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, and using two lights with close wavelengths complicates wavelength separation and decreases measurement efficiency.
Innovation Solution
A three-dimensional measurement device that splits incident light into two lights with near wavelengths, allowing them to enter different positions in the optical system without interference, enabling simultaneous imaging and improving measurement efficiency by eliminating the need for wavelength separation and maintaining accurate optical path differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If two different lights with small wavelength difference are used to expand measurement range, then measurement range is improved, but wavelength separation becomes difficult and measurement efficiency decreases
Solution Approach 1:
The patent divides the optical system into two independent imaging paths, allowing simultaneous imaging of both wavelength lights without requiring wavelength separation. Each imaging unit captures interference fringe images of its corresponding wavelength light independently, eliminating the need for sequential imaging and wavelength separation operations.
2Length of stationary object
If two different lights with small wavelength difference are used to expand measurement range, then measurement range is improved, but optical path adjustment complexity increases
Solution Approach 1:
The optical system is segmented into two independent imaging paths with separate imaging units. This segmentation allows each path to be optimized independently for its specific wavelength, simplifying optical path adjustments compared to a single system attempting to handle both wavelengths sequentially with separation components.
3Measurement precision
If conventional single wavelength measurement is used, then measurement accuracy is maintained, but measurement range is insufficient
Solution Approach 1:
The patent merges two wavelength measurement systems into a single interferometer by implementing two imaging units that simultaneously capture interference fringe images of two different wavelength lights. This merging allows the system to achieve both the measurement accuracy of single-wavelength interferometry and the expanded measurement range of multi-wavelength approaches, without requiring complex wavelength separation or sequential imaging.
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 expands the measurement range, enhances measurement efficiency, and maintains high accuracy by allowing two lights with near wavelengths to be used without interference, reducing the complexity of optical path adjustments and improving imaging time.
Implementation Method 1
a polarizing beam splitter configured to transmit a first polarized light (P-polarized light) and reflect a second polarized light (S-polarized light)
Implementation Method 2
a quarter wave plate arranged to transform the first polarized light into a first circularly polarized light and transform the second polarized light into a second circularly polarized light
Implementation Method 3
to combine the measurement light and the reference light to a combined light and emit the combined light
Data Source
Figure 1
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AI summary
There is provided a three-dimensional measurement device that uses two different lights of different wavelengths to expand the measurement range and improve the measurement efficiency. The three-dimensional measurement device 1 includes a polarizing beam splitter 20 configured to split a predetermined incident light into two polarized lights having polarizing directions orthogonal to each other, to radiate one of the two polarized lights as a measurement light to a work W and the other as a reference light to a reference surface 23, and to recombine the two polarized lights to a combined light and emit the combined light; a first projection optical system 2A configured to cause a first light having a first wavelength to enter a first surface 20a of the polarizing beam splitter 20; a second projection optical system 2B configured to cause a second light having a second wavelength to enter a second surface 20b of the polarizing beam splitter 20; a first imaging system 4A configured to take an image of the first light emitted from the second surface 20b of the polarizing beam splitter 20; and a second imaging system 4B configured to take an image of the second light emitted from the first surface 20a of the polarizing beam splitter 20.