Amplitude and phase analysis in digital dynamic holography.

Area of Science:

• Optics and Photonics
• Mechanical Engineering
• Materials Science

Background:

• Lensless in-line digital holographic interferometry is a promising technique for analyzing small objects.
• Microelectromechanical systems (MEMS) require dynamic characterization for performance evaluation.
• Magnifying the object wave using a diverging beam is crucial for this analysis.

Purpose of the Study:

• To investigate the effect of object-to-CCD distance on vibration analysis sensitivity in lensless digital holography.
• To study the influence of this distance on both amplitude-modulated and phase information.
• To provide experimental and theoretical explanations for observed phenomena.

Main Methods:

• Utilizing lensless in-line digital holographic interferometry.
• Employing a diverging beam to magnify the object wave.
• Conducting experiments with varying object-to-CCD distances.
• Analyzing amplitude-modulated and phase information from holographic fringes.

Main Results:

• Increased object-to-CCD distance enhances sensitivity of amplitude-modulated time-average fringes.
• Reduced object-to-CCD distance increases phase sensitivity in double-exposure time-average fringes.
• Contradictory effects on amplitude and phase sensitivity were observed and explained.

Conclusions:

• Object-to-CCD distance is a critical parameter for optimizing vibration analysis in lensless digital holography.
• The technique is well-suited for dynamic characterization of micro-objects like MEMS devices.
• Understanding the distance-dependent sensitivity is key for accurate deformation measurement.