Optical Fiber Proximity Sensor for Micro Distance Measurement

This paper demonstrates an optical fiber proximity sensor for micro distance measurement. The optical fiber was used to detect a silver plate which acted as an obstacle. A flat end of a standard single mode optical fiber was functioned to emit the broadband light at near infrared wavelength region and receive the reflected light from the obstacle. The distance between the optical fiber and the obstacle was varied from $0\mu \mathrm{m}$ to 400 $\mu \mathrm{m}$. We experimentally characterized the sensor sensitivity based on their free spectral range. The optical fiber tip has shown its potential for proximity sensing application with sensitivity value of 0.0199 $\mathrm{nm}/\mu\mathrm{m}$ and regression value up to 0.9126.