Borescope Fringe Phase Shift Distance Measurement
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Solution Overview
Problem
Current borescopes and endoscopes face challenges in obtaining accurate 3D surface mapping and dimensional measurements due to limitations in existing techniques, such as stereo viewing, dot projection, and single line profiling, which are often time-consuming, require significant computing capacity, and are not suitable for full-field object measurement, especially in small, inaccessible locations with complex surfaces.
Innovation Solution
A borescope/endoscope system that employs phase-shift analysis using a plurality of light emitters to project fringe sets with varying phase-shifts, allowing for the computation of ripple metric values to determine an approximated object distance, enabling efficient 3D surface mapping and measurement even on complex surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stereo viewing or dot projection methods are used to obtain 3D data, then 3D surface mapping can be provided, but the process is time-consuming and requires significant computing capacity
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing reference fringe patterns and their corresponding phase information before actual measurement. During measurement, the system compares captured fringe patterns against these pre-stored references, eliminating the need for time-consuming real-time 3D reconstruction computations while maintaining accurate 3D surface mapping.
2Measurement precision
If multiple fringe sets with physical offsets are used to determine absolute phase, then accurate distance measurement can be obtained, but the device complexity increases
Solution Approach 1:
The patent uses copying by creating synthetic fringe patterns through digital signal processing rather than physically offsetting multiple light sources. The system generates multiple fringe set images sequentially using a single light source, where each fringe set is created by shifting the pattern digitally. This approach maintains the measurement accuracy of multiple offset fringes while significantly reducing the physical device complexity and number of required light sources.
3Device complexity
If a single line profile is scanned to build a 3D surface map, then computational resources are reduced, but proper positioning becomes difficult and measurements on non-flat surfaces are error-prone
Solution Approach 1:
The patent applies dimensionality change by transitioning from a single-line (1D) profile scan to a full-field fringe pattern (2D or 3D) measurement approach. Instead of scanning one line at a time, the system projects and captures two-dimensional fringe patterns across the entire field of view, enabling simultaneous measurement of multiple points on complex surfaces. This maintains lower computational requirements while dramatically improving positioning accuracy and measurement reliability on non-flat surfaces.
4Volume of moving object
If existing 3D measurement methods are used in small probes, then the probe size can be reduced, but full-field surface mapping capability is lost
Solution Approach 1:
The patent replaces mechanical scanning systems with optical/digital fringe pattern analysis. Instead of mechanically scanning a single line through a small probe, the system uses digitally generated and captured fringe patterns to achieve full-field mapping. This substitution enables small probes to perform comprehensive surface mapping without requiring large mechanical travel ranges or complex scanning mechanisms, maintaining both compact probe size and full-field measurement capability.
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
The system provides accurate and efficient full-field 3D surface mapping and dimensional measurements, overcoming the limitations of existing methods by minimizing phase ripple errors and requiring less computational power, making it suitable for small, complex surfaces.
Implementation Method 1
The light pattern of one fringe set exhibits a phase-shift relative to the light patterns of the other fringe sets, and the phase-shift varies as the distance from the origin of the plurality of fringe sets varies.
Data Source
AI summary
A system for determining an object distance z includes a plurality of light emitters. A group of at least one of the plurality of light emitters includes an emitter group, and the pattern projected when one emitter group is emitting includes a fringe set. The light pattern of one fringe set exhibits a phase-shift relative to the light patterns of the other fringe sets, and the phase-shift varies as the distance from the origin of the plurality of fringe sets varies. The system further includes a processing unit that is configured to compute a ripple metric value associated with each of a plurality of possible z values. The processing unit is further configured to determine an approximated z value using the computed ripple metric values. A probe system is also provided. The probe system is configured to project a plurality of fringe sets from the probe onto an object. The light pattern of one fringe set exhibits a phase-shift relative to the light patterns of the other fringe sets, and the phase-shift varies as the distance from the origin of the plurality of fringe sets varies. The probe system is further configured to compute a ripple metric value associated with each of a plurality of possible z values, where z is an object distance. The probe system is also configured to determine an approximated z value using the computed ripple metric values. A method for determining an object distance z is also provided.