Estimation of metal surface roughness using fiber optic displacement sensor

A fiber optic displacement sensor is proposed to estimate the roughness of metal surface using the intensity modulation technique. A light beam is launched onto the metal surface via a bundled fiber. The reflected light from the surface is collected and then routed to a silicon detector. The level of roughness for aluminum, stainless steel and copper samples are estimated to be approximately 27, 26, and 20% respectively by fixing the object within the linear range of the sensor. The output voltages are measured as a function of lateral distance to estimate the roughness of the surface.     

Effect of tilting angles on the performance of reflective and transmitting types of fiber optic-based displacement sensors

The performances of the fiber optic-based displacement sensor with reflective and transmitting techniques were investigated. The effects of axial displacement on the detected voltage were investigated for different tilting angles of the reflective and receiving fibers. Three types of light sources were used, yellow and red He-Ne including a green pointer laser at peak wavelengths of 594, 633, and 533 nm correspondingly. The highest sensitivity and resolution were obtained at 0.0017 mV/μm and 4 μm, respectively with the employment of a 594 nm laser as the light source. These were attributed to the output power and beam quality of the laser which was the highest. The tilting angles didn’t change the sensitivity and resolution of the sensors in both setups. The widest linear range was obtained at 2410 μm with the transmitting technique. The simplicity of the design, high degree of sensitivity, linear range, non-contact measurement and low cost fabrication make it suitable for industrially-orientated applications that include control and micro-displacement in the hazardous region.