Stroboscopic white-light interferometry of vibrating microstructures.

Area of Science:

• Optics and Photonics
• Micro-electro-mechanical Systems (MEMS)
• Vibration Analysis

Background:

• Characterizing dynamic surface behavior in microstructures is crucial for MEMS device development.
• Existing methods often lack the resolution or frequency range to capture subtle out-of-plane vibrations.
• High-frequency, low-amplitude motion analysis is essential for understanding MEMS resonator performance.

Purpose of the Study:

• To introduce a novel LED-based stroboscopic white-light interferometer for high-resolution surface vibration mapping.
• To present a frequency-domain data analysis technique for enhanced vibration measurement accuracy.
• To demonstrate the system's capability in analyzing microstructures with sub-nanometer amplitude resolution.

Main Methods:

• Utilizing a LED-based stroboscopic white-light interferometer for interferometric phase measurements.
• Implementing a frequency-domain data analysis approach leveraging high-resolution phase data.
• Applying the technique to a square-plate silicon MEMS resonator to image vibration modes.

Main Results:

• Successfully mapped out-of-plane surface vibration fields in a MEMS resonator.
• Achieved sub-nanometer amplitude resolution for vibration frequencies up to tens of MHz.
• Demonstrated a minimum detectable vibration amplitude below 100 picometers for modes between 3 and 14 MHz.

Conclusions:

• The developed interferometer and analysis method provide unprecedented resolution for mapping micro-vibrations.
• This technique is effective for characterizing dynamic behavior in electrically excited microstructures.
• The system offers a powerful tool for research and development in MEMS and related fields.