Incoherent Optical Fiber Bundle Calibration via Time-of-Flight
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Solution Overview
Problem
The open-ended, incoherent bundle of optical fibers faces challenges in determining the precise position of fiber tips at the front end due to their random bending and movement, leading to a 'shuffled' image at the camera end, which complicates image calibration and requires a method to map the relative positions of the fibers from the scene end to the camera end.
Innovation Solution
A calibration process using time-of-flight sensors, such as streak cameras or SPAD cameras, is employed to emit pulse trains of light and measure the time of arrival at the camera end, allowing for the calculation of a map that corrects the image by determining the position of each fiber tip, enabling the 'de-shuffling' of the image and maintaining image accuracy even as fibers move or change position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fibers at the open end are allowed to bend freely and spread out to increase flexibility and field of view, then the imaging capability in irregular cavities and wide area coverage is improved, but the position of fiber tips becomes random and unknown, leading to a shuffled image that requires calibration
Solution Approach 1:
The patent applies preliminary action by performing calibration before actual imaging to establish the initial mapping between fiber positions at the open end and corresponding camera pixels. This pre-established map allows the system to compensate for fiber movements during subsequent imaging operations, maintaining measurement precision while preserving fiber flexibility.
Solution Approach 2:
The patent implements feedback by continuously monitoring fiber positions using time-of-flight sensors and updating the calibration map in real-time. This feedback mechanism allows the system to adapt to fiber movements and maintain accurate spatial correspondence between the scene and captured images, resolving the contradiction between fiber flexibility and position precision.
2Measurement precision
If calibration is performed to determine fiber tip positions and correct the shuffled image, then image accuracy is improved, but the system complexity and calibration time increase
Solution Approach 1:
The patent applies self-service by enabling the fiber bundle to serve its own calibration function. The same fiber bundle that captures images is used to deliver calibration light pulses, and the system uses itself as the measurement target. This eliminates the need for separate calibration equipment and reduces system complexity while maintaining image accuracy.
Solution Approach 2:
The patent discards the shuffled image and recovers the correct spatial information by processing the time-of-flight data to reconstruct the calibration map. This approach transforms the problematic shuffled image into useful calibration data, turning a waste product into a valuable resource for system operation.
3Reliability
If time-of-flight sensors are used to measure the position of fiber tips in real-time, then image fidelity is maintained during fiber movement, but the energy consumption and system complexity increase
Solution Approach 1:
The patent implements periodic action by performing calibration at specific intervals or triggers rather than continuously. The system can recalibrate when fiber movements are detected or at predetermined time intervals, reducing energy consumption while maintaining image fidelity during critical imaging periods. This periodic calibration approach balances reliability requirements with energy efficiency.
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 method effectively corrects the positional mismatch between the scene and the camera image, ensuring accurate representation of the scene, even in dynamic or turbid environments, and allows for real-time adjustments to maintain image fidelity.
Implementation Method 1
A computer determines a calibration map, based on a set of time signatures. The calibration map maps from a first set of coordinates, each indicating a position of a front end of a given fiber in the bundle to a second set of coordinates, each indicating a position of a back end of the given fiber in the bundle.
Data Source
AI summary
An open-ended, incoherent bundle of optical fibers transmits light from a nearby scene. A camera captures images of the back end of the fiber bundle. Because the fiber bundle is incoherent, the captured image is shuffled, in the sense that the relative position of pixels in the image differs from the relative position of the scene regions that correspond to the pixels. Calibration is performed in order to map from the front end positions to the back-end positions of the fibers. In the calibration, pulses of light are delivered, in such a way that the time at which light reflecting from a given pulse enters a given fiber directly correlates to the position of the front end of the given fiber. A time-of-flight sensor takes measurements indicative of these time signatures. Based on the map obtained from calibration, a computer de-shuffles the image.