Anticipatory Depth of Field Adjustment for OCT
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Solution Overview
Problem
Optical coherence tomography (OCT) systems face challenges in accurately imaging moving objects with curved surfaces due to inaccuracies in depth of field adjustment, leading to incomplete or out-of-focus scans.
Innovation Solution
A method and system for anticipatory depth of field adjustment in OCT, which determines working distances and adjusts the depth of field in real-time as the object moves, ensuring that the scanner head maintains focus on consecutive surface locations by using a distance determination module, depth-of-field module, and depth-of-field adjusting mechanism, allowing for continuous A-scans and aggregation into B-scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the depth of field is adjusted in real-time for each surface location, then the imaging accuracy is improved, but the adjustment frequency and system complexity increase
Solution Approach 1:
The system determines forward working distances at upcoming surface locations before the scanner head reaches them. By anticipating future working distances and pre-calculating the required depth of field adjustments, the system reduces real-time adjustment frequency while maintaining imaging accuracy. The depth of field is adjusted based on predicted rather than reactive measurements.
Solution Approach 2:
The patent implements dynamic depth of field adjustment that adapts to the moving object's surface geometry. The system continuously updates working distance predictions and adjusts the depth of field range accordingly, allowing the imaging system to maintain focus accuracy while reducing unnecessary adjustments through intelligent prediction of surface variations.
2Measurement precision
If the depth of field is adjusted frequently to maintain focus on moving objects, then the imaging quality is improved, but the scanning speed decreases
Solution Approach 1:
By determining forward working distances in advance and predicting the required depth of field adjustments before they are needed, the system minimizes interruptive adjustments during scanning. This allows continuous scanning at higher speeds while maintaining imaging quality through pre-planned focus adjustments.
Solution Approach 2:
The system enables continuous scanning by predicting surface geometry and preparing depth of field adjustments in advance, rather than stopping or pausing to adjust focus reactively. The scanner head maintains continuous motion while the depth of field is dynamically adapted based on predicted working distances at upcoming locations.
3Measurement precision
If the working distance is determined for each surface location, then the inspection accuracy is improved, but the measurement time increases
Solution Approach 1:
The system determines forward working distances at multiple upcoming surface locations before the scanner head reaches them. By performing these measurements in advance and using them to predict the required depth of field, the system eliminates the need for time-consuming real-time measurements at each location, thereby maintaining inspection accuracy while reducing total measurement time.
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 efficient and accurate surface inspection of moving objects with curved surfaces by anticipating and adjusting the depth of field, reducing the need for frequent adjustments and allowing for more comprehensive B-scans, even when the object is in motion.
Implementation Method 1
optical coherence tomography (OCT)... direct optical beams returned from the reflective element and the object to a detector for detection of an interference effect
Data Source
AI summary
A system and method for surface inspection of an object using optical coherence tomography (OCT) with anticipatory depth of field adjustment is provided. The method includes determining a present working distance and one or more forward working distances; determining a present depth of field in which the surface of the object is in focus at the location of the present working distance and at as many of the consecutive forward surface locations as determined possible; changing to the present depth of field; performing an A-scan of the object; moving the object such that the scanner head is directed at each of the consecutive forward surface locations determined to be in the present depth of field; and performing an A-scan at each of the consecutive forward surface locations determined to be in the present depth of field.