Opto-Mechanical Transducer Alignment via Collimated Beam Reflection

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Solution Overview

Problem

Conventional optical alignment methods for micro-opto-electromechanical systems are complex and time-consuming, often requiring extensive scanning and data analysis to achieve precise alignment, which can lead to poor performance and increased costs due to the difficulty in determining the correct position of the light beam's waist point.

Innovation Solution

The use of a gradient-index (GRIN) lens combined with a collimating lens in a single optical fiber block facilitates optical alignment by allowing for the direct reading of reflected power, simplifying the alignment process and reducing the need for complex scanning, while reflective fiducial marks provide passive alignment feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional optical alignment methods using focused beams are used, then alignment precision can be achieved, but the system complexity and time consumption increase significantly

Engineering Contradiction:
Improvealignment precisionVSAvoidalignment system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of focusing a beam and scanning to find the waist position (conventional method), the patent uses a collimated beam and scans to find the point of maximum reflected power. This inverted approach eliminates the need to determine the waist position and simplifies the alignment system while maintaining precision.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements a feedback mechanism where the reflected power from the membrane is continuously monitored during scanning. The position of maximum reflected power provides real-time feedback to determine optimal alignment, replacing complex data analysis of focused beam scans with a straightforward maximum-detection feedback loop.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If conventional optical alignment methods with extensive scanning are used, then alignment can be achieved, but time consumption increases

Engineering Contradiction:
Improvealignment accuracyVSAvoidalignment time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the essential measurement needed for alignment - the reflected power of a collimated beam - and eliminates unnecessary steps such as determining waist position, performing multiple scans at different depths, and complex data analysis. This extraction of the core measurement function reduces time consumption while preserving alignment accuracy.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The method skips the time-consuming steps of conventional alignment by directly scanning with a collimated beam and identifying the maximum reflected power point. This rushing through the essential measurement without unnecessary intermediate steps significantly reduces alignment time while maintaining precision.

Inventive Principle:
Principle #21Skipping (Rushing through)

3Ease of operation

If focused beam alignment is used, then optical alignment can be performed, but the difficulty in determining waist position results in poor performance

Engineering Contradiction:
Improvealignment easeVSAvoidwaist position determination precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent inverts the conventional approach by using a collimated beam instead of a focused beam. This eliminates the difficult-to-determine waist position parameter entirely, as collimated beams have a uniform profile that is much easier to align and measure, thereby improving both ease of operation and measurement precision.

Inventive Principle:
Principle #13The other way round (Inversion)

4Measurement precision

If complex scanning and data analysis are performed for alignment, then alignment can be achieved, but costs in terms of time and consumption increase

Engineering Contradiction:
Improvealignment precisionVSAvoidalignment efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent extracts only the essential measurement - reflected power of a collimated beam - and eliminates complex scanning procedures and data analysis steps. This extraction of the core function improves productivity by reducing the computational and temporal resources needed while maintaining alignment precision through the straightforward maximum-detection method.

Inventive Principle:
Principle #2Taking out (Extraction)

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 enables faster, more accurate optical alignment with standard equipment, reducing alignment errors and improving system performance by using the reflected power of a collimated light beam, thus streamlining the alignment process and enhancing stability in relative positional arrangements.

Implementation Method 1

The optical element incorporates a light focusing path configured to focus a light beam to a focal point at the membrane

Methodology Applied
Scientific EffectGradient-index (GRIN) lens focusing: Lens

Implementation Method 2

The optical element incorporates a light collimating path configured to collimate the light beam

Methodology Applied
Scientific EffectCollimation: Lens

Implementation Method 3

at least one reflective facet facing the optically transparent substrate is provided at the piezoelectric membrane... guide light reflected from the at least one reflective facet to the input end

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3919945B1An opto-mechanical transducer apparatus and corresponding method
Publication Date: 2024.06.26 STMICROELECTRONICS SRL
  • EP3919945B1 patent drawingFigure 1~2B
  • EP3919945B1 patent drawingFigure 3~4
  • EP3919945B1 patent drawingFigure 5~7

AI summary

An apparatus (10), comprising: an optically transparent substrate (18) having a first surface and a second surface opposed the first surface; a piezoelectric membrane (20) arranged at the first surface of the optically transparent substrate (18), the piezoelectric membrane (20) configured to oscillate as a result of light propagated through the optically transparent substrate (18) impinging onto the piezoelectric membrane (20), wherein at least one reflective facet (40) facing the optically transparent substrate (18) is provided at the piezoelectric membrane (20) ; an optical element (30) configured to receive a light beam at an input end and to guide the light beam towards an output end couplable to the second surface of the optically transparent substrate (18), The optical element (30) incorporates: a light focusing path (32) configured to focus (320) a light beam at a focal point (FP) at the piezoelectric membrane (20), and at least one light collimating path (34) configured to collimate the light beam onto the at least one reflective facet (40), wherein the optical element (30) is configured to guide light reflected (R, 31) from the at least one reflective facet (40) to the input end, wherein the light reflected (R, 31) to the input end is indicative of the position of the optical element (30) with respect to the focal point (FP).