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Updated: Jul 6, 2026
10:28
Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization
Published on: July 5, 2016
Pulsed digital holography for high-speed contouring that uses a two-wavelength method
G Pedrini1, P Fröning, H J Tiziani
1Institut für Technische Optik, UniversitätStuttgart, Pfaffenwaldring 9, D-70569 Stuttgart, Germany.
Applied Optics
|March 6, 2008
Summary
This study introduces a rapid shape measurement technique using a pulsed ruby laser. The method achieves high accuracy by digitally reconstructing holograms at two wavelengths, unaffected by environmental disturbances.
Area of Science:
- Optical Metrology
- Holography
- Laser Technology
Background:
- Accurate shape measurement is crucial in various scientific and industrial fields.
- Traditional methods can be slow and susceptible to environmental noise.
Purpose of the Study:
- To develop a fast and robust method for shape measurement.
- To minimize the impact of environmental disturbances on measurement accuracy.
Main Methods:
- Utilized a pulsed ruby laser with a tunable etalon for two-wavelength generation.
- Recorded two holograms at distinct wavelengths within microseconds using a CCD camera.
- Digitally reconstructed holograms to calculate wave-front phase differences.
Main Results:
- Successfully measured object shape by subtracting phase data from dual-wavelength holograms.
- Demonstrated immunity to low-frequency environmental disturbances like air turbulence and vibrations.
- Presented experimental validation of the proposed technique.
Conclusions:
- The two-wavelength holographic method offers a fast and reliable solution for shape measurement.
- The technique's resilience to environmental factors makes it suitable for challenging conditions.
- Digital reconstruction and phase subtraction provide precise shape determination.
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