Noncontact single-fiber-optic proximity sensor using a laser-fabricated tap

Area of Science:

• Optoelectronics
• Fiber optics sensing
• Photonics

Background:

• Proximity sensing is crucial in various industrial and scientific applications.
• Traditional proximity sensors may face limitations in certain environments or require physical contact.
• Fiber-optic sensors offer potential advantages due to their small size, immunity to electromagnetic interference, and remote sensing capabilities.

Purpose of the Study:

• To develop a simple, noncontact, fiber-optic proximity sensor.
• To utilize a laser-micromachined tap on a single multimode optical fiber for distance measurement.
• To investigate the sensor's performance based on reflected light intensity and target surface characteristics.

Main Methods:

• A fiber-optic tap was fabricated on a multimode optical fiber using laser micromachining.
• The sensor was designed to direct light onto a target surface and measure the fraction of light coupled back into the fiber.
• The system monitored both the incident light and the back-reflected light to determine proximity and compensate for source intensity variations.

Main Results:

• The amount of light recoupled into the fiber was found to be dependent on the distance between the fiber end and the target surface.
• Target surface roughness was identified as another parameter influencing the recoupled light intensity.
• A method was established to compensate for source intensity fluctuations by analyzing the ratio of counterpropagating light beams.

Conclusions:

• A functional noncontact fiber-optic proximity sensor was successfully developed.
• The sensor's design allows for distance measurement based on optical feedback.
• The developed sensor offers a robust solution for proximity detection, with potential for calibration and compensation for environmental factors.