Optical Interferometry Feedback for Laser Penetration Depth Control
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Solution Overview
Problem
Current laser technologies face challenges in achieving precise axial control during material processing, particularly in surgical and industrial applications, due to limitations in controlling the depth of laser beam penetration, leading to issues such as unintended tissue damage and weld quality problems.
Innovation Solution
An apparatus and method utilizing an optical interferometer to generate an interferometry output based on optical path lengths, which is used to control processing parameters such as beam power and duration, enabling real-time feedback for precise material modification processes like welding, cutting, and sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If laser processing is used for non-transparent tissue, then surgical application is enabled, but depth control deteriorates
Solution Approach 1:
The patent introduces optical coherence tomography as an intermediary measurement system between the laser and the tissue. The OCT system acts as a mediator that provides real-time depth information about laser penetration into the tissue, enabling closed-loop control. This intermediary allows the system to maintain depth control precision in heterogeneous, non-transparent tissues where direct measurement would be impossible, thus resolving the contradiction between surgical applicability and depth control.
2Reliability
If standard metrology techniques are used for laser processing, then quality assurance is achieved, but measurement accuracy deteriorates due to plasma and high aspect ratio holes
Solution Approach 1:
The patent replaces standard mechanical and electrical metrology techniques with optical field-based measurement using optical coherence tomography. The OCT system uses low-intensity probe beams that are not affected by plasma generation or electrical interference. It provides direct optical measurement of depth and material structure without physical contact with the processing zone, eliminating the measurement errors caused by plasma, high aspect ratio holes, and other harsh conditions, thus maintaining both quality assurance and measurement precision.
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 solution provides precise control over laser processing, improving the accuracy and reliability of material modification by monitoring and adjusting the depth of penetration, thereby enhancing surgical precision and industrial process quality.
Implementation Method 1
an optical interferometer that produces an interferometry output using at least a component of the imaging light that is delivered to the sample location, the interferometry output based on at least one optical path length to the sample location compared to another optical path length
Data Source
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AI summary
Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser, sintering, and welding applications. An imaging optical source that produces imaging light. A feedback controller controls at least one processing parameter of the material modification process based on an interferometry output generated using the imaging light. A method of processing interferograms is provided based on homodyne filtering. A method of generating a record of a material modification process using an interferometry output is provided.