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Simple multifrequency and phase-shifting fringe-projection system based on two-wavelength lateral shearing
Dalip Singh Mehta1, Satish Kumar Dubey, M Mosarraf Hossain
1Laser Applications and Holography Laboratory, Instrument Design Development Centre, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India. dsmehta@iddc.iitd.ernet.in
Applied Optics
|December 21, 2005
Summary
We developed a new 3D shape measurement system using two-wavelength lateral shearing interferometry (LSI). This compact and vibration-insensitive system offers precise measurements for discontinuous objects.
Area of Science:
- Optical Metrology
- Interferometry
Background:
- Accurate 3D shape measurement is crucial in various scientific and industrial fields.
- Traditional fringe projection systems can be sensitive to vibrations and complex to set up.
Purpose of the Study:
- To propose a simple, robust, and cost-effective multifrequency phase-shifting fringe projection system.
- To leverage two-wavelength lateral shearing interferometry (LSI) for enhanced 3D shape measurement.
Main Methods:
- Utilized a wedge-shaped plate lateral shearing interferometer to generate a spatial carrier frequency.
- Employed two-wavelengths simultaneously to create a synthetic interferogram with low spatial-carrier frequency.
- Achieved phase-shifted fringe patterns by translating the wedge plate.
Main Results:
- Successfully demonstrated 3D shape measurement of a discontinuous object.
- The system generates a significant spatial-carrier frequency, further enhanced by wavelength change or defocusing.
- Phase-shifted fringe patterns were reliably obtained.
Conclusions:
- The proposed system is insensitive to external vibrations due to its common-path interferometry design.
- The system is compact, relatively inexpensive, and suitable for measuring discontinuous objects.
- This LSI-based fringe projection system offers a practical solution for 3D metrology.