Direct optical digital detection of diaphragm deflection: maximum resolution

Area of Science:

• Optics
• Mechanical Engineering
• Signal Processing

Background:

• Analog mechanical motion detection often requires complex electronic systems.
• Optical interferometry offers a non-contact method for precise measurement.
• Acoustic pressure-induced diaphragm deformation is a key phenomenon in various sensors.

Purpose of the Study:

• To develop and validate a direct optical digital detection method for analog mechanical diaphragm motion.
• To theoretically and experimentally investigate the performance of a Michelson interferometer for this application.
• To determine the factors influencing the resolution of optical analog-to-digital (A-D) conversion.

Main Methods:

• Utilizing a Michelson interferometer to detect diaphragm deformation caused by acoustic pressure.
• Employing a He-Ne laser, a 2.54-cm diameter diaphragm, and multimode optical fibers as the detector.
• Performing theoretical calculations to assess the impact of detector width on resolution.

Main Results:

• Theoretical analysis indicates a maximum resolution of 9 bits with a single-mode optical fiber detector.
• Experimental results achieved an 8-bit A-D conversion using multimode optical fibers.
• The study confirms the feasibility of optical digital detection for mechanical motion.

Conclusions:

• Michelson interferometry provides an effective means for the direct optical digital detection of mechanical diaphragm motion.
• Detector width is a critical parameter for optimizing the resolution of optical A-D conversion.
• The demonstrated 8-bit resolution shows promise for applications requiring precise optical sensing of acoustic pressure.