achromatic emission and detection channel waveguides, a beam splitter, and a focusing lens arrangement to split and collect light efficiently, decoupling the requirements of the illuminating and detection stages, and allowing for high-density, mechanically robust, and easily assembled devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fiber optics bundles are used for multichannel confocal sensing, then the number of measurement channels can be increased, but the device complexity and manufacturing difficulty increase significantly

Engineering Contradiction:
Improvenumber of measurement channelsVSAvoiddevice complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical fiber optics bundle system with an integrated optics circuit system. The integrated optics circuit uses planar waveguides and optical components fabricated on a substrate to achieve multichannel light splitting and collection, eliminating the need for complex fiber bundle assemblies and reducing manufacturing difficulty while maintaining high channel density.

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

Solution Approach 2:

The patent merges multiple optical functions (light splitting, waveguide transmission, light collection, and detection) into a single integrated optics circuit platform. This consolidation integrates the emission channel waveguides, detection channel waveguides, and optical components into one unified device, reducing overall system complexity compared to separate fiber bundle components.

Inventive Principle:
Principle #5Merging (Combining)

2Productivity

If fiber optics bundles are used, then multichannel measurement is enabled, but alignment precision and manufacturing constraints become more severe

Engineering Contradiction:
Improvemultichannel measurement capabilityVSAvoidalignment precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent replaces the alignment-sensitive mechanical fiber bundle system with a monolithic integrated optics circuit where all optical paths are defined by fabricated waveguides on a substrate. This eliminates the need for post-assembly alignment of multiple fiber components, as the optical paths are predetermined by the circuit layout, significantly reducing manufacturing precision requirements.

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

3Ease of manufacture

If optical fiber geometry is optimized for manufacturing, then ease of manufacture improves, but channel density and lateral resolution decrease

Engineering Contradiction:
Improveease of manufactureVSAvoidchannel density
Core Design Contradiction:
Ease of manufactureVSArea of moving object

Solution Approach 1:

The patent replaces the optical fiber bundle system with an integrated optics circuit system where light is guided through planar waveguides fabricated on a substrate. This substitution allows for much smaller pitch between channels since the waveguides can be manufactured with precise sub-millimeter spacing using standard semiconductor fabrication techniques, achieving high channel density without the geometric constraints of optical fibers.

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

4Productivity

If fiber couplers are used for light distribution, then multichannel illumination is achieved, but wavelength-dependent biases are introduced

Engineering Contradiction:
Improvemultichannel illuminationVSAvoidmeasurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces fiber coupler-based light distribution with integrated optics circuit waveguides that guide light through fixed physical paths. The achromatic design of the waveguides and the confocal optical arrangement eliminate wavelength-dependent coupling variations, providing more uniform light distribution across all channels and reducing measurement biases.

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

5Productivity

If high channel density is achieved with fiber bundles, then productivity increases, but lateral resolution and pitch between beams are reduced

Engineering Contradiction:
Improvechannel densityVSAvoidpitch between beams
Core Design Contradiction:
ProductivityVSLength of moving object

Solution Approach 1:

The patent replaces the fiber bundle system with an integrated optics circuit where light is emitted from closely spaced waveguide apertures on a planar substrate. This allows for much smaller pitch between emission points compared to fiber core diameters, enabling high channel density while maintaining fine spatial resolution for beam separation.

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

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 a high-density, high-resolution confocal sensor with improved alignment and manufacturing efficiency, reducing crosstalk and wavelength-dependent biases, and facilitating the creation of systems with hundreds of channels, while maintaining optimal optical and metrological characteristics.

Implementation Method 1

a beam splitter arranged (i) for directing said emitted light beams from said first integrated optics circuit to said inspected sample through said at least one focusing lens arrangement and (ii) for directing said reflected light beams from said measured sample through said at least one focusing lens arrangement into said second integrated optics circuit

Methodology Applied
Scientific EffectBeam splitting: Reflection

Implementation Method 2

a confocal detection scheme comprises a light emitting aperture and a light collection aperture on one side of a focusing lens arrangement whose optical conjugates (or images) through that focusing lens arrangement are superposed

Methodology Applied
Scientific EffectFocusing: Focusing

Implementation Method 3

a first integrated optics circuit arranged for splitting a light beam coming from said at least one light source into a plurality of emitted light beams applied to a high-density array of emitting apertures

Methodology Applied
Scientific EffectWaveguide transmission: Waveguide (optics)

Data Source

PatentEP3431918B1Multichannel confocal sensor and related method for inspecting a sample
Publication Date: 2021.03.31 UNITY SEMICONDUCTOR
  • EP3431918B1 patent drawingFigure 1
  • EP3431918B1 patent drawingFigure 2~3c

AI summary

A multichannel confocal sensor comprises a light source (14), a focusing lens arrangement (10), and an optical detector (25). This sensor further includes: - a first integrated optics circuit (11) arranged for splitting a light beam (24) coming from said broadband light source into a plurality of emitted light beams applied to a high-density array of emitting apertures (29), - a second integrated optics circuit (20) arranged for collecting on a plurality of collection apertures (18) a plurality of reflected light beams from a sample to be inspected (17) and for transferring said reflected light beams to the optical detector (25), - a beam splitter (22) arranged (i) for directing said emitted light beams from the first integrated optics circuit (11) to the inspected substrate (17) through the focusing lens arrangement (10) and (ii) for directing the reflected light beams from the inspected sample (17) through the focusing lens arrangement (10) into the second integrated optics circuit (20).