3D Measurement Device Using Dual-Wavelength Interferometry
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Solution Overview
Problem
Conventional three-dimensional measurement devices using interferometers face limitations in measurement range and accuracy due to the wavelength of measurement light, leading to insufficient measurement of objects with height differences greater than half the wavelength, and require complex structures and multiple imaging operations, which can be affected by vibrations and increase measurement time.
Innovation Solution
A three-dimensional measurement device employing an optical system that splits incident light into measurement and reference light, allowing for interference fringe image acquisition without the need for large-scale moving mechanisms, enabling accurate height measurement beyond the conventional range using a combination of two lights with different wavelengths and phase shift methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the wavelength of measurement light is increased to expand measurement range, then measurement range is improved, but measurement accuracy deteriorates
Solution Approach 1:
The patent divides the measurement process into multiple wavelength measurements. By measuring at different wavelengths and combining the results, the system achieves both extended measurement range and maintained accuracy. Each wavelength measurement covers a specific range, and their combination provides comprehensive coverage without sacrificing precision.
Solution Approach 2:
The patent changes the wavelength parameter of measurement light to resolve the contradiction. By using multiple wavelengths (e.g., 1500nm and 1064nm) instead of a single wavelength, the system can measure objects with height differences beyond half the wavelength while maintaining accuracy through wavelength-dependent phase measurement.
2Adaptability or versatility
If a focal point moving mechanism is added to measure height beyond measurement range, then measurement range is improved, but device complexity increases
Solution Approach 1:
The patent replaces the mechanical focal point moving mechanism with an optical solution using multiple wavelengths. Instead of physically moving components to change focus, the system uses wavelength diversity to achieve the same effect, eliminating complex mechanical structures while maintaining the ability to measure beyond the conventional measurement range.
Solution Approach 2:
The patent makes the interference measurement system multi-functional by enabling it to measure both within and beyond the conventional measurement range without additional mechanical components. The same optical system performs multiple measurement functions by utilizing different wavelengths, eliminating the need for specialized mechanisms.
3Adaptability or versatility
If multiple imaging operations are performed to measure height beyond measurement range, then measurement range is improved, but measurement time increases
Solution Approach 1:
The patent enables continuous measurement by capturing interference patterns at multiple wavelengths simultaneously or in rapid succession. This eliminates the need for repeated imaging operations at different focal positions, maintaining continuous measurement capability while extending the measurable height range.
Solution Approach 2:
The patent adds the wavelength dimension to the measurement process. Instead of extending measurement range by moving through space (focal position changes), the system uses wavelength variation as an additional dimension, allowing range extension without additional imaging operations.
4Adaptability or versatility
If multiple imaging operations are performed to measure height beyond measurement range, then measurement range is improved, but measurement accuracy deteriorates due to vibration
Solution Approach 1:
The patent segments the measurement into wavelength-based components rather than requiring sequential imaging at different positions. By measuring at multiple wavelengths from a fixed position, the system avoids vibration-induced errors while maintaining extended 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
This configuration improves measurement accuracy and efficiency by simplifying the structure, reducing the number of imaging operations, and minimizing the impact of vibrations, while expanding the measurement range and enhancing the precision of height measurements.
Implementation Method 1
a phase shift method, based on a plurality of interference fringe images having different phases
Implementation Method 2
to recombine the two lights to combined light and emit the combined light
Data Source
AI summary
A three-dimensional measurement device includes: an optical system that splits incident light into two lights, radiates one of the two lights as measurement light to a measured object and the other of the two lights as reference light to a reference surface, and recombines the two lights into combined light to emit the combined light; a light emitter that emits predetermined light entering the predetermined optical system; an imaging system that takes an image of output light emitted from the optical system; and an image processor that performs three-dimensional measurement of a predetermined measurement area of the measured object based on an interference fringe image obtained by the imaging system. The image processor obtains intensity image data at a predetermined position along an optical axis direction at each coordinate position in the measurement area by reconstruction based on an interference fringe image of the measurement area.