Adjustable Coupler Optical Waveguide Interferometer
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Solution Overview
Problem
Existing optical waveguide interferometers face low sensitivity due to diffusely reflecting or scattering material surfaces, leading to aberrated and mismatched wavefronts between probe and reference beams, resulting in weak and imprecise signals for ultrasonic wave detection.
Innovation Solution
An optical waveguide interferometer with an adjustable coupler allows for precise setting of the gap between the probe segment end and the workpiece, enabling the distance to be a desired fraction or multiple of the wavelength of light, minimizing distortions and using a pulsed laser and optical fibers for accurate data generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser probe beam is directed onto a diffusely reflecting or scattering material surface, then the surface vibration can be detected, but the reflected beam becomes highly aberrated and mismatched with the reference beam, resulting in weak and imprecise signals
Solution Approach 1:
The patent introduces an optical waveguide as an intermediary component between the laser probe beam and the material surface. The waveguide couples the reference beam and probe beam through its core, allowing both beams to propagate along the same path and maintain wavefront matching even when detecting vibrations from diffusely reflecting surfaces. This intermediary structure resolves the contradiction by preserving signal strength while enabling detection precision.
Solution Approach 2:
The patent merges the reference beam and probe beam paths by directing both beams through the optical waveguide core. This combining approach ensures that both beams experience identical optical path conditions and maintain coherent wavefronts, eliminating the mismatch problem that occurs with conventional separate beam paths when detecting diffuse surface vibrations.
2Measurement precision
If the gap between the probe segment end and the workpiece is not precisely controlled, then path length fluctuations occur, but setting a precise gap requires adjustable coupling mechanisms
Solution Approach 1:
The optical waveguide structure provides self-aligning and self-stabilizing properties that automatically maintain consistent optical path lengths. The waveguide's physical structure inherently guides both beams along the same path, eliminating the need for complex external adjustment mechanisms to maintain precise gap control, thus achieving measurement precision without excessive device complexity.
3Measurement precision
If discrete optical detectors are arranged in a pattern to image acoustic sources, then surface vibration patterns can be detected, but the system remains sensitive to fluctuations in path lengths between the probe beam and surface
Solution Approach 1:
The optical waveguide acts as an intermediary that stabilizes the optical path length between the laser source and the material surface. By guiding both the probe and reference beams through the waveguide core, the system eliminates sensitivity to external path length fluctuations, thereby improving both the accuracy of acoustic source location and the stability of measurements.
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 configuration enhances the accuracy and precision of ultrasonic wave detection by minimizing path length fluctuations and maintaining consistent interference patterns, allowing for precise determination of material properties like thickness and composition.
Implementation Method 1
mixing the reflected probe beam with a stable reference beam and measuring the amplitude and frequency or phase of the photodetector output intensity fluctuations
Implementation Method 2
detected with a photodetector
Implementation Method 3
setting the gap between the probe segment end and the workpiece so that the distance therebetween is a desired fraction or multiple of the wavelength of light emitted from the probe segment end
Data Source
AI summary
A material sensing apparatus comprises an excitation source configured to induce waves in a workpiece, and an optical waveguide interferometer configured to sense the induced waves in the workpiece. The optical waveguide interferometer comprises a probe segment having a probe segment end, and an adjustable coupler configured to permit setting a gap between the probe segment end and the workpiece. A controller is coupled to the adjustable coupler and configured to set the gap between the probe segment end and the workpiece.