Characterization of a low-cost optical flow sensor when using an external laser as a direct illumination source

Area of Science:

• Optics
• Mechanical Engineering
• Sensor Technology

Background:

• Optical flow sensors are commonly used for motion detection.
• Measuring surface displacements and oscillations often requires specialized and expensive equipment.
• Integrating low-cost sensors offers potential for wider accessibility in metrology.

Purpose of the Study:

• To characterize a novel measurement system combining a low-cost optical flow sensor and a laser for surface displacement and oscillation analysis.
• To determine the optimal configuration (angle and distance) of the optical flow sensor relative to a diffuser surface for accurate measurements.
• To evaluate the system's capability for detecting low-frequency mechanical oscillations.

Main Methods:

• A measurement system was developed using a laser source, a diffuser surface, and an optical flow sensor.
• The optical flow sensor's position was varied in terms of angle (0° to >150°) and distance from the diffuser surface.
• Surface displacements and low-frequency (up to 0.01 Hz) mechanical oscillations were applied and measured.

Main Results:

• The highest sensitivity and accuracy (R² > 0.99, <1.29% error) for displacement measurement were achieved when the sensor was behind the diffuser, aligned with the laser (0°).
• Measurement accuracy degraded significantly at angles greater than 150° (sensor in front).
• Increasing the distance between the sensor and the surface linearly increased sensitivity (R² = 0.99) and measurement range for oscillations.

Conclusions:

• The developed system offers a low-cost, effective method for measuring surface displacements and mechanical oscillations.
• Optimal sensor placement is critical for maximizing measurement sensitivity and accuracy.
• The system demonstrates potential for non-contact, high-sensitivity measurement of low-frequency vibrations.